alpha.go RawHistoryFolder

1package wayland
2
3import (
4	"math"
5
6	"github.com/bnema/go-wayland-bindings/server/alphamodifier"
7	"github.com/bnema/go-wayland-bindings/server/wayland"
8	"github.com/bnema/purego-libwayland/server"
9)
10
11// wp_alpha_modifier_v1: a client fades a whole surface (Wine's layered
12// windows) without redrawing it. The multiplier is double-buffered and
13// travels with the content as Fade; the renderer blends it.
14
15func registerAlphaModifier(d *server.Display, s *Server) error {
16	return alphamodifier.NewWpAlphaModifierV1Global(d, 1, func(c server.Client, v, id uint32) {
17		_, _ = alphamodifier.NewWpAlphaModifierV1(c, int32(v), id, alphaManager{s})
18	})
19}
20
21type alphaManager struct{ server *Server }
22
23func (alphaManager) Destroy(*alphamodifier.WpAlphaModifierV1) {}
24
25func (m alphaManager) GetSurface(r *alphamodifier.WpAlphaModifierV1, id uint32, surf *wayland.Surface) {
26	state := m.server.surfaceOf(surf)
27	if state != nil && state.alpha != nil {
28		r.PostError(uint32(alphamodifier.WpAlphaModifierV1ErrorAlreadyConstructed), "surface already has an alpha modifier")
29		return
30	}
31	h := &alphaHandler{surface: state}
32	res, err := alphamodifier.NewWpAlphaModifierSurfaceV1(r.Client(), r.Version(), id, h)
33	if err != nil || state == nil {
34		return
35	}
36	state.alpha = h
37	res.OnDestroy = func() {
38		// Destroying it sets the multiplier back to opaque, double-buffered.
39		if state.alpha == h {
40			state.alpha = nil
41			state.next.fade = 0
42		}
43	}
44}
45
46type alphaHandler struct{ surface *surface }
47
48func (*alphaHandler) Destroy(*alphamodifier.WpAlphaModifierSurfaceV1) {}
49
50func (h *alphaHandler) SetMultiplier(r *alphamodifier.WpAlphaModifierSurfaceV1, factor uint32) {
51	if h.surface == nil || h.surface.destroyed || h.surface.alpha != h {
52		r.PostError(uint32(alphamodifier.WpAlphaModifierSurfaceV1ErrorNoSurface), "wl_surface was destroyed")
53		return
54	}
55	h.surface.next.fade = fade(factor)
56}
57
58// fade turns a multiplier (0 transparent, UINT32_MAX opaque) into Fade.
59func fade(factor uint32) float32 {
60	return float32(1 - float64(factor)/math.MaxUint32)
61}