ui: introduce OpColor, a specialized OpImage for uniform colors

To avoid allocating an image.Image for OpImage.

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

ui/app/internal/gpu/gpu.go

@@ -5,6 +5,7 @@ package gpu
 import (
 	"fmt"
 	"image"
+	"image/color"
 	"math"
 	"runtime"
 	"strings"
@@ -70,6 +71,8 @@ type drawOps struct {
 	// Current OpImage image and rect, if any.
 	img     image.Image
 	imgRect image.Rectangle
+	// Current OpColor, if any.
+	color color.NRGBA
 }
 
 type drawState struct {
@@ -693,6 +696,11 @@ loop:
 				cpath.path = data
 				d.pathOps = append(d.pathOps, cpath)
 			}
+		case ops.TypeColor:
+			var op gdraw.OpColor
+			op.Decode(data, r.Refs)
+			d.img = nil
+			d.color = op.Col
 		case ops.TypeImage:
 			var op gdraw.OpImage
 			op.Decode(data, r.Refs)
@@ -756,7 +764,11 @@ func expandPathOp(p *pathOp, clip image.Rectangle) {
 
 func (d *drawOps) materialFor(cache *resourceCache, rect f32.Rectangle, off f32.Point, clip image.Rectangle) material {
 	var m material
-	if uniform, ok := d.img.(*image.Uniform); ok {
+	if d.img == nil {
+		m.material = materialColor
+		m.color = gamma(d.color.RGBA())
+		m.opaque = m.color[3] == 1.0
+	} else if uniform, ok := d.img.(*image.Uniform); ok {
 		m.material = materialColor
 		m.color = gamma(uniform.RGBA())
 		m.opaque = m.color[3] == 1.0

ui/draw/draw.go

@@ -5,6 +5,7 @@ package draw
 import (
 	"encoding/binary"
 	"image"
+	"image/color"
 	"math"
 
 	"gioui.org/ui"
@@ -18,6 +19,10 @@ type OpImage struct {
 	Rect image.Rectangle
 }
 
+type OpColor struct {
+	Col color.NRGBA
+}
+
 type OpDraw struct {
 	Rect f32.Rectangle
 }
@@ -57,6 +62,30 @@ func (i *OpImage) Decode(data []byte, refs []interface{}) {
 	}
 }
 
+func (c OpColor) Add(o *ui.Ops) {
+	data := make([]byte, ops.TypeColorLen)
+	data[0] = byte(ops.TypeColor)
+	data[1] = c.Col.R
+	data[2] = c.Col.G
+	data[3] = c.Col.B
+	data[4] = c.Col.A
+	o.Write(data)
+}
+
+func (c *OpColor) Decode(data []byte, refs []interface{}) {
+	if ops.OpType(data[0]) != ops.TypeColor {
+		panic("invalid op")
+	}
+	*c = OpColor{
+		Col: color.NRGBA{
+			R: data[1],
+			G: data[2],
+			B: data[3],
+			A: data[4],
+		},
+	}
+}
+
 func (d OpDraw) Add(o *ui.Ops) {
 	data := make([]byte, ops.TypeDrawLen)
 	data[0] = byte(ops.TypeDraw)

ui/internal/ops/ops.go

@@ -29,6 +29,7 @@ const (
 	TypeClip
 	TypeImage
 	TypeDraw
+	TypeColor
 	TypePointerHandler
 	TypeKeyHandler
 	TypeHideInput
@@ -45,6 +46,7 @@ const (
 	TypeClipLen           = 1 + 4
 	TypeImageLen          = 1 + 4 + 4*4
 	TypeDrawLen           = 1 + 4*4
+	TypeColorLen          = 1 + 4
 	TypePointerHandlerLen = 1 + 4 + 4 + 1
 	TypeKeyHandlerLen     = 1 + 4 + 1
 	TypeHideInputLen      = 1
@@ -61,6 +63,7 @@ var typeLengths = [...]int{
 	TypeClipLen,
 	TypeImageLen,
 	TypeDrawLen,
+	TypeColorLen,
 	TypePointerHandlerLen,
 	TypeKeyHandlerLen,
 	TypeHideInputLen,