widget/material: added support for Vertical axis to Slider

Adding an axis to the Float widget, allows positioning the Slider one not only horizontally but also vertically.
Also update the fill ops while there.

Signed-off-by: pierre <pierre.curto@gmail.com>

widget/float.go

@@ -14,6 +14,7 @@ import (
 // Float is for selecting a value in a range.
 type Float struct {
 	Value float32
+	Axis  layout.Axis
 
 	drag    gesture.Drag
 	pos     float32 // position normalized to [0, 1]
@@ -24,13 +25,15 @@ type Float struct {
 // Dragging returns whether the value is being interacted with.
 func (f *Float) Dragging() bool { return f.drag.Dragging() }
 
-// Layout processes events.
+// Layout updates the value according to drag events along the f's main axis.
+//
+// The range of f is set by the minimum constraints main axis value.
 func (f *Float) Layout(gtx layout.Context, pointerMargin int, min, max float32) layout.Dimensions {
 	size := gtx.Constraints.Min
-	f.length = float32(size.X)
+	f.length = float32(f.Axis.Convert(size).X)
 
 	var de *pointer.Event
-	for _, e := range f.drag.Events(gtx.Metric, gtx, gesture.Horizontal) {
+	for _, e := range f.drag.Events(gtx.Metric, gtx, gesture.Axis(f.Axis)) {
 		if e.Type == pointer.Press || e.Type == pointer.Drag {
 			de = &e
 		}
@@ -38,7 +41,11 @@ func (f *Float) Layout(gtx layout.Context, pointerMargin int, min, max float32)
 
 	value := f.Value
 	if de != nil {
-		f.pos = de.Position.X / f.length
+		xy := de.Position.X
+		if f.Axis == layout.Vertical {
+			xy = de.Position.Y
+		}
+		f.pos = xy / f.length
 		value = min + (max-min)*f.pos
 	} else if min != max {
 		f.pos = value/(max-min) - min
@@ -53,9 +60,11 @@ func (f *Float) Layout(gtx layout.Context, pointerMargin int, min, max float32)
 	}
 
 	defer op.Save(gtx.Ops).Load()
-	rect := image.Rectangle{Max: size}
-	rect.Min.X -= pointerMargin
-	rect.Max.X += pointerMargin
+	margin := f.Axis.Convert(image.Pt(pointerMargin, 0))
+	rect := image.Rectangle{
+		Min: margin.Mul(-1),
+		Max: size.Add(margin),
+	}
 	pointer.Rect(rect).Add(gtx.Ops)
 	f.drag.Add(gtx.Ops)