Add double tapping to mobile and don't allow both single and double tap events to fire

internal/driver/glfw/window.go

@@ -3,6 +3,7 @@ package glfw
 import "C"
 import (
 	"bytes"
+	"context"
 	"image"
 	_ "image/png" // for the icon
 	"runtime"
@@ -21,7 +22,7 @@ import (
 
 const (
 	scrollSpeed      = 10
-	doubleClickDelay = 500 // ms (maximum interval between clicks for double click detection)
+	doubleClickDelay = 300 // ms (maximum interval between clicks for double click detection)
 )
 
 var (
@@ -73,6 +74,8 @@ type window struct {
 	mouseClickTime     time.Time
 	mouseLastClick     fyne.CanvasObject
 	mousePressed       fyne.CanvasObject
+	mouseClickCount    int
+	mouseCancelFunc    context.CancelFunc
 	onClosed           func()
 	onCloseIntercepted func()
 
@@ -656,7 +659,6 @@ func (w *window) mouseClicked(_ *glfw.Window, btn glfw.MouseButton, action glfw.
 		co, _ = w.mouseDragged.(fyne.CanvasObject)
 		ev.Position = w.mousePos.Subtract(w.mouseDraggedOffset).Subtract(co.Position())
 	}
-
 	button, modifiers := convertMouseButton(btn, mods)
 	if wid, ok := co.(desktop.Mouseable); ok {
 		mev := new(desktop.MouseEvent)
@@ -685,54 +687,75 @@ func (w *window) mouseClicked(_ *glfw.Window, btn glfw.MouseButton, action glfw.
 		w.mouseButton = 0
 	}
 
-	// Check for double click/tap
-	doubleTapped := false
-	if action == glfw.Release && button == desktop.LeftMouseButton {
-		now := time.Now()
-		// we can safely subtract the first "zero" time as it'll be much larger than doubleClickDelay
-		if now.Sub(w.mouseClickTime).Nanoseconds()/1e6 <= doubleClickDelay && w.mouseLastClick == co {
-			if wid, ok := co.(fyne.DoubleTappable); ok {
-				doubleTapped = true
-				w.queueEvent(func() { wid.DoubleTapped(ev) })
-			}
+	if wid, ok := co.(fyne.Draggable); ok {
+		if action == glfw.Press {
+			w.mouseDragPos = w.mousePos
+			w.mouseDragged = wid
+			w.mouseDraggedOffset = w.mousePos.Subtract(co.Position()).Subtract(ev.Position)
 		}
-		w.mouseClickTime = now
-		w.mouseLastClick = co
 	}
-
+	if action == glfw.Release && w.mouseDragged != nil {
+		if w.mouseDragStarted {
+			w.queueEvent(w.mouseDragged.DragEnd)
+			w.mouseDragStarted = false
+		}
+		if w.objIsDragged(w.mouseOver) && !w.objIsDragged(coMouse) {
+			w.mouseOut()
+		}
+		w.mouseDragged = nil
+	}
 	_, tap := co.(fyne.Tappable)
 	_, altTap := co.(fyne.SecondaryTappable)
-	// Prevent Tapped from triggering if DoubleTapped has been sent
-	if (tap || altTap) && !doubleTapped {
+	if tap || altTap {
 		if action == glfw.Press {
 			w.mousePressed = co
 		} else if action == glfw.Release {
 			if co == w.mousePressed {
 				if button == desktop.RightMouseButton && altTap {
 					w.queueEvent(func() { co.(fyne.SecondaryTappable).TappedSecondary(ev) })
-				} else if button == desktop.LeftMouseButton && tap {
-					w.queueEvent(func() { co.(fyne.Tappable).Tapped(ev) })
 				}
 			}
-			w.mousePressed = nil
 		}
 	}
-	if wid, ok := co.(fyne.Draggable); ok {
-		if action == glfw.Press {
-			w.mouseDragPos = w.mousePos
-			w.mouseDragged = wid
-			w.mouseDraggedOffset = w.mousePos.Subtract(co.Position()).Subtract(ev.Position)
+
+	// Check for double click/tap on left mouse button
+	if action == glfw.Release && button == desktop.LeftMouseButton {
+		_, doubleTap := co.(fyne.DoubleTappable)
+		if doubleTap {
+			w.mouseClickCount++
+			w.mouseLastClick = co
+			if w.mouseCancelFunc != nil {
+				w.mouseCancelFunc()
+			}
+			go w.waitForDoubleTap(co, ev, action, button)
+		} else {
+			if wid, ok := co.(fyne.Tappable); ok {
+				w.queueEvent(func() { wid.Tapped(ev) })
+			}
 		}
+		w.mousePressed = nil
 	}
-	if action == glfw.Release && w.mouseDragged != nil {
-		if w.mouseDragStarted {
-			w.queueEvent(w.mouseDragged.DragEnd)
-			w.mouseDragStarted = false
-		}
-		if w.objIsDragged(w.mouseOver) && !w.objIsDragged(coMouse) {
-			w.mouseOut()
+}
+
+func (w *window) waitForDoubleTap(co fyne.CanvasObject, ev *fyne.PointEvent, action glfw.Action, button desktop.MouseButton) {
+	var ctx context.Context
+	ctx, w.mouseCancelFunc = context.WithDeadline(context.TODO(), time.Now().Add(time.Millisecond*doubleClickDelay))
+	defer w.mouseCancelFunc()
+	select {
+	case <-ctx.Done():
+		if w.mouseClickCount == 2 && w.mouseLastClick == co {
+			if wid, ok := co.(fyne.DoubleTappable); ok {
+				w.queueEvent(func() { wid.DoubleTapped(ev) })
+			}
+		} else if co == w.mousePressed {
+			if wid, ok := co.(fyne.Tappable); ok {
+				w.queueEvent(func() { wid.Tapped(ev) })
+			}
 		}
-		w.mouseDragged = nil
+		w.mouseClickCount = 0
+		w.mouseCancelFunc = nil
+		w.mouseLastClick = nil
+		return
 	}
 }
 

internal/driver/glfw/window_test.go

@@ -465,11 +465,13 @@ func TestWindow_TappedSecondary_OnPrimaryOnlyTarget(t *testing.T) {
 	w.mouseClicked(w.viewport, glfw.MouseButton2, glfw.Press, 0)
 	w.mouseClicked(w.viewport, glfw.MouseButton2, glfw.Release, 0)
 	w.waitForEvents()
+
 	assert.False(t, tapped)
 
 	w.mouseClicked(w.viewport, glfw.MouseButton1, glfw.Press, 0)
 	w.mouseClicked(w.viewport, glfw.MouseButton1, glfw.Release, 0)
 	w.waitForEvents()
+
 	assert.True(t, tapped)
 }
 
@@ -497,13 +499,15 @@ func TestWindow_TappedIgnoresScrollerClip(t *testing.T) {
 	w.mouseClicked(w.viewport, glfw.MouseButton1, glfw.Release, 0)
 
 	w.waitForEvents()
+
 	assert.False(t, tapped, "Tapped button that was clipped")
 
 	w.mousePos = fyne.NewPos(10, 120)
 	w.mouseClicked(w.viewport, glfw.MouseButton1, glfw.Press, 0)
 	w.mouseClicked(w.viewport, glfw.MouseButton1, glfw.Release, 0)
 
 	w.waitForEvents()
+
 	assert.True(t, tapped, "Tapped button that was clipped")
 }
 
@@ -519,6 +523,7 @@ func TestWindow_TappedIgnoredWhenMovedOffOfTappable(t *testing.T) {
 	w.mouseClicked(w.viewport, glfw.MouseButton1, glfw.Release, 0)
 
 	w.waitForEvents()
+
 	assert.Equal(t, 1, tapped, "Button 1 should be tapped")
 	tapped = 0
 
@@ -527,12 +532,14 @@ func TestWindow_TappedIgnoredWhenMovedOffOfTappable(t *testing.T) {
 	w.mouseClicked(w.viewport, glfw.MouseButton1, glfw.Release, 0)
 
 	w.waitForEvents()
+
 	assert.Equal(t, 0, tapped, "button was tapped without mouse press & release on it %d", tapped)
 
 	w.mouseClicked(w.viewport, glfw.MouseButton1, glfw.Press, 0)
 	w.mouseClicked(w.viewport, glfw.MouseButton1, glfw.Release, 0)
 
 	w.waitForEvents()
+
 	assert.Equal(t, 2, tapped, "Button 2 should be tapped")
 }