gesture: report one event at a time

Events are now delivered one at a time, and this change makes the
corresponding change to gestures.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

widget/button.go

@@ -116,7 +116,11 @@ func (b *Clickable) Update(gtx layout.Context) (Click, bool) {
 			NumClicks: c,
 		}, true
 	}
-	for _, e := range b.click.Update(gtx.Source) {
+	for {
+		e, ok := b.click.Update(gtx.Source)
+		if !ok {
+			break
+		}
 		switch e.Kind {
 		case gesture.KindClick:
 			if l := len(b.history); l > 0 {

widget/dnd.go

@@ -53,7 +53,11 @@ func (d *Draggable) Dragging() bool {
 // requested to offer data, if any
 func (d *Draggable) Update(gtx layout.Context) (mime string, requested bool) {
 	pos := d.pos
-	for _, ev := range d.drag.Update(gtx.Metric, gtx.Source, gesture.Both) {
+	for {
+		ev, ok := d.drag.Update(gtx.Metric, gtx.Source, gesture.Both)
+		if !ok {
+			break
+		}
 		switch ev.Kind {
 		case pointer.Press:
 			d.click = ev.Position

widget/editor.go

@@ -316,10 +316,18 @@ func (e *Editor) processPointer(gtx layout.Context) {
 
 func (e *Editor) clickDragEvents(gtx layout.Context) []event.Event {
 	var combinedEvents []event.Event
-	for _, evt := range e.clicker.Update(gtx.Source) {
+	for {
+		evt, ok := e.clicker.Update(gtx.Source)
+		if !ok {
+			break
+		}
 		combinedEvents = append(combinedEvents, evt)
 	}
-	for _, evt := range e.dragger.Update(gtx.Metric, gtx.Source, gesture.Both) {
+	for {
+		evt, ok := e.dragger.Update(gtx.Metric, gtx.Source, gesture.Both)
+		if !ok {
+			break
+		}
 		combinedEvents = append(combinedEvents, evt)
 	}
 	return combinedEvents

widget/enum.go

@@ -47,7 +47,11 @@ func (e *Enum) Update(gtx layout.Context) bool {
 	e.hovering = false
 	changed := false
 	for _, state := range e.keys {
-		for _, ev := range state.click.Update(gtx.Source) {
+		for {
+			ev, ok := state.click.Update(gtx.Source)
+			if !ok {
+				break
+			}
 			switch ev.Kind {
 			case gesture.KindPress:
 				if ev.Source == pointer.Mouse {

widget/float.go

@@ -48,7 +48,11 @@ func (f *Float) Layout(gtx layout.Context, axis layout.Axis, pointerMargin unit.
 // The range of f is set by the minimum constraints main axis value.
 func (f *Float) Update(gtx layout.Context) bool {
 	changed := false
-	for _, e := range f.drag.Update(gtx.Metric, gtx.Source, gesture.Axis(f.axis)) {
+	for {
+		e, ok := f.drag.Update(gtx.Metric, gtx.Source, gesture.Axis(f.axis))
+		if !ok {
+			break
+		}
 		if f.length > 0 && (e.Kind == pointer.Press || e.Kind == pointer.Drag) {
 			pos := e.Position.X
 			if f.axis == layout.Vertical {

widget/list.go

@@ -61,7 +61,11 @@ func (s *Scrollbar) Update(gtx layout.Context, axis layout.Axis, viewportStart,
 	}
 
 	// Jump to a click in the track.
-	for _, event := range s.track.Update(gtx.Source) {
+	for {
+		event, ok := s.track.Update(gtx.Source)
+		if !ok {
+			break
+		}
 		if event.Kind != gesture.KindClick ||
 			event.Modifiers != key.Modifiers(0) ||
 			event.NumClicks > 1 {
@@ -80,7 +84,11 @@ func (s *Scrollbar) Update(gtx layout.Context, axis layout.Axis, viewportStart,
 	}
 
 	// Offset to account for any drags.
-	for _, event := range s.drag.Update(gtx.Metric, gtx.Source, gesture.Axis(axis)) {
+	for {
+		event, ok := s.drag.Update(gtx.Metric, gtx.Source, gesture.Axis(axis))
+		if !ok {
+			break
+		}
 		switch event.Kind {
 		case pointer.Drag:
 		case pointer.Release, pointer.Cancel:
@@ -136,7 +144,11 @@ func (s *Scrollbar) Update(gtx layout.Context, axis layout.Axis, viewportStart,
 
 	// Process events from the indicator so that hover is
 	// detected properly.
-	_ = s.indicator.Update(gtx.Source)
+	for {
+		if _, ok := s.indicator.Update(gtx.Source); !ok {
+			break
+		}
+	}
 }
 
 // AddTrack configures the track click listener for the scrollbar to use

widget/selectable.go

@@ -283,10 +283,18 @@ func (e *Selectable) processPointer(gtx layout.Context) {
 
 func (e *Selectable) clickDragEvents(gtx layout.Context) []event.Event {
 	var combinedEvents []event.Event
-	for _, evt := range e.clicker.Update(gtx.Source) {
+	for {
+		evt, ok := e.clicker.Update(gtx.Source)
+		if !ok {
+			break
+		}
 		combinedEvents = append(combinedEvents, evt)
 	}
-	for _, evt := range e.dragger.Update(gtx.Metric, gtx.Source, gesture.Both) {
+	for {
+		evt, ok := e.dragger.Update(gtx.Metric, gtx.Source, gesture.Both)
+		if !ok {
+			break
+		}
 		combinedEvents = append(combinedEvents, evt)
 	}
 	return combinedEvents