Add the capability to scroll in RichText, leaving space for great opt…

…imisation

In the future this will simplify Entry and others

cmd/fyne_demo/tutorials/widget.go

@@ -172,6 +172,7 @@ Normal **Bold** *Italic* [Link](https://fyne.io/) and some ` + "`Code`" + `.
 This styled row should also wrap as expected, but only *when required*.
 
 > An interesting quote here, most likely sharing some very interesting wisdom.`)
+	rich.Scroll = container.ScrollBoth
 
 	radioAlign := widget.NewRadioGroup([]string{"Text Alignment Leading", "Text Alignment Center", "Text Alignment Trailing"}, func(s string) {
 		var align fyne.TextAlign
@@ -234,12 +235,11 @@ This styled row should also wrap as expected, but only *when required*.
 		),
 		label,
 		hyperlink,
-		rich,
 	)
 
 	grid := makeTextGrid()
-	return fyne.NewContainerWithLayout(layout.NewBorderLayout(fixed, grid, nil, nil),
-		fixed, entryLoremIpsum, grid)
+	return container.NewBorder(fixed, grid, nil, nil,
+		container.NewGridWithRows(2, rich, entryLoremIpsum))
 }
 
 func makeInputTab(_ fyne.Window) fyne.CanvasObject {

widget/richtext.go

@@ -10,6 +10,7 @@ import (
 	"fyne.io/fyne/v2"
 	"fyne.io/fyne/v2/canvas"
 	"fyne.io/fyne/v2/internal/widget"
+	"fyne.io/fyne/v2/layout"
 	"fyne.io/fyne/v2/theme"
 )
 
@@ -24,9 +25,12 @@ type RichText struct {
 	BaseWidget
 	Segments []RichTextSegment
 	Wrapping fyne.TextWrap
+	Scroll   widget.ScrollDirection
 
 	inset     fyne.Size     // this varies due to how the widget works (entry with scroller vs others with padding)
 	rowBounds []rowBoundary // cache for boundaries
+	scr       *widget.Scroll
+	prop      *canvas.Rectangle // used to apply text minsize to the scroller `scr`, if present - TODO improve #2464
 
 	visualCache map[RichTextSegment][]fyne.CanvasObject
 	cacheLock   sync.Mutex
@@ -38,6 +42,7 @@ type RichText struct {
 // Since: 2.1
 func NewRichText(segments ...RichTextSegment) *RichText {
 	t := &RichText{Segments: segments}
+	t.Scroll = widget.ScrollNone
 	t.updateRowBounds()
 	return t
 }
@@ -55,6 +60,12 @@ func NewRichTextWithText(text string) *RichText {
 
 // CreateRenderer is a private method to Fyne which links this widget to its renderer
 func (t *RichText) CreateRenderer() fyne.WidgetRenderer {
+	if t.scr == nil && t.Scroll != widget.ScrollNone {
+		t.prop = canvas.NewRectangle(color.Transparent)
+		t.scr = widget.NewScroll(&fyne.Container{Layout: layout.NewMaxLayout(), Objects: []fyne.CanvasObject{
+			t.prop, &fyne.Container{}}})
+	}
+
 	t.ExtendBaseWidget(t)
 	r := &textRenderer{obj: t}
 
@@ -374,7 +385,16 @@ func (t *RichText) updateRowBounds() {
 				if len(last.segments) == 1 {
 					begin = last.begin
 				}
-				text := string([]rune(textSeg.Text)[begin:last.end])
+				runes := []rune(textSeg.Text)
+				// check ranges - as we resize it can be wrong?
+				if begin > len(runes) {
+					begin = len(runes)
+				}
+				end := last.end
+				if end > len(runes) {
+					end = len(runes)
+				}
+				text := string(runes[begin:end])
 				lastWidth := fyne.MeasureText(text, textSeg.size(), textSeg.Style.TextStyle).Width
 				if len(retBounds) == 1 {
 					wrapWidth -= lastWidth
@@ -413,6 +433,10 @@ func (r *textRenderer) Layout(size fyne.Size) {
 	r.obj.propertyLock.RLock()
 	bounds := r.obj.rowBounds
 	objs := r.Objects()
+	if r.obj.scr != nil {
+		r.obj.scr.Resize(size)
+		objs = r.obj.scr.Content.(*fyne.Container).Objects[1].(*fyne.Container).Objects
+	}
 	r.obj.propertyLock.RUnlock()
 
 	left := theme.Padding()*2 - r.obj.inset.Width
@@ -473,7 +497,11 @@ func (r *textRenderer) MinSize() fyne.Size {
 	r.obj.propertyLock.RLock()
 	bounds := r.obj.rowBounds
 	wrap := r.obj.Wrapping
+	scroll := r.obj.Scroll
 	objs := r.Objects()
+	if r.obj.scr != nil {
+		objs = r.obj.scr.Content.(*fyne.Container).Objects[1].(*fyne.Container).Objects
+	}
 	r.obj.propertyLock.RUnlock()
 
 	height := float32(0)
@@ -512,13 +540,29 @@ func (r *textRenderer) MinSize() fyne.Size {
 		charMinSize := r.obj.charMinSize(false, fyne.TextStyle{})
 		height = charMinSize.Height
 	}
-	return fyne.NewSize(width, height).
+	min := fyne.NewSize(width, height).
 		Add(fyne.NewSize(theme.Padding()*4, theme.Padding()*4).Subtract(r.obj.inset).Subtract(r.obj.inset))
+
+	if r.obj.scr != nil {
+		r.obj.prop.SetMinSize(min)
+	}
+
+	switch scroll {
+	case widget.ScrollBoth:
+		return fyne.NewSize(32, 32)
+	case widget.ScrollHorizontalOnly:
+		return fyne.NewSize(32, min.Height)
+	case widget.ScrollVerticalOnly:
+		return fyne.NewSize(min.Width, 32)
+	default:
+		return min
+	}
 }
 
 func (r *textRenderer) Refresh() {
 	r.obj.propertyLock.RLock()
 	bounds := r.obj.rowBounds
+	scroll := r.obj.Scroll
 	r.obj.propertyLock.RUnlock()
 
 	var objs []fyne.CanvasObject
@@ -555,7 +599,15 @@ func (r *textRenderer) Refresh() {
 	}
 
 	r.obj.propertyLock.Lock()
-	r.SetObjects(objs)
+	if r.obj.scr != nil {
+		r.obj.scr.Content = &fyne.Container{Layout: layout.NewMaxLayout(), Objects: []fyne.CanvasObject{
+			r.obj.prop, &fyne.Container{Objects: objs}}}
+		r.obj.scr.Direction = scroll
+		r.SetObjects([]fyne.CanvasObject{r.obj.scr})
+		r.obj.scr.Refresh()
+	} else {
+		r.SetObjects(objs)
+	}
 	r.obj.propertyLock.Unlock()
 
 	r.Layout(r.obj.Size())

widget/richtext_test.go

@@ -6,6 +6,7 @@ import (
 	"fyne.io/fyne/v2"
 	"fyne.io/fyne/v2/canvas"
 	"fyne.io/fyne/v2/internal/cache"
+	"fyne.io/fyne/v2/internal/widget"
 	"fyne.io/fyne/v2/test"
 	"fyne.io/fyne/v2/theme"
 	"github.com/stretchr/testify/assert"
@@ -97,6 +98,20 @@ func TestText_RowLength(t *testing.T) {
 	assert.Equal(t, 5, rl)
 }
 
+func TestText_Scroll(t *testing.T) {
+	text1 := NewRichTextWithText("test1\ntest2")
+	text2 := NewRichTextWithText("test1\ntest2")
+	text2.Scroll = widget.ScrollBoth
+
+	assert.Less(t, text2.MinSize().Width, text1.MinSize().Width)
+	assert.Less(t, text2.MinSize().Height, text1.MinSize().Height)
+
+	text3 := NewRichTextWithText("test1\ntest2")
+	text3.Scroll = widget.ScrollVerticalOnly
+	assert.Equal(t, text3.MinSize().Width, text1.MinSize().Width)
+	assert.Less(t, text3.MinSize().Height, text1.MinSize().Height)
+}
+
 func TestText_InsertAt(t *testing.T) {
 	type fields struct {
 		buffer string