widget,widget/material: export Enum.Value

The Value method both updated the enum value and returned it.

In order to access the current value withoutm, expose the Value
field of the enum and rename the method to Update. As a bonus we
can get rid of the SetValue method as well.

Updates gio#96

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

widget/enum.go

@@ -6,9 +6,10 @@ import (
 )
 
 type Enum struct {
+	Value string
+
 	clicks []gesture.Click
 	values []string
-	value  string
 }
 
 func index(vs []string, t string) int {
@@ -20,32 +21,26 @@ func index(vs []string, t string) int {
 	return -1
 }
 
-// Value processes events and returns the last selected value, or
-// the empty string.
-func (e *Enum) Value(gtx *layout.Context) string {
+// Update the Value according to incoming events.
+func (e *Enum) Update(gtx *layout.Context) {
 	for i := range e.clicks {
 		for _, ev := range e.clicks[i].Events(gtx) {
 			switch ev.Type {
 			case gesture.TypeClick:
-				e.value = e.values[i]
+				e.Value = e.values[i]
 			}
 		}
 	}
-	return e.value
 }
 
 // Layout adds the event handler for key.
-func (rg *Enum) Layout(gtx *layout.Context, key string) {
-	if index(rg.values, key) == -1 {
-		rg.values = append(rg.values, key)
-		rg.clicks = append(rg.clicks, gesture.Click{})
-		rg.clicks[len(rg.clicks)-1].Add(gtx.Ops)
+func (e *Enum) Layout(gtx *layout.Context, key string) {
+	if index(e.values, key) == -1 {
+		e.values = append(e.values, key)
+		e.clicks = append(e.clicks, gesture.Click{})
+		e.clicks[len(e.clicks)-1].Add(gtx.Ops)
 	} else {
-		idx := index(rg.values, key)
-		rg.clicks[idx].Add(gtx.Ops)
+		idx := index(e.values, key)
+		e.clicks[idx].Add(gtx.Ops)
 	}
 }
-
-func (rg *Enum) SetValue(value string) {
-	rg.value = value
-}