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>

font/opentype/opentype.go

@@ -185,6 +185,7 @@ func textPath(buf *sfnt.Buffer, ppem fixed.Int26_6, f *opentype, str []text.Glyp
 	var lastPos f32.Point
 	var builder clip.Path
 	ops := new(op.Ops)
+	m := op.Record(ops)
 	var x fixed.Int26_6
 	builder.Begin(ops)
 	for _, g := range str {
@@ -238,7 +239,7 @@ func textPath(buf *sfnt.Buffer, ppem fixed.Int26_6, f *opentype, str []text.Glyp
 		x += g.Advance
 	}
 	builder.End().Add(ops)
-	return op.CallOp{Ops: ops}
+	return m.Stop()
 }
 
 func readGlyphs(r io.Reader) ([]text.Glyph, error) {

internal/opconst/ops.go

@@ -8,8 +8,8 @@ type OpType byte
 const firstOpIndex = 200
 
 const (
-	TypeMacroDef OpType = iota + firstOpIndex
-	TypeMacro
+	TypeMacro OpType = iota + firstOpIndex
+	TypeCall
 	TypeTransform
 	TypeLayer
 	TypeInvalidate
@@ -26,12 +26,11 @@ const (
 	TypeAux
 	TypeClip
 	TypeProfile
-	TypeCall
 )
 
 const (
-	TypeMacroDefLen     = 1 + 4 + 4
 	TypeMacroLen        = 1 + 4 + 4
+	TypeCallLen         = 1 + 4 + 4
 	TypeTransformLen    = 1 + 4*2
 	TypeLayerLen        = 1
 	TypeRedrawLen       = 1 + 8
@@ -48,13 +47,12 @@ const (
 	TypeAuxLen          = 1
 	TypeClipLen         = 1 + 4*4
 	TypeProfileLen      = 1
-	TypeCallLen         = 1
 )
 
 func (t OpType) Size() int {
 	return [...]int{
-		TypeMacroDefLen,
 		TypeMacroLen,
+		TypeCallLen,
 		TypeTransformLen,
 		TypeLayerLen,
 		TypeRedrawLen,
@@ -71,7 +69,6 @@ func (t OpType) Size() int {
 		TypeAuxLen,
 		TypeClipLen,
 		TypeProfileLen,
-		TypeCallLen,
 	}[t-firstOpIndex]
 }
 

internal/ops/reader.go

@@ -33,12 +33,8 @@ type Key struct {
 
 // Shadow of op.MacroOp.
 type macroOp struct {
-	pc pc
-}
-
-// Shadow of op.CallOp.
-type callOp struct {
 	ops *op.Ops
+	pc  pc
 }
 
 type pc struct {
@@ -98,32 +94,14 @@ func (r *Reader) Decode() (EncodedOp, bool) {
 			n += block.endPC.data - r.pc.data - opconst.TypeAuxLen
 			data = data[:n]
 		case opconst.TypeCall:
-			var op callOp
-			op.decode(data, refs)
-			endPC := pc{
-				data: len(op.ops.Data()),
-				refs: len(op.ops.Refs()),
-			}
-			retPC := r.pc
-			retPC.data += n
-			retPC.refs += nrefs
-			r.stack = append(r.stack, macro{
-				ops:   r.ops,
-				retPC: retPC,
-				endPC: endPC,
-			})
-			r.pc = pc{}
-			r.ops = op.ops
-			continue
-		case opconst.TypeMacro:
 			var op macroOp
-			op.decode(data)
-			macroData := r.ops.Data()[op.pc.data:]
-			if opconst.OpType(macroData[0]) != opconst.TypeMacroDef {
+			op.decode(data, refs)
+			macroData := op.ops.Data()[op.pc.data:]
+			if opconst.OpType(macroData[0]) != opconst.TypeMacro {
 				panic("invalid macro reference")
 			}
 			var opDef opMacroDef
-			opDef.decode(macroData[:opconst.TypeMacroDef.Size()])
+			opDef.decode(macroData[:opconst.TypeMacro.Size()])
 			retPC := r.pc
 			retPC.data += n
 			retPC.refs += nrefs
@@ -132,11 +110,12 @@ func (r *Reader) Decode() (EncodedOp, bool) {
 				retPC: retPC,
 				endPC: opDef.endpc,
 			})
+			r.ops = op.ops
 			r.pc = op.pc
-			r.pc.data += opconst.TypeMacroDef.Size()
-			r.pc.refs += opconst.TypeMacroDef.NumRefs()
+			r.pc.data += opconst.TypeMacro.Size()
+			r.pc.refs += opconst.TypeMacro.NumRefs()
 			continue
-		case opconst.TypeMacroDef:
+		case opconst.TypeMacro:
 			var op opMacroDef
 			op.decode(data)
 			r.pc = op.endpc
@@ -149,7 +128,7 @@ func (r *Reader) Decode() (EncodedOp, bool) {
 }
 
 func (op *opMacroDef) decode(data []byte) {
-	if opconst.OpType(data[0]) != opconst.TypeMacroDef {
+	if opconst.OpType(data[0]) != opconst.TypeMacro {
 		panic("invalid op")
 	}
 	bo := binary.LittleEndian
@@ -163,23 +142,15 @@ func (op *opMacroDef) decode(data []byte) {
 	}
 }
 
-func (m *callOp) decode(data []byte, refs []interface{}) {
+func (m *macroOp) decode(data []byte, refs []interface{}) {
 	if opconst.OpType(data[0]) != opconst.TypeCall {
 		panic("invalid op")
 	}
-	*m = callOp{
-		ops: refs[0].(*op.Ops),
-	}
-}
-
-func (m *macroOp) decode(data []byte) {
-	if opconst.OpType(data[0]) != opconst.TypeMacro {
-		panic("invalid op")
-	}
 	bo := binary.LittleEndian
 	dataIdx := int(int32(bo.Uint32(data[1:])))
 	refsIdx := int(int32(bo.Uint32(data[5:])))
 	*m = macroOp{
+		ops: refs[0].(*op.Ops),
 		pc: pc{
 			data: dataIdx,
 			refs: refsIdx,

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 {

op/clip/clip.go

@@ -35,12 +35,12 @@ type Path struct {
 // If you need to reset the clip to its previous values after
 // applying a Op, use op.StackOp.
 type Op struct {
-	macro  op.MacroOp
+	call   op.CallOp
 	bounds f32.Rectangle
 }
 
 func (p Op) Add(o *op.Ops) {
-	p.macro.Add()
+	p.call.Add(o)
 	data := o.Write(opconst.TypeClipLen)
 	data[0] = byte(opconst.TypeClip)
 	bo := binary.LittleEndian
@@ -281,9 +281,9 @@ func (p *Path) simpleQuadTo(ctrl, to f32.Point) {
 // End the path and return a clip operation that represents it.
 func (p *Path) End() Op {
 	p.end()
-	p.macro.Stop()
+	c := p.macro.Stop()
 	return Op{
-		macro:  p.macro,
+		call:   c,
 		bounds: p.bounds,
 	}
 }

op/op.go

@@ -49,12 +49,6 @@ end of a function :
 
   defer op.Push(ops).Pop()
 
-The CallOp invokes another operation list:
-
-	ops := new(op.Ops)
-	ops2 := new(op.Ops)
-	op.CallOp{Ops: ops2}.Add(ops)
-
 The MacroOp records a list of operations to be executed later:
 
 	ops := new(op.Ops)
@@ -63,10 +57,10 @@ The MacroOp records a list of operations to be executed later:
 	op.InvalidateOp{}.Add(ops)
 	...
 	// End recording.
-	macro.Stop()
+	call := macro.Stop()
 
-	// replay the recorded operations by calling Add:
-	macro.Add()
+	// replay the recorded operations:
+	call.Add(ops)
 
 */
 package op
@@ -110,11 +104,11 @@ type MacroOp struct {
 	pc  pc
 }
 
-// CallOp invokes all the operations from a separate
-// operations list.
+// CallOp invokes the operations recorded by Record.
 type CallOp struct {
 	// Ops is the list of operations to invoke.
-	Ops *Ops
+	ops *Ops
+	pc  pc
 }
 
 // InvalidateOp requests a redraw at the given time. Use
@@ -146,15 +140,6 @@ type pc struct {
 	refs int
 }
 
-// Add the call to the operation list.
-func (c CallOp) Add(o *Ops) {
-	if c.Ops == nil {
-		return
-	}
-	data := o.Write(opconst.TypeCallLen, c.Ops)
-	data[0] = byte(opconst.TypeCall)
-}
-
 // Push (save) the current operations state.
 func Push(o *Ops) StackOp {
 	s := StackOp{
@@ -224,38 +209,43 @@ func Record(o *Ops) MacroOp {
 		pc:  o.pc(),
 	}
 	// Reserve room for a macro definition. Updated in Stop.
-	m.ops.Write(opconst.TypeMacroDefLen)
+	m.ops.Write(opconst.TypeMacroLen)
 	m.fill()
 	return m
 }
 
-// Stop ends a previously started recording.
-func (m MacroOp) Stop() {
+// Stop ends a previously started recording and returns an
+// operation for replaying it.
+func (m MacroOp) Stop() CallOp {
 	m.ops.macroStack.pop(m.id)
 	m.fill()
+	return CallOp{
+		ops: m.ops,
+		pc:  m.pc,
+	}
 }
 
 func (m MacroOp) fill() {
 	pc := m.ops.pc()
 	// Fill out the macro definition reserved in Record.
 	data := m.ops.data[m.pc.data:]
-	data = data[:opconst.TypeMacroDefLen]
-	data[0] = byte(opconst.TypeMacroDef)
+	data = data[:opconst.TypeMacroLen]
+	data[0] = byte(opconst.TypeMacro)
 	bo := binary.LittleEndian
 	bo.PutUint32(data[1:], uint32(pc.data))
 	bo.PutUint32(data[5:], uint32(pc.refs))
 }
 
 // Add the recorded list of operations.
-func (m MacroOp) Add() {
-	if m.ops == nil {
+func (c CallOp) Add(o *Ops) {
+	if c.ops == nil {
 		return
 	}
-	data := m.ops.Write(opconst.TypeMacroLen)
-	data[0] = byte(opconst.TypeMacro)
+	data := o.Write(opconst.TypeCallLen, c.ops)
+	data[0] = byte(opconst.TypeCall)
 	bo := binary.LittleEndian
-	bo.PutUint32(data[1:], uint32(m.pc.data))
-	bo.PutUint32(data[5:], uint32(m.pc.refs))
+	bo.PutUint32(data[1:], uint32(c.pc.data))
+	bo.PutUint32(data[5:], uint32(c.pc.refs))
 }
 
 func (r InvalidateOp) Add(o *Ops) {

widget/material/editor.go

@@ -44,7 +44,7 @@ func (e EditorStyle) Layout(gtx layout.Context) layout.Dimensions {
 	paint.ColorOp{Color: e.HintColor}.Add(gtx.Ops)
 	tl := widget.Label{Alignment: e.Editor.Alignment}
 	dims := tl.Layout(gtx, e.shaper, e.Font, e.TextSize, e.Hint)
-	macro.Stop()
+	call := macro.Stop()
 	if w := dims.Size.X; gtx.Constraints.Min.X < w {
 		gtx.Constraints.Min.X = w
 	}
@@ -56,7 +56,7 @@ func (e EditorStyle) Layout(gtx layout.Context) layout.Dimensions {
 		paint.ColorOp{Color: e.Color}.Add(gtx.Ops)
 		e.Editor.PaintText(gtx)
 	} else {
-		macro.Add()
+		call.Add(gtx.Ops)
 	}
 	paint.ColorOp{Color: e.Color}.Add(gtx.Ops)
 	e.Editor.PaintCaret(gtx)