op: change CallOp to be a return value from MacroOp.Stop

Converting

	macro := op.Record(ops)
	...
	macro.Stop()

	macro.Add()

to

	macro := op.Record(ops)
	...
	call := macro.Stop()

	call.Add(ops)

Which is more general (call.Add can take a different ops than the op.Record
that started it), and enforced the order between Stop and the subsequent Add.

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

layout/flex.go

@@ -28,8 +28,8 @@ type FlexChild struct {
 	widget Widget
 
 	// Scratch space.
-	macro op.MacroOp
-	dims  Dimensions
+	call op.CallOp
+	dims Dimensions
 }
 
 // Spacing determine the spacing mode for a Flex.
@@ -93,10 +93,10 @@ func (f Flex) Layout(gtx Context, children ...FlexChild) Dimensions {
 		gtx := gtx
 		gtx.Constraints = cs
 		dims := child.widget(gtx)
-		macro.Stop()
+		c := macro.Stop()
 		sz := axisMain(f.Axis, dims.Size)
 		size += sz
-		children[i].macro = macro
+		children[i].call = c
 		children[i].dims = dims
 	}
 	rigidSize := size
@@ -127,10 +127,10 @@ func (f Flex) Layout(gtx Context, children ...FlexChild) Dimensions {
 		gtx := gtx
 		gtx.Constraints = cs
 		dims := child.widget(gtx)
-		macro.Stop()
+		c := macro.Stop()
 		sz := axisMain(f.Axis, dims.Size)
 		size += sz
-		children[i].macro = macro
+		children[i].call = c
 		children[i].dims = dims
 	}
 	var maxCross int
@@ -176,7 +176,7 @@ func (f Flex) Layout(gtx Context, children ...FlexChild) Dimensions {
 		}
 		stack := op.Push(gtx.Ops)
 		op.TransformOp{}.Offset(FPt(axisPoint(f.Axis, mainSize, cross))).Add(gtx.Ops)
-		child.macro.Add()
+		child.call.Add(gtx.Ops)
 		stack.Pop()
 		mainSize += axisMain(f.Axis, dims.Size)
 		if i < len(children)-1 {

layout/layout.go

@@ -158,7 +158,7 @@ func (a Direction) Layout(gtx Context, w Widget) Dimensions {
 	cs := gtx.Constraints
 	gtx.Constraints.Min = image.Point{}
 	dims := w(gtx)
-	macro.Stop()
+	call := macro.Stop()
 	sz := dims.Size
 	if sz.X < cs.Min.X {
 		sz.X = cs.Min.X
@@ -181,7 +181,7 @@ func (a Direction) Layout(gtx Context, w Widget) Dimensions {
 	}
 	stack := op.Push(gtx.Ops)
 	op.TransformOp{}.Offset(FPt(p)).Add(gtx.Ops)
-	macro.Add()
+	call.Add(gtx.Ops)
 	stack.Pop()
 	return Dimensions{
 		Size:     sz,

layout/list.go

@@ -12,8 +12,8 @@ import (
 )
 
 type scrollChild struct {
-	size  image.Point
-	macro op.MacroOp
+	size image.Point
+	call op.CallOp
 }
 
 // List displays a subsection of a potentially infinitely
@@ -181,8 +181,8 @@ func (l *List) nextDir() iterationDir {
 
 // End the current child by specifying its dimensions.
 func (l *List) end(dims Dimensions) {
-	l.child.Stop()
-	child := scrollChild{dims.Size, l.child}
+	call := l.child.Stop()
+	child := scrollChild{dims.Size, call}
 	mainSize := axisMain(l.Axis, child.size)
 	l.maxSize += mainSize
 	switch l.dir {
@@ -260,7 +260,7 @@ func (l *List) layout() Dimensions {
 		stack := op.Push(ops)
 		clip.Rect{Rect: FRect(r)}.Op(ops).Add(ops)
 		op.TransformOp{}.Offset(FPt(axisPoint(l.Axis, pos, cross))).Add(ops)
-		child.macro.Add()
+		child.call.Add(ops)
 		stack.Pop()
 		pos += childSize
 	}
@@ -277,10 +277,10 @@ func (l *List) layout() Dimensions {
 		pos = mainMax
 	}
 	dims := axisPoint(l.Axis, pos, maxCross)
-	l.macro.Stop()
+	call := l.macro.Stop()
 	defer op.Push(l.ctx.Ops).Pop()
 	pointer.Rect(image.Rectangle{Max: dims}).Add(ops)
 	l.scroll.Add(ops)
-	l.macro.Add()
+	call.Add(ops)
 	return Dimensions{Size: dims}
 }

layout/stack.go

@@ -22,8 +22,8 @@ type StackChild struct {
 	widget   Widget
 
 	// Scratch space.
-	macro op.MacroOp
-	dims  Dimensions
+	call op.CallOp
+	dims Dimensions
 }
 
 // Stacked returns a Stack child that is laid out with no minimum
@@ -58,14 +58,14 @@ func (s Stack) Layout(gtx Context, children ...StackChild) Dimensions {
 		gtx := gtx
 		gtx.Constraints.Min = image.Pt(0, 0)
 		dims := w.widget(gtx)
-		macro.Stop()
+		call := macro.Stop()
 		if w := dims.Size.X; w > maxSZ.X {
 			maxSZ.X = w
 		}
 		if h := dims.Size.Y; h > maxSZ.Y {
 			maxSZ.Y = h
 		}
-		children[i].macro = macro
+		children[i].call = call
 		children[i].dims = dims
 	}
 	// Then lay out Expanded children.
@@ -79,14 +79,14 @@ func (s Stack) Layout(gtx Context, children ...StackChild) Dimensions {
 			Min: maxSZ, Max: gtx.Constraints.Max,
 		}
 		dims := w.widget(gtx)
-		macro.Stop()
+		call := macro.Stop()
 		if w := dims.Size.X; w > maxSZ.X {
 			maxSZ.X = w
 		}
 		if h := dims.Size.Y; h > maxSZ.Y {
 			maxSZ.Y = h
 		}
-		children[i].macro = macro
+		children[i].call = call
 		children[i].dims = dims
 	}
 
@@ -109,7 +109,7 @@ func (s Stack) Layout(gtx Context, children ...StackChild) Dimensions {
 		}
 		stack := op.Push(gtx.Ops)
 		op.TransformOp{}.Offset(FPt(p)).Add(gtx.Ops)
-		ch.macro.Add()
+		ch.call.Add(gtx.Ops)
 		stack.Pop()
 		if baseline == 0 {
 			if b := ch.dims.Baseline; b != 0 {