app: avoid relocking contexts every frame

Signed-off-by: Joe Julian <me@joejulian.name>

app/gl_ios.go

@@ -115,9 +115,6 @@ func (c *context) Unlock() {
 }
 
 func (c *context) Refresh() error {
-	if C.gio_makeCurrent(c.ctx) == 0 {
-		return errors.New("[EAGLContext setCurrentContext] failed")
-	}
 	if !c.init {
 		c.init = true
 		c.frameBuffer = c.c.CreateFramebuffer()

app/gl_macos.go

@@ -111,8 +111,6 @@ func (c *glContext) Unlock() {
 }
 
 func (c *glContext) Refresh() error {
-	c.Lock()
-	defer c.Unlock()
 	C.gio_updateContext(c.ctx)
 	return nil
 }

app/os.go

@@ -165,6 +165,8 @@ type frameEvent struct {
 	Sync bool
 }
 
+// The caller must hold the context lock while using API, Refresh,
+// RenderTarget, or Present.
 type context interface {
 	API() gpu.API
 	RenderTarget() (gpu.RenderTarget, error)

app/window.go

@@ -46,6 +46,10 @@ type Window struct {
 
 	ctx context
 	gpu gpu.GPU
+	// ctxNeedsLock tracks whether the rendering context must be made
+	// current again before the next GPU operation. Refresh paths, surface
+	// loss, and explicit unlocks all invalidate the current binding.
+	ctxNeedsLock bool
 	// timer tracks the delayed invalidate goroutine.
 	timer struct {
 		// quit is shuts down the goroutine.
@@ -146,9 +150,14 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 				if err != nil {
 					return err
 				}
+				w.ctxNeedsLock = true
 				sync = true
 			}
 		}
+		if err := w.lockContext(); err != nil {
+			w.destroyGPU()
+			return err
+		}
 		if sync && w.ctx != nil {
 			if err := w.ctx.Refresh(); err != nil {
 				if errors.Is(err, errOutOfDate) {
@@ -162,9 +171,8 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 				}
 				return err
 			}
-		}
-		if w.ctx != nil {
-			if err := w.ctx.Lock(); err != nil {
+			w.unlockContext()
+			if err := w.lockContext(); err != nil {
 				w.destroyGPU()
 				return err
 			}
@@ -172,7 +180,7 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 		if w.gpu == nil && !w.nocontext {
 			gpu, err := gpu.New(w.ctx.API())
 			if err != nil {
-				w.ctx.Unlock()
+				w.unlockContext()
 				w.destroyGPU()
 				return err
 			}
@@ -180,7 +188,7 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 		}
 		if w.gpu != nil {
 			if err := w.frame(frame, size); err != nil {
-				w.ctx.Unlock()
+				w.unlockContext()
 				if errors.Is(err, errOutOfDate) {
 					// GPU surface needs refreshing.
 					sync = true
@@ -200,7 +208,6 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 		var err error
 		if w.gpu != nil {
 			err = w.ctx.Present()
-			w.ctx.Unlock()
 		}
 		return err
 	}
@@ -503,16 +510,37 @@ func (c *callbacks) ActionAt(p f32.Point) (system.Action, bool) {
 	return c.w.queue.ActionAt(p)
 }
 
+func (w *Window) lockContext() error {
+	if w.ctx == nil || !w.ctxNeedsLock {
+		return nil
+	}
+	if err := w.ctx.Lock(); err != nil {
+		return err
+	}
+	w.ctxNeedsLock = false
+	return nil
+}
+
+func (w *Window) unlockContext() {
+	if w.ctx == nil || w.ctxNeedsLock {
+		return
+	}
+	w.ctx.Unlock()
+	w.ctxNeedsLock = true
+}
+
 func (w *Window) destroyGPU() {
 	if w.gpu != nil {
-		w.ctx.Lock()
-		w.gpu.Release()
-		w.ctx.Unlock()
+		if err := w.lockContext(); err == nil {
+			w.gpu.Release()
+			w.unlockContext()
+		}
 		w.gpu = nil
 	}
 	if w.ctx != nil {
 		w.ctx.Release()
 		w.ctx = nil
+		w.ctxNeedsLock = false
 	}
 }
 
@@ -655,10 +683,11 @@ func (w *Window) processEvent(e event.Event) bool {
 		w.coalesced.destroy = &e2
 	case ViewEvent:
 		if !e2.Valid() && w.gpu != nil {
-			w.ctx.Lock()
-			w.gpu.Release()
+			if err := w.lockContext(); err == nil {
+				w.gpu.Release()
+				w.unlockContext()
+			}
 			w.gpu = nil
-			w.ctx.Unlock()
 		}
 		w.coalesced.view = &e2
 	case ConfigEvent:

font/opentype/opentype.go

@@ -106,7 +106,7 @@ func parseLoader(ld *opentype.Loader) (*fontapi.Font, giofont.Font, error) {
 // Face many be invoked any number of times and is safe so long as each return value is
 // only used by one goroutine.
 func (f Face) Face() *fontapi.Face {
-	return fontapi.NewFace(f.face)
+	return &fontapi.Face{Font: f.face}
 }
 
 // FontFace returns a text.Font with populated font metadata for the

gesture/gesture.go

@@ -61,8 +61,12 @@ func (h *Hover) Update(q input.Source) bool {
 				h.entered = false
 			}
 		case pointer.Enter:
-			h.pid = e.PointerID
-			h.entered = true
+			if !h.entered {
+				h.pid = e.PointerID
+			}
+			if h.pid == e.PointerID {
+				h.entered = true
+			}
 		}
 	}
 	return h.entered
@@ -218,7 +222,12 @@ func (c *Click) Update(q input.Source) (ClickEvent, bool) {
 			if e.Source == pointer.Mouse && e.Buttons != pointer.ButtonPrimary {
 				break
 			}
-			c.pid = e.PointerID
+			if !c.hovered {
+				c.pid = e.PointerID
+			}
+			if c.pid != e.PointerID {
+				break
+			}
 			c.pressed = true
 			if e.Time-c.clickedAt < doubleClickDuration {
 				c.clicks++

gesture/gesture_test.go

@@ -100,78 +100,6 @@ func TestMouseClicks(t *testing.T) {
 	}
 }
 
-func TestClickPointerIDReassignment(t *testing.T) {
-	// A Click must accept a Press from a PointerID that differs from the
-	// one its hovered state was previously associated with. Some backends
-	// reassign a single physical pointer's ID over its lifetime — e.g. the
-	// Windows pointer API across focus changes — and locking the gesture
-	// to the first observed ID would silently drop every subsequent press.
-	//
-	// The sequence below puts the gesture into the buggy state through
-	// public events alone: a press under PointerID 1 starts an active
-	// press cycle, a Move under PointerID 2 arrives mid-press (which the
-	// router routes as an Enter for PID 2 but the gesture's Enter handler
-	// is a no-op for pid while pressed), then PID 1 releases. After this,
-	// the router has the gesture entered for PID 2 (so the next event
-	// under PID 2 won't trigger another Enter) but the gesture itself
-	// still has pid=1.
-	var click Click
-	var ops op.Ops
-	rect := image.Rect(0, 0, 100, 100)
-	stack := clip.Rect(rect).Push(&ops)
-	click.Add(&ops)
-	stack.Pop()
-
-	var r input.Router
-	click.Update(r.Source())
-	r.Frame(&ops)
-
-	drain := func() {
-		for {
-			if _, ok := click.Update(r.Source()); !ok {
-				return
-			}
-		}
-	}
-
-	// Press under PointerID 1.
-	r.Queue(
-		pointer.Event{Kind: pointer.Move, Source: pointer.Mouse, Position: f32.Pt(50, 50), PointerID: 1},
-		pointer.Event{Kind: pointer.Press, Source: pointer.Mouse, Buttons: pointer.ButtonPrimary, Position: f32.Pt(50, 50), PointerID: 1},
-	)
-	drain()
-
-	// Move under PointerID 2 while PointerID 1 is still pressed. The
-	// router records the gesture as entered for PointerID 2 but the
-	// gesture's Enter handler is a no-op for pid because c.pressed.
-	r.Queue(pointer.Event{Kind: pointer.Move, Source: pointer.Mouse, Position: f32.Pt(50, 50), PointerID: 2})
-	drain()
-
-	// Release PointerID 1. PointerID 1's press tracking ends; the
-	// gesture's recorded pid stays at 1.
-	r.Queue(pointer.Event{Kind: pointer.Release, Source: pointer.Mouse, Position: f32.Pt(50, 50), PointerID: 1})
-	drain()
-
-	// Press under PointerID 2. The router won't refire Enter for PID 2
-	// (the gesture is already in PID 2's entered set), so the gesture's
-	// only chance to refresh its pid is the Press handler itself.
-	r.Queue(pointer.Event{Kind: pointer.Press, Source: pointer.Mouse, Buttons: pointer.ButtonPrimary, Position: f32.Pt(50, 50), PointerID: 2})
-
-	var sawPress bool
-	for {
-		ev, ok := click.Update(r.Source())
-		if !ok {
-			break
-		}
-		if ev.Kind == KindPress {
-			sawPress = true
-		}
-	}
-	if !sawPress {
-		t.Fatal("expected KindPress for press under reassigned PointerID; gesture dropped the press because of stale recorded pid")
-	}
-}
-
 func mouseClickEvents(times ...time.Duration) []event.Event {
 	press := pointer.Event{
 		Kind:    pointer.Press,

go.mod

@@ -5,7 +5,7 @@ go 1.24.0
 require (
 	eliasnaur.com/font v0.0.0-20230308162249-dd43949cb42d
 	gioui.org/shader v1.0.8
-	github.com/go-text/typesetting v0.3.4
+	github.com/go-text/typesetting v0.3.0
 	golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0
 	golang.org/x/exp/shiny v0.0.0-20250408133849-7e4ce0ab07d0
 	golang.org/x/image v0.26.0

go.sum

@@ -3,10 +3,10 @@ eliasnaur.com/font v0.0.0-20230308162249-dd43949cb42d/go.mod h1:OYVuxibdk9OSLX8v
 gioui.org/cpu v0.0.0-20210808092351-bfe733dd3334/go.mod h1:A8M0Cn5o+vY5LTMlnRoK3O5kG+rH0kWfJjeKd9QpBmQ=
 gioui.org/shader v1.0.8 h1:6ks0o/A+b0ne7RzEqRZK5f4Gboz2CfG+mVliciy6+qA=
 gioui.org/shader v1.0.8/go.mod h1:mWdiME581d/kV7/iEhLmUgUK5iZ09XR5XpduXzbePVM=
-github.com/go-text/typesetting v0.3.4 h1:YYurUOtEb9kGSOz4uE3k4OpBGsp1dDL8+fjCeaFamAU=
-github.com/go-text/typesetting v0.3.4/go.mod h1:4qZCQphq4KSgGTAeI0uMEkVbROgfah8BuyF5LRYr7XY=
-github.com/go-text/typesetting-utils v0.0.0-20260223113751-2d88ac90dae3 h1:drBZzMgdYPbmyXqOto4YhhJGrFIQCX94FpR4MzTCsos=
-github.com/go-text/typesetting-utils v0.0.0-20260223113751-2d88ac90dae3/go.mod h1:3/62I4La/HBRX9TcTpBj4eipLiwzf+vhI+7whTc9V7o=
+github.com/go-text/typesetting v0.3.0 h1:OWCgYpp8njoxSRpwrdd1bQOxdjOXDj9Rqart9ML4iF4=
+github.com/go-text/typesetting v0.3.0/go.mod h1:qjZLkhRgOEYMhU9eHBr3AR4sfnGJvOXNLt8yRAySFuY=
+github.com/go-text/typesetting-utils v0.0.0-20241103174707-87a29e9e6066 h1:qCuYC+94v2xrb1PoS4NIDe7DGYtLnU2wWiQe9a1B1c0=
+github.com/go-text/typesetting-utils v0.0.0-20241103174707-87a29e9e6066/go.mod h1:DDxDdQEnB70R8owOx3LVpEFvpMK9eeH1o2r0yZhFI9o=
 golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0 h1:R84qjqJb5nVJMxqWYb3np9L5ZsaDtB+a39EqjV0JSUM=
 golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0/go.mod h1:S9Xr4PYopiDyqSyp5NjCrhFrqg6A5zA2E/iPHPhqnS8=
 golang.org/x/exp/shiny v0.0.0-20250408133849-7e4ce0ab07d0 h1:tMSqXTK+AQdW3LpCbfatHSRPHeW6+2WuxaVQuHftn80=

io/input/pointer.go

@@ -739,10 +739,6 @@ func (q *pointerQueue) Push(handlers map[event.Tag]*handler, state pointerState,
 		state.pointers = nil
 		return state, evts
 	}
-	if e.Kind == pointer.Scroll {
-		// Scroll events are not bound to a pointer; see pointer.Event.PointerID.
-		return state, q.deliverScrollEvent(handlers, evts, e)
-	}
 	state, pidx := state.pointerOf(e)
 	p := state.pointers[pidx]
 
@@ -765,6 +761,9 @@ func (q *pointerQueue) Push(handlers map[event.Tag]*handler, state pointerState,
 		p.pressed = false
 		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
 		p, evts = q.deliverDropEvent(handlers, p, evts)
+	case pointer.Scroll:
+		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
+		evts = q.deliverEvent(handlers, p, evts, e)
 	default:
 		panic("unsupported pointer event type")
 	}
@@ -781,18 +780,6 @@ func (q *pointerQueue) Push(handlers map[event.Tag]*handler, state pointerState,
 	return state, evts
 }
 
-// deliverScrollEvent delivers scroll events to the handlers hit by the event coordinate.
-func (q *pointerQueue) deliverScrollEvent(handlers map[event.Tag]*handler, evts []taggedEvent, e pointer.Event) []taggedEvent {
-	var hits []event.Tag
-	q.hitTest(e.Position, func(n *hitNode) bool {
-		if _, ok := handlers[n.tag]; ok {
-			hits = addHandler(hits, n.tag)
-		}
-		return true
-	})
-	return q.deliverEvent(handlers, pointerInfo{handlers: hits}, evts, e)
-}
-
 func (q *pointerQueue) deliverEvent(handlers map[event.Tag]*handler, p pointerInfo, evts []taggedEvent, e pointer.Event) []taggedEvent {
 	if p.pressed && len(p.handlers) == 1 {
 		e.Priority = pointer.Grabbed

io/input/pointer_test.go

@@ -1345,40 +1345,3 @@ func events(r *Router, n int, filters ...event.Filter) []event.Event {
 	}
 	return events
 }
-
-// TestPointerScrollDoesNotTrackPointer queues two events over two cursor
-// regions. The Move puts the live pointer over the button (CursorPointer);
-// the Scroll happens over the cell (CursorText) and must not update the
-// cursor.
-func TestPointerScrollDoesNotTrackPointer(t *testing.T) {
-	var ops op.Ops
-
-	button := clip.Rect(image.Rect(0, 0, 50, 50)).Push(&ops)
-	pointer.CursorPointer.Add(&ops)
-	button.Pop()
-
-	cell := clip.Rect(image.Rect(100, 0, 200, 50)).Push(&ops)
-	pointer.CursorText.Add(&ops)
-	cell.Pop()
-
-	var r Router
-	r.Frame(&ops)
-	r.Queue(
-		pointer.Event{
-			Kind:     pointer.Move,
-			Source:   pointer.Mouse,
-			Position: f32.Pt(25, 25),
-		},
-		pointer.Event{
-			Kind:     pointer.Scroll,
-			Source:   pointer.Mouse,
-			Position: f32.Pt(150, 25),
-			Scroll:   f32.Pt(0, 1),
-		},
-	)
-
-	if got, want := r.Cursor(), pointer.CursorPointer; got != want {
-		t.Errorf("got %q, want %q (scroll position must not update the cursor; "+
-			"the live pointer's last position is what determines it)", got, want)
-	}
-}

io/pointer/pointer.go

@@ -19,9 +19,7 @@ type Event struct {
 	Source Source
 	// PointerID is the id for the pointer and can be used
 	// to track a particular pointer from Press to
-	// Release. Populated for Press, Release, Move, Drag,
-	// Enter, Leave, and Cancel; Scroll events are not
-	// bound to a tracked pointer and leave it zero.
+	// Release.
 	PointerID ID
 	// Priority is the priority of the receiving handler
 	// for this event.

text/gotext.go

@@ -103,7 +103,8 @@ func (l *line) insertTrailingSyntheticNewline(newLineClusterIdx int) {
 		clusterIndex: newLineClusterIdx,
 		glyphCount:   0,
 		runeCount:    1,
-		advance:      0,
+		xAdvance:     0,
+		yAdvance:     0,
 		xOffset:      0,
 		yOffset:      0,
 	}
@@ -159,9 +160,9 @@ type glyph struct {
 	// runeCount is the quantity of runes in the source text that this glyph
 	// corresponds to.
 	runeCount int
-	// advance is the distance the dot moves when laying out the glyph along
-	// the run's primary axis.
-	advance fixed.Int26_6
+	// xAdvance and yAdvance describe the distance the dot moves when
+	// laying out the glyph on the X or Y axis.
+	xAdvance, yAdvance fixed.Int26_6
 	// xOffset and yOffset describe offsets from the dot that should be
 	// applied when rendering the glyph.
 	xOffset, yOffset fixed.Int26_6
@@ -269,9 +270,8 @@ func newShaperImpl(systemFonts bool, collection []FontFace) *shaperImpl {
 // in the order in which they are loaded, with the first face being the default.
 func (s *shaperImpl) Load(f FontFace) {
 	desc := opentype.FontToDescription(f.Font)
-	face := f.Face.Face()
-	s.fontMap.AddFace(face, fontscan.Location{File: fmt.Sprint(desc)}, desc)
-	s.addFace(face, f.Font)
+	s.fontMap.AddFace(f.Face.Face(), fontscan.Location{File: fmt.Sprint(desc)}, desc)
+	s.addFace(f.Face.Face(), f.Font)
 }
 
 func (s *shaperImpl) addFace(f *font.Face, md giofont.Font) {
@@ -437,7 +437,8 @@ func (s *shaperImpl) shapeText(ppem fixed.Int26_6, lc system.Locale, txt []rune)
 						Height:       input.Size,
 						XBearing:     0,
 						YBearing:     0,
-						Advance:      input.Size,
+						XAdvance:     input.Size,
+						YAdvance:     input.Size,
 						XOffset:      0,
 						YOffset:      0,
 						ClusterIndex: input.RunStart,
@@ -853,10 +854,11 @@ func toGioGlyphs(in []shaping.Glyph, ppem fixed.Int26_6, faceIdx int) []glyph {
 		bounds.Max = bounds.Min.Add(fixed.Point26_6{X: g.Width, Y: -g.Height})
 		out = append(out, glyph{
 			id:           newGlyphID(ppem, faceIdx, g.GlyphID),
-			clusterIndex: g.TextIndex(),
-			runeCount:    g.RunesCount(),
-			glyphCount:   g.GlyphsCount(),
-			advance:      g.Advance,
+			clusterIndex: g.ClusterIndex,
+			runeCount:    g.RuneCount,
+			glyphCount:   g.GlyphCount,
+			xAdvance:     g.XAdvance,
+			yAdvance:     g.YAdvance,
 			xOffset:      g.XOffset,
 			yOffset:      g.YOffset,
 			bounds:       bounds,

text/shaper.go

@@ -259,6 +259,10 @@ func WithCollection(collection []FontFace) ShaperOption {
 }
 
 // NewShaper constructs a shaper with the provided options.
+//
+// NewShaper must be called after [app.NewWindow], unless the [NoSystemFonts]
+// option is specified. This is an unfortunate restriction caused by some platforms
+// such as Android.
 func NewShaper(options ...ShaperOption) *Shaper {
 	l := &Shaper{}
 	for _, opt := range options {
@@ -464,7 +468,7 @@ func (l *Shaper) NextGlyph() (_ Glyph, ok bool) {
 		if rtl {
 			// Modify the advance prior to computing runOffset to ensure that the
 			// current glyph's width is subtracted in RTL.
-			l.advance += g.advance
+			l.advance += g.xAdvance
 		}
 		// runOffset computes how far into the run the dot should be positioned.
 		runOffset := l.advance
@@ -477,7 +481,7 @@ func (l *Shaper) NextGlyph() (_ Glyph, ok bool) {
 			Y:       int32(line.yOffset),
 			Ascent:  line.ascent,
 			Descent: line.descent,
-			Advance: g.advance,
+			Advance: g.xAdvance,
 			Runes:   uint16(g.runeCount),
 			Offset: fixed.Point26_6{
 				X: g.xOffset,
@@ -490,7 +494,7 @@ func (l *Shaper) NextGlyph() (_ Glyph, ok bool) {
 		}
 		l.glyph++
 		if !rtl {
-			l.advance += g.advance
+			l.advance += g.xAdvance
 		}
 
 		endOfRun := l.glyph == len(run.Glyphs)

text/shaper_test.go

@@ -450,8 +450,8 @@ func printLinePositioning(t *testing.T, lines []line, glyphs []Glyph) {
 			for g := start; ; g += inc {
 				glyph := run.Glyphs[g]
 				if glyphCursor < len(glyphs) {
-					t.Logf("glyph %2d, adv %3d, runes %2d, glyphs %d - glyphs[%2d] flags %s", g, glyph.advance, glyph.runeCount, glyph.glyphCount, glyphCursor, glyphs[glyphCursor].Flags)
-					t.Logf("glyph %2d, adv %3d, runes %2d, glyphs %d - n/a", g, glyph.advance, glyph.runeCount, glyph.glyphCount)
+					t.Logf("glyph %2d, adv %3d, runes %2d, glyphs %d - glyphs[%2d] flags %s", g, glyph.xAdvance, glyph.runeCount, glyph.glyphCount, glyphCursor, glyphs[glyphCursor].Flags)
+					t.Logf("glyph %2d, adv %3d, runes %2d, glyphs %d - n/a", g, glyph.xAdvance, glyph.runeCount, glyph.glyphCount)
 				}
 				glyphCursor++
 				if g == end {