Introduce a new theme size name for rounded scrollbar corners

cmd/fyne_demo/main.go

@@ -253,10 +253,10 @@ func makeNav(setTutorial func(tutorial tutorials.Tutorial), loadPrevious bool) f
 
 	themes := container.NewGridWithColumns(2,
 		widget.NewButton("Dark", func() {
-			a.Settings().SetTheme(&forcedVariant{Theme: theme.DefaultTheme(), variant: theme.VariantDark})
+			//a.Settings().SetTheme(&forcedVariant{Theme: theme.DefaultTheme(), variant: theme.VariantDark})
 		}),
 		widget.NewButton("Light", func() {
-			a.Settings().SetTheme(&forcedVariant{Theme: theme.DefaultTheme(), variant: theme.VariantLight})
+			//a.Settings().SetTheme(&forcedVariant{Theme: theme.DefaultTheme(), variant: theme.VariantLight})
 		}),
 	)
 

container/testdata/doctabs/mobile/hover_none.xml

@@ -22,7 +22,7 @@
 					</widget>
 					<widget pos="0,30" size="110x6" type="*widget.scrollBarArea">
 						<widget pos="0,3" size="77x3" type="*widget.scrollBar">
-							<rectangle fillColor="scrollbar" size="77x3"/>
+							<rectangle fillColor="scrollbar" radius="3" size="77x3"/>
 						</widget>
 					</widget>
 				</widget>

internal/widget/scroller.go

@@ -51,6 +51,7 @@ func (r *scrollBarRenderer) MinSize() fyne.Size {
 
 func (r *scrollBarRenderer) Refresh() {
 	r.background.FillColor = theme.Color(theme.ColorNameScrollBar)
+	r.background.CornerRadius = theme.Size(theme.SizeNameScrollBarRadius)
 	r.background.Refresh()
 }
 
@@ -68,6 +69,7 @@ type scrollBar struct {
 
 func (b *scrollBar) CreateRenderer() fyne.WidgetRenderer {
 	background := canvas.NewRectangle(theme.Color(theme.ColorNameScrollBar))
+	background.CornerRadius = theme.Size(theme.SizeNameScrollBarRadius)
 	r := &scrollBarRenderer{
 		scrollBar:  b,
 		background: background,

test/theme.go

@@ -79,6 +79,7 @@ func NewTheme() fyne.Theme {
 			theme.SizeNameInputBorder:        float32(5),
 			theme.SizeNameInputRadius:        float32(2),
 			theme.SizeNameSelectionRadius:    float32(6),
+			theme.SizeNameScrollBarRadius:    float32(0),
 		},
 	}
 }
@@ -140,6 +141,7 @@ func Theme() fyne.Theme {
 				theme.SizeNameInputBorder:        float32(2),
 				theme.SizeNameInputRadius:        float32(4),
 				theme.SizeNameSelectionRadius:    float32(4),
+				theme.SizeNameScrollBarRadius:    float32(0),
 			},
 		}
 	}
@@ -176,8 +178,9 @@ func (t *configurableTheme) Icon(n fyne.ThemeIconName) fyne.Resource {
 }
 
 func (t *configurableTheme) Size(s fyne.ThemeSizeName) float32 {
-	if t.sizes[s] == 0 {
+	if _, ok := t.sizes[s]; !ok {
 		fyne.LogError(fmt.Sprintf("size %s not defined in theme %s", s, t.name), nil)
+		return 0
 	}
 
 	return t.sizes[s]

theme/size.go

@@ -72,6 +72,11 @@ const (
 	//
 	// Since: 2.4
 	SizeNameSelectionRadius fyne.ThemeSizeName = "selectionRadius"
+
+	// SizeNameScrollBarRadius is the name of theme lookup for the scroll bar corner radius.
+	//
+	// Since: 2.5
+	SizeNameScrollBarRadius = "scrollBarRadius"
 )
 
 // CaptionTextSize returns the size for caption text.
@@ -134,6 +139,13 @@ func SelectionRadiusSize() float32 {
 	return Current().Size(SizeNameSelectionRadius)
 }
 
+// ScrollBarRadiusSize returns the scroll bar corner radius size.
+//
+// Since: 2.5
+func ScrollBarRadiusSize() float32 {
+	return Current().Size(SizeNameScrollBarRadius)
+}
+
 // SeparatorThicknessSize is the standard thickness of the separator widget.
 //
 // Since: 2.0

theme/theme.go

@@ -171,6 +171,8 @@ func (t *builtinTheme) Size(s fyne.ThemeSizeName) float32 {
 		return 5
 	case SizeNameSelectionRadius:
 		return 3
+	case SizeNameScrollBarRadius:
+		return 3
 	default:
 		return 0
 	}