feat(cef): scroll fluidity, video playback, and diagnostic improvements

- Detect monitor refresh rate via GdkMonitor and match CEF frame rate
  (120Hz monitor gets 120fps instead of hardcoded 60fps)
- Enable Chromium smooth scrolling for mouse wheel momentum/easing
- Enable kinetic scroll flag on GTK EventControllerScroll
- Always enable AudioHandler (unblocks video decode pipeline)
- Add autoplay-policy flag for muted video autoplay (Reddit feeds)
- Inject video diagnostic JS (pierces Shadow DOM, traces MSE codecs)
  TODO: remove once video playback is stable

commit: 73a16999217db83617c01044b2875fedc2d3f33a
author: brice · 7mo ago · 2026-03-23 18:57 UTC
committer: brice · 6mo ago · 2026-03-28 04:38 UTC
parent: e564832
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

5 files · +153 -11

M internal/infrastructure/cef/app.go +15 -6


@@ -28,20 +28,29 @@ const maxCmdLineLogLen = 200
28	28
29	29		func (a *dumberApp) OnBeforeCommandLineProcessing(processType string, commandLine purecef.CommandLine) {
30	30		log := logging.FromContext(a.engine.ctx)
31		-	cmdline := ""
32	31		if commandLine != nil {
33		-	cmdline = commandLine.GetCommandLineString()
	32	+	// Enable Chromium's built-in smooth scrolling animation — without this,
	33	+	// mouse wheel scroll jumps in discrete steps with no momentum/easing.
	34	+	commandLine.AppendSwitch("enable-smooth-scrolling")
	35	+
	36	+	// Allow video autoplay without requiring user gesture — sites like
	37	+	// Reddit autoplay muted videos in the feed; without this policy
	38	+	// Chromium blocks them, showing an infinite spinner.
	39	+	commandLine.AppendSwitchWithValue("autoplay-policy", "no-user-gesture-required")
	40	+
	41	+
	42	+	cmdline := commandLine.GetCommandLineString()
34	43		if len(cmdline) > maxCmdLineLogLen {
35	44		runes := []rune(cmdline)
36	45		if len(runes) > maxCmdLineLogLen {
37	46		cmdline = string(runes[:maxCmdLineLogLen]) + "…"
38	47		}
39	48		}
	49	+	log.Debug().
	50	+	Str("process_type", processType).
	51	+	Str("command_line", cmdline).
	52	+	Msg("cef: OnBeforeCommandLineProcessing")
40	53		}
41		-	log.Debug().
42		-	Str("process_type", processType).
43		-	Str("command_line", cmdline).
44		-	Msg("cef: OnBeforeCommandLineProcessing")
45	54		}
46	55		func (a *dumberApp) OnRegisterCustomSchemes(registrar purecef.SchemeRegistrar) {
47	56		options := int32(purecef.SchemeOptionsSchemeOptionStandard \|

 func (a *dumberApp) OnBeforeCommandLineProcessing(processType string, commandLine purecef.CommandLine) {
 	log := logging.FromContext(a.engine.ctx)
-	cmdline := ""
 	if commandLine != nil {
-		cmdline = commandLine.GetCommandLineString()
+		// Enable Chromium's built-in smooth scrolling animation — without this,
+		// mouse wheel scroll jumps in discrete steps with no momentum/easing.
+		commandLine.AppendSwitch("enable-smooth-scrolling")
+		// Allow video autoplay without requiring user gesture — sites like
+		// Reddit autoplay muted videos in the feed; without this policy
+		// Chromium blocks them, showing an infinite spinner.
+		commandLine.AppendSwitchWithValue("autoplay-policy", "no-user-gesture-required")
+		cmdline := commandLine.GetCommandLineString()
 		if len(cmdline) > maxCmdLineLogLen {
 			runes := []rune(cmdline)
 			if len(runes) > maxCmdLineLogLen {
 				cmdline = string(runes[:maxCmdLineLogLen]) + "…"
 			}
 		}
+		log.Debug().
+			Str("process_type", processType).
+			Str("command_line", cmdline).
+			Msg("cef: OnBeforeCommandLineProcessing")
 	}
-	log.Debug().
-		Str("process_type", processType).
-		Str("command_line", cmdline).
-		Msg("cef: OnBeforeCommandLineProcessing")
 }
 func (a *dumberApp) OnRegisterCustomSchemes(registrar purecef.SchemeRegistrar) {
 	options := int32(purecef.SchemeOptionsSchemeOptionStandard |

M internal/infrastructure/cef/content_injector.go +98 -0


@@ -66,6 +66,100 @@ const scrollbarAutoHideJS = `(function(){
66	66		});
67	67		})();`
68	68
	69	+	// videoDiagnosticJS monitors all <video> elements on the page and logs their
	70	+	// state changes to the console. This helps diagnose playback issues in CEF OSR.
	71	+	// TODO: remove once video playback is stable.
	72	+	const videoDiagnosticJS = `(function(){
	73	+	var tag = '[VIDEO-DIAG]';
	74	+	var events = ['loadstart','loadedmetadata','loadeddata','canplay','canplaythrough',
	75	+	'play','playing','pause','waiting','stalled','error','abort','emptied','suspend'];
	76	+
	77	+	function monitor(v, label) {
	78	+	if (v._dumberDiag) return;
	79	+	v._dumberDiag = true;
	80	+	console.warn(tag, label, 'src:', (v.src\|\|'').substring(0,80),
	81	+	'currentSrc:', (v.currentSrc\|\|'').substring(0,80),
	82	+	'readyState:', v.readyState, 'networkState:', v.networkState,
	83	+	'preload:', v.preload, 'autoplay:', v.autoplay);
	84	+	events.forEach(function(evt) {
	85	+	v.addEventListener(evt, function() {
	86	+	var err = v.error ? ('code='+v.error.code+' msg='+v.error.message) : 'none';
	87	+	console.warn(tag, evt, label, 'ready:', v.readyState, 'net:', v.networkState,
	88	+	'paused:', v.paused, 'error:', err, 'src:', (v.currentSrc\|\|v.src\|\|'').substring(0,80));
	89	+	});
	90	+	});
	91	+	}
	92	+
	93	+	// Recursively scan a root (document or shadowRoot) for video elements.
	94	+	function scanRoot(root, label) {
	95	+	root.querySelectorAll('video').forEach(function(v, i) { monitor(v, label+'#'+i); });
	96	+	// Pierce shadow DOMs.
	97	+	root.querySelectorAll('*').forEach(function(el) {
	98	+	if (el.shadowRoot) {
	99	+	scanRoot(el.shadowRoot, label+'>'+el.tagName.toLowerCase());
	100	+	// Observe inside shadow root too.
	101	+	observeRoot(el.shadowRoot, label+'>'+el.tagName.toLowerCase());
	102	+	}
	103	+	});
	104	+	}
	105	+
	106	+	function observeRoot(root, label) {
	107	+	new MutationObserver(function(muts) {
	108	+	muts.forEach(function(m) {
	109	+	m.addedNodes.forEach(function(n) {
	110	+	if (n.nodeName === 'VIDEO') monitor(n, label+'-dyn');
	111	+	if (n.querySelectorAll) {
	112	+	n.querySelectorAll('video').forEach(function(v) { monitor(v, label+'-nested'); });
	113	+	}
	114	+	// New element might have shadow root.
	115	+	if (n.shadowRoot) {
	116	+	scanRoot(n.shadowRoot, label+'>'+n.tagName.toLowerCase());
	117	+	observeRoot(n.shadowRoot, label+'>'+n.tagName.toLowerCase());
	118	+	}
	119	+	});
	120	+	});
	121	+	}).observe(root, {childList:true, subtree:true});
	122	+	}
	123	+
	124	+	// Patch attachShadow to automatically observe new shadow roots.
	125	+	var origAttach = Element.prototype.attachShadow;
	126	+	Element.prototype.attachShadow = function(opts) {
	127	+	var sr = origAttach.call(this, opts);
	128	+	console.warn(tag, 'shadowRoot attached on', this.tagName.toLowerCase());
	129	+	observeRoot(sr, 'shadow>'+this.tagName.toLowerCase());
	130	+	return sr;
	131	+	};
	132	+
	133	+	// Also intercept MediaSource to trace usage.
	134	+	if (window.MediaSource) {
	135	+	var origAddSB = MediaSource.prototype.addSourceBuffer;
	136	+	MediaSource.prototype.addSourceBuffer = function(mime) {
	137	+	console.warn(tag, 'MediaSource.addSourceBuffer:', mime,
	138	+	'supported:', MediaSource.isTypeSupported(mime));
	139	+	try { return origAddSB.call(this, mime); }
	140	+	catch(e) { console.error(tag, 'addSourceBuffer FAILED:', e.message, 'mime:', mime); throw e; }
	141	+	};
	142	+	var origURL = URL.createObjectURL;
	143	+	URL.createObjectURL = function(obj) {
	144	+	var url = origURL.call(this, obj);
	145	+	if (obj instanceof MediaSource) {
	146	+	console.warn(tag, 'URL.createObjectURL(MediaSource):', url.substring(0,80));
	147	+	}
	148	+	return url;
	149	+	};
	150	+	}
	151	+
	152	+	// Initial scan.
	153	+	scanRoot(document, 'doc');
	154	+
	155	+	// Observe document for new elements.
	156	+	observeRoot(document.documentElement, 'doc');
	157	+
	158	+	console.warn(tag, 'diagnostic active, MSE:', !!window.MediaSource,
	159	+	'h264:', MediaSource ? MediaSource.isTypeSupported('video/mp4; codecs="avc1.4d401e"') : 'n/a',
	160	+	'aac:', MediaSource ? MediaSource.isTypeSupported('audio/mp4; codecs="mp4a.40.2"') : 'n/a');
	161	+	})();`
	162	+
69	163		// contentInjector implements port.ContentInjector for the CEF engine.
70	164		// It stores CSS strings and injects them into webviews via ExecuteJavaScript.
71	165		// Thread-safe: InjectThemeCSS may be called from the UI thread while OnLoadEnd

@@ -181,6 +275,10 @@ func (ci contentInjector) onLoadEnd(wv WebView) {
181	275		// All pages get custom scrollbar styling with auto-hide.
182	276		ci.injectCSS(wv, "dumber-scrollbar", scrollbarCSS)
183	277		wv.RunJavaScript(context.Background(), scrollbarAutoHideJS)
	278	+
	279	+	// Video playback diagnostic — logs video element state changes.
	280	+	// TODO: remove once video playback is stable.
	281	+	wv.RunJavaScript(context.Background(), videoDiagnosticJS)
184	282		}
185	283
186	284		// injectCSS injects a CSS string as a <style> element via JavaScript.


@@ -66,6 +66,100 @@ const scrollbarAutoHideJS = `(function(){
66	});	66		});
67	})();`	67		})();`
68		68
		69	+	// videoDiagnosticJS monitors all <video> elements on the page and logs their
		70	+	// state changes to the console. This helps diagnose playback issues in CEF OSR.
		71	+	// TODO: remove once video playback is stable.
		72	+	const videoDiagnosticJS = `(function(){
		73	+	var tag = '[VIDEO-DIAG]';
		74	+	var events = ['loadstart','loadedmetadata','loadeddata','canplay','canplaythrough',
		75	+	'play','playing','pause','waiting','stalled','error','abort','emptied','suspend'];
		76	+
		77	+	function monitor(v, label) {
		78	+	if (v._dumberDiag) return;
		79	+	v._dumberDiag = true;
		80	+	console.warn(tag, label, 'src:', (v.src\|\|'').substring(0,80),
		81	+	'currentSrc:', (v.currentSrc\|\|'').substring(0,80),
		82	+	'readyState:', v.readyState, 'networkState:', v.networkState,
		83	+	'preload:', v.preload, 'autoplay:', v.autoplay);
		84	+	events.forEach(function(evt) {
		85	+	v.addEventListener(evt, function() {
		86	+	var err = v.error ? ('code='+v.error.code+' msg='+v.error.message) : 'none';
		87	+	console.warn(tag, evt, label, 'ready:', v.readyState, 'net:', v.networkState,
		88	+	'paused:', v.paused, 'error:', err, 'src:', (v.currentSrc\|\|v.src\|\|'').substring(0,80));
		89	+	});
		90	+	});
		91	+	}
		92	+
		93	+	// Recursively scan a root (document or shadowRoot) for video elements.
		94	+	function scanRoot(root, label) {
		95	+	root.querySelectorAll('video').forEach(function(v, i) { monitor(v, label+'#'+i); });
		96	+	// Pierce shadow DOMs.
		97	+	root.querySelectorAll('*').forEach(function(el) {
		98	+	if (el.shadowRoot) {
		99	+	scanRoot(el.shadowRoot, label+'>'+el.tagName.toLowerCase());
		100	+	// Observe inside shadow root too.
		101	+	observeRoot(el.shadowRoot, label+'>'+el.tagName.toLowerCase());
		102	+	}
		103	+	});
		104	+	}
		105	+
		106	+	function observeRoot(root, label) {
		107	+	new MutationObserver(function(muts) {
		108	+	muts.forEach(function(m) {
		109	+	m.addedNodes.forEach(function(n) {
		110	+	if (n.nodeName === 'VIDEO') monitor(n, label+'-dyn');
		111	+	if (n.querySelectorAll) {
		112	+	n.querySelectorAll('video').forEach(function(v) { monitor(v, label+'-nested'); });
		113	+	}
		114	+	// New element might have shadow root.
		115	+	if (n.shadowRoot) {
		116	+	scanRoot(n.shadowRoot, label+'>'+n.tagName.toLowerCase());
		117	+	observeRoot(n.shadowRoot, label+'>'+n.tagName.toLowerCase());
		118	+	}
		119	+	});
		120	+	});
		121	+	}).observe(root, {childList:true, subtree:true});
		122	+	}
		123	+
		124	+	// Patch attachShadow to automatically observe new shadow roots.
		125	+	var origAttach = Element.prototype.attachShadow;
		126	+	Element.prototype.attachShadow = function(opts) {
		127	+	var sr = origAttach.call(this, opts);
		128	+	console.warn(tag, 'shadowRoot attached on', this.tagName.toLowerCase());
		129	+	observeRoot(sr, 'shadow>'+this.tagName.toLowerCase());
		130	+	return sr;
		131	+	};
		132	+
		133	+	// Also intercept MediaSource to trace usage.
		134	+	if (window.MediaSource) {
		135	+	var origAddSB = MediaSource.prototype.addSourceBuffer;
		136	+	MediaSource.prototype.addSourceBuffer = function(mime) {
		137	+	console.warn(tag, 'MediaSource.addSourceBuffer:', mime,
		138	+	'supported:', MediaSource.isTypeSupported(mime));
		139	+	try { return origAddSB.call(this, mime); }
		140	+	catch(e) { console.error(tag, 'addSourceBuffer FAILED:', e.message, 'mime:', mime); throw e; }
		141	+	};
		142	+	var origURL = URL.createObjectURL;
		143	+	URL.createObjectURL = function(obj) {
		144	+	var url = origURL.call(this, obj);
		145	+	if (obj instanceof MediaSource) {
		146	+	console.warn(tag, 'URL.createObjectURL(MediaSource):', url.substring(0,80));
		147	+	}
		148	+	return url;
		149	+	};
		150	+	}
		151	+
		152	+	// Initial scan.
		153	+	scanRoot(document, 'doc');
		154	+
		155	+	// Observe document for new elements.
		156	+	observeRoot(document.documentElement, 'doc');
		157	+
		158	+	console.warn(tag, 'diagnostic active, MSE:', !!window.MediaSource,
		159	+	'h264:', MediaSource ? MediaSource.isTypeSupported('video/mp4; codecs="avc1.4d401e"') : 'n/a',
		160	+	'aac:', MediaSource ? MediaSource.isTypeSupported('audio/mp4; codecs="mp4a.40.2"') : 'n/a');
		161	+	})();`
		162	+
69	// contentInjector implements port.ContentInjector for the CEF engine.	163		// contentInjector implements port.ContentInjector for the CEF engine.
70	// It stores CSS strings and injects them into webviews via ExecuteJavaScript.	164		// It stores CSS strings and injects them into webviews via ExecuteJavaScript.
71	// Thread-safe: InjectThemeCSS may be called from the UI thread while OnLoadEnd	165		// Thread-safe: InjectThemeCSS may be called from the UI thread while OnLoadEnd

@@ -181,6 +275,10 @@ func (ci contentInjector) onLoadEnd(wv WebView) {
181	// All pages get custom scrollbar styling with auto-hide.	275		// All pages get custom scrollbar styling with auto-hide.
182	ci.injectCSS(wv, "dumber-scrollbar", scrollbarCSS)	276		ci.injectCSS(wv, "dumber-scrollbar", scrollbarCSS)
183	wv.RunJavaScript(context.Background(), scrollbarAutoHideJS)	277		wv.RunJavaScript(context.Background(), scrollbarAutoHideJS)
		278	+
		279	+	// Video playback diagnostic — logs video element state changes.
		280	+	// TODO: remove once video playback is stable.
		281	+	wv.RunJavaScript(context.Background(), videoDiagnosticJS)
184	}	282		}
185		283
186	// injectCSS injects a CSS string as a <style> element via JavaScript.	284		// injectCSS injects a CSS string as a <style> element via JavaScript.

M internal/infrastructure/cef/engine_init.go +34 -0


@@ -127,6 +127,14 @@ func wireEngine(
127	127
128	128		scale := detectHiDPIScale(logger)
129	129
	130	+	// If frame rate is the static default (60), try to match the monitor's
	131	+	// actual refresh rate for smoother scrolling on high-refresh displays.
	132	+	if windowlessFrameRate == 60 {
	133	+	if hz := detectMonitorRefreshRate(logger); hz > 0 {
	134	+	windowlessFrameRate = hz
	135	+	}
	136	+	}
	137	+
130	138		factory := newWebViewFactory(eng, gl, webViewFactoryOptions{
131	139		scale: scale,
132	140		windowlessFrameRate: windowlessFrameRate,

@@ -184,6 +192,32 @@ func detectHiDPIScale(logger *zerolog.Logger) int32 {
184	192		return 1
185	193		}
186	194
	195	+	// detectMonitorRefreshRate queries the primary GDK monitor for its refresh rate.
	196	+	// Returns the rate in Hz (e.g., 120 for a 120Hz display), or 0 if detection fails.
	197	+	func detectMonitorRefreshRate(logger *zerolog.Logger) int32 {
	198	+	display := gdk.DisplayGetDefault()
	199	+	if display == nil {
	200	+	return 0
	201	+	}
	202	+	monitors := display.GetMonitors()
	203	+	if monitors == nil {
	204	+	return 0
	205	+	}
	206	+	obj := monitors.GetObject(0)
	207	+	if obj == nil {
	208	+	return 0
	209	+	}
	210	+	mon := &gdk.Monitor{}
	211	+	mon.SetGoPointer(obj.GoPointer())
	212	+	milliHz := mon.GetRefreshRate()
	213	+	if milliHz <= 0 {
	214	+	return 0
	215	+	}
	216	+	hz := int32(milliHz / 1000)
	217	+	logger.Info().Int32("refresh_rate_hz", hz).Msg("cef: detected monitor refresh rate")
	218	+	return hz
	219	+	}
	220	+
187	221		// appendIfMissing appends flag to args if it's not already present.
188	222		func appendIfMissing(args []string, flag string) []string {
189	223		for _, a := range args {


@@ -127,6 +127,14 @@ func wireEngine(
127		127
128	scale := detectHiDPIScale(logger)	128		scale := detectHiDPIScale(logger)
129		129
		130	+	// If frame rate is the static default (60), try to match the monitor's
		131	+	// actual refresh rate for smoother scrolling on high-refresh displays.
		132	+	if windowlessFrameRate == 60 {
		133	+	if hz := detectMonitorRefreshRate(logger); hz > 0 {
		134	+	windowlessFrameRate = hz
		135	+	}
		136	+	}
		137	+
130	factory := newWebViewFactory(eng, gl, webViewFactoryOptions{	138		factory := newWebViewFactory(eng, gl, webViewFactoryOptions{
131	scale: scale,	139		scale: scale,
132	windowlessFrameRate: windowlessFrameRate,	140		windowlessFrameRate: windowlessFrameRate,

@@ -184,6 +192,32 @@ func detectHiDPIScale(logger *zerolog.Logger) int32 {
184	return 1	192		return 1
185	}	193		}
186		194
		195	+	// detectMonitorRefreshRate queries the primary GDK monitor for its refresh rate.
		196	+	// Returns the rate in Hz (e.g., 120 for a 120Hz display), or 0 if detection fails.
		197	+	func detectMonitorRefreshRate(logger *zerolog.Logger) int32 {
		198	+	display := gdk.DisplayGetDefault()
		199	+	if display == nil {
		200	+	return 0
		201	+	}
		202	+	monitors := display.GetMonitors()
		203	+	if monitors == nil {
		204	+	return 0
		205	+	}
		206	+	obj := monitors.GetObject(0)
		207	+	if obj == nil {
		208	+	return 0
		209	+	}
		210	+	mon := &gdk.Monitor{}
		211	+	mon.SetGoPointer(obj.GoPointer())
		212	+	milliHz := mon.GetRefreshRate()
		213	+	if milliHz <= 0 {
		214	+	return 0
		215	+	}
		216	+	hz := int32(milliHz / 1000)
		217	+	logger.Info().Int32("refresh_rate_hz", hz).Msg("cef: detected monitor refresh rate")
		218	+	return hz
		219	+	}
		220	+
187	// appendIfMissing appends flag to args if it's not already present.	221		// appendIfMissing appends flag to args if it's not already present.
188	func appendIfMissing(args []string, flag string) []string {	222		func appendIfMissing(args []string, flag string) []string {
189	for _, a := range args {	223		for _, a := range args {

M internal/infrastructure/cef/input_bridge.go +1 -1


@@ -107,7 +107,7 @@ func (ib inputBridge) attachTo(glArea gtk.GLArea) {
107	107		glArea.AddController(&click.EventController)
108	108
109	109		// Scroll
110		-	scroll := gtk.NewEventControllerScroll(gtk.EventControllerScrollBothAxesValue)
	110	+	scroll := gtk.NewEventControllerScroll(gtk.EventControllerScrollBothAxesValue \| gtk.EventControllerScrollKineticValue)
111	111		scrollCb := func(_ gtk.EventControllerScroll, dx, dy float64) bool {
112	112		ib.onScroll(dx, dy)
113	113		return true


@@ -107,7 +107,7 @@ func (ib inputBridge) attachTo(glArea gtk.GLArea) {
107		glArea.AddController(&click.EventController)	107		glArea.AddController(&click.EventController)
108			108
109		// Scroll	109		// Scroll
110	-	scroll := gtk.NewEventControllerScroll(gtk.EventControllerScrollBothAxesValue)	110	+	scroll := gtk.NewEventControllerScroll(gtk.EventControllerScrollBothAxesValue \| gtk.EventControllerScrollKineticValue)
111		scrollCb := func(_ gtk.EventControllerScroll, dx, dy float64) bool {	111		scrollCb := func(_ gtk.EventControllerScroll, dx, dy float64) bool {
112		ib.onScroll(dx, dy)	112		ib.onScroll(dx, dy)
113		return true	113		return true

M internal/infrastructure/cef/webview_handlers.go +5 -4


@@ -34,10 +34,11 @@ var (
34	34		// ===========================================================================
35	35
36	36		func (h *handlerSet) GetAudioHandler() purecef.AudioHandler {
37		-	if h.enableAudioHandler {
38		-	return h
39		-	}
40		-	return nil
	37	+	// Always return the audio handler — without it, CEF has no audio output
	38	+	// path and refuses to start media decoding, breaking all video playback.
	39	+	// The handler accepts audio but discards packets (no-op) until a real
	40	+	// audio backend (PipeWire/PulseAudio) is wired up.
	41	+	return h
41	42		}
42	43		func (h *handlerSet) GetCommandHandler() purecef.CommandHandler { return nil }
43	44		func (h *handlerSet) GetContextMenuHandler() purecef.ContextMenuHandler {

 // ===========================================================================
 func (h *handlerSet) GetAudioHandler() purecef.AudioHandler {
-	if h.enableAudioHandler {
+	// Always return the audio handler — without it, CEF has no audio output
-		return h
+	// path and refuses to start media decoding, breaking all video playback.
-	}
+	// The handler accepts audio but discards packets (no-op) until a real
-	return nil
+	// audio backend (PipeWire/PulseAudio) is wired up.
+	return h
 }
 func (h *handlerSet) GetCommandHandler() purecef.CommandHandler { return nil }
 func (h *handlerSet) GetContextMenuHandler() purecef.ContextMenuHandler {