feat(core): snap touchpad gestures one step per gesture (#86)

* feat(core): snap touchpad swipes one step per gesture

Workspace and column swipes share a snap tracker modeled on libadwaita:
a swipe reaches the next workspace or column edge at most, resists past
it, sticks near each step while dragging, and on lift goes on to the next
step when quick or settles on the closest when slow. Column snap points
closer than a tenth of the view merge. Discrete and four-finger swipes
use the same tracker for their single step, and a two-finger scroll in
the overview moves the selection one step per scroll.

* fix(core): keep snap swipes continuous and scroll locks per gesture

The snap tracker precomputes its detent stops, so a swipe caught past an
edge starts without a jump and updates no longer allocate. A rest view
between merged column edges becomes a point, so a slow swipe never
settles behind it. Step swipes use a real rubber band instead of a zero
one that produced NaN. The overview's one-step lock applies to two-finger
scrolling only and every scroll stop clears it on all monitors.

* fix(core): drop a column swipe when its usable area changes

A column swipe measures its snap points in the usable area it began
with. An output resize or a panel change mid-swipe now lets the swipe go,
as a workspace change does, instead of landing on stale points. Tests
cover the resize, focus with no fully shown column, and the snap point
merge at the last column's end.

* test(core): cover quick swipes from between points and far landings

Step swipes get their own points instead of sharing a package slice, and
the step test checks the target and velocity of one landing.

* fix(core): drop a column swipe when its snap points move

A column swipe now keeps the snap points it began with and lets go when
the layout no longer has them: a window mapped or resized, other gaps,
an output resize or a panel. Tests check the drop on the first update
and reach the wide-column focus through a full-width column.

* feat(core): repeat column steps in one overview finger scroll

A two-finger scroll sideways in the overview steps to the next column
after a short distance, then once per longer distance, and stays on
columns. Up or down it still steps once per scroll, so a stacked card is
easy to pick.

* fix(core): keep the overview's sideways scroll lock to two fingers

A sideways two-finger scroll still on the pad no longer slows wheel or
continuous column steps nor drops their vertical steps; they start from
zero. Tests cover the wheel after a sideways scroll, the stop, a large
frame and reopening.

commit: 9a9b02bced4b580db4ca308ac1f6aef3224721b2
author: bnema · 21d ago · 2026-10-02 02:04 UTC
committer: GitHub · 21d ago · 2026-10-02 02:04 UTC
parent: 6f718b0
signature: GPG UnverifiedB5690EEEBB952194 The key is unknown

11 files · +825 -101

M docs/config.md +6 -4


@@ -66,10 +66,12 @@ bind.Cmd+p = workspace presentation
66	66
67	67		## Touchpad
68	68
69		-	A three-finger swipe follows the fingers:
	69	+	A three-finger swipe follows the fingers and moves one step at most, so a quick swipe never skips a column or a workspace:
70	70
71		-	- Left or right scrolls the columns (`scroll` overflow). When the fingers lift, the view keeps the swipe's speed, slows down and settles on a column edge; the focus moves to a column fully on screen.
72		-	- Up or down slides between numbered workspaces and settles on the nearest one the swipe's speed reaches. It stops with some resistance at the first and last workspace.
	71	+	- Left or right scrolls the columns (`scroll` overflow) to the next column edge; the focus moves to a column fully on screen.
	72	+	- Up or down slides to the next numbered workspace.
	73	+
	74	+	The view sticks a little near each step and catches up between them. Past the next step it resists; lift and swipe again to go further. When the fingers lift, a quick swipe goes on to the next step and a slow one settles on the closest.
73	75
74	76		With `natural-scroll = off`, a swipe left shows the columns to the left and a swipe up shows the workspace above. `natural-scroll = on` moves the content with the fingers, so both are reversed.
75	77

@@ -182,7 +184,7 @@ The focus binds (`focus-column-left/right`, `focus-window-up/down`, `cmd+arrows`
182	184
183	185		Each workspace's [stash](#stash), hidden or not, shows as a pile of cards on the left of its row, which stays centred unless it would overlap the pile: its selected window in front, up to three others behind it, dimmed. In the pile, `h` / `l` browse the stash and `l` past its last window returns to the front card. A successful up/down move through the stack leaves the stash and selects the new front card. `return` or a click on a card closes the overview with the stash shown on that window.
184	186
185		-	A four-finger swipe up opens the overview and a swipe down closes it on the selection, whatever `touchpad.natural-scroll` says. Two-finger scrolling and the mouse wheel move the selection: left and right through the columns, up and down through stack cards before crossing workspaces, following `touchpad.natural-scroll`. A three-finger swipe moves it one step when the fingers lift.
	187	+	A four-finger swipe up opens the overview and a swipe down closes it on the selection, whatever `touchpad.natural-scroll` says. Two-finger scrolling and the mouse wheel move the selection: left and right through the columns, up and down through stack cards before crossing workspaces, following `touchpad.natural-scroll`. A two-finger scroll sideways moves it to the next column after a short distance, then one column per longer distance, and stays on the columns until the fingers lift; up or down it moves one step per scroll, so a card in a stack is easy to pick. The wheel moves one step per notch. A three-finger swipe moves it one step when the fingers lift.
186	188
187	189		Return or a click on a front tile or peeking card commits it; card changes remain provisional until then. `close-window` targets the selected preview. Move-to-workspace binds (`move-column-to-workspace`, `move-window-to-workspace`) move the selected preview at once and keep the overview open; with `focus.follow-move`, the selection follows it. Escape does not undo a move, and the row that received the window keeps it focused. A selected stash card, or a row with no preview, does not move. Other window mutation binds (moving within the row, resizing, maximizing, fullscreen and stash toggles) and moving a workspace to another monitor are disabled while the overview is open. Workspace and monitor navigation, launch and quit binds remain active.
188	190


@@ -66,10 +66,12 @@ bind.Cmd+p = workspace presentation
66			66
67		## Touchpad	67		## Touchpad
68			68
69	-	A three-finger swipe follows the fingers:	69	+	A three-finger swipe follows the fingers and moves one step at most, so a quick swipe never skips a column or a workspace:
70			70
71	-	- Left or right scrolls the columns (`scroll` overflow). When the fingers lift, the view keeps the swipe's speed, slows down and settles on a column edge; the focus moves to a column fully on screen.	71	+	- Left or right scrolls the columns (`scroll` overflow) to the next column edge; the focus moves to a column fully on screen.
72	-	- Up or down slides between numbered workspaces and settles on the nearest one the swipe's speed reaches. It stops with some resistance at the first and last workspace.	72	+	- Up or down slides to the next numbered workspace.
			73	+
			74	+	The view sticks a little near each step and catches up between them. Past the next step it resists; lift and swipe again to go further. When the fingers lift, a quick swipe goes on to the next step and a slow one settles on the closest.
73			75
74		With `natural-scroll = off`, a swipe left shows the columns to the left and a swipe up shows the workspace above. `natural-scroll = on` moves the content with the fingers, so both are reversed.	76		With `natural-scroll = off`, a swipe left shows the columns to the left and a swipe up shows the workspace above. `natural-scroll = on` moves the content with the fingers, so both are reversed.
75			77

@@ -182,7 +184,7 @@ The focus binds (`focus-column-left/right`, `focus-window-up/down`, `cmd+arrows`
182			184
183		Each workspace's [stash](#stash), hidden or not, shows as a pile of cards on the left of its row, which stays centred unless it would overlap the pile: its selected window in front, up to three others behind it, dimmed. In the pile, `h` / `l` browse the stash and `l` past its last window returns to the front card. A successful up/down move through the stack leaves the stash and selects the new front card. `return` or a click on a card closes the overview with the stash shown on that window.	185		Each workspace's [stash](#stash), hidden or not, shows as a pile of cards on the left of its row, which stays centred unless it would overlap the pile: its selected window in front, up to three others behind it, dimmed. In the pile, `h` / `l` browse the stash and `l` past its last window returns to the front card. A successful up/down move through the stack leaves the stash and selects the new front card. `return` or a click on a card closes the overview with the stash shown on that window.
184			186
185	-	A four-finger swipe up opens the overview and a swipe down closes it on the selection, whatever `touchpad.natural-scroll` says. Two-finger scrolling and the mouse wheel move the selection: left and right through the columns, up and down through stack cards before crossing workspaces, following `touchpad.natural-scroll`. A three-finger swipe moves it one step when the fingers lift.	187	+	A four-finger swipe up opens the overview and a swipe down closes it on the selection, whatever `touchpad.natural-scroll` says. Two-finger scrolling and the mouse wheel move the selection: left and right through the columns, up and down through stack cards before crossing workspaces, following `touchpad.natural-scroll`. A two-finger scroll sideways moves it to the next column after a short distance, then one column per longer distance, and stays on the columns until the fingers lift; up or down it moves one step per scroll, so a card in a stack is easy to pick. The wheel moves one step per notch. A three-finger swipe moves it one step when the fingers lift.
186			188
187		Return or a click on a front tile or peeking card commits it; card changes remain provisional until then. `close-window` targets the selected preview. Move-to-workspace binds (`move-column-to-workspace`, `move-window-to-workspace`) move the selected preview at once and keep the overview open; with `focus.follow-move`, the selection follows it. Escape does not undo a move, and the row that received the window keeps it focused. A selected stash card, or a row with no preview, does not move. Other window mutation binds (moving within the row, resizing, maximizing, fullscreen and stash toggles) and moving a workspace to another monitor are disabled while the overview is open. Workspace and monitor navigation, launch and quit binds remain active.	189		Return or a click on a front tile or peeking card commits it; card changes remain provisional until then. `close-window` targets the selected preview. Move-to-workspace binds (`move-column-to-workspace`, `move-window-to-workspace`) move the selected preview at once and keep the overview open; with `focus.follow-move`, the selection follows it. Escape does not undo a move, and the row that received the window keeps it focused. A selected stash card, or a row with no preview, does not move. Other window mutation binds (moving within the row, resizing, maximizing, fullscreen and stash toggles) and moving a workspace to another monitor are disabled while the overview is open. Workspace and monitor navigation, launch and quit binds remain active.
188			190

M internal/core/gesture.go +52 -47


@@ -9,10 +9,12 @@ import (
9	9		)
10	10
11	11		// A three-finger swipe follows the fingers: sideways it scrolls the columns,
12		-	// up or down it slides between workspaces. When the fingers lift, the view
13		-	// lands where the swipe's speed would carry it and a spring takes it there
14		-	// (motion.go). Where the view cannot slide (fixed overflow, the stash, a
15		-	// float, a fullscreen window), the swipe runs one focus action instead.
	12	+	// up or down it slides between workspaces. Each swipe moves one step at
	13	+	// most (snapswipe.go): the next column edge or the next workspace. When
	14	+	// the fingers lift, a quick swipe goes on to that step, a slow one settles
	15	+	// on the closest, and a spring takes the view there (motion.go). Where the
	16	+	// view cannot slide (fixed overflow, the stash, a float, a fullscreen
	17	+	// window, the overview), the swipe runs one focus action instead.
16	18
17	19		const (
18	20		// swipeDecide is the touchpad distance before the swipe picks its axis

@@ -24,10 +26,6 @@ const (
24	26		// workspaceSwipeMovement is the touchpad distance that slides one
25	27		// workspace.
26	28		workspaceSwipeMovement = 300.0
27		-	// discreteSwipeMin is the projected distance a swipe needs to run a
28		-	// focus action where the view cannot slide, or a four-finger swipe to
29		-	// open or close the overview (half of niri's 300).
30		-	discreteSwipeMin = 150.0
31	29		)
32	30
33	31		type swipeMode uint8

@@ -51,18 +49,20 @@ type swipeGesture struct {
51	49		mode swipeMode
52	50		horizontal bool
53	51		cx, cy float64
54		-	// tracker adds up the movement along the chosen axis, natural scroll
55		-	// applied: positive scrolls right or down.
56		-	tracker swipeTracker
	52	+	// snap follows the movement along the chosen axis, natural scroll
	53	+	// applied: positive scrolls right or down. Its view is absolute: the
	54	+	// columns' x in pixels or the monitor's fractional workspace index,
	55	+	// so a focus change during the swipe does not move the fingers' view.
	56	+	// A discrete or overview swipe counts steps of -1, 0 or 1.
	57	+	snap snapSwipe
57	58		// ws is the workspace whose columns scroll, or the active one when a
58		-	// workspace slide began; start is where the view was when the swipe
59		-	// took over: its x in pixels (columns) or the monitor's fractional
60		-	// workspace index (workspaces). Both are absolute, so a focus change
61		-	// during the swipe does not move the fingers' view.
62		-	ws *Workspace
63		-	start float64
64		-	// list is the numbered workspaces when a workspace slide began: start
65		-	// indexes it, so the slide ends if the list changes.
	59	+	// workspace slide began.
	60	+	ws *Workspace
	61	+	// points are ws's column snap points when a column swipe began: the
	62	+	// swipe ends if the layout no longer has them.
	63	+	points []float64
	64	+	// list is the numbered workspaces when a workspace slide began: the
	65	+	// slide indexes it, so it ends if the list changes.
66	66		list []*Workspace
67	67		// opens is the monitor's overviewOpens when the swipe picked its
68	68		// mode: a slide the overview opened over is dropped, even once the

@@ -76,6 +76,14 @@ func (g swipeGesture) listChanged(m Monitor) bool {
76	76		return m.overviewOpens != g.opens \|\| m.shown != nil \|\| m.Workspaces[m.Active] != g.ws \|\| !slices.Equal(m.Workspaces, g.list)
77	77		}
78	78
	79	+	// columnsChanged reports whether a column swipe lost its workspace: it is
	80	+	// no longer shown or slidable, its snap points moved (an output resize, a
	81	+	// panel, a window mapped or resized, other gaps), or the overview opened
	82	+	// over it.
	83	+	func (g swipeGesture) columnsChanged(m Monitor) bool {
	84	+	return m.overviewOpens != g.opens \|\| m.Current() != g.ws \|\| !g.ws.slidable() \|\| !slices.Equal(g.ws.snapPoints(), g.points)
	85	+	}
	86	+
79	87		// swipeSign turns finger movement into view movement: natural scroll moves
80	88		// the content with the fingers.
81	89		func (c *Core) swipeSign() float64 {

@@ -119,19 +127,19 @@ func (c *Core) swipeUpdate(u ports.SwipeUpdate) bool {
119	127		if g.mode == swipeOverview {
120	128		// Like niri, the overview gesture ignores natural scroll: the
121	129		// fingers going up open it.
122		-	g.tracker.push(d, u.Time)
	130	+	g.snap.push(d, u.Time)
123	131		return false
124	132		}
125		-	g.tracker.push(d*c.swipeSign(), u.Time)
	133	+	g.snap.push(d*c.swipeSign(), u.Time)
126	134		m := g.screen.mon
127	135		switch g.mode {
128	136		case swipeColumns:
129		-	if m.overviewOpens != g.opens \|\| m.Current() != g.ws \|\| !g.ws.slidable() {
	137	+	if g.columnsChanged(m) {
130	138		g.ws.stopSlide()
131	139		g.mode = swipeDropped
132	140		return true
133	141		}
134		-	g.ws.shift = g.start + g.tracker.pos*g.ws.swipeScale() - float64(g.ws.ViewX)
	142	+	g.ws.shift = g.snap.pos() - float64(g.ws.ViewX)
135	143		return true
136	144		case swipeWorkspaces:
137	145		if g.listChanged(m) {

@@ -139,8 +147,7 @@ func (c *Core) swipeUpdate(u ports.SwipeUpdate) bool {
139	147		g.mode = swipeDropped
140	148		return true
141	149		}
142		-	f := workspaceBand.clamp(0, float64(len(m.Workspaces)-1), g.start+g.tracker.pos/workspaceSwipeMovement)
143		-	m.switchOff = f - float64(m.Active)
	150	+	m.switchOff = g.snap.pos() - float64(m.Active)
144	151		return true
145	152		}
146	153		return false

@@ -155,17 +162,17 @@ func (c Core) decide(g swipeGesture) {
155	162		w := m.Current()
156	163		switch {
157	164		case g.fingers == 4 && !g.horizontal:
158		-	g.mode = swipeOverview
	165	+	g.mode, g.snap = swipeOverview, newStepSwipe()
159	166		case g.fingers == 4:
160	167		// Four fingers sideways do nothing.
161	168		g.mode = swipeDropped
162	169		case m.ov.open:
163	170		// The overview does not slide: the swipe moves its selection.
164		-	g.mode = swipeDiscrete
	171	+	g.mode, g.snap = swipeDiscrete, newStepSwipe()
165	172		case g.horizontal && w.slidable():
166		-	g.mode, g.ws = swipeColumns, w
	173	+	g.mode, g.ws, g.points = swipeColumns, w, w.snapPoints()
167	174		w.motion = nil
168		-	g.start = float64(w.ViewX) + w.shift
	175	+	g.snap = newSnapSwipe(float64(w.ViewX)+w.shift, float64(w.ViewX), w.swipeScale(), g.points, workspaceBand.scaled(float64(w.Usable.W)))
169	176		case !g.horizontal && m.shown == nil:
170	177		// A landing slide measured in an older list lands at once first.
171	178		if m.switchList != nil && !slices.Equal(m.switchList, m.Workspaces) {

@@ -174,9 +181,9 @@ func (c Core) decide(g swipeGesture) {
174	181		g.mode, g.ws = swipeWorkspaces, m.Workspaces[m.Active]
175	182		g.list = slices.Clone(m.Workspaces)
176	183		m.switchMotion, m.switchList = nil, nil
177		-	g.start = float64(m.Active) + m.switchOff
	184	+	g.snap = newSnapSwipe(float64(m.Active)+m.switchOff, float64(m.Active), 1/workspaceSwipeMovement, indexPoints(len(m.Workspaces)), workspaceBand)
178	185		default:
179		-	g.mode = swipeDiscrete
	186	+	g.mode, g.snap = swipeDiscrete, newStepSwipe()
180	187		}
181	188		}
182	189

@@ -188,40 +195,38 @@ func (c *Core) swipeEnd(e ports.SwipeEnd) (shown bool) {
188	195		if g == nil \|\| !c.hasScreen(g.screen) {
189	196		return false
190	197		}
191		-	// Idle time before the lift slows the swipe down.
192		-	g.tracker.push(0, e.Time)
193	198		now := c.now()
194	199		m := g.screen.mon
195	200		switch g.mode {
196	201		case swipeColumns:
197	202		w := g.ws
198		-	if m.overviewOpens != g.opens \|\| m.Current() != w \|\| !w.slidable() {
	203	+	if g.columnsChanged(m) {
199	204		w.stopSlide()
200	205		return false
201	206		}
202		-	scale := w.swipeScale()
203	207		shown := float64(w.ViewX) + w.shift
	208	+	target, velocity := g.snap.end(e.Cancelled, e.Time)
204	209		if !e.Cancelled {
205		-	target := g.start + g.tracker.projectedEnd()*scale
206		-	w.ViewX, w.Focus = w.snap(target, target >= shown)
	210	+	view := int(math.Round(target))
	211	+	w.Focus = w.snapFocus(view, target >= shown)
	212	+	w.ViewX = view
207	213		// A column wider than the view aligns as focus moves align it.
208	214		w.scroll()
209	215		c.focusScreen = c.screenIndex(g.screen.name())
210	216		c.keyboard.takeBack()
211	217		}
212	218		w.shift = shown - float64(w.ViewX)
213		-	w.motion = newMotion(viewSpring(w.shift, g.tracker.velocity()*scale), now)
	219	+	w.motion = newMotion(viewSpring(w.shift, velocity), now)
214	220		case swipeWorkspaces:
215	221		if g.listChanged(m) {
216	222		m.stopSwitch()
217	223		return false
218	224		}
219		-	last := float64(len(m.Workspaces) - 1)
220	225		cur := float64(m.Active) + m.switchOff
221		-	velocity := g.tracker.velocity() / workspaceSwipeMovement * workspaceBand.clampDerivative(0, last, g.start+g.tracker.pos/workspaceSwipeMovement)
	226	+	target, velocity := g.snap.end(e.Cancelled, e.Time)
222	227		idx := m.Active
223	228		if !e.Cancelled {
224		-	idx = int(math.Round(min(max(g.start+g.tracker.projectedEnd()/workspaceSwipeMovement, 0), last)))
	229	+	idx = int(math.Round(target))
225	230		}
226	231		// Focus may drop the empty workspace left behind and renumber the
227	232		// list: the slide keeps measuring in the list it began on.

@@ -237,8 +242,8 @@ func (c *Core) swipeEnd(e ports.SwipeEnd) (shown bool) {
237	242		m.switchOff, m.switchList = off, g.list
238	243		m.switchMotion = newMotion(workspaceSpring(off, velocity), now)
239	244		case swipeOverview:
240		-	p := g.tracker.projectedEnd()
241		-	if e.Cancelled \|\| math.Abs(p) < discreteSwipeMin \|\| (p < 0) == m.ov.open {
	245	+	step := g.snap.step(e.Cancelled, e.Time)
	246	+	if step == 0 \|\| (step < 0) == m.ov.open {
242	247		return false
243	248		}
244	249		before := m.Current()

@@ -247,17 +252,17 @@ func (c *Core) swipeEnd(e ports.SwipeEnd) (shown bool) {
247	252		c.keyboard.takeBack()
248	253		return m.Current() != before
249	254		case swipeDiscrete:
250		-	p := g.tracker.projectedEnd()
251		-	if e.Cancelled \|\| math.Abs(p) < discreteSwipeMin {
	255	+	step := g.snap.step(e.Cancelled, e.Time)
	256	+	if step == 0 {
252	257		return false
253	258		}
254	259		a := ActionFocusWorkspaceDown
255	260		switch {
256		-	case g.horizontal && p < 0:
	261	+	case g.horizontal && step < 0:
257	262		a = ActionFocusColumnLeft
258	263		case g.horizontal:
259	264		a = ActionFocusColumnRight
260		-	case p < 0:
	265	+	case step < 0:
261	266		a = ActionFocusWorkspaceUp
262	267		}
263	268		// Focus actions act on the focused screen: the swipe's, unless the

 )
 // A three-finger swipe follows the fingers: sideways it scrolls the columns,
-// up or down it slides between workspaces. When the fingers lift, the view
+// up or down it slides between workspaces. Each swipe moves one step at
-// lands where the swipe's speed would carry it and a spring takes it there
+// most (snapswipe.go): the next column edge or the next workspace. When
-// (motion.go). Where the view cannot slide (fixed overflow, the stash, a
+// the fingers lift, a quick swipe goes on to that step, a slow one settles
-// float, a fullscreen window), the swipe runs one focus action instead.
+// on the closest, and a spring takes the view there (motion.go). Where the
+// view cannot slide (fixed overflow, the stash, a float, a fullscreen
+// window, the overview), the swipe runs one focus action instead.
 const (
 	// swipeDecide is the touchpad distance before the swipe picks its axis
 	// workspaceSwipeMovement is the touchpad distance that slides one
 	// workspace.
 	workspaceSwipeMovement = 300.0
-	// discreteSwipeMin is the projected distance a swipe needs to run a
-	// focus action where the view cannot slide, or a four-finger swipe to
-	// open or close the overview (half of niri's 300).
-	discreteSwipeMin = 150.0
 )
 type swipeMode uint8
 	mode       swipeMode
 	horizontal bool
 	cx, cy     float64
-	// tracker adds up the movement along the chosen axis, natural scroll
+	// snap follows the movement along the chosen axis, natural scroll
-	// applied: positive scrolls right or down.
+	// applied: positive scrolls right or down. Its view is absolute: the
-	tracker swipeTracker
+	// columns' x in pixels or the monitor's fractional workspace index,
+	// so a focus change during the swipe does not move the fingers' view.
+	// A discrete or overview swipe counts steps of -1, 0 or 1.
+	snap snapSwipe
 	// ws is the workspace whose columns scroll, or the active one when a
-	// workspace slide began; start is where the view was when the swipe
+	// workspace slide began.
-	// took over: its x in pixels (columns) or the monitor's fractional
+	ws *Workspace
-	// workspace index (workspaces). Both are absolute, so a focus change
+	// points are ws's column snap points when a column swipe began: the
-	// during the swipe does not move the fingers' view.
+	// swipe ends if the layout no longer has them.
-	ws    *Workspace
+	points []float64
-	start float64
+	// list is the numbered workspaces when a workspace slide began: the
-	// list is the numbered workspaces when a workspace slide began: start
+	// slide indexes it, so it ends if the list changes.
-	// indexes it, so the slide ends if the list changes.
 	list []*Workspace
 	// opens is the monitor's overviewOpens when the swipe picked its
 	// mode: a slide the overview opened over is dropped, even once the
 	return m.overviewOpens != g.opens || m.shown != nil || m.Workspaces[m.Active] != g.ws || !slices.Equal(m.Workspaces, g.list)
 }
+// columnsChanged reports whether a column swipe lost its workspace: it is
+// no longer shown or slidable, its snap points moved (an output resize, a
+// panel, a window mapped or resized, other gaps), or the overview opened
+// over it.
+func (g *swipeGesture) columnsChanged(m *Monitor) bool {
+	return m.overviewOpens != g.opens || m.Current() != g.ws || !g.ws.slidable() || !slices.Equal(g.ws.snapPoints(), g.points)
+}
 // swipeSign turns finger movement into view movement: natural scroll moves
 // the content with the fingers.
 func (c *Core) swipeSign() float64 {
 	if g.mode == swipeOverview {
 		// Like niri, the overview gesture ignores natural scroll: the
 		// fingers going up open it.
-		g.tracker.push(d, u.Time)
+		g.snap.push(d, u.Time)
 		return false
 	}
-	g.tracker.push(d*c.swipeSign(), u.Time)
+	g.snap.push(d*c.swipeSign(), u.Time)
 	m := g.screen.mon
 	switch g.mode {
 	case swipeColumns:
-		if m.overviewOpens != g.opens || m.Current() != g.ws || !g.ws.slidable() {
+		if g.columnsChanged(m) {
 			g.ws.stopSlide()
 			g.mode = swipeDropped
 			return true
 		}
-		g.ws.shift = g.start + g.tracker.pos*g.ws.swipeScale() - float64(g.ws.ViewX)
+		g.ws.shift = g.snap.pos() - float64(g.ws.ViewX)
 		return true
 	case swipeWorkspaces:
 		if g.listChanged(m) {
 			g.mode = swipeDropped
 			return true
 		}
-		f := workspaceBand.clamp(0, float64(len(m.Workspaces)-1), g.start+g.tracker.pos/workspaceSwipeMovement)
+		m.switchOff = g.snap.pos() - float64(m.Active)
-		m.switchOff = f - float64(m.Active)
 		return true
 	}
 	return false
 	w := m.Current()
 	switch {
 	case g.fingers == 4 && !g.horizontal:
-		g.mode = swipeOverview
+		g.mode, g.snap = swipeOverview, newStepSwipe()
 	case g.fingers == 4:
 		// Four fingers sideways do nothing.
 		g.mode = swipeDropped
 	case m.ov.open:
 		// The overview does not slide: the swipe moves its selection.
-		g.mode = swipeDiscrete
+		g.mode, g.snap = swipeDiscrete, newStepSwipe()
 	case g.horizontal && w.slidable():
-		g.mode, g.ws = swipeColumns, w
+		g.mode, g.ws, g.points = swipeColumns, w, w.snapPoints()
 		w.motion = nil
-		g.start = float64(w.ViewX) + w.shift
+		g.snap = newSnapSwipe(float64(w.ViewX)+w.shift, float64(w.ViewX), w.swipeScale(), g.points, workspaceBand.scaled(float64(w.Usable.W)))
 	case !g.horizontal && m.shown == nil:
 		// A landing slide measured in an older list lands at once first.
 		if m.switchList != nil && !slices.Equal(m.switchList, m.Workspaces) {
 		g.mode, g.ws = swipeWorkspaces, m.Workspaces[m.Active]
 		g.list = slices.Clone(m.Workspaces)
 		m.switchMotion, m.switchList = nil, nil
-		g.start = float64(m.Active) + m.switchOff
+		g.snap = newSnapSwipe(float64(m.Active)+m.switchOff, float64(m.Active), 1/workspaceSwipeMovement, indexPoints(len(m.Workspaces)), workspaceBand)
 	default:
-		g.mode = swipeDiscrete
+		g.mode, g.snap = swipeDiscrete, newStepSwipe()
 	}
 }
 	if g == nil || !c.hasScreen(g.screen) {
 		return false
 	}
-	// Idle time before the lift slows the swipe down.
-	g.tracker.push(0, e.Time)
 	now := c.now()
 	m := g.screen.mon
 	switch g.mode {
 	case swipeColumns:
 		w := g.ws
-		if m.overviewOpens != g.opens || m.Current() != w || !w.slidable() {
+		if g.columnsChanged(m) {
 			w.stopSlide()
 			return false
 		}
-		scale := w.swipeScale()
 		shown := float64(w.ViewX) + w.shift
+		target, velocity := g.snap.end(e.Cancelled, e.Time)
 		if !e.Cancelled {
-			target := g.start + g.tracker.projectedEnd()*scale
+			view := int(math.Round(target))
-			w.ViewX, w.Focus = w.snap(target, target >= shown)
+			w.Focus = w.snapFocus(view, target >= shown)
+			w.ViewX = view
 			// A column wider than the view aligns as focus moves align it.
 			w.scroll()
 			c.focusScreen = c.screenIndex(g.screen.name())
 			c.keyboard.takeBack()
 		}
 		w.shift = shown - float64(w.ViewX)
-		w.motion = newMotion(viewSpring(w.shift, g.tracker.velocity()*scale), now)
+		w.motion = newMotion(viewSpring(w.shift, velocity), now)
 	case swipeWorkspaces:
 		if g.listChanged(m) {
 			m.stopSwitch()
 			return false
 		}
-		last := float64(len(m.Workspaces) - 1)
 		cur := float64(m.Active) + m.switchOff
-		velocity := g.tracker.velocity() / workspaceSwipeMovement * workspaceBand.clampDerivative(0, last, g.start+g.tracker.pos/workspaceSwipeMovement)
+		target, velocity := g.snap.end(e.Cancelled, e.Time)
 		idx := m.Active
 		if !e.Cancelled {
-			idx = int(math.Round(min(max(g.start+g.tracker.projectedEnd()/workspaceSwipeMovement, 0), last)))
+			idx = int(math.Round(target))
 		}
 		// Focus may drop the empty workspace left behind and renumber the
 		// list: the slide keeps measuring in the list it began on.
 		m.switchOff, m.switchList = off, g.list
 		m.switchMotion = newMotion(workspaceSpring(off, velocity), now)
 	case swipeOverview:
-		p := g.tracker.projectedEnd()
+		step := g.snap.step(e.Cancelled, e.Time)
-		if e.Cancelled || math.Abs(p) < discreteSwipeMin || (p < 0) == m.ov.open {
+		if step == 0 || (step < 0) == m.ov.open {
 			return false
 		}
 		before := m.Current()
 		c.keyboard.takeBack()
 		return m.Current() != before
 	case swipeDiscrete:
-		p := g.tracker.projectedEnd()
+		step := g.snap.step(e.Cancelled, e.Time)
-		if e.Cancelled || math.Abs(p) < discreteSwipeMin {
+		if step == 0 {
 			return false
 		}
 		a := ActionFocusWorkspaceDown
 		switch {
-		case g.horizontal && p < 0:
+		case g.horizontal && step < 0:
 			a = ActionFocusColumnLeft
 		case g.horizontal:
 			a = ActionFocusColumnRight
-		case p < 0:
+		case step < 0:
 			a = ActionFocusWorkspaceUp
 		}
 		// Focus actions act on the focused screen: the swipe's, unless the

M internal/core/input.go +1 -0


@@ -136,6 +136,7 @@ func (c *Core) handleInput(ctx context.Context, ev ports.InputEvent) error {
136	136		}
137	137		return nil
138	138		case ports.PointerAxis:
	139	+	c.scrollStop(v)
139	140		// In the overview, scrolling moves the selection.
140	141		if c.cur().mon.ov.open && !c.overviewKeyboardTaken() {
141	142		if c.cur().mon.overviewScroll(v) {


@@ -136,6 +136,7 @@ func (c *Core) handleInput(ctx context.Context, ev ports.InputEvent) error {
136	}	136		}
137	return nil	137		return nil
138	case ports.PointerAxis:	138		case ports.PointerAxis:
		139	+	c.scrollStop(v)
139	// In the overview, scrolling moves the selection.	140		// In the overview, scrolling moves the selection.
140	if c.cur().mon.ov.open && !c.overviewKeyboardTaken() {	141		if c.cur().mon.ov.open && !c.overviewKeyboardTaken() {
141	if c.cur().mon.overviewScroll(v) {	142		if c.cur().mon.overviewScroll(v) {

M internal/core/motion.go +7 -1


@@ -178,9 +178,15 @@ func (m *motion) at(now time.Time) (float64, bool) {
178	178		// it moves, never more than limit.
179	179		type rubberBand struct{ stiffness, limit float64 }
180	180
181		-	// workspaceBand holds a workspace swipe past the first or last workspace.
	181	+	// workspaceBand holds a swipe past the steps it may reach, in steps: a
	182	+	// twentieth of a workspace at most. Column swipes scale it to pixels.
182	183		var workspaceBand = rubberBand{stiffness: 0.5, limit: 0.05}
183	184
	185	+	// scaled is the band measured in units k times smaller.
	186	+	func (r rubberBand) scaled(k float64) rubberBand {
	187	+	return rubberBand{stiffness: r.stiffness, limit: r.limit * k}
	188	+	}
	189	+
184	190		func (r rubberBand) band(x float64) float64 {
185	191		return (1 - 1/(xr.stiffness/r.limit+1)) r.limit
186	192		}

 // it moves, never more than limit.
 type rubberBand struct{ stiffness, limit float64 }
-// workspaceBand holds a workspace swipe past the first or last workspace.
+// workspaceBand holds a swipe past the steps it may reach, in steps: a
+// twentieth of a workspace at most. Column swipes scale it to pixels.
 var workspaceBand = rubberBand{stiffness: 0.5, limit: 0.05}
+// scaled is the band measured in units k times smaller.
+func (r rubberBand) scaled(k float64) rubberBand {
+	return rubberBand{stiffness: r.stiffness, limit: r.limit * k}
+}
 func (r rubberBand) band(x float64) float64 {
 	return (1 - 1/(x*r.stiffness/r.limit+1)) * r.limit
 }

M internal/core/motion_test.go +236 -10


@@ -2,6 +2,7 @@ package core
2	2
3	3		import (
4	4		"math"
	5	+	"slices"
5	6		"testing"
6	7		"time"
7	8		)

@@ -122,21 +123,246 @@ func TestSnap(t *testing.T) {
122	123		for i := range 4 {
123	124		w.Columns = append(w.Columns, Column{Windows: []WindowID{WindowID(i + 1)}})
124	125		}
	126	+	if got := w.snapPoints(); !slices.Equal(got, []float64{0, 400, 800}) {
	127	+	t.Fatalf("snap points %v", got)
	128	+	}
125	129		for _, tc := range []struct {
126		-	target float64
127		-	forward bool
128	130		view int
	131	+	forward bool
129	132		focus int
130	133		}{
131		-	{target: 130, forward: true, view: 0, focus: 0},
132		-	{target: 330, forward: true, view: 400, focus: 2},
133		-	{target: 330, forward: false, view: 400, focus: 1},
134		-	{target: 5000, forward: true, view: 800, focus: 3},
135		-	{target: -900, forward: false, view: 0, focus: 0},
	134	+	{view: 0, forward: true, focus: 0},
	135	+	{view: 400, forward: true, focus: 2},
	136	+	{view: 400, forward: false, focus: 1},
	137	+	{view: 800, forward: true, focus: 3},
	138	+	} {
	139	+	if focus := w.snapFocus(tc.view, tc.forward); focus != tc.focus {
	140	+	t.Errorf("snapFocus(%d, %t) = %d; want %d", tc.view, tc.forward, focus, tc.focus)
	141	+	}
	142	+	}
	143	+	}
	144	+
	145	+	// Column edges closer than snapSpacing merge: a step always shows. The
	146	+	// last column's end stays, dropping a point close before it.
	147	+	func TestSnapPointsMergeClose(t *testing.T) {
	148	+	for _, tc := range []struct {
	149	+	widths []int
	150	+	want []float64
	151	+	}{
	152	+	// Views aligning a column: 0, 600, 640 (merged into 600), 1000.
	153	+	{[]int{600, 400, 640, 360}, []float64{0, 600, 1000}},
	154	+	// 0, 360, 600, 960 and the end 1000: 960 goes, 1000 stays.
	155	+	{[]int{600, 360, 400, 640}, []float64{0, 360, 600, 1000}},
	156	+	// Columns narrower than the view: one point.
	157	+	{[]int{300, 300}, []float64{0}},
	158	+	} {
	159	+	w := &Workspace{Output: Rect{W: 1000, H: 600}, Usable: Rect{W: 1000, H: 600}}
	160	+	for _, px := range tc.widths {
	161	+	w.Columns = append(w.Columns, Column{Width: Width{Pixels: px}, Windows: []WindowID{WindowID(len(w.Columns) + 1)}})
	162	+	}
	163	+	if got := w.snapPoints(); !slices.Equal(got, tc.want) {
	164	+	t.Errorf("widths %v: snap points %v, want %v", tc.widths, got, tc.want)
	165	+	}
	166	+	}
	167	+	}
	168	+
	169	+	// swipe pushes n updates of delta, 8 ms apart, from time 0.
	170	+	func swipe(s *snapSwipe, n int, delta float64) time.Duration {
	171	+	at := time.Duration(0)
	172	+	for range n {
	173	+	at += 8 * time.Millisecond
	174	+	s.push(delta, at)
	175	+	}
	176	+	return at
	177	+	}
	178	+
	179	+	// slowSwipe pushes dist over two seconds and rests before the lift.
	180	+	func slowSwipe(s *snapSwipe, dist float64) time.Duration {
	181	+	at := time.Duration(0)
	182	+	for range 40 {
	183	+	at += 50 * time.Millisecond
	184	+	s.push(dist/40, at)
	185	+	}
	186	+	return at + 200*time.Millisecond
	187	+	}
	188	+
	189	+	func workspaceSnap(start float64) snapSwipe {
	190	+	return newSnapSwipe(start, math.Round(start), 1/workspaceSwipeMovement, indexPoints(5), workspaceBand)
	191	+	}
	192	+
	193	+	// One swipe reaches the next workspace at most, however fast or far: a
	194	+	// slow one settles on the closest, back unless past halfway; a cancelled
	195	+	// one returns.
	196	+	func TestSnapSwipeOneStep(t *testing.T) {
	197	+	for _, tc := range []struct {
	198	+	name string
	199	+	push func(*snapSwipe) time.Duration
	200	+	cancelled bool
	201	+	want float64
	202	+	}{
	203	+	{"quick flick down", func(s *snapSwipe) time.Duration { return swipe(s, 6, 30) }, false, 3},
	204	+	{"quick flick up", func(s *snapSwipe) time.Duration { return swipe(s, 6, -30) }, false, 1},
	205	+	{"hard long flick", func(s *snapSwipe) time.Duration { return swipe(s, 30, 60) }, false, 3},
	206	+	{"short quick flick", func(s *snapSwipe) time.Duration { return swipe(s, 3, 20) }, false, 3},
	207	+	{"slow short", func(s *snapSwipe) time.Duration { return slowSwipe(s, 100) }, false, 2},
	208	+	{"slow past half", func(s *snapSwipe) time.Duration { return slowSwipe(s, 200) }, false, 3},
	209	+	{"slow far up", func(s *snapSwipe) time.Duration { return slowSwipe(s, -900) }, false, 1},
	210	+	{"cancelled", func(s *snapSwipe) time.Duration { return swipe(s, 10, 30) }, true, 2},
	211	+	// Most of the way down, then a hard flick back: one step up.
	212	+	{"forward then hard back", func(s *snapSwipe) time.Duration {
	213	+	at := slowSwipe(s, 250)
	214	+	for range 4 {
	215	+	at += 8 * time.Millisecond
	216	+	s.push(-30, at)
	217	+	}
	218	+	return at
	219	+	}, false, 1},
	220	+	} {
	221	+	s := workspaceSnap(2)
	222	+	at := tc.push(&s)
	223	+	if p := s.pos(); p < 1-workspaceBand.limit \|\| p > 3+workspaceBand.limit {
	224	+	t.Errorf("%s: view %v went past the neighbors", tc.name, p)
	225	+	}
	226	+	if got, _ := s.end(tc.cancelled, at); got != tc.want {
	227	+	t.Errorf("%s: landed on %v, want %v", tc.name, got, tc.want)
	228	+	}
	229	+	}
	230	+	}
	231	+
	232	+	// A swipe caught during a landing steps from the landing: one more.
	233	+	func TestSnapSwipeDuringLanding(t *testing.T) {
	234	+	s := newSnapSwipe(2.6, 3, 1/workspaceSwipeMovement, indexPoints(5), workspaceBand)
	235	+	at := swipe(&s, 6, 30)
	236	+	if p := s.pos(); p > 4+workspaceBand.limit {
	237	+	t.Fatalf("view %v went past 4", p)
	238	+	}
	239	+	if got, _ := s.end(false, at); got != 4 {
	240	+	t.Fatalf("landed on %v, want 4", got)
	241	+	}
	242	+	}
	243	+
	244	+	// From a view between points (a merged column edge) a slow swipe never
	245	+	// settles behind where it started; a quick one reaches the points around.
	246	+	func TestSnapSwipeRestBetweenPoints(t *testing.T) {
	247	+	for _, tc := range []struct {
	248	+	name string
	249	+	push func(*snapSwipe) time.Duration
	250	+	want float64
	251	+	}{
	252	+	{"slow", func(s *snapSwipe) time.Duration { return slowSwipe(s, 5) }, 640},
	253	+	{"quick back", func(s *snapSwipe) time.Duration { return swipe(s, 4, -40) }, 600},
	254	+	{"quick on", func(s *snapSwipe) time.Duration { return swipe(s, 4, 40) }, 1000},
	255	+	} {
	256	+	s := newSnapSwipe(640, 640, 1, []float64{0, 600, 1000}, workspaceBand.scaled(1000))
	257	+	at := tc.push(&s)
	258	+	if got, _ := s.end(false, at); got != tc.want {
	259	+	t.Errorf("%s: landed on %v, want %v", tc.name, got, tc.want)
	260	+	}
	261	+	}
	262	+	}
	263	+
	264	+	// A swipe caught while sliding to a far workspace lands on that one or
	265	+	// its neighbors, never back where the slide shows.
	266	+	func TestSnapSwipeCaughtFarFromRest(t *testing.T) {
	267	+	for _, delta := range []float64{-60, 60} {
	268	+	s := newSnapSwipe(0.5, 4, 1/workspaceSwipeMovement, indexPoints(6), workspaceBand)
	269	+	at := swipe(&s, 20, delta)
	270	+	if got, _ := s.end(false, at); got < 3 \|\| got > 5 {
	271	+	t.Errorf("delta %v: landed on %v, want 3 to 5", delta, got)
	272	+	}
	273	+	}
	274	+	}
	275	+
	276	+	// The view follows the fingers in their direction, without jumps, from a
	277	+	// start on a point, between points, or caught past the edge (a spring back
	278	+	// from the rubber band); near a point it sticks, a full step shows whole.
	279	+	func TestSnapSwipeDetents(t *testing.T) {
	280	+	for _, start := range []float64{2, 2.4, -0.03, 4.03} {
	281	+	s := workspaceSnap(start)
	282	+	if p := s.pos(); math.Abs(p-start) > 1e-9 {
	283	+	t.Fatalf("start %v shows %v", start, p)
	284	+	}
	285	+	for _, dir := range []float64{1, -1} {
	286	+	s := workspaceSnap(start)
	287	+	prev := s.pos()
	288	+	for i := range 400 {
	289	+	s.push(dir, time.Duration(i)*time.Millisecond)
	290	+	p := s.pos()
	291	+	if (p-prev)*dir < 0 \|\| math.Abs(p-prev) > 0.01 {
	292	+	t.Fatalf("start %v dir %v: view %v then %v at %d", start, dir, prev, p, i)
	293	+	}
	294	+	prev = p
	295	+	}
	296	+	}
	297	+	}
	298	+	s := workspaceSnap(2)
	299	+	s.push(300, 0)
	300	+	if p := s.pos(); math.Abs(p-3) > 1e-9 {
	301	+	t.Fatalf("a full step shows %v", p)
	302	+	}
	303	+	s = workspaceSnap(2)
	304	+	s.push(30, 0)
	305	+	if p := s.pos(); p >= 2.1 \|\| p <= 2 {
	306	+	t.Fatalf("near a point the view moved to %v for 0.1", p)
	307	+	}
	308	+	}
	309	+
	310	+	// One workspace: nowhere to go, the view resists and stays.
	311	+	func TestSnapSwipeSinglePoint(t *testing.T) {
	312	+	s := newSnapSwipe(0, 0, 1/workspaceSwipeMovement, indexPoints(1), workspaceBand)
	313	+	at := swipe(&s, 10, 40)
	314	+	if p := s.pos(); p <= 0 \|\| p > workspaceBand.limit {
	315	+	t.Fatalf("view %v", p)
	316	+	}
	317	+	target, velocity := s.end(false, at)
	318	+	if target != 0 \|\| math.IsNaN(velocity) {
	319	+	t.Fatalf("landed on %v at %v", target, velocity)
	320	+	}
	321	+	}
	322	+
	323	+	func TestStepSwipe(t *testing.T) {
	324	+	for _, tc := range []struct {
	325	+	name string
	326	+	push func(*snapSwipe) time.Duration
	327	+	cancelled bool
	328	+	want int
	329	+	}{
	330	+	{"quick back", func(s *snapSwipe) time.Duration { return swipe(s, 3, -40) }, false, -1},
	331	+	{"quick on", func(s *snapSwipe) time.Duration { return swipe(s, 3, 40) }, false, 1},
	332	+	{"hard", func(s *snapSwipe) time.Duration { return swipe(s, 30, 80) }, false, 1},
	333	+	{"slow short", func(s *snapSwipe) time.Duration { return slowSwipe(s, -100) }, false, 0},
	334	+	{"slow past half", func(s *snapSwipe) time.Duration { return slowSwipe(s, -200) }, false, -1},
	335	+	{"cancelled", func(s *snapSwipe) time.Duration { return swipe(s, 3, 40) }, true, 0},
136	336		} {
137		-	view, focus := w.snap(tc.target, tc.forward)
138		-	if view != tc.view \|\| focus != tc.focus {
139		-	t.Errorf("snap(%v, %t) = %d, %d; want %d, %d", tc.target, tc.forward, view, focus, tc.view, tc.focus)
	337	+	s := newStepSwipe()
	338	+	at := tc.push(&s)
	339	+	target, v := s.end(tc.cancelled, at)
	340	+	if got := int(math.Round(target)); got != tc.want {
	341	+	t.Errorf("%s: step %d, want %d", tc.name, got, tc.want)
	342	+	}
	343	+	if math.IsNaN(v) {
	344	+	t.Errorf("%s: velocity NaN", tc.name)
	345	+	}
	346	+	}
	347	+	}
	348	+
	349	+	// With no column fully shown (a column wider than the space between the
	350	+	// gaps), the focus goes to the column at the left edge.
	351	+	func TestSnapFocusWideColumn(t *testing.T) {
	352	+	w := &Workspace{Output: Rect{W: 800, H: 600}, Usable: Rect{W: 800, H: 600}, Gaps: 10}
	353	+	for i := range 3 {
	354	+	w.Columns = append(w.Columns, Column{Windows: []WindowID{WindowID(i + 1)}})
	355	+	}
	356	+	// Full width with gaps: 780 wide, between 10 and 790. The view
	357	+	// columnX(1)+1 shifts it 1 px left, so it is not fully shown.
	358	+	w.Columns[1].FullWidth = true
	359	+	if !w.slidable() {
	360	+	t.Fatal("the workspace does not scroll")
	361	+	}
	362	+	view := w.columnX(1) - w.Usable.X - w.gap() + 1
	363	+	for _, forward := range []bool{true, false} {
	364	+	if focus := w.snapFocus(view, forward); focus != 1 {
	365	+	t.Fatalf("forward=%t: focus %d, want the wide column 1", forward, focus)
140	366		}
141	367		}
142	368		}


@@ -2,6 +2,7 @@ package core
2			2
3		import (	3		import (
4		"math"	4		"math"
			5	+	"slices"
5		"testing"	6		"testing"
6		"time"	7		"time"
7		)	8		)

@@ -122,21 +123,246 @@ func TestSnap(t *testing.T) {
122		for i := range 4 {	123		for i := range 4 {
123		w.Columns = append(w.Columns, Column{Windows: []WindowID{WindowID(i + 1)}})	124		w.Columns = append(w.Columns, Column{Windows: []WindowID{WindowID(i + 1)}})
124		}	125		}
			126	+	if got := w.snapPoints(); !slices.Equal(got, []float64{0, 400, 800}) {
			127	+	t.Fatalf("snap points %v", got)
			128	+	}
125		for _, tc := range []struct {	129		for _, tc := range []struct {
126	-	target float64
127	-	forward bool
128		view int	130		view int
			131	+	forward bool
129		focus int	132		focus int
130		}{	133		}{
131	-	{target: 130, forward: true, view: 0, focus: 0},	134	+	{view: 0, forward: true, focus: 0},
132	-	{target: 330, forward: true, view: 400, focus: 2},	135	+	{view: 400, forward: true, focus: 2},
133	-	{target: 330, forward: false, view: 400, focus: 1},	136	+	{view: 400, forward: false, focus: 1},
134	-	{target: 5000, forward: true, view: 800, focus: 3},	137	+	{view: 800, forward: true, focus: 3},
135	-	{target: -900, forward: false, view: 0, focus: 0},	138	+	} {
			139	+	if focus := w.snapFocus(tc.view, tc.forward); focus != tc.focus {
			140	+	t.Errorf("snapFocus(%d, %t) = %d; want %d", tc.view, tc.forward, focus, tc.focus)
			141	+	}
			142	+	}
			143	+	}
			144	+
			145	+	// Column edges closer than snapSpacing merge: a step always shows. The
			146	+	// last column's end stays, dropping a point close before it.
			147	+	func TestSnapPointsMergeClose(t *testing.T) {
			148	+	for _, tc := range []struct {
			149	+	widths []int
			150	+	want []float64
			151	+	}{
			152	+	// Views aligning a column: 0, 600, 640 (merged into 600), 1000.
			153	+	{[]int{600, 400, 640, 360}, []float64{0, 600, 1000}},
			154	+	// 0, 360, 600, 960 and the end 1000: 960 goes, 1000 stays.
			155	+	{[]int{600, 360, 400, 640}, []float64{0, 360, 600, 1000}},
			156	+	// Columns narrower than the view: one point.
			157	+	{[]int{300, 300}, []float64{0}},
			158	+	} {
			159	+	w := &Workspace{Output: Rect{W: 1000, H: 600}, Usable: Rect{W: 1000, H: 600}}
			160	+	for _, px := range tc.widths {
			161	+	w.Columns = append(w.Columns, Column{Width: Width{Pixels: px}, Windows: []WindowID{WindowID(len(w.Columns) + 1)}})
			162	+	}
			163	+	if got := w.snapPoints(); !slices.Equal(got, tc.want) {
			164	+	t.Errorf("widths %v: snap points %v, want %v", tc.widths, got, tc.want)
			165	+	}
			166	+	}
			167	+	}
			168	+
			169	+	// swipe pushes n updates of delta, 8 ms apart, from time 0.
			170	+	func swipe(s *snapSwipe, n int, delta float64) time.Duration {
			171	+	at := time.Duration(0)
			172	+	for range n {
			173	+	at += 8 * time.Millisecond
			174	+	s.push(delta, at)
			175	+	}
			176	+	return at
			177	+	}
			178	+
			179	+	// slowSwipe pushes dist over two seconds and rests before the lift.
			180	+	func slowSwipe(s *snapSwipe, dist float64) time.Duration {
			181	+	at := time.Duration(0)
			182	+	for range 40 {
			183	+	at += 50 * time.Millisecond
			184	+	s.push(dist/40, at)
			185	+	}
			186	+	return at + 200*time.Millisecond
			187	+	}
			188	+
			189	+	func workspaceSnap(start float64) snapSwipe {
			190	+	return newSnapSwipe(start, math.Round(start), 1/workspaceSwipeMovement, indexPoints(5), workspaceBand)
			191	+	}
			192	+
			193	+	// One swipe reaches the next workspace at most, however fast or far: a
			194	+	// slow one settles on the closest, back unless past halfway; a cancelled
			195	+	// one returns.
			196	+	func TestSnapSwipeOneStep(t *testing.T) {
			197	+	for _, tc := range []struct {
			198	+	name string
			199	+	push func(*snapSwipe) time.Duration
			200	+	cancelled bool
			201	+	want float64
			202	+	}{
			203	+	{"quick flick down", func(s *snapSwipe) time.Duration { return swipe(s, 6, 30) }, false, 3},
			204	+	{"quick flick up", func(s *snapSwipe) time.Duration { return swipe(s, 6, -30) }, false, 1},
			205	+	{"hard long flick", func(s *snapSwipe) time.Duration { return swipe(s, 30, 60) }, false, 3},
			206	+	{"short quick flick", func(s *snapSwipe) time.Duration { return swipe(s, 3, 20) }, false, 3},
			207	+	{"slow short", func(s *snapSwipe) time.Duration { return slowSwipe(s, 100) }, false, 2},
			208	+	{"slow past half", func(s *snapSwipe) time.Duration { return slowSwipe(s, 200) }, false, 3},
			209	+	{"slow far up", func(s *snapSwipe) time.Duration { return slowSwipe(s, -900) }, false, 1},
			210	+	{"cancelled", func(s *snapSwipe) time.Duration { return swipe(s, 10, 30) }, true, 2},
			211	+	// Most of the way down, then a hard flick back: one step up.
			212	+	{"forward then hard back", func(s *snapSwipe) time.Duration {
			213	+	at := slowSwipe(s, 250)
			214	+	for range 4 {
			215	+	at += 8 * time.Millisecond
			216	+	s.push(-30, at)
			217	+	}
			218	+	return at
			219	+	}, false, 1},
			220	+	} {
			221	+	s := workspaceSnap(2)
			222	+	at := tc.push(&s)
			223	+	if p := s.pos(); p < 1-workspaceBand.limit \|\| p > 3+workspaceBand.limit {
			224	+	t.Errorf("%s: view %v went past the neighbors", tc.name, p)
			225	+	}
			226	+	if got, _ := s.end(tc.cancelled, at); got != tc.want {
			227	+	t.Errorf("%s: landed on %v, want %v", tc.name, got, tc.want)
			228	+	}
			229	+	}
			230	+	}
			231	+
			232	+	// A swipe caught during a landing steps from the landing: one more.
			233	+	func TestSnapSwipeDuringLanding(t *testing.T) {
			234	+	s := newSnapSwipe(2.6, 3, 1/workspaceSwipeMovement, indexPoints(5), workspaceBand)
			235	+	at := swipe(&s, 6, 30)
			236	+	if p := s.pos(); p > 4+workspaceBand.limit {
			237	+	t.Fatalf("view %v went past 4", p)
			238	+	}
			239	+	if got, _ := s.end(false, at); got != 4 {
			240	+	t.Fatalf("landed on %v, want 4", got)
			241	+	}
			242	+	}
			243	+
			244	+	// From a view between points (a merged column edge) a slow swipe never
			245	+	// settles behind where it started; a quick one reaches the points around.
			246	+	func TestSnapSwipeRestBetweenPoints(t *testing.T) {
			247	+	for _, tc := range []struct {
			248	+	name string
			249	+	push func(*snapSwipe) time.Duration
			250	+	want float64
			251	+	}{
			252	+	{"slow", func(s *snapSwipe) time.Duration { return slowSwipe(s, 5) }, 640},
			253	+	{"quick back", func(s *snapSwipe) time.Duration { return swipe(s, 4, -40) }, 600},
			254	+	{"quick on", func(s *snapSwipe) time.Duration { return swipe(s, 4, 40) }, 1000},
			255	+	} {
			256	+	s := newSnapSwipe(640, 640, 1, []float64{0, 600, 1000}, workspaceBand.scaled(1000))
			257	+	at := tc.push(&s)
			258	+	if got, _ := s.end(false, at); got != tc.want {
			259	+	t.Errorf("%s: landed on %v, want %v", tc.name, got, tc.want)
			260	+	}
			261	+	}
			262	+	}
			263	+
			264	+	// A swipe caught while sliding to a far workspace lands on that one or
			265	+	// its neighbors, never back where the slide shows.
			266	+	func TestSnapSwipeCaughtFarFromRest(t *testing.T) {
			267	+	for _, delta := range []float64{-60, 60} {
			268	+	s := newSnapSwipe(0.5, 4, 1/workspaceSwipeMovement, indexPoints(6), workspaceBand)
			269	+	at := swipe(&s, 20, delta)
			270	+	if got, _ := s.end(false, at); got < 3 \|\| got > 5 {
			271	+	t.Errorf("delta %v: landed on %v, want 3 to 5", delta, got)
			272	+	}
			273	+	}
			274	+	}
			275	+
			276	+	// The view follows the fingers in their direction, without jumps, from a
			277	+	// start on a point, between points, or caught past the edge (a spring back
			278	+	// from the rubber band); near a point it sticks, a full step shows whole.
			279	+	func TestSnapSwipeDetents(t *testing.T) {
			280	+	for _, start := range []float64{2, 2.4, -0.03, 4.03} {
			281	+	s := workspaceSnap(start)
			282	+	if p := s.pos(); math.Abs(p-start) > 1e-9 {
			283	+	t.Fatalf("start %v shows %v", start, p)
			284	+	}
			285	+	for _, dir := range []float64{1, -1} {
			286	+	s := workspaceSnap(start)
			287	+	prev := s.pos()
			288	+	for i := range 400 {
			289	+	s.push(dir, time.Duration(i)*time.Millisecond)
			290	+	p := s.pos()
			291	+	if (p-prev)*dir < 0 \|\| math.Abs(p-prev) > 0.01 {
			292	+	t.Fatalf("start %v dir %v: view %v then %v at %d", start, dir, prev, p, i)
			293	+	}
			294	+	prev = p
			295	+	}
			296	+	}
			297	+	}
			298	+	s := workspaceSnap(2)
			299	+	s.push(300, 0)
			300	+	if p := s.pos(); math.Abs(p-3) > 1e-9 {
			301	+	t.Fatalf("a full step shows %v", p)
			302	+	}
			303	+	s = workspaceSnap(2)
			304	+	s.push(30, 0)
			305	+	if p := s.pos(); p >= 2.1 \|\| p <= 2 {
			306	+	t.Fatalf("near a point the view moved to %v for 0.1", p)
			307	+	}
			308	+	}
			309	+
			310	+	// One workspace: nowhere to go, the view resists and stays.
			311	+	func TestSnapSwipeSinglePoint(t *testing.T) {
			312	+	s := newSnapSwipe(0, 0, 1/workspaceSwipeMovement, indexPoints(1), workspaceBand)
			313	+	at := swipe(&s, 10, 40)
			314	+	if p := s.pos(); p <= 0 \|\| p > workspaceBand.limit {
			315	+	t.Fatalf("view %v", p)
			316	+	}
			317	+	target, velocity := s.end(false, at)
			318	+	if target != 0 \|\| math.IsNaN(velocity) {
			319	+	t.Fatalf("landed on %v at %v", target, velocity)
			320	+	}
			321	+	}
			322	+
			323	+	func TestStepSwipe(t *testing.T) {
			324	+	for _, tc := range []struct {
			325	+	name string
			326	+	push func(*snapSwipe) time.Duration
			327	+	cancelled bool
			328	+	want int
			329	+	}{
			330	+	{"quick back", func(s *snapSwipe) time.Duration { return swipe(s, 3, -40) }, false, -1},
			331	+	{"quick on", func(s *snapSwipe) time.Duration { return swipe(s, 3, 40) }, false, 1},
			332	+	{"hard", func(s *snapSwipe) time.Duration { return swipe(s, 30, 80) }, false, 1},
			333	+	{"slow short", func(s *snapSwipe) time.Duration { return slowSwipe(s, -100) }, false, 0},
			334	+	{"slow past half", func(s *snapSwipe) time.Duration { return slowSwipe(s, -200) }, false, -1},
			335	+	{"cancelled", func(s *snapSwipe) time.Duration { return swipe(s, 3, 40) }, true, 0},
136		} {	336		} {
137	-	view, focus := w.snap(tc.target, tc.forward)	337	+	s := newStepSwipe()
138	-	if view != tc.view \|\| focus != tc.focus {	338	+	at := tc.push(&s)
139	-	t.Errorf("snap(%v, %t) = %d, %d; want %d, %d", tc.target, tc.forward, view, focus, tc.view, tc.focus)	339	+	target, v := s.end(tc.cancelled, at)
			340	+	if got := int(math.Round(target)); got != tc.want {
			341	+	t.Errorf("%s: step %d, want %d", tc.name, got, tc.want)
			342	+	}
			343	+	if math.IsNaN(v) {
			344	+	t.Errorf("%s: velocity NaN", tc.name)
			345	+	}
			346	+	}
			347	+	}
			348	+
			349	+	// With no column fully shown (a column wider than the space between the
			350	+	// gaps), the focus goes to the column at the left edge.
			351	+	func TestSnapFocusWideColumn(t *testing.T) {
			352	+	w := &Workspace{Output: Rect{W: 800, H: 600}, Usable: Rect{W: 800, H: 600}, Gaps: 10}
			353	+	for i := range 3 {
			354	+	w.Columns = append(w.Columns, Column{Windows: []WindowID{WindowID(i + 1)}})
			355	+	}
			356	+	// Full width with gaps: 780 wide, between 10 and 790. The view
			357	+	// columnX(1)+1 shifts it 1 px left, so it is not fully shown.
			358	+	w.Columns[1].FullWidth = true
			359	+	if !w.slidable() {
			360	+	t.Fatal("the workspace does not scroll")
			361	+	}
			362	+	view := w.columnX(1) - w.Usable.X - w.gap() + 1
			363	+	for _, forward := range []bool{true, false} {
			364	+	if focus := w.snapFocus(view, forward); focus != 1 {
			365	+	t.Fatalf("forward=%t: focus %d, want the wide column 1", forward, focus)
140		}	366		}
141		}	367		}
142		}	368		}

M internal/core/overview.go +64 -14


@@ -24,6 +24,11 @@ type overviewState struct {
24	24		selected WindowID
25	25		selectedAt int
26	26		scrollX, scrollY float64
	27	+	// scrolled is set once a two-finger scroll stepped up or down: it
	28	+	// waits for the fingers to lift before the next step. sideways is set
	29	+	// once it stepped to a column: it stays on columns and steps once per
	30	+	// overviewScrollRepeat.
	31	+	scrolled, sideways bool
27	32		}
28	33
29	34		// rowSnapshot is a row as the overview first showed it: browsing moves its

@@ -71,7 +76,7 @@ func (m *Monitor) ToggleOverview() {
71	76		m.stopSwitch()
72	77		m.each(func(w *Workspace) { w.stopSlide() })
73	78		m.ov.open, m.ov.from, m.ov.back = true, w, m.back
74		-	m.ov.scrollX, m.ov.scrollY = 0, 0
	79	+	m.ov.scrollX, m.ov.scrollY, m.ov.scrolled, m.ov.sideways = 0, 0, false, false
75	80		m.overviewOpens++
76	81		m.selectRow()
77	82		}

@@ -892,21 +897,45 @@ func (m *Monitor) overviewFocus(a Action) bool {
892	897		return true
893	898		}
894	899
895		-	// overviewScrollStep is the two-finger scroll distance, in libinput's
896		-	// pointer units, that moves the selection one column or workspace.
897		-	const overviewScrollStep = 60
	900	+	const (
	901	+	// overviewScrollStep is the scroll distance, in libinput's pointer
	902	+	// units, that moves the selection one column or workspace.
	903	+	overviewScrollStep = 60
	904	+	// overviewScrollRepeat is the two-finger distance of each further
	905	+	// column step in one scroll: longer than the first, so a short scroll
	906	+	// reaches the next column exactly and a long one goes on.
	907	+	overviewScrollRepeat = 150
	908	+	)
898	909
899		-	// overviewScroll moves the overview selection with a scroll frame: two
900		-	// fingers step once per overviewScrollStep on the axis they move most
901		-	// along, a wheel once per notch (high-resolution wheels add up their
902		-	// fractions of a notch). Vertical steps select cards first, then rows;
903		-	// touchpad.natural-scroll flips both axes as libinput reports.
	910	+	// overviewScroll moves the overview selection with a scroll frame: a row
	911	+	// step when the vertical scroll reaches overviewScrollStep and leads, else
	912	+	// a column step. Two fingers step to the next column after
	913	+	// overviewScrollStep, then once per overviewScrollRepeat, and stay on
	914	+	// columns until they lift; up or down they step once per scroll, so a card
	915	+	// in a stack is easy to pick.
	916	+	// Continuous scrolling steps once per overviewScrollStep and a wheel once
	917	+	// per notch (high-resolution wheels add up their fractions of a notch).
	918	+	// Vertical steps select cards first, then rows; touchpad.natural-scroll
	919	+	// flips both axes as libinput reports. The end of a scroll resets it
	920	+	// (scrollStop).
904	921		func (m *Monitor) overviewScroll(a ports.PointerAxis) (changed bool) {
905	922		if a.Vertical.Stop \|\| a.Horizontal.Stop {
906		-	// Fingers lifted: the next scroll starts from zero.
907		-	m.ov.scrollX, m.ov.scrollY = 0, 0
908	923		return false
909	924		}
	925	+	finger := a.Source == ports.AxisFinger
	926	+	if finger && m.ov.scrolled {
	927	+	return false
	928	+	}
	929	+	// A sideways finger scroll stays on columns; other sources do not, and
	930	+	// start from zero rather than from its leftover.
	931	+	sideways := finger && m.ov.sideways
	932	+	if !finger && m.ov.sideways {
	933	+	m.ov.scrollX, m.ov.scrollY = 0, 0
	934	+	}
	935	+	stepX := float64(overviewScrollStep)
	936	+	if sideways {
	937	+	stepX = overviewScrollRepeat
	938	+	}
910	939		add := func(acc *float64, ax ports.ScrollAxis) {
911	940		switch {
912	941		case !ax.Set:

@@ -916,7 +945,9 @@ func (m *Monitor) overviewScroll(a ports.PointerAxis) (changed bool) {
916	945		*acc += ax.Value
917	946		}
918	947		}
919		-	add(&m.ov.scrollY, a.Vertical)
	948	+	if !sideways {
	949	+	add(&m.ov.scrollY, a.Vertical)
	950	+	}
920	951		add(&m.ov.scrollX, a.Horizontal)
921	952		for {
922	953		switch {

@@ -924,10 +955,17 @@ func (m *Monitor) overviewScroll(a ports.PointerAxis) (changed bool) {
924	955		m.OverviewMove(0, sign(m.ov.scrollY))
925	956		m.ov.scrollY -= float64(sign(m.ov.scrollY)) * overviewScrollStep
926	957		m.ov.scrollX = 0
927		-	case math.Abs(m.ov.scrollX) >= overviewScrollStep:
	958	+	if finger {
	959	+	m.ov.scrollX, m.ov.scrollY, m.ov.scrolled = 0, 0, true
	960	+	return true
	961	+	}
	962	+	case math.Abs(m.ov.scrollX) >= stepX:
928	963		m.OverviewMove(sign(m.ov.scrollX), 0)
929		-	m.ov.scrollX -= float64(sign(m.ov.scrollX)) * overviewScrollStep
	964	+	m.ov.scrollX -= float64(sign(m.ov.scrollX)) * stepX
930	965		m.ov.scrollY = 0
	966	+	if finger {
	967	+	m.ov.sideways, stepX = true, overviewScrollRepeat
	968	+	}
931	969		default:
932	970		return changed
933	971		}

@@ -935,6 +973,18 @@ func (m *Monitor) overviewScroll(a ports.PointerAxis) (changed bool) {
935	973		}
936	974		}
937	975
	976	+	// scrollStop ends a scroll on every monitor: the fingers lifted, maybe
	977	+	// after the pointer took the focus to another output, so the next scroll
	978	+	// starts from zero wherever it goes.
	979	+	func (c *Core) scrollStop(a ports.PointerAxis) {
	980	+	if !a.Vertical.Stop && !a.Horizontal.Stop {
	981	+	return
	982	+	}
	983	+	for _, sc := range c.screens {
	984	+	sc.mon.ov.scrollX, sc.mon.ov.scrollY, sc.mon.ov.scrolled, sc.mon.ov.sideways = 0, 0, false, false
	985	+	}
	986	+	}
	987	+
938	988		func sign(v float64) int {
939	989		if v < 0 {
940	990		return -1

 	selected         WindowID
 	selectedAt       int
 	scrollX, scrollY float64
+	// scrolled is set once a two-finger scroll stepped up or down: it
+	// waits for the fingers to lift before the next step. sideways is set
+	// once it stepped to a column: it stays on columns and steps once per
+	// overviewScrollRepeat.
+	scrolled, sideways bool
 }
 // rowSnapshot is a row as the overview first showed it: browsing moves its
 	m.stopSwitch()
 	m.each(func(w *Workspace) { w.stopSlide() })
 	m.ov.open, m.ov.from, m.ov.back = true, w, m.back
-	m.ov.scrollX, m.ov.scrollY = 0, 0
+	m.ov.scrollX, m.ov.scrollY, m.ov.scrolled, m.ov.sideways = 0, 0, false, false
 	m.overviewOpens++
 	m.selectRow()
 }
 	return true
 }
-// overviewScrollStep is the two-finger scroll distance, in libinput's
+const (
-// pointer units, that moves the selection one column or workspace.
+	// overviewScrollStep is the scroll distance, in libinput's pointer
-const overviewScrollStep = 60
+	// units, that moves the selection one column or workspace.
+	overviewScrollStep = 60
+	// overviewScrollRepeat is the two-finger distance of each further
+	// column step in one scroll: longer than the first, so a short scroll
+	// reaches the next column exactly and a long one goes on.
+	overviewScrollRepeat = 150
+)
-// overviewScroll moves the overview selection with a scroll frame: two
+// overviewScroll moves the overview selection with a scroll frame: a row
-// fingers step once per overviewScrollStep on the axis they move most
+// step when the vertical scroll reaches overviewScrollStep and leads, else
-// along, a wheel once per notch (high-resolution wheels add up their
+// a column step. Two fingers step to the next column after
-// fractions of a notch). Vertical steps select cards first, then rows;
+// overviewScrollStep, then once per overviewScrollRepeat, and stay on
-// touchpad.natural-scroll flips both axes as libinput reports.
+// columns until they lift; up or down they step once per scroll, so a card
+// in a stack is easy to pick.
+// Continuous scrolling steps once per overviewScrollStep and a wheel once
+// per notch (high-resolution wheels add up their fractions of a notch).
+// Vertical steps select cards first, then rows; touchpad.natural-scroll
+// flips both axes as libinput reports. The end of a scroll resets it
+// (scrollStop).
 func (m *Monitor) overviewScroll(a ports.PointerAxis) (changed bool) {
 	if a.Vertical.Stop || a.Horizontal.Stop {
-		// Fingers lifted: the next scroll starts from zero.
-		m.ov.scrollX, m.ov.scrollY = 0, 0
 		return false
 	}
+	finger := a.Source == ports.AxisFinger
+	if finger && m.ov.scrolled {
+		return false
+	}
+	// A sideways finger scroll stays on columns; other sources do not, and
+	// start from zero rather than from its leftover.
+	sideways := finger && m.ov.sideways
+	if !finger && m.ov.sideways {
+		m.ov.scrollX, m.ov.scrollY = 0, 0
+	}
+	stepX := float64(overviewScrollStep)
+	if sideways {
+		stepX = overviewScrollRepeat
+	}
 	add := func(acc *float64, ax ports.ScrollAxis) {
 		switch {
 		case !ax.Set:
 			*acc += ax.Value
 		}
 	}
-	add(&m.ov.scrollY, a.Vertical)
+	if !sideways {
+		add(&m.ov.scrollY, a.Vertical)
+	}
 	add(&m.ov.scrollX, a.Horizontal)
 	for {
 		switch {
 			m.OverviewMove(0, sign(m.ov.scrollY))
 			m.ov.scrollY -= float64(sign(m.ov.scrollY)) * overviewScrollStep
 			m.ov.scrollX = 0
-		case math.Abs(m.ov.scrollX) >= overviewScrollStep:
+			if finger {
+				m.ov.scrollX, m.ov.scrollY, m.ov.scrolled = 0, 0, true
+				return true
+			}
+		case math.Abs(m.ov.scrollX) >= stepX:
 			m.OverviewMove(sign(m.ov.scrollX), 0)
-			m.ov.scrollX -= float64(sign(m.ov.scrollX)) * overviewScrollStep
+			m.ov.scrollX -= float64(sign(m.ov.scrollX)) * stepX
 			m.ov.scrollY = 0
+			if finger {
+				m.ov.sideways, stepX = true, overviewScrollRepeat
+			}
 		default:
 			return changed
 		}
 	}
 }
+// scrollStop ends a scroll on every monitor: the fingers lifted, maybe
+// after the pointer took the focus to another output, so the next scroll
+// starts from zero wherever it goes.
+func (c *Core) scrollStop(a ports.PointerAxis) {
+	if !a.Vertical.Stop && !a.Horizontal.Stop {
+		return
+	}
+	for _, sc := range c.screens {
+		sc.mon.ov.scrollX, sc.mon.ov.scrollY, sc.mon.ov.scrolled, sc.mon.ov.sideways = 0, 0, false, false
+	}
+}
 func sign(v float64) int {
 	if v < 0 {
 		return -1

M internal/core/overview_input_test.go +6 -2


@@ -226,18 +226,22 @@ func TestOverviewTwoFingerScroll(t *testing.T) {
226	226		finger := func(dx, dy float64) ports.PointerAxis {
227	227		return ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Value: dx}, Vertical: ports.ScrollAxis{Set: true, Value: dy}}
228	228		}
229		-	// 50 left, lifted, then 50 and 50 left: one step (to 2). Without the
230		-	// reset it would be two (to 1), and the l below would land on 2.
	229	+	// 50 left, lifted, then 50, 50 and 100 left: one step (to 2), the
	230	+	// next ones are longer. Without the reset it would be two (to 1), and
	231	+	// the l below would land on 2.
231	232		input <- finger(-50, 5)
232	233		input <- ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}}
233	234		input <- finger(-50, 5)
234	235		input <- finger(-50, 0)
	236	+	input <- finger(-100, 0)
235	237		sceneMatch(t, scenes, focused(2))
	238	+	input <- ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}}
236	239		input <- ports.KeyEvent{Keysym: "l", Pressed: true}
237	240		sceneMatch(t, scenes, focused(3))
238	241		input <- ports.KeyEvent{Keysym: "l"}
239	242		input <- finger(-60, 0)
240	243		sceneMatch(t, scenes, focused(2))
	244	+	input <- ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}}
241	245		// A wheel notch down has nowhere to go (no workspace below with
242	246		// windows); a finger scroll left moves on.
243	247		input <- ports.PointerAxis{Source: ports.AxisWheel, Vertical: ports.ScrollAxis{Set: true, Value: 15, V120: 120}}

 	finger := func(dx, dy float64) ports.PointerAxis {
 		return ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Value: dx}, Vertical: ports.ScrollAxis{Set: true, Value: dy}}
 	}
-	// 50 left, lifted, then 50 and 50 left: one step (to 2). Without the
+	// 50 left, lifted, then 50, 50 and 100 left: one step (to 2), the
-	// reset it would be two (to 1), and the l below would land on 2.
+	// next ones are longer. Without the reset it would be two (to 1), and
+	// the l below would land on 2.
 	input <- finger(-50, 5)
 	input <- ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}}
 	input <- finger(-50, 5)
 	input <- finger(-50, 0)
+	input <- finger(-100, 0)
 	sceneMatch(t, scenes, focused(2))
+	input <- ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}}
 	input <- ports.KeyEvent{Keysym: "l", Pressed: true}
 	sceneMatch(t, scenes, focused(3))
 	input <- ports.KeyEvent{Keysym: "l"}
 	input <- finger(-60, 0)
 	sceneMatch(t, scenes, focused(2))
+	input <- ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}}
 	// A wheel notch down has nowhere to go (no workspace below with
 	// windows); a finger scroll left moves on.
 	input <- ports.PointerAxis{Source: ports.AxisWheel, Vertical: ports.ScrollAxis{Set: true, Value: 15, V120: 120}}

M internal/core/overview_test.go +80 -0


@@ -653,3 +653,83 @@ func TestOverviewScrollSteps(t *testing.T) {
653	653		t.Fatalf("two notches from 3 landed on %d, want 1 (started on %d)", f, start)
654	654		}
655	655		}
	656	+
	657	+	// A two-finger scroll sideways steps to the next column after
	658	+	// overviewScrollStep, then once per overviewScrollRepeat, and stays on
	659	+	// columns; up or down it steps once until the fingers lift. Reopening the
	660	+	// overview, a wheel notch and continuous scrolling are not held by it.
	661	+	func TestOverviewFingerScroll(t *testing.T) {
	662	+	finger := func(dx, dy float64) ports.PointerAxis {
	663	+	return ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Value: dx}, Vertical: ports.ScrollAxis{Set: true, Value: dy}}
	664	+	}
	665	+	m := overviewMonitor()
	666	+	focused := func() WindowID { f, _ := m.Focused(); return f }
	667	+	m.Current().FocusID(3)
	668	+	m.ToggleOverview()
	669	+	// 70: one column; 100 more is under the longer repeat step.
	670	+	if !m.overviewScroll(finger(-70, 0)) \|\| focused() != 2 {
	671	+	t.Fatalf("first step on %d", focused())
	672	+	}
	673	+	if m.overviewScroll(finger(-100, 0)) {
	674	+	t.Fatal("stepped again before overviewScrollRepeat")
	675	+	}
	676	+	// The fingers drift down: still on columns, no row step.
	677	+	if m.overviewScroll(finger(0, 200)) {
	678	+	t.Fatal("a sideways scroll stepped down")
	679	+	}
	680	+	if !m.overviewScroll(finger(-50, 0)) \|\| focused() != 1 {
	681	+	t.Fatalf("long scroll on %d, want 1", focused())
	682	+	}
	683	+	// The fingers still rest: a wheel notch steps one column as always.
	684	+	if !m.overviewScroll(ports.PointerAxis{Source: ports.AxisWheel, Horizontal: ports.ScrollAxis{Set: true, V120: 120}}) \|\| focused() != 2 {
	685	+	t.Fatalf("wheel after a sideways scroll on %d, want 2", focused())
	686	+	}
	687	+	// Once lifted, the next scroll starts with the short step again, and
	688	+	// one large frame takes the short step then a repeat.
	689	+	c := &Core{screens: []*screen{{mon: m}}}
	690	+	c.scrollStop(ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}})
	691	+	if !m.overviewScroll(finger(220, 0)) \|\| focused() != 3 {
	692	+	t.Fatalf("large frame on %d, want 3", focused())
	693	+	}
	694	+	// Reopening forgets a sideways scroll left without its stop.
	695	+	m.CancelOverview()
	696	+	m.Current().FocusID(3)
	697	+	m.ToggleOverview()
	698	+	if !m.overviewScroll(finger(-70, 0)) \|\| focused() != 2 {
	699	+	t.Fatalf("reopened sideways scroll on %d, want 2", focused())
	700	+	}
	701	+
	702	+	// Vertical: one step per scroll, through the stack's cards.
	703	+	sm := stackMonitor()
	704	+	sm.ToggleOverview()
	705	+	before, _ := sm.Focused()
	706	+	if !sm.overviewScroll(finger(0, 70)) {
	707	+	t.Fatal("first vertical step")
	708	+	}
	709	+	after, _ := sm.Focused()
	710	+	if after == before {
	711	+	t.Fatal("vertical step selected nothing new")
	712	+	}
	713	+	if sm.overviewScroll(finger(0, 400)) {
	714	+	t.Fatal("the same vertical scroll stepped twice")
	715	+	}
	716	+	if !sm.overviewScroll(ports.PointerAxis{Source: ports.AxisWheel, Vertical: ports.ScrollAxis{Set: true, V120: -120}}) {
	717	+	t.Fatal("wheel held by the finger scroll")
	718	+	}
	719	+	// A sideways finger scroll does not hold a vertical wheel notch.
	720	+	sm.CancelOverview()
	721	+	sm.ToggleOverview()
	722	+	sm.overviewScroll(finger(70, 0))
	723	+	if !sm.overviewScroll(ports.PointerAxis{Source: ports.AxisWheel, Vertical: ports.ScrollAxis{Set: true, V120: 120}}) {
	724	+	t.Fatal("vertical wheel held by a sideways finger scroll")
	725	+	}
	726	+	sm.CancelOverview()
	727	+	sm.ToggleOverview()
	728	+	if !sm.overviewScroll(finger(0, 70)) {
	729	+	t.Fatal("reopened overview still held the old scroll")
	730	+	}
	731	+	cont := ports.PointerAxis{Source: ports.AxisContinuous, Vertical: ports.ScrollAxis{Set: true, Value: -70}}
	732	+	if !sm.overviewScroll(cont) {
	733	+	t.Fatal("continuous scroll held by the finger scroll")
	734	+	}
	735	+	}


@@ -653,3 +653,83 @@ func TestOverviewScrollSteps(t *testing.T) {
653	t.Fatalf("two notches from 3 landed on %d, want 1 (started on %d)", f, start)	653		t.Fatalf("two notches from 3 landed on %d, want 1 (started on %d)", f, start)
654	}	654		}
655	}	655		}
		656	+
		657	+	// A two-finger scroll sideways steps to the next column after
		658	+	// overviewScrollStep, then once per overviewScrollRepeat, and stays on
		659	+	// columns; up or down it steps once until the fingers lift. Reopening the
		660	+	// overview, a wheel notch and continuous scrolling are not held by it.
		661	+	func TestOverviewFingerScroll(t *testing.T) {
		662	+	finger := func(dx, dy float64) ports.PointerAxis {
		663	+	return ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Value: dx}, Vertical: ports.ScrollAxis{Set: true, Value: dy}}
		664	+	}
		665	+	m := overviewMonitor()
		666	+	focused := func() WindowID { f, _ := m.Focused(); return f }
		667	+	m.Current().FocusID(3)
		668	+	m.ToggleOverview()
		669	+	// 70: one column; 100 more is under the longer repeat step.
		670	+	if !m.overviewScroll(finger(-70, 0)) \|\| focused() != 2 {
		671	+	t.Fatalf("first step on %d", focused())
		672	+	}
		673	+	if m.overviewScroll(finger(-100, 0)) {
		674	+	t.Fatal("stepped again before overviewScrollRepeat")
		675	+	}
		676	+	// The fingers drift down: still on columns, no row step.
		677	+	if m.overviewScroll(finger(0, 200)) {
		678	+	t.Fatal("a sideways scroll stepped down")
		679	+	}
		680	+	if !m.overviewScroll(finger(-50, 0)) \|\| focused() != 1 {
		681	+	t.Fatalf("long scroll on %d, want 1", focused())
		682	+	}
		683	+	// The fingers still rest: a wheel notch steps one column as always.
		684	+	if !m.overviewScroll(ports.PointerAxis{Source: ports.AxisWheel, Horizontal: ports.ScrollAxis{Set: true, V120: 120}}) \|\| focused() != 2 {
		685	+	t.Fatalf("wheel after a sideways scroll on %d, want 2", focused())
		686	+	}
		687	+	// Once lifted, the next scroll starts with the short step again, and
		688	+	// one large frame takes the short step then a repeat.
		689	+	c := &Core{screens: []*screen{{mon: m}}}
		690	+	c.scrollStop(ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}})
		691	+	if !m.overviewScroll(finger(220, 0)) \|\| focused() != 3 {
		692	+	t.Fatalf("large frame on %d, want 3", focused())
		693	+	}
		694	+	// Reopening forgets a sideways scroll left without its stop.
		695	+	m.CancelOverview()
		696	+	m.Current().FocusID(3)
		697	+	m.ToggleOverview()
		698	+	if !m.overviewScroll(finger(-70, 0)) \|\| focused() != 2 {
		699	+	t.Fatalf("reopened sideways scroll on %d, want 2", focused())
		700	+	}
		701	+
		702	+	// Vertical: one step per scroll, through the stack's cards.
		703	+	sm := stackMonitor()
		704	+	sm.ToggleOverview()
		705	+	before, _ := sm.Focused()
		706	+	if !sm.overviewScroll(finger(0, 70)) {
		707	+	t.Fatal("first vertical step")
		708	+	}
		709	+	after, _ := sm.Focused()
		710	+	if after == before {
		711	+	t.Fatal("vertical step selected nothing new")
		712	+	}
		713	+	if sm.overviewScroll(finger(0, 400)) {
		714	+	t.Fatal("the same vertical scroll stepped twice")
		715	+	}
		716	+	if !sm.overviewScroll(ports.PointerAxis{Source: ports.AxisWheel, Vertical: ports.ScrollAxis{Set: true, V120: -120}}) {
		717	+	t.Fatal("wheel held by the finger scroll")
		718	+	}
		719	+	// A sideways finger scroll does not hold a vertical wheel notch.
		720	+	sm.CancelOverview()
		721	+	sm.ToggleOverview()
		722	+	sm.overviewScroll(finger(70, 0))
		723	+	if !sm.overviewScroll(ports.PointerAxis{Source: ports.AxisWheel, Vertical: ports.ScrollAxis{Set: true, V120: 120}}) {
		724	+	t.Fatal("vertical wheel held by a sideways finger scroll")
		725	+	}
		726	+	sm.CancelOverview()
		727	+	sm.ToggleOverview()
		728	+	if !sm.overviewScroll(finger(0, 70)) {
		729	+	t.Fatal("reopened overview still held the old scroll")
		730	+	}
		731	+	cont := ports.PointerAxis{Source: ports.AxisContinuous, Vertical: ports.ScrollAxis{Set: true, Value: -70}}
		732	+	if !sm.overviewScroll(cont) {
		733	+	t.Fatal("continuous scroll held by the finger scroll")
		734	+	}
		735	+	}

M internal/core/slide.go +37 -15


@@ -2,6 +2,7 @@ package core
2	2
3	3		import (
4	4		"math"
	5	+	"slices"
5	6		"time"
6	7		)
7	8

@@ -37,33 +38,54 @@ func (w *Workspace) swipeScale() float64 {
37	38		return float64(w.Usable.W) / viewSwipeMovement
38	39		}
39	40
40		-	// snap returns the view closest to target that aligns a column edge with
41		-	// the usable area, never past the first or last column, and the column to
42		-	// focus there: the current one while it stays fully shown, else the
43		-	// furthest fully shown column toward the swipe (forward is rightward).
44		-	func (w *Workspace) snap(target float64, forward bool) (view, focus int) {
	41	+	// snapPoints are the sorted views that align a column edge with the usable
	42	+	// area, never past the first or last column. Points closer than a
	43	+	// snapSpacing of the usable width merge into the first: a swipe step
	44	+	// always moves the view visibly.
	45	+	func (w *Workspace) snapPoints() []float64 {
45	46		g := w.gap()
46	47		minX, maxX := w.Usable.X+g, w.Usable.X+w.Usable.W-g
47	48		last := len(w.Columns) - 1
48	49		lo := w.columnX(0) - minX
49	50		hi := max(w.columnX(last)+w.columnWidth(last)-maxX, lo)
50		-	view, best := lo, math.Inf(1)
51		-	try := func(v int) {
52		-	v = min(max(v, lo), hi)
53		-	if d := math.Abs(float64(v) - target); d < best {
54		-	view, best = v, d
	51	+	views := make([]int, 0, 2*len(w.Columns))
	52	+	for i := range w.Columns {
	53	+	views = append(views, min(max(w.columnX(i)-minX, lo), hi), min(max(w.columnX(i)+w.columnWidth(i)-maxX, lo), hi))
	54	+	}
	55	+	slices.Sort(views)
	56	+	minStep := float64(w.Usable.W) * snapSpacing
	57	+	points := []float64{float64(lo)}
	58	+	for _, v := range views {
	59	+	if float64(v)-points[len(points)-1] >= minStep {
	60	+	points = append(points, float64(v))
55	61		}
56	62		}
57		-	for i := range w.Columns {
58		-	try(w.columnX(i) - minX)
59		-	try(w.columnX(i) + w.columnWidth(i) - maxX)
	63	+	// The last column's end stays a point; a point close before it goes.
	64	+	if n := len(points); float64(hi) != points[n-1] {
	65	+	if n > 1 && float64(hi)-points[n-1] < minStep {
	66	+	points = points[:n-1]
	67	+	}
	68	+	points = append(points, float64(hi))
60	69		}
	70	+	return points
	71	+	}
	72	+
	73	+	// snapSpacing is the smallest distance between column snap points, in
	74	+	// usable widths.
	75	+	const snapSpacing = 0.1
	76	+
	77	+	// snapFocus is the column to focus at view: the current one while it stays
	78	+	// fully shown at the current view, else the furthest fully shown column
	79	+	// toward the swipe (forward is rightward).
	80	+	func (w *Workspace) snapFocus(view int, forward bool) (focus int) {
	81	+	g := w.gap()
	82	+	minX, maxX := w.Usable.X+g, w.Usable.X+w.Usable.W-g
61	83		full := func(i int) bool {
62	84		x := w.columnX(i) - view
63	85		return x >= minX && x+w.columnWidth(i) <= maxX
64	86		}
65	87		if full(w.Focus) && view == w.ViewX {
66		-	return view, w.Focus
	88	+	return w.Focus
67	89		}
68	90		focus = -1
69	91		for i := range w.Columns {

@@ -80,7 +102,7 @@ func (w *Workspace) snap(target float64, forward bool) (view, focus int) {
80	102		}
81	103		}
82	104		}
83		-	return view, focus
	105	+	return focus
84	106		}
85	107
86	108		func (m *Monitor) stopSwitch() { m.switchOff, m.switchMotion, m.switchList = 0, nil, nil }

 import (
 	"math"
+	"slices"
 	"time"
 )
 	return float64(w.Usable.W) / viewSwipeMovement
 }
-// snap returns the view closest to target that aligns a column edge with
+// snapPoints are the sorted views that align a column edge with the usable
-// the usable area, never past the first or last column, and the column to
+// area, never past the first or last column. Points closer than a
-// focus there: the current one while it stays fully shown, else the
+// snapSpacing of the usable width merge into the first: a swipe step
-// furthest fully shown column toward the swipe (forward is rightward).
+// always moves the view visibly.
-func (w *Workspace) snap(target float64, forward bool) (view, focus int) {
+func (w *Workspace) snapPoints() []float64 {
 	g := w.gap()
 	minX, maxX := w.Usable.X+g, w.Usable.X+w.Usable.W-g
 	last := len(w.Columns) - 1
 	lo := w.columnX(0) - minX
 	hi := max(w.columnX(last)+w.columnWidth(last)-maxX, lo)
-	view, best := lo, math.Inf(1)
+	views := make([]int, 0, 2*len(w.Columns))
-	try := func(v int) {
+	for i := range w.Columns {
-		v = min(max(v, lo), hi)
+		views = append(views, min(max(w.columnX(i)-minX, lo), hi), min(max(w.columnX(i)+w.columnWidth(i)-maxX, lo), hi))
-		if d := math.Abs(float64(v) - target); d < best {
+	}
-			view, best = v, d
+	slices.Sort(views)
+	minStep := float64(w.Usable.W) * snapSpacing
+	points := []float64{float64(lo)}
+	for _, v := range views {
+		if float64(v)-points[len(points)-1] >= minStep {
+			points = append(points, float64(v))
 		}
 	}
-	for i := range w.Columns {
+	// The last column's end stays a point; a point close before it goes.
-		try(w.columnX(i) - minX)
+	if n := len(points); float64(hi) != points[n-1] {
-		try(w.columnX(i) + w.columnWidth(i) - maxX)
+		if n > 1 && float64(hi)-points[n-1] < minStep {
+			points = points[:n-1]
+		}
+		points = append(points, float64(hi))
 	}
+	return points
+}
+// snapSpacing is the smallest distance between column snap points, in
+// usable widths.
+const snapSpacing = 0.1
+// snapFocus is the column to focus at view: the current one while it stays
+// fully shown at the current view, else the furthest fully shown column
+// toward the swipe (forward is rightward).
+func (w *Workspace) snapFocus(view int, forward bool) (focus int) {
+	g := w.gap()
+	minX, maxX := w.Usable.X+g, w.Usable.X+w.Usable.W-g
 	full := func(i int) bool {
 		x := w.columnX(i) - view
 		return x >= minX && x+w.columnWidth(i) <= maxX
 	}
 	if full(w.Focus) && view == w.ViewX {
-		return view, w.Focus
+		return w.Focus
 	}
 	focus = -1
 	for i := range w.Columns {
 			}
 		}
 	}
-	return view, focus
+	return focus
 }
 func (m *Monitor) stopSwitch() { m.switchOff, m.switchMotion, m.switchList = 0, nil, nil }

A internal/core/snapswipe.go +187 -0

@@ -0,0 +1,187 @@
	1	+	package core
	2	+
	3	+	import (
	4	+	"math"
	5	+	"slices"
	6	+	"time"
	7	+	)
	8	+
	9	+	// A snap swipe moves a view through sorted snap points (libadwaita's swipe
	10	+	// tracker): one gesture reaches the neighbors of the point it starts from
	11	+	// at most, so a quick flick never skips a point. Past them the view resists
	12	+	// (rubber band); between points it sticks near each point and speeds up in
	13	+	// between (detents). When the fingers lift, a quick swipe goes on to the
	14	+	// next point in its direction; a slow one settles on the closest point.
	15	+
	16	+	const (
	17	+	// snapVelocity is the touchpad speed, in units per second, above which
	18	+	// a swipe goes on to the next point (libadwaita's touchpad threshold).
	19	+	snapVelocity = 600.0
	20	+	// detent is how much the view sticks near a snap point: it follows the
	21	+	// fingers at 1-detent there and 1+detent halfway between points.
	22	+	detent = 0.3
	23	+	// snapEpsilon is how close to a point counts as on it.
	24	+	snapEpsilon = 1e-6
	25	+	)
	26	+
	27	+	type snapSwipe struct {
	28	+	tracker swipeTracker
	29	+	// scale turns touchpad units into view units.
	30	+	scale float64
	31	+	// start is the view shown when the swipe began; points are sorted.
	32	+	start float64
	33	+	points []float64
	34	+	// home indexes the point the view rests on or lands on when the swipe
	35	+	// began: the swipe steps from it, so a swipe during a landing goes one
	36	+	// step past the landing, not from wherever the slide shows.
	37	+	home int
	38	+	// landLo and landHi are home's neighbors: where the swipe may land.
	39	+	landLo, landHi float64
	40	+	// lo and hi bound the fingers' view before resistance: the neighbors,
	41	+	// widened to start when a slide was caught past them.
	42	+	lo, hi float64
	43	+	// stops are the detent ends: the points within [lo, hi], and start.
	44	+	stops []float64
	45	+	band rubberBand
	46	+	}
	47	+
	48	+	// newSnapSwipe follows a swipe from the view start toward points, the view
	49	+	// resting on or heading to rest. A rest between points becomes a point:
	50	+	// a slow swipe never settles behind the view it started from.
	51	+	func newSnapSwipe(start, rest, scale float64, points []float64, band rubberBand) snapSwipe {
	52	+	s := snapSwipe{scale: scale, start: start, points: points, band: band}
	53	+	s.points = withPoint(s.points, rest)
	54	+	s.home = s.closest(rest)
	55	+	s.landLo = s.points[max(s.home-1, 0)]
	56	+	s.landHi = s.points[min(s.home+1, len(s.points)-1)]
	57	+	s.lo, s.hi = min(s.landLo, start), max(s.landHi, start)
	58	+	for _, v := range s.points {
	59	+	if v >= s.lo && v <= s.hi {
	60	+	s.stops = append(s.stops, v)
	61	+	}
	62	+	}
	63	+	s.stops = withPoint(s.stops, start)
	64	+	return s
	65	+	}
	66	+
	67	+	// withPoint returns sorted points with v added unless one is within
	68	+	// snapEpsilon of it.
	69	+	func withPoint(points []float64, v float64) []float64 {
	70	+	i, _ := slices.BinarySearch(points, v)
	71	+	if i < len(points) && points[i]-v <= snapEpsilon \|\| i > 0 && v-points[i-1] <= snapEpsilon {
	72	+	return points
	73	+	}
	74	+	return slices.Insert(slices.Clone(points), i, v)
	75	+	}
	76	+
	77	+	// indexPoints are the points 0 to n-1: one per workspace.
	78	+	func indexPoints(n int) []float64 {
	79	+	points := make([]float64, n)
	80	+	for i := range points {
	81	+	points[i] = float64(i)
	82	+	}
	83	+	return points
	84	+	}
	85	+
	86	+	func (s *snapSwipe) closest(pos float64) int {
	87	+	best := 0
	88	+	for i, v := range s.points {
	89	+	if math.Abs(v-pos) < math.Abs(s.points[best]-pos) {
	90	+	best = i
	91	+	}
	92	+	}
	93	+	return best
	94	+	}
	95	+
	96	+	func (s *snapSwipe) push(delta float64, at time.Duration) { s.tracker.push(delta, at) }
	97	+
	98	+	// raw is where the fingers put the view, before resistance and detents.
	99	+	func (s snapSwipe) raw() float64 { return s.start + s.tracker.poss.scale }
	100	+
	101	+	// pos is the view shown: rubber-banded past the bounds, with detents
	102	+	// between them.
	103	+	func (s *snapSwipe) pos() float64 {
	104	+	x := s.raw()
	105	+	if x < s.lo \|\| x > s.hi {
	106	+	return s.band.clamp(s.lo, s.hi, x)
	107	+	}
	108	+	a, b, ok := s.around(x)
	109	+	if !ok {
	110	+	return x
	111	+	}
	112	+	t := (x - a) / (b - a)
	113	+	return a + (b-a)(t-detentmath.Sin(2math.Pit)/(2*math.Pi))
	114	+	}
	115	+
	116	+	// slope is the derivative of pos at the fingers' view.
	117	+	func (s *snapSwipe) slope() float64 {
	118	+	x := s.raw()
	119	+	if x < s.lo \|\| x > s.hi {
	120	+	return s.band.clampDerivative(s.lo, s.hi, x)
	121	+	}
	122	+	a, b, ok := s.around(x)
	123	+	if !ok {
	124	+	return 1
	125	+	}
	126	+	return 1 - detentmath.Cos(2math.Pi*(x-a)/(b-a))
	127	+	}
	128	+
	129	+	// around returns the stops around x, which lies within [lo, hi].
	130	+	func (s *snapSwipe) around(x float64) (a, b float64, ok bool) {
	131	+	for i := 1; i < len(s.stops); i++ {
	132	+	if x <= s.stops[i] {
	133	+	a, b = s.stops[i-1], s.stops[i]
	134	+	return a, b, b-a > snapEpsilon
	135	+	}
	136	+	}
	137	+	return 0, 0, false
	138	+	}
	139	+
	140	+	// end is the point the swipe settles on when the fingers lift (home when
	141	+	// cancelled), and the view's speed for the spring there, in view units
	142	+	// per second.
	143	+	func (s *snapSwipe) end(cancelled bool, at time.Duration) (target, velocity float64) {
	144	+	// Idle time before the lift slows the swipe down.
	145	+	s.tracker.push(0, at)
	146	+	v := s.tracker.velocity()
	147	+	velocity = v * s.scale * s.slope()
	148	+	switch {
	149	+	case cancelled:
	150	+	return s.points[s.home], velocity
	151	+	case math.Abs(v) < snapVelocity:
	152	+	return min(max(s.points[s.closest(s.raw())], s.landLo), s.landHi), velocity
	153	+	}
	154	+	// A quick swipe lands on the first landing point at or past where its
	155	+	// speed would carry it, in its direction.
	156	+	proj := min(max(s.start+s.tracker.projectedEnd()*s.scale, s.landLo), s.landHi)
	157	+	land := [3]float64{s.landLo, s.points[s.home], s.landHi}
	158	+	if v > 0 {
	159	+	for _, p := range land {
	160	+	if p >= proj-snapEpsilon {
	161	+	return p, velocity
	162	+	}
	163	+	}
	164	+	}
	165	+	// proj lies within [landLo, landHi]: one of them always matches.
	166	+	for _, p := range slices.Backward(land[:]) {
	167	+	if p <= proj+snapEpsilon {
	168	+	return p, velocity
	169	+	}
	170	+	}
	171	+	return s.landLo, velocity
	172	+	}
	173	+
	174	+	// discreteSwipeMovement is the touchpad distance of one step of a swipe
	175	+	// that runs an action instead of sliding the view.
	176	+	const discreteSwipeMovement = 300.0
	177	+
	178	+	// newStepSwipe is a swipe that settles on a step of -1, 0 or 1.
	179	+	func newStepSwipe() snapSwipe {
	180	+	return newSnapSwipe(0, 0, 1/discreteSwipeMovement, []float64{-1, 0, 1}, workspaceBand)
	181	+	}
	182	+
	183	+	// step is where a step swipe settles when the fingers lift.
	184	+	func (s *snapSwipe) step(cancelled bool, at time.Duration) int {
	185	+	target, _ := s.end(cancelled, at)
	186	+	return int(math.Round(target))
	187	+	}

@@ -0,0 +1,187 @@
	1	+	package core
	2	+
	3	+	import (
	4	+	"math"
	5	+	"slices"
	6	+	"time"
	7	+	)
	8	+
	9	+	// A snap swipe moves a view through sorted snap points (libadwaita's swipe
	10	+	// tracker): one gesture reaches the neighbors of the point it starts from
	11	+	// at most, so a quick flick never skips a point. Past them the view resists
	12	+	// (rubber band); between points it sticks near each point and speeds up in
	13	+	// between (detents). When the fingers lift, a quick swipe goes on to the
	14	+	// next point in its direction; a slow one settles on the closest point.
	15	+
	16	+	const (
	17	+	// snapVelocity is the touchpad speed, in units per second, above which
	18	+	// a swipe goes on to the next point (libadwaita's touchpad threshold).
	19	+	snapVelocity = 600.0
	20	+	// detent is how much the view sticks near a snap point: it follows the
	21	+	// fingers at 1-detent there and 1+detent halfway between points.
	22	+	detent = 0.3
	23	+	// snapEpsilon is how close to a point counts as on it.
	24	+	snapEpsilon = 1e-6
	25	+	)
	26	+
	27	+	type snapSwipe struct {
	28	+	tracker swipeTracker
	29	+	// scale turns touchpad units into view units.
	30	+	scale float64
	31	+	// start is the view shown when the swipe began; points are sorted.
	32	+	start float64
	33	+	points []float64
	34	+	// home indexes the point the view rests on or lands on when the swipe
	35	+	// began: the swipe steps from it, so a swipe during a landing goes one
	36	+	// step past the landing, not from wherever the slide shows.
	37	+	home int
	38	+	// landLo and landHi are home's neighbors: where the swipe may land.
	39	+	landLo, landHi float64
	40	+	// lo and hi bound the fingers' view before resistance: the neighbors,
	41	+	// widened to start when a slide was caught past them.
	42	+	lo, hi float64
	43	+	// stops are the detent ends: the points within [lo, hi], and start.
	44	+	stops []float64
	45	+	band rubberBand
	46	+	}
	47	+
	48	+	// newSnapSwipe follows a swipe from the view start toward points, the view
	49	+	// resting on or heading to rest. A rest between points becomes a point:
	50	+	// a slow swipe never settles behind the view it started from.
	51	+	func newSnapSwipe(start, rest, scale float64, points []float64, band rubberBand) snapSwipe {
	52	+	s := snapSwipe{scale: scale, start: start, points: points, band: band}
	53	+	s.points = withPoint(s.points, rest)
	54	+	s.home = s.closest(rest)
	55	+	s.landLo = s.points[max(s.home-1, 0)]
	56	+	s.landHi = s.points[min(s.home+1, len(s.points)-1)]
	57	+	s.lo, s.hi = min(s.landLo, start), max(s.landHi, start)
	58	+	for _, v := range s.points {
	59	+	if v >= s.lo && v <= s.hi {
	60	+	s.stops = append(s.stops, v)
	61	+	}
	62	+	}
	63	+	s.stops = withPoint(s.stops, start)
	64	+	return s
	65	+	}
	66	+
	67	+	// withPoint returns sorted points with v added unless one is within
	68	+	// snapEpsilon of it.
	69	+	func withPoint(points []float64, v float64) []float64 {
	70	+	i, _ := slices.BinarySearch(points, v)
	71	+	if i < len(points) && points[i]-v <= snapEpsilon \|\| i > 0 && v-points[i-1] <= snapEpsilon {
	72	+	return points
	73	+	}
	74	+	return slices.Insert(slices.Clone(points), i, v)
	75	+	}
	76	+
	77	+	// indexPoints are the points 0 to n-1: one per workspace.
	78	+	func indexPoints(n int) []float64 {
	79	+	points := make([]float64, n)
	80	+	for i := range points {
	81	+	points[i] = float64(i)
	82	+	}
	83	+	return points
	84	+	}
	85	+
	86	+	func (s *snapSwipe) closest(pos float64) int {
	87	+	best := 0
	88	+	for i, v := range s.points {
	89	+	if math.Abs(v-pos) < math.Abs(s.points[best]-pos) {
	90	+	best = i
	91	+	}
	92	+	}
	93	+	return best
	94	+	}
	95	+
	96	+	func (s *snapSwipe) push(delta float64, at time.Duration) { s.tracker.push(delta, at) }
	97	+
	98	+	// raw is where the fingers put the view, before resistance and detents.
	99	+	func (s snapSwipe) raw() float64 { return s.start + s.tracker.poss.scale }
	100	+
	101	+	// pos is the view shown: rubber-banded past the bounds, with detents
	102	+	// between them.
	103	+	func (s *snapSwipe) pos() float64 {
	104	+	x := s.raw()
	105	+	if x < s.lo \|\| x > s.hi {
	106	+	return s.band.clamp(s.lo, s.hi, x)
	107	+	}
	108	+	a, b, ok := s.around(x)
	109	+	if !ok {
	110	+	return x
	111	+	}
	112	+	t := (x - a) / (b - a)
	113	+	return a + (b-a)(t-detentmath.Sin(2math.Pit)/(2*math.Pi))
	114	+	}
	115	+
	116	+	// slope is the derivative of pos at the fingers' view.
	117	+	func (s *snapSwipe) slope() float64 {
	118	+	x := s.raw()
	119	+	if x < s.lo \|\| x > s.hi {
	120	+	return s.band.clampDerivative(s.lo, s.hi, x)
	121	+	}
	122	+	a, b, ok := s.around(x)
	123	+	if !ok {
	124	+	return 1
	125	+	}
	126	+	return 1 - detentmath.Cos(2math.Pi*(x-a)/(b-a))
	127	+	}
	128	+
	129	+	// around returns the stops around x, which lies within [lo, hi].
	130	+	func (s *snapSwipe) around(x float64) (a, b float64, ok bool) {
	131	+	for i := 1; i < len(s.stops); i++ {
	132	+	if x <= s.stops[i] {
	133	+	a, b = s.stops[i-1], s.stops[i]
	134	+	return a, b, b-a > snapEpsilon
	135	+	}
	136	+	}
	137	+	return 0, 0, false
	138	+	}
	139	+
	140	+	// end is the point the swipe settles on when the fingers lift (home when
	141	+	// cancelled), and the view's speed for the spring there, in view units
	142	+	// per second.
	143	+	func (s *snapSwipe) end(cancelled bool, at time.Duration) (target, velocity float64) {
	144	+	// Idle time before the lift slows the swipe down.
	145	+	s.tracker.push(0, at)
	146	+	v := s.tracker.velocity()
	147	+	velocity = v * s.scale * s.slope()
	148	+	switch {
	149	+	case cancelled:
	150	+	return s.points[s.home], velocity
	151	+	case math.Abs(v) < snapVelocity:
	152	+	return min(max(s.points[s.closest(s.raw())], s.landLo), s.landHi), velocity
	153	+	}
	154	+	// A quick swipe lands on the first landing point at or past where its
	155	+	// speed would carry it, in its direction.
	156	+	proj := min(max(s.start+s.tracker.projectedEnd()*s.scale, s.landLo), s.landHi)
	157	+	land := [3]float64{s.landLo, s.points[s.home], s.landHi}
	158	+	if v > 0 {
	159	+	for _, p := range land {
	160	+	if p >= proj-snapEpsilon {
	161	+	return p, velocity
	162	+	}
	163	+	}
	164	+	}
	165	+	// proj lies within [landLo, landHi]: one of them always matches.
	166	+	for _, p := range slices.Backward(land[:]) {
	167	+	if p <= proj+snapEpsilon {
	168	+	return p, velocity
	169	+	}
	170	+	}
	171	+	return s.landLo, velocity
	172	+	}
	173	+
	174	+	// discreteSwipeMovement is the touchpad distance of one step of a swipe
	175	+	// that runs an action instead of sliding the view.
	176	+	const discreteSwipeMovement = 300.0
	177	+
	178	+	// newStepSwipe is a swipe that settles on a step of -1, 0 or 1.
	179	+	func newStepSwipe() snapSwipe {
	180	+	return newSnapSwipe(0, 0, 1/discreteSwipeMovement, []float64{-1, 0, 1}, workspaceBand)
	181	+	}
	182	+
	183	+	// step is where a step swipe settles when the fingers lift.
	184	+	func (s *snapSwipe) step(cancelled bool, at time.Duration) int {
	185	+	target, _ := s.end(cancelled, at)
	186	+	return int(math.Round(target))
	187	+	}

M internal/core/swipe_test.go +149 -8


@@ -166,13 +166,20 @@ func TestSwipeFollowsFingers(t *testing.T) {
166	166		r.input <- ports.SwipeUpdate{DX: -10, Time: r.at}
167	167		s := r.move(t, -10, 0)
168	168		after, _ := rectOf(s, 2)
169		-	// 10 units of 1200 per 800 px view: 7 px, not snapped to a column.
170		-	if d := after.X - before.X; d != 7 {
	169	+	// 10 units of 1200 per 800 px view are 7 px; near the resting view
	170	+	// the detent holds the view back a little.
	171	+	if d := after.X - before.X; d <= 0 \|\| d >= 7 {
171	172		t.Fatalf("column moved %d px with the fingers", d)
172	173		}
173		-	s = r.move(t, -30, 0)
174		-	if got, _ := rectOf(s, 2); got.X-before.X != 27 {
175		-	t.Fatalf("column moved %d px after 40 units", got.X-before.X)
	174	+	// Halfway to the next column edge (400 px: 600 units) the view has
	175	+	// caught up with the fingers; a full step shows whole.
	176	+	s = r.move(t, -290, 0)
	177	+	if got, _ := rectOf(s, 2); got.X-before.X != 200 {
	178	+	t.Fatalf("column moved %d px halfway", got.X-before.X)
	179	+	}
	180	+	s = r.move(t, -300, 0)
	181	+	if got, _ := rectOf(s, 2); got.X-before.X != 400 {
	182	+	t.Fatalf("column moved %d px after a full step", got.X-before.X)
176	183		}
177	184		}
178	185

@@ -478,13 +485,13 @@ func TestSwipeKeptWhenAnotherOutputSwitchesWorkspace(t *testing.T) {
478	485		}
479	486		// The swipe on DP-1 still follows the fingers.
480	487		var got ports.Rect
481		-	for _, sc := range receiveMove(t, r, -30) {
	488	+	for _, sc := range receiveMove(t, r, -570) {
482	489		if sc.Output == wide.Name {
483	490		got, _ = rectOf(sc, 2)
484	491		}
485	492		}
486		-	// 60 units at 2/3 px each: 40 px.
487		-	if got.X-before.X != 40 {
	493	+	// 600 units at 2/3 px each: a full step of 400 px.
	494	+	if got.X-before.X != 400 {
488	495		t.Fatalf("column 2 moved %d px", got.X-before.X)
489	496		}
490	497		}

@@ -684,3 +691,137 @@ func TestOverviewOpenedMidSwipeDropsIt(t *testing.T) {
684	691		}
685	692		}
686	693		}
	694	+
	695	+	// A hard flick down from the first of four workspaces lands on the second:
	696	+	// one swipe never skips a workspace.
	697	+	func TestSwipeHardFlickMovesOneWorkspace(t *testing.T) {
	698	+	r := startSwipe(t, nil)
	699	+	for id := ports.WindowID(1); id <= 4; id++ {
	700	+	r.mapWindow(t, id)
	701	+	r.key(t, "Next", ports.ModAlt)
	702	+	}
	703	+	for range 4 {
	704	+	r.key(t, "Prior", ports.ModAlt)
	705	+	}
	706	+	r.flick(t, 20, 0, 60)
	707	+	s := r.settle(t)
	708	+	if got, ok := rectOf(s, 2); !ok \|\| got.Y != 0 {
	709	+	t.Fatalf("hard flick did not land on workspace 2: %v %t", got, ok)
	710	+	}
	711	+	}
	712	+
	713	+	// A hard flick across many columns moves the view one column edge.
	714	+	func TestSwipeHardFlickMovesOneColumn(t *testing.T) {
	715	+	r := startSwipe(t, nil)
	716	+	for id := ports.WindowID(1); id <= 5; id++ {
	717	+	r.mapWindow(t, id)
	718	+	}
	719	+	// The view shows 4 and 5; a hard flick left shows 3 and 4, not 1.
	720	+	r.flick(t, 20, -60, 0)
	721	+	s := r.settle(t)
	722	+	if got, ok := rectOf(s, 3); !ok \|\| got.X != 0 {
	723	+	t.Fatalf("column 3 at %v %t, want the left edge", got, ok)
	724	+	}
	725	+	}
	726	+
	727	+	// A two-finger scroll that steps in the overview and ends with the pointer
	728	+	// on another output does not hold the next scroll back.
	729	+	func TestOverviewScrollStopOnOtherOutput(t *testing.T) {
	730	+	r := startSwipe(t, nil)
	731	+	threeColumns(t, r)
	732	+	r.plug(t, ports.OutputInfo{Name: "DP-2", Width: 800, Height: 600, RefreshMilli: 60000})
	733	+	r.key(t, "o", ports.ModAlt)
	734	+	selected := func(s ports.Scene) ports.WindowID {
	735	+	for _, w := range s.Windows {
	736	+	if w.Focused && w.Preview > 0 {
	737	+	return w.ID
	738	+	}
	739	+	}
	740	+	return 0
	741	+	}
	742	+	on := func(id ports.WindowID) func(ports.Scene) bool {
	743	+	return func(s ports.Scene) bool { return s.Output == wide.Name && selected(s) == id }
	744	+	}
	745	+	finger := func(dx float64) ports.PointerAxis {
	746	+	return ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Value: dx}}
	747	+	}
	748	+	r.input <- ports.PointerMotion{X: 100, Y: 300}
	749	+	r.input <- finger(-70)
	750	+	sceneMatch(t, r.scenes, on(2))
	751	+	// The pointer crosses to DP-2 and the fingers lift there.
	752	+	r.input <- ports.PointerMotion{X: 1000, Y: 300}
	753	+	r.input <- ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}}
	754	+	r.input <- ports.PointerMotion{X: 100, Y: 300}
	755	+	r.input <- finger(-70)
	756	+	sceneMatch(t, r.scenes, on(1))
	757	+	}
	758	+
	759	+	// The output shrinks mid-swipe: the snap points no longer hold, so the
	760	+	// swipe lets go. The view shows what the resize alone shows, and the rest
	761	+	// of the swipe moves nothing.
	762	+	func TestSwipeOutputResizedMidSwipe(t *testing.T) {
	763	+	smaller := ports.OutputInfo{Name: wide.Name, Width: 600, Height: 600, RefreshMilli: 60000}
	764	+	four := func(r *swipeRig) {
	765	+	for id := ports.WindowID(1); id <= 4; id++ {
	766	+	r.mapWindow(t, id)
	767	+	}
	768	+	}
	769	+	plain := startSwipe(t, nil)
	770	+	four(plain)
	771	+	plain.output <- ports.OutputAdded{Info: smaller}
	772	+	want := scene(t, plain.scenes)
	773	+
	774	+	r := startSwipe(t, nil)
	775	+	four(r)
	776	+	r.begin()
	777	+	for range 3 {
	778	+	r.move(t, -40, 0)
	779	+	}
	780	+	r.output <- ports.OutputAdded{Info: smaller}
	781	+	scene(t, r.scenes)
	782	+	// The first update after the resize lets go: the slide stops.
	783	+	s := r.move(t, -40, 0)
	784	+	for _, id := range []ports.WindowID{1, 2, 3, 4} {
	785	+	w, _ := rectOf(want, id)
	786	+	if got, _ := rectOf(s, id); got != w {
	787	+	t.Fatalf("window %d at %+v after the next update, want %+v", id, got, w)
	788	+	}
	789	+	}
	790	+	for range 2 {
	791	+	r.at += 8 * time.Millisecond
	792	+	r.input <- ports.SwipeUpdate{DX: -40, Time: r.at}
	793	+	}
	794	+	s = r.end(t, false)
	795	+	for _, id := range []ports.WindowID{1, 2, 3, 4} {
	796	+	w, _ := rectOf(want, id)
	797	+	if got, _ := rectOf(s, id); got != w {
	798	+	t.Fatalf("window %d at %+v, want %+v as without the swipe", id, got, w)
	799	+	}
	800	+	}
	801	+	}
	802	+
	803	+	// A window maps mid-swipe: the column snap points moved, so the swipe lets
	804	+	// go and the view shows what the map alone shows.
	805	+	func TestSwipeWindowMappedMidSwipe(t *testing.T) {
	806	+	plain := startSwipe(t, nil)
	807	+	threeColumns(t, plain)
	808	+	want := plain.mapWindow(t, 4)[0]
	809	+
	810	+	r := startSwipe(t, nil)
	811	+	threeColumns(t, r)
	812	+	r.begin()
	813	+	for range 3 {
	814	+	r.move(t, -40, 0)
	815	+	}
	816	+	r.mapWindow(t, 4)
	817	+	r.move(t, -40, 0)
	818	+	r.at += 8 * time.Millisecond
	819	+	r.input <- ports.SwipeUpdate{DX: -40, Time: r.at}
	820	+	s := r.end(t, false)
	821	+	for _, id := range []ports.WindowID{1, 2, 3, 4} {
	822	+	w, _ := rectOf(want, id)
	823	+	if got, _ := rectOf(s, id); got != w {
	824	+	t.Fatalf("window %d at %+v, want %+v as without the swipe", id, got, w)
	825	+	}
	826	+	}
	827	+	}


@@ -166,13 +166,20 @@ func TestSwipeFollowsFingers(t *testing.T) {
166		r.input <- ports.SwipeUpdate{DX: -10, Time: r.at}	166		r.input <- ports.SwipeUpdate{DX: -10, Time: r.at}
167		s := r.move(t, -10, 0)	167		s := r.move(t, -10, 0)
168		after, _ := rectOf(s, 2)	168		after, _ := rectOf(s, 2)
169	-	// 10 units of 1200 per 800 px view: 7 px, not snapped to a column.	169	+	// 10 units of 1200 per 800 px view are 7 px; near the resting view
170	-	if d := after.X - before.X; d != 7 {	170	+	// the detent holds the view back a little.
			171	+	if d := after.X - before.X; d <= 0 \|\| d >= 7 {
171		t.Fatalf("column moved %d px with the fingers", d)	172		t.Fatalf("column moved %d px with the fingers", d)
172		}	173		}
173	-	s = r.move(t, -30, 0)	174	+	// Halfway to the next column edge (400 px: 600 units) the view has
174	-	if got, _ := rectOf(s, 2); got.X-before.X != 27 {	175	+	// caught up with the fingers; a full step shows whole.
175	-	t.Fatalf("column moved %d px after 40 units", got.X-before.X)	176	+	s = r.move(t, -290, 0)
			177	+	if got, _ := rectOf(s, 2); got.X-before.X != 200 {
			178	+	t.Fatalf("column moved %d px halfway", got.X-before.X)
			179	+	}
			180	+	s = r.move(t, -300, 0)
			181	+	if got, _ := rectOf(s, 2); got.X-before.X != 400 {
			182	+	t.Fatalf("column moved %d px after a full step", got.X-before.X)
176		}	183		}
177		}	184		}
178			185

@@ -478,13 +485,13 @@ func TestSwipeKeptWhenAnotherOutputSwitchesWorkspace(t *testing.T) {
478		}	485		}
479		// The swipe on DP-1 still follows the fingers.	486		// The swipe on DP-1 still follows the fingers.
480		var got ports.Rect	487		var got ports.Rect
481	-	for _, sc := range receiveMove(t, r, -30) {	488	+	for _, sc := range receiveMove(t, r, -570) {
482		if sc.Output == wide.Name {	489		if sc.Output == wide.Name {
483		got, _ = rectOf(sc, 2)	490		got, _ = rectOf(sc, 2)
484		}	491		}
485		}	492		}
486	-	// 60 units at 2/3 px each: 40 px.	493	+	// 600 units at 2/3 px each: a full step of 400 px.
487	-	if got.X-before.X != 40 {	494	+	if got.X-before.X != 400 {
488		t.Fatalf("column 2 moved %d px", got.X-before.X)	495		t.Fatalf("column 2 moved %d px", got.X-before.X)
489		}	496		}
490		}	497		}

@@ -684,3 +691,137 @@ func TestOverviewOpenedMidSwipeDropsIt(t *testing.T) {
684		}	691		}
685		}	692		}
686		}	693		}
			694	+
			695	+	// A hard flick down from the first of four workspaces lands on the second:
			696	+	// one swipe never skips a workspace.
			697	+	func TestSwipeHardFlickMovesOneWorkspace(t *testing.T) {
			698	+	r := startSwipe(t, nil)
			699	+	for id := ports.WindowID(1); id <= 4; id++ {
			700	+	r.mapWindow(t, id)
			701	+	r.key(t, "Next", ports.ModAlt)
			702	+	}
			703	+	for range 4 {
			704	+	r.key(t, "Prior", ports.ModAlt)
			705	+	}
			706	+	r.flick(t, 20, 0, 60)
			707	+	s := r.settle(t)
			708	+	if got, ok := rectOf(s, 2); !ok \|\| got.Y != 0 {
			709	+	t.Fatalf("hard flick did not land on workspace 2: %v %t", got, ok)
			710	+	}
			711	+	}
			712	+
			713	+	// A hard flick across many columns moves the view one column edge.
			714	+	func TestSwipeHardFlickMovesOneColumn(t *testing.T) {
			715	+	r := startSwipe(t, nil)
			716	+	for id := ports.WindowID(1); id <= 5; id++ {
			717	+	r.mapWindow(t, id)
			718	+	}
			719	+	// The view shows 4 and 5; a hard flick left shows 3 and 4, not 1.
			720	+	r.flick(t, 20, -60, 0)
			721	+	s := r.settle(t)
			722	+	if got, ok := rectOf(s, 3); !ok \|\| got.X != 0 {
			723	+	t.Fatalf("column 3 at %v %t, want the left edge", got, ok)
			724	+	}
			725	+	}
			726	+
			727	+	// A two-finger scroll that steps in the overview and ends with the pointer
			728	+	// on another output does not hold the next scroll back.
			729	+	func TestOverviewScrollStopOnOtherOutput(t *testing.T) {
			730	+	r := startSwipe(t, nil)
			731	+	threeColumns(t, r)
			732	+	r.plug(t, ports.OutputInfo{Name: "DP-2", Width: 800, Height: 600, RefreshMilli: 60000})
			733	+	r.key(t, "o", ports.ModAlt)
			734	+	selected := func(s ports.Scene) ports.WindowID {
			735	+	for _, w := range s.Windows {
			736	+	if w.Focused && w.Preview > 0 {
			737	+	return w.ID
			738	+	}
			739	+	}
			740	+	return 0
			741	+	}
			742	+	on := func(id ports.WindowID) func(ports.Scene) bool {
			743	+	return func(s ports.Scene) bool { return s.Output == wide.Name && selected(s) == id }
			744	+	}
			745	+	finger := func(dx float64) ports.PointerAxis {
			746	+	return ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Value: dx}}
			747	+	}
			748	+	r.input <- ports.PointerMotion{X: 100, Y: 300}
			749	+	r.input <- finger(-70)
			750	+	sceneMatch(t, r.scenes, on(2))
			751	+	// The pointer crosses to DP-2 and the fingers lift there.
			752	+	r.input <- ports.PointerMotion{X: 1000, Y: 300}
			753	+	r.input <- ports.PointerAxis{Source: ports.AxisFinger, Horizontal: ports.ScrollAxis{Set: true, Stop: true}}
			754	+	r.input <- ports.PointerMotion{X: 100, Y: 300}
			755	+	r.input <- finger(-70)
			756	+	sceneMatch(t, r.scenes, on(1))
			757	+	}
			758	+
			759	+	// The output shrinks mid-swipe: the snap points no longer hold, so the
			760	+	// swipe lets go. The view shows what the resize alone shows, and the rest
			761	+	// of the swipe moves nothing.
			762	+	func TestSwipeOutputResizedMidSwipe(t *testing.T) {
			763	+	smaller := ports.OutputInfo{Name: wide.Name, Width: 600, Height: 600, RefreshMilli: 60000}
			764	+	four := func(r *swipeRig) {
			765	+	for id := ports.WindowID(1); id <= 4; id++ {
			766	+	r.mapWindow(t, id)
			767	+	}
			768	+	}
			769	+	plain := startSwipe(t, nil)
			770	+	four(plain)
			771	+	plain.output <- ports.OutputAdded{Info: smaller}
			772	+	want := scene(t, plain.scenes)
			773	+
			774	+	r := startSwipe(t, nil)
			775	+	four(r)
			776	+	r.begin()
			777	+	for range 3 {
			778	+	r.move(t, -40, 0)
			779	+	}
			780	+	r.output <- ports.OutputAdded{Info: smaller}
			781	+	scene(t, r.scenes)
			782	+	// The first update after the resize lets go: the slide stops.
			783	+	s := r.move(t, -40, 0)
			784	+	for _, id := range []ports.WindowID{1, 2, 3, 4} {
			785	+	w, _ := rectOf(want, id)
			786	+	if got, _ := rectOf(s, id); got != w {
			787	+	t.Fatalf("window %d at %+v after the next update, want %+v", id, got, w)
			788	+	}
			789	+	}
			790	+	for range 2 {
			791	+	r.at += 8 * time.Millisecond
			792	+	r.input <- ports.SwipeUpdate{DX: -40, Time: r.at}
			793	+	}
			794	+	s = r.end(t, false)
			795	+	for _, id := range []ports.WindowID{1, 2, 3, 4} {
			796	+	w, _ := rectOf(want, id)
			797	+	if got, _ := rectOf(s, id); got != w {
			798	+	t.Fatalf("window %d at %+v, want %+v as without the swipe", id, got, w)
			799	+	}
			800	+	}
			801	+	}
			802	+
			803	+	// A window maps mid-swipe: the column snap points moved, so the swipe lets
			804	+	// go and the view shows what the map alone shows.
			805	+	func TestSwipeWindowMappedMidSwipe(t *testing.T) {
			806	+	plain := startSwipe(t, nil)
			807	+	threeColumns(t, plain)
			808	+	want := plain.mapWindow(t, 4)[0]
			809	+
			810	+	r := startSwipe(t, nil)
			811	+	threeColumns(t, r)
			812	+	r.begin()
			813	+	for range 3 {
			814	+	r.move(t, -40, 0)
			815	+	}
			816	+	r.mapWindow(t, 4)
			817	+	r.move(t, -40, 0)
			818	+	r.at += 8 * time.Millisecond
			819	+	r.input <- ports.SwipeUpdate{DX: -40, Time: r.at}
			820	+	s := r.end(t, false)
			821	+	for _, id := range []ports.WindowID{1, 2, 3, 4} {
			822	+	w, _ := rectOf(want, id)
			823	+	if got, _ := rectOf(s, id); got != w {
			824	+	t.Fatalf("window %d at %+v, want %+v as without the swipe", id, got, w)
			825	+	}
			826	+	}
			827	+	}