Scrollbars respond to mouse dragging more naturally

backends/x/event.go

@@ -272,10 +272,7 @@ func (window *Window) compressMotionNotify (
 		typedEvent, ok := untypedEvent.Event.(xproto.MotionNotifyEvent)
 		if !ok { continue }
 
-		if firstEvent.Event == typedEvent.Event &&
-			typedEvent.Detail >= 4 &&
-			typedEvent.Detail <= 7 {
-
+		if firstEvent.Event == typedEvent.Event {
 			lastEvent = typedEvent
 			defer func (index int) {
 				xevent.DequeueAt(window.backend.connection, index)

elements/basic/scrollcontainer.go

@@ -20,7 +20,7 @@ type ScrollContainer struct {
 		exists bool
 		enabled bool
 		dragging bool
-		dragOffset image.Point
+		dragOffset int
 		gutter image.Rectangle
 		bar image.Rectangle
 	}
@@ -29,7 +29,7 @@ type ScrollContainer struct {
 		exists bool
 		enabled bool
 		dragging bool
-		dragOffset image.Point
+		dragOffset int
 		gutter image.Rectangle
 		bar image.Rectangle
 	}
@@ -111,12 +111,16 @@ func (element *ScrollContainer) HandleKeyUp (key tomo.Key, modifiers tomo.Modifi
 
 func (element *ScrollContainer) HandleMouseDown (x, y int, button tomo.Button) {
 	point := image.Pt(x, y)
-	if point.In(element.horizontal.gutter) {
+	if point.In(element.horizontal.bar) {
 		element.horizontal.dragging = true
+		element.horizontal.dragOffset =
+			point.Sub(element.horizontal.bar.Min).X
 		element.dragHorizontalBar(point)
 		
-	} else if point.In(element.vertical.gutter) {
+	} else if point.In(element.vertical.bar) {
 		element.vertical.dragging = true
+		element.vertical.dragOffset =
+			point.Sub(element.vertical.bar.Min).Y
 		element.dragVerticalBar(point)
 		
 	} else if child, ok := element.child.(tomo.MouseTarget); ok {
@@ -353,8 +357,7 @@ func (element *ScrollContainer) dragHorizontalBar (mousePosition image.Point) {
 	scrollX :=
 		float64(element.child.ScrollContentBounds().Dx()) /
 		float64(element.horizontal.gutter.Dx()) *
-		float64 (
-			mousePosition.X - element.horizontal.bar.Dx() / 2)
+		float64(mousePosition.X - element.horizontal.dragOffset)
 	scrollY := element.child.ScrollViewportBounds().Min.Y
 	element.child.ScrollTo(image.Pt(int(scrollX), scrollY))
 }
@@ -363,8 +366,7 @@ func (element *ScrollContainer) dragVerticalBar (mousePosition image.Point) {
 	scrollY :=
 		float64(element.child.ScrollContentBounds().Dy()) /
 		float64(element.vertical.gutter.Dy()) *
-		float64 (
-			mousePosition.Y - element.vertical.bar.Dy() / 2)
+		float64(mousePosition.Y - element.vertical.dragOffset)
 	scrollX := element.child.ScrollViewportBounds().Min.X
 	element.child.ScrollTo(image.Pt(scrollX, int(scrollY)))
 }