seeking, layout update

ui/layouts/leftmiddlerightlayout.go

@@ -7,17 +7,20 @@ import (
 )
 
 // Lays out up to 3 objects such that the middle object, Objects[1],
-// is centered in the available space and takes up a fixed width.
-// The left, and right (if non-nil), split the leftover space equally.
+// is centered in the available space and takes up a fixed width,
+// or optionally a fraction of the overall space.
+// The left, and right split the leftover space equally.
 type LeftMiddleRightLayout struct {
-	middleWidth float32
-	hbox        fyne.Layout
+	middleWidthMin      float32
+	middleWidthFraction float32
+	hbox                fyne.Layout
 }
 
-func NewLeftMiddleRightLayout(middleWidth float32) *LeftMiddleRightLayout {
+func NewLeftMiddleRightLayout(middleWidthMin, middleWidthFraction float32) *LeftMiddleRightLayout {
 	return &LeftMiddleRightLayout{
-		middleWidth: middleWidth,
-		hbox:        layout.NewHBoxLayout(),
+		middleWidthMin:      middleWidthMin,
+		middleWidthFraction: middleWidthFraction,
+		hbox:                layout.NewHBoxLayout(),
 	}
 }
 
@@ -25,20 +28,21 @@ func (b *LeftMiddleRightLayout) MinSize(objects []fyne.CanvasObject) fyne.Size {
 	hboxSize := b.hbox.MinSize(objects)
 	return fyne.Size{
 		Height: hboxSize.Height,
-		Width:  hboxSize.Width + fyne.Max(0, b.middleWidth-objects[1].MinSize().Width),
+		Width:  hboxSize.Width + fyne.Max(0, b.middleWidthMin-objects[1].MinSize().Width),
 	}
 }
 
 func (b *LeftMiddleRightLayout) Layout(objects []fyne.CanvasObject, size fyne.Size) {
 	pad := theme.Padding()
-	midW := fyne.Max(b.middleWidth, objects[1].MinSize().Width)
+	lrMinWidth := fyne.Max(objects[0].MinSize().Width, objects[2].MinSize().Width)
+	midMinWidth := fyne.Max(b.middleWidthMin, objects[1].MinSize().Width)
+	midMaxWidth := size.Width - lrMinWidth*2 - pad*4
+	midW := fyne.Min(midMaxWidth, fyne.Max(midMinWidth, b.middleWidthFraction*size.Width))
 	lrW := (size.Width - midW - pad*4) / 2
 	objects[0].Resize(fyne.NewSize(lrW, size.Height))
 	objects[0].Move(fyne.NewPos(pad, 0))
 	objects[1].Resize(fyne.NewSize(midW, size.Height))
 	objects[1].Move(fyne.NewPos(lrW+pad*2, 0))
-	if objects[2] != nil {
-		objects[2].Resize(fyne.NewSize(lrW, size.Height))
-		objects[2].Move(fyne.NewPos(lrW+midW+pad*3, 0))
-	}
+	objects[2].Resize(fyne.NewSize(lrW, size.Height))
+	objects[2].Move(fyne.NewPos(lrW+midW+pad*3, 0))
 }