widget{,/material}: [API] split interactive and non-interactive text widgets

This commit separates the types for interactive and non-interactive text within
package widget. widget.Selectable is used for all interactive text. widget.Label
is used for all non-interactive text. There is no longer a field on widget.Label
to provide it with a Selectable. If you want selectable text and are not relying
upon the material pacakge API, you need to create widget.Selectables instead of
widget.Labels. The material package's LabelStyle API is unchanged.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

widget/label.go

@@ -16,7 +16,8 @@ import (
 	"golang.org/x/image/math/fixed"
 )
 
-// Label is a widget for laying out and drawing text.
+// Label is a widget for laying out and drawing text. Labels are always
+// non-interactive text. They cannot be selected or copied.
 type Label struct {
 	// Alignment specifies the text alignment.
 	Alignment text.Alignment
@@ -25,28 +26,10 @@ type Label struct {
 	// Truncator is the text that will be shown at the end of the final
 	// line if MaxLines is exceeded. Defaults to "…" if empty.
 	Truncator string
-	// Selectable optionally provides text selection state. If nil,
-	// text will not be selectable.
-	Selectable *Selectable
 }
 
-// Layout the label with the given shaper, font, size, text, and materials. If the Selectable field is
-// populated, the label will support text selection. Otherwise, it will be non-interactive. The textMaterial
-// and selectionMaterial op.CallOps are responsible for setting the painting material for the text glyphs
-// and the text selection rectangles, respectively.
-func (l Label) Layout(gtx layout.Context, lt *text.Shaper, font text.Font, size unit.Sp, txt string, textMaterial, selectionMaterial op.CallOp) layout.Dimensions {
-	if l.Selectable == nil {
-		return l.layout(gtx, lt, font, size, txt, textMaterial, selectionMaterial)
-	}
-	l.Selectable.text.Alignment = l.Alignment
-	l.Selectable.text.MaxLines = l.MaxLines
-	l.Selectable.text.Truncator = l.Truncator
-	l.Selectable.SetText(txt)
-	return l.Selectable.Layout(gtx, lt, font, size, textMaterial, selectionMaterial)
-}
-
-// layout the text as non-interactive.
-func (l Label) layout(gtx layout.Context, lt *text.Shaper, font text.Font, size unit.Sp, txt string, textMaterial, selectionMaterial op.CallOp) layout.Dimensions {
+// Layout the label with the given shaper, font, size, text, and material.
+func (l Label) Layout(gtx layout.Context, lt *text.Shaper, font text.Font, size unit.Sp, txt string, textMaterial op.CallOp) layout.Dimensions {
 	cs := gtx.Constraints
 	textSize := fixed.I(gtx.Sp(size))
 	lt.LayoutString(text.Parameters{

widget/material/button.go

@@ -119,7 +119,7 @@ func (b ButtonStyle) Layout(gtx layout.Context) layout.Dimensions {
 		return b.Inset.Layout(gtx, func(gtx layout.Context) layout.Dimensions {
 			colMacro := op.Record(gtx.Ops)
 			paint.ColorOp{Color: b.Color}.Add(gtx.Ops)
-			return widget.Label{Alignment: text.Middle}.Layout(gtx, b.shaper, b.Font, b.TextSize, b.Text, colMacro.Stop(), op.CallOp{})
+			return widget.Label{Alignment: text.Middle}.Layout(gtx, b.shaper, b.Font, b.TextSize, b.Text, colMacro.Stop())
 		})
 	})
 }

widget/material/checkable.go

@@ -76,7 +76,7 @@ func (c *checkable) layout(gtx layout.Context, checked, hovered bool) layout.Dim
 			return layout.UniformInset(2).Layout(gtx, func(gtx layout.Context) layout.Dimensions {
 				colMacro := op.Record(gtx.Ops)
 				paint.ColorOp{Color: c.Color}.Add(gtx.Ops)
-				return widget.Label{}.Layout(gtx, c.shaper, c.Font, c.TextSize, c.Label, colMacro.Stop(), op.CallOp{})
+				return widget.Label{}.Layout(gtx, c.shaper, c.Font, c.TextSize, c.Label, colMacro.Stop())
 			})
 		}),
 	)

widget/material/editor.go

@@ -61,7 +61,7 @@ func (e EditorStyle) Layout(gtx layout.Context) layout.Dimensions {
 
 	macro := op.Record(gtx.Ops)
 	tl := widget.Label{Alignment: e.Editor.Alignment, MaxLines: maxlines}
-	dims := tl.Layout(gtx, e.shaper, e.Font, e.TextSize, e.Hint, hintColor, selectionColor)
+	dims := tl.Layout(gtx, e.shaper, e.Font, e.TextSize, e.Hint, hintColor)
 	call := macro.Stop()
 
 	if w := dims.Size.X; gtx.Constraints.Min.X < w {

widget/material/label.go

@@ -14,6 +14,9 @@ import (
 	"gioui.org/widget"
 )
 
+// LabelStyle configures the presentation of text. If the State field is set, the
+// label will be laid out as interactive (able to be selected and copied). Otherwise,
+// the label will be non-interactive.
 type LabelStyle struct {
 	// Face defines the text style.
 	Font text.Font
@@ -109,6 +112,12 @@ func (l LabelStyle) Layout(gtx layout.Context) layout.Dimensions {
 	paint.ColorOp{Color: l.SelectionColor}.Add(gtx.Ops)
 	selectColor := selectColorMacro.Stop()
 
-	tl := widget.Label{Alignment: l.Alignment, MaxLines: l.MaxLines, Selectable: l.State}
-	return tl.Layout(gtx, l.shaper, l.Font, l.TextSize, l.Text, textColor, selectColor)
+	if l.State != nil {
+		if l.State.Text() != l.Text {
+			l.State.SetText(l.Text)
+		}
+		return l.State.Layout(gtx, l.shaper, l.Font, l.TextSize, textColor, selectColor)
+	}
+	tl := widget.Label{Alignment: l.Alignment, MaxLines: l.MaxLines}
+	return tl.Layout(gtx, l.shaper, l.Font, l.TextSize, l.Text, textColor)
 }

widget/selectable_test.go

@@ -46,9 +46,8 @@ func TestSelectableMove(t *testing.T) {
 	gtx.Queue = newQueue(key.FocusEvent{Focus: true})
 	s := new(Selectable)
 
-	Label{
-		Selectable: s,
-	}.Layout(gtx, cache, text.Font{}, fontSize, str, op.CallOp{}, op.CallOp{})
+	s.SetText(str)
+	s.Layout(gtx, cache, text.Font{}, fontSize, op.CallOp{}, op.CallOp{})
 
 	testKey := func(keyName string) {
 		// Select 345
@@ -62,9 +61,8 @@ func TestSelectableMove(t *testing.T) {
 
 		// Press the key
 		gtx.Queue = newQueue(key.Event{State: key.Press, Name: keyName})
-		Label{
-			Selectable: s,
-		}.Layout(gtx, cache, font, fontSize, str, op.CallOp{}, op.CallOp{})
+		s.SetText(str)
+		s.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 
 		if expected, got := "", s.SelectedText(); expected != got {
 			t.Errorf("KeyName %s, expected %q, got %q", keyName, expected, got)
@@ -102,12 +100,10 @@ func TestSelectableConfigurations(t *testing.T) {
 					gtx.Constraints.Min = gtx.Constraints.Max
 				}
 				s := new(Selectable)
-				label := Label{
-					Alignment:  alignment,
-					Selectable: s,
-				}
-				interactiveDims := label.Layout(gtx, cache, font, fontSize, sentence, op.CallOp{}, op.CallOp{})
-				staticDims := label.Layout(gtx, cache, font, fontSize, sentence, op.CallOp{}, op.CallOp{})
+				s.text.Alignment = alignment
+				s.SetText(sentence)
+				interactiveDims := s.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
+				staticDims := Label{Alignment: alignment}.Layout(gtx, cache, font, fontSize, sentence, op.CallOp{})
 
 				if interactiveDims != staticDims {
 					t.Errorf("expected consistent dimensions, static returned %#+v, interactive returned %#+v", staticDims, interactiveDims)

widget/text_bench_test.go

@@ -97,7 +97,7 @@ func BenchmarkLabelStatic(b *testing.B) {
 		l := Label{}
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
-			l.Layout(gtx, cache, font, fontSize, runesStr, op.CallOp{}, op.CallOp{})
+			l.Layout(gtx, cache, font, fontSize, runesStr, op.CallOp{})
 			if render {
 				win.Frame(gtx.Ops)
 			}
@@ -132,7 +132,7 @@ func BenchmarkLabelDynamic(b *testing.B) {
 			a := rand.Intn(len(runes))
 			b := rand.Intn(len(runes))
 			runes[a], runes[b] = runes[b], runes[a]
-			l.Layout(gtx, cache, font, fontSize, string(runes), op.CallOp{}, op.CallOp{})
+			l.Layout(gtx, cache, font, fontSize, string(runes), op.CallOp{})
 			if render {
 				win.Frame(gtx.Ops)
 			}