From f08568a6dfc3890dcc8ea76c11f1a4cd436a57c1 Mon Sep 17 00:00:00 2001
From: Elias Naur <mail@eliasnaur.com>
Date: Tue, 5 May 2020 11:33:41 +0200
Subject: [PATCH] widget: report whether Value changed after Enum.Update and
 Bool.Update

Signed-off-by: Elias Naur <mail@eliasnaur.com>
---
 widget/bool.go | 7 +++++--
 widget/enum.go | 7 +++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/widget/bool.go b/widget/bool.go
index cbef01c8..ec459ac3 100644
--- a/widget/bool.go
+++ b/widget/bool.go
@@ -14,8 +14,10 @@ type Bool struct {
 	gesture gesture.Click
 }
 
-// Update the checked state according to incoming events.
-func (b *Bool) Update(gtx *layout.Context) {
+// Update the checked state according to incoming events,
+// and reports whether Value changed.
+func (b *Bool) Update(gtx *layout.Context) bool {
+	was := b.Value
 	for _, e := range b.gesture.Events(gtx) {
 		switch e.Type {
 		case gesture.TypeClick:
@@ -26,6 +28,7 @@ func (b *Bool) Update(gtx *layout.Context) {
 			b.Value = !b.Value
 		}
 	}
+	return b.Value != was
 }
 
 func (b *Bool) Layout(gtx *layout.Context) {
diff --git a/widget/enum.go b/widget/enum.go
index 0b10bada..6068740d 100644
--- a/widget/enum.go
+++ b/widget/enum.go
@@ -21,8 +21,10 @@ func index(vs []string, t string) int {
 	return -1
 }
 
-// Update the Value according to incoming events.
-func (e *Enum) Update(gtx *layout.Context) {
+// Update the Value according to incoming events, and
+// reports whether Value changed.
+func (e *Enum) Update(gtx *layout.Context) bool {
+	was := e.Value
 	for i := range e.clicks {
 		for _, ev := range e.clicks[i].Events(gtx) {
 			switch ev.Type {
@@ -31,6 +33,7 @@ func (e *Enum) Update(gtx *layout.Context) {
 			}
 		}
 	}
+	return e.Value != was
 }
 
 // Layout adds the event handler for key.