widget/material: add Switch widget

Signed-off-by: Elias Naur <mail@eliasnaur.com>

widget/bool.go

@@ -8,19 +8,26 @@ import (
 type Bool struct {
 	Value bool
 
-	click gesture.Click
+	// Last is the last registered click.
+	Last Click
+
+	gesture gesture.Click
 }
 
 // Update the checked state according to incoming events.
 func (b *Bool) Update(gtx *layout.Context) {
-	for _, e := range b.click.Events(gtx) {
+	for _, e := range b.gesture.Events(gtx) {
 		switch e.Type {
 		case gesture.TypeClick:
+			b.Last = Click{
+				Time:     gtx.Now(),
+				Position: e.Position,
+			}
 			b.Value = !b.Value
 		}
 	}
 }
 
 func (b *Bool) Layout(gtx *layout.Context) {
-	b.click.Add(gtx.Ops)
+	b.gesture.Add(gtx.Ops)
 }