Merge pull request #2108 from fpabl0/fix/1748

Call OnChanged only when the slider.Value has changed, fixes #1748

widget/slider.go

@@ -100,7 +100,14 @@ func (s *Slider) DragEnd() {
 func (s *Slider) Dragged(e *fyne.DragEvent) {
 	ratio := s.getRatio(&(e.PointEvent))
 
+	lastValue := s.Value
+
 	s.updateValue(ratio)
+
+	if lastValue == s.Value {
+		return
+	}
+
 	s.Refresh()
 
 	if s.OnChanged != nil {
@@ -174,9 +181,15 @@ func (s *Slider) SetValue(value float64) {
 		return
 	}
 
+	lastValue := s.Value
+
 	s.Value = value
 	s.clampValueToRange()
 
+	if lastValue == s.Value {
+		return
+	}
+
 	if s.OnChanged != nil {
 		s.OnChanged(s.Value)
 	}

widget/slider_test.go

@@ -118,7 +118,8 @@ func TestSlider_VerticalLayout(t *testing.T) {
 }
 
 func TestSlider_OnChanged(t *testing.T) {
-	slider := NewSlider(0, 1)
+	slider := NewSlider(0, 2)
+	slider.Resize(slider.MinSize())
 	assert.Empty(t, slider.OnChanged)
 
 	changes := 0
@@ -130,9 +131,18 @@ func TestSlider_OnChanged(t *testing.T) {
 	assert.Equal(t, 0, changes)
 
 	slider.SetValue(0.5)
+	assert.Equal(t, 0, changes)
+
+	drag := &fyne.DragEvent{}
+	drag.PointEvent.Position = fyne.NewPos(25, 2)
+	slider.Dragged(drag)
+	assert.Equal(t, 1, changes)
+
+	drag.PointEvent.Position = fyne.NewPos(25, 2)
+	slider.Dragged(drag)
 	assert.Equal(t, 1, changes)
 
-	drag := &fyne.DragEvent{Dragged: fyne.NewDelta(10, 2)}
+	drag.PointEvent.Position = fyne.NewPos(50, 2)
 	slider.Dragged(drag)
 	assert.Equal(t, 2, changes)
 }