op/clip: split clip operations into its own package

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

app/internal/gpu/gpu.go

@@ -119,7 +119,7 @@ type material struct {
 	uvOffset f32.Point
 }
 
-// clipOp is the shadow of paint.ClipOp.
+// clipOp is the shadow of clip.Op.
 type clipOp struct {
 	bounds f32.Rectangle
 }

font/opentype/opentype.go

@@ -11,7 +11,7 @@ import (
 
 	"gioui.org/f32"
 	"gioui.org/op"
-	"gioui.org/op/paint"
+	"gioui.org/op/clip"
 	"gioui.org/text"
 	"golang.org/x/image/font"
 	"golang.org/x/image/font/sfnt"
@@ -43,7 +43,7 @@ func (f *Font) Layout(ppem fixed.Int26_6, str string, opts text.LayoutOptions) *
 	return layoutText(&f.buf, ppem, str, &opentype{Font: f.font, Hinting: font.HintingFull}, opts)
 }
 
-func (f *Font) Shape(ppem fixed.Int26_6, str text.String) paint.ClipOp {
+func (f *Font) Shape(ppem fixed.Int26_6, str text.String) clip.Op {
 	return textPath(&f.buf, ppem, &opentype{Font: f.font, Hinting: font.HintingFull}, str)
 }
 
@@ -136,9 +136,9 @@ func layoutText(buf *sfnt.Buffer, ppem fixed.Int26_6, str string, f *opentype, o
 	return &text.Layout{Lines: lines}
 }
 
-func textPath(buf *sfnt.Buffer, ppem fixed.Int26_6, f *opentype, str text.String) paint.ClipOp {
+func textPath(buf *sfnt.Buffer, ppem fixed.Int26_6, f *opentype, str text.String) clip.Op {
 	var lastPos f32.Point
-	var builder paint.Path
+	var builder clip.Path
 	ops := new(op.Ops)
 	var x fixed.Int26_6
 	var advIdx int

layout/list.go

@@ -8,7 +8,7 @@ import (
 	"gioui.org/gesture"
 	"gioui.org/io/pointer"
 	"gioui.org/op"
-	"gioui.org/op/paint"
+	"gioui.org/op/clip"
 )
 
 type scrollChild struct {
@@ -248,7 +248,7 @@ func (l *List) layout() Dimensions {
 		}
 		var stack op.StackOp
 		stack.Push(ops)
-		paint.RectClip(r).Add(ops)
+		clip.Rect(r).Add(ops)
 		op.TransformOp{}.Offset(toPointF(axisPoint(l.Axis, pos, cross))).Add(ops)
 		child.macro.Add(ops)
 		stack.Pop()

op/clip/clip.go

@@ -1,9 +1,10 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-package paint
+package clip
 
 import (
 	"encoding/binary"
+	"image"
 	"math"
 
 	"gioui.org/f32"
@@ -12,10 +13,13 @@ import (
 	"gioui.org/op"
 )
 
-// Path constructs a ClipOp clip path described by lines and
+// Path constructs a Op clip path described by lines and
-// Bézier curves. Path generates no garbage and can be used for
+// Bézier curves, where drawing outside the Path is discarded.
-// dynamic paths; path data is stored directly in the Ops list
+// The inside-ness of a pixel is determines by the even-odd rule,
-// supplied to Begin.
+// similar to the SVG rule of the same name.
+//
+// Path generates no garbage and can be used for dynamic paths; path
+// data is stored directly in the Ops list supplied to Begin.
 type Path struct {
 	ops       *op.Ops
 	contour   int
@@ -25,17 +29,17 @@ type Path struct {
 	macro     op.MacroOp
 }
 
-// ClipOp sets the current clip to the intersection of
+// Op sets the current clip to the intersection of
 // the existing clip with this clip.
 //
 // If you need to reset the clip to its previous values after
-// applying a ClipOp, use op.StackOp.
+// applying a Op, use op.StackOp.
-type ClipOp struct {
+type Op struct {
 	macro  op.MacroOp
 	bounds f32.Rectangle
 }
 
-func (p ClipOp) Add(o *op.Ops) {
+func (p Op) Add(o *op.Ops) {
 	p.macro.Add(o)
 	data := o.Write(opconst.TypeClipLen)
 	data[0] = byte(opconst.TypeClip)
@@ -46,7 +50,7 @@ func (p ClipOp) Add(o *op.Ops) {
 	bo.PutUint32(data[13:], math.Float32bits(p.bounds.Max.Y))
 }
 
-// Begin the path, storing the path data and final ClipOp into ops.
+// Begin the path, storing the path data and final Op into ops.
 func (p *Path) Begin(ops *op.Ops) {
 	p.ops = ops
 	p.macro.Record(ops)
@@ -270,12 +274,24 @@ func (p *Path) simpleQuadTo(ctrl, to f32.Point) {
 	p.pen = to
 }
 
-// End the path and return the resulting ClipOp.
+// End the path and return a clip operation that represents it.
-func (p *Path) End() ClipOp {
+func (p *Path) End() Op {
 	p.end()
 	p.macro.Stop()
-	return ClipOp{
+	return Op{
 		macro:  p.macro,
 		bounds: p.bounds,
 	}
 }
+
+// Rect returns the clip area of a pixel aligned rectangular area.
+func Rect(r image.Rectangle) Op {
+	return Op{bounds: toRectF(r)}
+}
+
+func toRectF(r image.Rectangle) f32.Rectangle {
+	return f32.Rectangle{
+		Min: f32.Point{X: float32(r.Min.X), Y: float32(r.Min.Y)},
+		Max: f32.Point{X: float32(r.Max.X), Y: float32(r.Max.Y)},
+	}
+}

op/clip/doc.go

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+/*
+Package clip provides operations for clipping paint operations.
+Drawing outside the current clip area is ignored.
+
+The current clip is initially the infinite set. An Op sets the clip
+to the intersection of the current clip and the clip area it
+represents. If you need to reset the current clip to its value
+before applying an Op, use op.StackOp.
+
+General clipping areas are constructed with Path. Simpler special
+cases such as rectangular clip areas also exist as convenient
+constructors.
+*/
+package clip

op/paint/doc.go

@@ -1,15 +1,12 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
 /*
-Package paint provides operations for 2D graphics.
+Package paint provides drawing operations for 2D graphics.
 
 The PaintOp operation draws the current material into a rectangular
 area, taking the current clip path and transformation into account.
 
 The material is set by either a ColorOp for a constant color, or
 ImageOp for an image.
-
-The ClipOp operation sets the clip path. Drawing outside the clip
-path is ignored. A path is a closed shape of lines or curves.
 */
 package paint

op/paint/paint.go

@@ -102,16 +102,3 @@ func (d PaintOp) Add(o *op.Ops) {
 	bo.PutUint32(data[9:], math.Float32bits(d.Rect.Max.X))
 	bo.PutUint32(data[13:], math.Float32bits(d.Rect.Max.Y))
 }
-
-// RectClip returns a ClipOp corresponding to a pixel aligned
-// rectangular area.
-func RectClip(r image.Rectangle) ClipOp {
-	return ClipOp{bounds: toRectF(r)}
-}
-
-func toRectF(r image.Rectangle) f32.Rectangle {
-	return f32.Rectangle{
-		Min: f32.Point{X: float32(r.Min.X), Y: float32(r.Min.Y)},
-		Max: f32.Point{X: float32(r.Max.X), Y: float32(r.Max.Y)},
-	}
-}

text/lru.go

@@ -3,7 +3,7 @@
 package text
 
 import (
-	"gioui.org/op/paint"
+	"gioui.org/op/clip"
 	"golang.org/x/image/math/fixed"
 )
 
@@ -26,7 +26,7 @@ type layoutElem struct {
 type path struct {
 	next, prev *path
 	key        pathKey
-	val        paint.ClipOp
+	val        clip.Op
 }
 
 type layoutKey struct {
@@ -81,16 +81,16 @@ func (l *layoutCache) insert(lt *layoutElem) {
 	lt.next.prev = lt
 }
 
-func (c *pathCache) Get(k pathKey) (paint.ClipOp, bool) {
+func (c *pathCache) Get(k pathKey) (clip.Op, bool) {
 	if v, ok := c.m[k]; ok {
 		c.remove(v)
 		c.insert(v)
 		return v.val, true
 	}
-	return paint.ClipOp{}, false
+	return clip.Op{}, false
 }
 
-func (c *pathCache) Put(k pathKey, v paint.ClipOp) {
+func (c *pathCache) Put(k pathKey, v clip.Op) {
 	if c.m == nil {
 		c.m = make(map[pathKey]*path)
 		c.head = new(path)

text/lru_test.go

@@ -6,7 +6,7 @@ import (
 	"strconv"
 	"testing"
 
-	"gioui.org/op/paint"
+	"gioui.org/op/clip"
 )
 
 func TestLayoutLRU(t *testing.T) {
@@ -24,7 +24,7 @@ func TestLayoutLRU(t *testing.T) {
 func TestPathLRU(t *testing.T) {
 	c := new(pathCache)
 	put := func(i int) {
-		c.Put(pathKey{str: strconv.Itoa(i)}, paint.ClipOp{})
+		c.Put(pathKey{str: strconv.Itoa(i)}, clip.Op{})
 	}
 	get := func(i int) bool {
 		_, ok := c.Get(pathKey{str: strconv.Itoa(i)})

text/shaper.go

@@ -5,7 +5,7 @@ package text
 import (
 	"unicode/utf8"
 
-	"gioui.org/op/paint"
+	"gioui.org/op/clip"
 	"gioui.org/unit"
 	"golang.org/x/image/math/fixed"
 )
@@ -46,7 +46,7 @@ func (s *Shaper) Layout(c unit.Converter, font Font, str string, opts LayoutOpti
 	return tf.layout(fixed.I(c.Px(font.Size)), str, opts)
 }
 
-func (s *Shaper) Shape(c unit.Converter, font Font, str String) paint.ClipOp {
+func (s *Shaper) Shape(c unit.Converter, font Font, str String) clip.Op {
 	tf := s.faceForFont(font)
 	return tf.shape(fixed.I(c.Px(font.Size)), str)
 }
@@ -99,9 +99,9 @@ func (t *face) layout(ppem fixed.Int26_6, str string, opts LayoutOptions) *Layou
 	return l
 }
 
-func (t *face) shape(ppem fixed.Int26_6, str String) paint.ClipOp {
+func (t *face) shape(ppem fixed.Int26_6, str String) clip.Op {
 	if t == nil {
-		return paint.ClipOp{}
+		return clip.Op{}
 	}
 	pk := pathKey{
 		ppem: ppem,

text/text.go

@@ -3,7 +3,7 @@
 package text
 
 import (
-	"gioui.org/op/paint"
+	"gioui.org/op/clip"
 	"gioui.org/unit"
 	"golang.org/x/image/math/fixed"
 )
@@ -61,7 +61,7 @@ type Font struct {
 // Face implements text layout and shaping for a particular font.
 type Face interface {
 	Layout(ppem fixed.Int26_6, str string, opts LayoutOptions) *Layout
-	Shape(ppem fixed.Int26_6, str String) paint.ClipOp
+	Shape(ppem fixed.Int26_6, str String) clip.Op
 }
 
 // Typeface identifies a particular typeface design. The empty

widget/editor.go

@@ -14,6 +14,7 @@ import (
 	"gioui.org/io/pointer"
 	"gioui.org/layout"
 	"gioui.org/op"
+	"gioui.org/op/clip"
 	"gioui.org/op/paint"
 	"gioui.org/text"
 	"gioui.org/unit"
@@ -79,7 +80,7 @@ type SubmitEvent struct {
 
 type line struct {
 	offset f32.Point
-	clip   paint.ClipOp
+	clip   clip.Op
 }
 
 const (

widget/material/image.go

@@ -8,6 +8,7 @@ import (
 	"gioui.org/f32"
 	"gioui.org/layout"
 	"gioui.org/op"
+	"gioui.org/op/clip"
 	"gioui.org/op/paint"
 	"gioui.org/unit"
 )
@@ -36,7 +37,7 @@ func (im Image) Layout(gtx *layout.Context) {
 	d := image.Point{X: cs.Width.Constrain(w), Y: cs.Height.Constrain(h)}
 	var s op.StackOp
 	s.Push(gtx.Ops)
-	paint.RectClip(image.Rectangle{Max: d}).Add(gtx.Ops)
+	clip.Rect(image.Rectangle{Max: d}).Add(gtx.Ops)
 	im.Src.Add(gtx.Ops)
 	paint.PaintOp{Rect: f32.Rectangle{Max: f32.Point{X: float32(w), Y: float32(h)}}}.Add(gtx.Ops)
 	s.Pop()

widget/material/material.go

@@ -10,6 +10,7 @@ import (
 	"gioui.org/font"
 	"gioui.org/layout"
 	"gioui.org/op"
+	"gioui.org/op/clip"
 	"gioui.org/op/paint"
 	"gioui.org/text"
 	"gioui.org/unit"
@@ -79,7 +80,7 @@ func fill(gtx *layout.Context, col color.RGBA) {
 func rrect(ops *op.Ops, width, height, se, sw, nw, ne float32) {
 	w, h := float32(width), float32(height)
 	const c = 0.55228475 // 4*(sqrt(2)-1)/3
-	var b paint.Path
+	var b clip.Path
 	b.Begin(ops)
 	b.Move(f32.Point{X: w, Y: h - se})
 	b.Cube(f32.Point{X: 0, Y: se * c}, f32.Point{X: -se + se*c, Y: se}, f32.Point{X: -se, Y: se}) // SE