Scrollbars can be dragged

scrollbar.go

@@ -67,6 +67,7 @@ func (this *Scrollbar) Link (box tomo.ContentBox) event.Cookie {
 
 func (this *Scrollbar) handleLinkedContentBoundsChange () {
 	if this.layout.linked == nil { return }
+	previousValue := this.layout.value
 	trackLength := this.layout.contentLength() - this.layout.viewportLength()
 	if trackLength == 0 {
 		this.layout.value = 0
@@ -74,13 +75,29 @@ func (this *Scrollbar) handleLinkedContentBoundsChange () {
 		this.layout.value = this.layout.contentPos() / trackLength
 	}
 	this.SetLayout(this.layout)
+	if this.layout.value != previousValue {
+		this.on.valueChange.Broadcast()
+	}
 }
 
 // SetValue sets the value of the scrollbar between 0 and 1, where 0 is scrolled
 // all the way to the left/top, and 1 is scrolled all the way to the
 // right/bottom.
 func (this *Scrollbar) SetValue (value float64) {
-	// TODO
+	if this.layout.linked == nil { return }
+	if value > 1 { value = 1 }
+	if value < 0 { value = 0 }
+	
+	trackLength := this.layout.contentLength() - this.layout.viewportLength()
+	position    := trackLength * value
+	point       := this.layout.linked.ContentBounds().Min
+	if this.layout.vertical {
+		point.Y = int(position)
+	} else {
+		point.X = int(position)
+	}
+	this.layout.linked.ScrollTo(point)
+	
 }
 
 // Value returns the value of the scrollbar between 0 and 1 where 0 is scrolled
@@ -127,14 +144,12 @@ func (this *Scrollbar) handleKeyDown (key input.Key, numpad bool) {
 func (this *Scrollbar) handleMouseDown (button input.Button) {
 	pointer := this.MousePosition()
 	handle  := this.handle.Bounds()
-	var above, within bool
 
-	if pointer.In(handle) {
+	within := pointer.In(handle)
-		within = true
+	var above bool; if this.layout.vertical {
-	} else if this.layout.vertical {
+		above = pointer.Y < handle.Min.Y + handle.Dy() / 2
-		above = pointer.Y < handle.Min.Y
 	} else {
-		above = pointer.X < handle.Min.X
+		above = pointer.X < handle.Min.X + handle.Dx() / 2
 	}
 
 	switch button {
@@ -189,7 +204,6 @@ func (this *Scrollbar) drag () {
 
 	if this.layout.vertical {
 		this.SetValue (
-			1 -
 			float64(pointer.Y) /
 			float64(gutter.Dy() - handle.Dy()))
 	} else {

slider.go

@@ -115,14 +115,12 @@ func (this *Slider) handleKeyDown (key input.Key, numpad bool) {
 func (this *Slider) handleMouseDown (button input.Button) {
 	pointer := this.MousePosition()
 	handle  := this.handle.Bounds()
-	var above, within bool
+	
-
+	within := pointer.In(handle)
-	if pointer.In(handle) {
+	var above bool; if this.layout.vertical {
-		within = true
+		above = pointer.Y < handle.Min.Y + handle.Dy() / 2
-	} else if this.layout.vertical {
-		above = pointer.Y < handle.Min.Y
 	} else {
-		above = pointer.X < handle.Min.X
+		above = pointer.X < handle.Min.X + handle.Dx() / 2
 	}
 
 	switch button {