Fixed vertical slider

slider.go

@@ -14,7 +14,7 @@ type Slider struct {
 	layout     sliderLayout
 	dragging   bool
 	dragOffset image.Point
-	
+
 	on struct {
 		valueChange event.FuncBroadcaster
 	}
@@ -34,7 +34,7 @@ func newSlider (orient string, value float64) *Slider {
 			vertical: orient == "vertical",
 		},
 	}
-	
+
 	this.Add(this.handle)
 	this.SetFocusable(true)
 	this.SetPropagateEvents(false)
@@ -74,18 +74,24 @@ func (this *Slider) OnValueChange (callback func ()) event.Cookie {
 }
 
 func (this *Slider) handleKeyDown (key input.Key, numpad bool) {
+	var increment float64; if this.layout.vertical {
+		increment = -0.05
+	} else {
+		increment = 0.05
+	}
+
 	switch key {
 	case input.KeyUp, input.KeyLeft:
 		if this.Modifiers().Alt {
 			this.SetValue(0)
 		} else {
-			this.SetValue(this.Value() - 0.05)		
+			this.SetValue(this.Value() - increment)
 		}
 	case input.KeyDown, input.KeyRight:
 		if this.Modifiers().Alt {
 			this.SetValue(1)
 		} else {
-			this.SetValue(this.Value() + 0.05)		
+			this.SetValue(this.Value() + increment)
 		}
 	case input.KeyHome:
 		this.SetValue(0)
@@ -98,7 +104,7 @@ func (this *Slider) handleMouseDown (button input.Button) {
 	pointer := this.MousePosition()
 	handle  := this.handle.Bounds()
 	var above, within bool
-	
+
 	if pointer.In(handle) {
 		within = true
 	} else if this.layout.vertical {
@@ -106,7 +112,7 @@ func (this *Slider) handleMouseDown (button input.Button) {
 	} else {
 		above = pointer.X < handle.Min.X
 	}
-	
+
 	switch button {
 	case input.ButtonLeft:
 		if within {
@@ -152,6 +158,7 @@ func (this *Slider) drag () {
 
 	if this.layout.vertical {
 		this.SetValue (
+			1 -
 			float64(pointer.Y) /
 			float64(gutter.Dy() - handle.Dy()))
 	} else {
@@ -185,10 +192,10 @@ func (this sliderLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
 	if len(boxes) != 1 { return }
 	handle := image.Rectangle { Max: boxes[0].MinimumSize() }
 	gutter := hints.Bounds
-	
+
 	if this.vertical {
 		height := gutter.Dy() - handle.Dy()
-		offset := int(float64(height) * this.value)
+		offset := int(float64(height) * (1 - this.value))
 		handle.Max.X = gutter.Dx()
 		boxes[0].SetBounds (
 			handle.