Merge pull request #5191 from andydotxyz/feature/mobilescroll

internal/driver/mobile/canvas.go

@@ -25,6 +25,7 @@ type canvas struct {
 	initialized    bool
 	lastTapDown    map[int]time.Time
 	lastTapDownPos map[int]fyne.Position
+	lastTapDelta   map[int]fyne.Delta
 	menu           fyne.CanvasObject
 	padded         bool
 	scale          float32
@@ -54,6 +55,7 @@ func newCanvas(dev fyne.Device) fyne.Canvas {
 		device:         d,
 		lastTapDown:    make(map[int]time.Time),
 		lastTapDownPos: make(map[int]fyne.Position),
+		lastTapDelta:   make(map[int]fyne.Delta),
 		padded:         true,
 		scale:          dev.SystemScaleForWindow(nil), // we don't need a window parameter on mobile,
 		touched:        make(map[int]mobile.Touchable),
@@ -258,6 +260,8 @@ func (c *canvas) tapMove(pos fyne.Position, tapID int,
 		return
 	}
 	c.lastTapDownPos[tapID] = pos
+	offset := fyne.Delta{DX: deltaX, DY: deltaY}
+	c.lastTapDelta[tapID] = offset
 
 	co, objPos, _ := c.findObjectAtPositionMatching(pos, func(object fyne.CanvasObject) bool {
 		if _, ok := object.(fyne.Draggable); ok {
@@ -292,7 +296,7 @@ func (c *canvas) tapMove(pos fyne.Position, tapID int,
 	ev := &fyne.DragEvent{}
 	draggedObjDelta := c.dragStart.Subtract(c.dragging.(fyne.CanvasObject).Position())
 	ev.Position = pos.Subtract(c.dragOffset).Add(draggedObjDelta)
-	ev.Dragged = fyne.Delta{DX: deltaX, DY: deltaY}
+	ev.Dragged = offset
 
 	dragCallback(c.dragging, ev)
 }
@@ -301,10 +305,11 @@ func (c *canvas) tapUp(pos fyne.Position, tapID int,
 	tapCallback func(fyne.Tappable, *fyne.PointEvent),
 	tapAltCallback func(fyne.SecondaryTappable, *fyne.PointEvent),
 	doubleTapCallback func(fyne.DoubleTappable, *fyne.PointEvent),
-	dragCallback func(fyne.Draggable)) {
+	dragCallback func(fyne.Draggable, *fyne.DragEvent)) {
 
 	if c.dragging != nil {
-		dragCallback(c.dragging)
+		previousDelta := c.lastTapDelta[tapID]
+		dragCallback(c.dragging, &fyne.DragEvent{Dragged: previousDelta})
 
 		c.dragging = nil
 		return

internal/driver/mobile/canvas_test.go

@@ -249,7 +249,7 @@ func Test_canvas_Tappable(t *testing.T) {
 	c.tapUp(fyne.NewPos(15, 15), 0, func(wid fyne.Tappable, ev *fyne.PointEvent) {
 	}, func(wid fyne.SecondaryTappable, ev *fyne.PointEvent) {
 	}, func(wid fyne.DoubleTappable, ev *fyne.PointEvent) {
-	}, func(wid fyne.Draggable) {
+	}, func(wid fyne.Draggable, ev *fyne.DragEvent) {
 	})
 	assert.True(t, content.up)
 
@@ -286,7 +286,7 @@ func Test_canvas_Tapped(t *testing.T) {
 		wid.TappedSecondary(ev)
 	}, func(wid fyne.DoubleTappable, ev *fyne.PointEvent) {
 		wid.DoubleTapped(ev)
-	}, func(wid fyne.Draggable) {
+	}, func(wid fyne.Draggable, ev *fyne.DragEvent) {
 	})
 
 	assert.True(t, tapped, "tap primary")
@@ -340,7 +340,7 @@ func Test_canvas_TappedMulti(t *testing.T) {
 	}, func(wid fyne.SecondaryTappable, ev *fyne.PointEvent) {
 	}, func(wid fyne.DoubleTappable, ev *fyne.PointEvent) {
 		wid.DoubleTapped(ev)
-	}, func(wid fyne.Draggable) {
+	}, func(wid fyne.Draggable, ev *fyne.DragEvent) {
 	})
 
 	assert.False(t, buttonTap, "button should not be tapped")
@@ -369,7 +369,7 @@ func Test_canvas_TappedSecondary(t *testing.T) {
 		wid.TappedSecondary(ev)
 	}, func(wid fyne.DoubleTappable, ev *fyne.PointEvent) {
 		wid.DoubleTapped(ev)
-	}, func(wid fyne.Draggable) {
+	}, func(wid fyne.Draggable, ev *fyne.DragEvent) {
 	})
 
 	assert.False(t, obj.tap, "don't tap primary")
@@ -464,7 +464,7 @@ func simulateTap(c *canvas) {
 	}, func(wid fyne.SecondaryTappable, ev *fyne.PointEvent) {
 	}, func(wid fyne.DoubleTappable, ev *fyne.PointEvent) {
 		wid.DoubleTapped(ev)
-	}, func(wid fyne.Draggable) {
+	}, func(wid fyne.Draggable, ev *fyne.DragEvent) {
 	})
 }
 

internal/driver/mobile/device_android.go

@@ -4,7 +4,7 @@ package mobile
 
 import "fyne.io/fyne/v2"
 
-const tapYOffset = -12.0 // to compensate for how we hold our fingers on the device
+const tapYOffset = -8.0 // to compensate for how we hold our fingers on the device
 
 func (*device) SystemScaleForWindow(_ fyne.Window) float32 {
 	if currentDPI >= 600 {

internal/driver/mobile/device_ios.go

@@ -4,7 +4,7 @@ package mobile
 
 import "fyne.io/fyne/v2"
 
-const tapYOffset = -12.0 // to compensate for how we hold our fingers on the device
+const tapYOffset = -8.0 // to compensate for how we hold our fingers on the device
 
 func (*device) SystemScaleForWindow(_ fyne.Window) float32 {
 	if currentDPI >= 450 {

internal/driver/mobile/driver.go

@@ -1,6 +1,7 @@
 package mobile
 
 import (
+	"math"
 	"runtime"
 	"strconv"
 	"sync/atomic"
@@ -30,9 +31,11 @@ import (
 )
 
 const (
-	tapMoveThreshold  = 4.0                    // how far can we move before it is a drag
-	tapSecondaryDelay = 300 * time.Millisecond // how long before secondary tap
-	tapDoubleDelay    = 500 * time.Millisecond // max duration between taps for a DoubleTap event
+	tapMoveDecay        = 0.92                   // how much should the scroll continue decay on each frame?
+	tapMoveEndThreshold = 2.0                    // at what offset will we stop decaying?
+	tapMoveThreshold    = 4.0                    // how far can we move before it is a drag
+	tapSecondaryDelay   = 300 * time.Millisecond // how long before secondary tap
+	tapDoubleDelay      = 500 * time.Millisecond // max duration between taps for a DoubleTap event
 )
 
 // Configuration is the system information about the current device
@@ -399,8 +402,27 @@ func (d *driver) tapUpCanvas(w *window, x, y float32, tapID touch.Sequence) {
 		w.QueueEvent(func() { wid.TappedSecondary(ev) })
 	}, func(wid fyne.DoubleTappable, ev *fyne.PointEvent) {
 		w.QueueEvent(func() { wid.DoubleTapped(ev) })
-	}, func(wid fyne.Draggable) {
-		w.QueueEvent(wid.DragEnd)
+	}, func(wid fyne.Draggable, ev *fyne.DragEvent) {
+		if math.Abs(float64(ev.Dragged.DX)) <= tapMoveEndThreshold && math.Abs(float64(ev.Dragged.DY)) <= tapMoveEndThreshold {
+			w.QueueEvent(wid.DragEnd)
+			return
+		}
+
+		go func() {
+			for math.Abs(float64(ev.Dragged.DX)) > tapMoveEndThreshold || math.Abs(float64(ev.Dragged.DY)) > tapMoveEndThreshold {
+				if math.Abs(float64(ev.Dragged.DX)) > 0 {
+					ev.Dragged.DX *= tapMoveDecay
+				}
+				if math.Abs(float64(ev.Dragged.DY)) > 0 {
+					ev.Dragged.DY *= tapMoveDecay
+				}
+
+				w.QueueEvent(func() { wid.Dragged(ev) })
+				time.Sleep(time.Millisecond * 16)
+			}
+
+			w.QueueEvent(wid.DragEnd)
+		}()
 	})
 }