restorable: Add restorable.Pixels

internal/restorable/image.go

@@ -17,12 +17,67 @@ package restorable
 import (
 	"errors"
 	"fmt"
+	"image/color"
 
 	"github.com/hajimehoshi/ebiten/internal/affine"
 	"github.com/hajimehoshi/ebiten/internal/graphics"
 	"github.com/hajimehoshi/ebiten/internal/graphicscommand"
 )
 
+type Pixels struct {
+	pixels []byte
+
+	length int
+
+	// color is used only when pixels == nil
+	color color.RGBA
+}
+
+func (p *Pixels) ensurePixels() {
+	if p.pixels != nil {
+		return
+	}
+	p.pixels = make([]byte, p.length)
+	if p.color.A == 0 {
+		return
+	}
+	for i := 0; i < p.length/4; i++ {
+		p.pixels[4*i] = p.color.R
+		p.pixels[4*i+1] = p.color.G
+		p.pixels[4*i+2] = p.color.B
+		p.pixels[4*i+3] = p.color.A
+	}
+}
+
+func (p *Pixels) CopyFrom(pix []byte, from int) {
+	p.ensurePixels()
+	copy(p.pixels[from:from+len(pix)], pix)
+}
+
+func (p *Pixels) At(i int) byte {
+	if i < 0 || p.length <= i {
+		panic(fmt.Sprintf("restorable: index out of range: %d for length: %d", i, p.length))
+	}
+	if p.pixels == nil {
+		switch i % 4 {
+		case 0:
+			return p.color.R
+		case 1:
+			return p.color.G
+		case 2:
+			return p.color.B
+		case 3:
+			return p.color.A
+		}
+	}
+	return p.pixels[i]
+}
+
+func (p *Pixels) Slice() []byte {
+	p.ensurePixels()
+	return p.pixels
+}
+
 // drawImageHistoryItem is an item for history of draw-image commands.
 type drawImageHistoryItem struct {
 	image    *Image
@@ -38,7 +93,7 @@ type drawImageHistoryItem struct {
 type Image struct {
 	image *graphicscommand.Image
 
-	basePixels []byte
+	basePixels *Pixels
 
 	// drawImageHistory is a set of draw-image commands.
 	// TODO: This should be merged with the similar command queue in package graphics (#433).
@@ -150,19 +205,9 @@ func (i *Image) fill(r, g, b, a uint8) {
 	}
 	i.image.DrawImage(emptyImage.image, vs, is, nil, c, graphics.FilterNearest, graphics.AddressClampToZero)
 
-	if a == 0 {
+	i.basePixels = &Pixels{
-		i.basePixels = nil
+		color:  color.RGBA{r, g, b, a},
-	} else {
+		length: 4 * w * h,
-		// TODO: Add baseColor?
-		if i.basePixels == nil {
-			i.basePixels = make([]byte, 4*w*h)
-		}
-		for idx := 0; idx < w*h; idx++ {
-			i.basePixels[4*idx] = r
-			i.basePixels[4*idx+1] = g
-			i.basePixels[4*idx+2] = b
-			i.basePixels[4*idx+3] = a
-		}
 	}
 	i.drawImageHistory = nil
 	i.stale = false
@@ -173,7 +218,7 @@ func (i *Image) IsVolatile() bool {
 }
 
 // BasePixelsForTesting returns the image's basePixels for testing.
-func (i *Image) BasePixelsForTesting() []byte {
+func (i *Image) BasePixelsForTesting() *Pixels {
 	return i.basePixels
 }
 
@@ -244,9 +289,11 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 	if x == 0 && y == 0 && width == w && height == h {
 		if pixels != nil {
 			if i.basePixels == nil {
-				i.basePixels = make([]byte, 4*w*h)
+				i.basePixels = &Pixels{
+					length: 4 * w * h,
+				}
 			}
-			copy(i.basePixels, pixels)
+			i.basePixels.CopyFrom(pixels, 0)
 		} else {
 			// If basePixels is nil, the restored pixels are cleared.
 			// See restore() implementation.
@@ -268,16 +315,18 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 	idx := 4 * (y*w + x)
 	if pixels != nil {
 		if i.basePixels == nil {
-			i.basePixels = make([]byte, 4*w*h)
+			i.basePixels = &Pixels{
+				length: 4 * w * h,
+			}
 		}
 		for j := 0; j < height; j++ {
-			copy(i.basePixels[idx:idx+4*width], pixels[4*j*width:4*(j+1)*width])
+			i.basePixels.CopyFrom(pixels[4*j*width:4*(j+1)*width], idx)
 			idx += 4 * w
 		}
 	} else if i.basePixels != nil {
 		zeros := make([]byte, 4*width)
 		for j := 0; j < height; j++ {
-			copy(i.basePixels[idx:idx+4*width], zeros)
+			i.basePixels.CopyFrom(zeros, idx)
 			idx += 4 * w
 		}
 	}
@@ -351,7 +400,7 @@ func (i *Image) At(x, y int) (byte, byte, byte, byte) {
 	}
 
 	idx := 4*x + 4*y*w
-	return i.basePixels[idx], i.basePixels[idx+1], i.basePixels[idx+2], i.basePixels[idx+3]
+	return i.basePixels.At(idx), i.basePixels.At(idx + 1), i.basePixels.At(idx + 2), i.basePixels.At(idx + 3)
 }
 
 // makeStaleIfDependingOn makes the image stale if the image depends on target.
@@ -366,7 +415,10 @@ func (i *Image) makeStaleIfDependingOn(target *Image) {
 
 // readPixelsFromGPU reads the pixels from GPU and resolves the image's 'stale' state.
 func (i *Image) readPixelsFromGPU() {
-	i.basePixels = i.image.Pixels()
+	i.basePixels = &Pixels{
+		pixels: i.image.Pixels(),
+		length: len(i.image.Pixels()),
+	}
 	i.drawImageHistory = nil
 	i.stale = false
 }
@@ -440,7 +492,7 @@ func (i *Image) restore() error {
 
 	gimg := graphicscommand.NewImage(w, h)
 	if i.basePixels != nil {
-		gimg.ReplacePixels(i.basePixels, 0, 0, w, h)
+		gimg.ReplacePixels(i.basePixels.Slice(), 0, 0, w, h)
 	} else {
 		// Clear the image explicitly.
 		pix := make([]uint8, w*h*4)
@@ -454,7 +506,10 @@ func (i *Image) restore() error {
 	}
 	i.image = gimg
 
-	i.basePixels = gimg.Pixels()
+	i.basePixels = &Pixels{
+		pixels: gimg.Pixels(),
+		length: len(gimg.Pixels()),
+	}
 	i.drawImageHistory = nil
 	i.stale = false
 	return nil

internal/restorable/images_test.go

@@ -44,9 +44,9 @@ func TestMain(m *testing.M) {
 	os.Exit(code)
 }
 
-func byteSliceToColor(b []byte, index int) color.RGBA {
+func pixelsToColor(p *Pixels, index int) color.RGBA {
 	i := index * 4
-	return color.RGBA{b[i], b[i+1], b[i+2], b[i+3]}
+	return color.RGBA{p.At(i), p.At(i + 1), p.At(i + 2), p.At(i + 3)}
 }
 
 func abs(x int) int {
@@ -68,30 +68,18 @@ func sameColors(c1, c2 color.RGBA, delta int) bool {
 		abs(int(c1.A)-int(c2.A)) <= delta
 }
 
-func fill(img *Image, r, g, b, a uint8) {
-	w, h := img.Size()
-	pix := make([]uint8, w*h*4)
-	for i := 0; i < w*h; i++ {
-		pix[4*i] = r
-		pix[4*i+1] = g
-		pix[4*i+2] = b
-		pix[4*i+3] = a
-	}
-	img.ReplacePixels(pix, 0, 0, w, h)
-}
-
 func TestRestore(t *testing.T) {
 	img0 := NewImage(1, 1)
 	defer img0.Dispose()
 
 	clr0 := color.RGBA{0x00, 0x00, 0x00, 0xff}
-	fill(img0, clr0.R, clr0.G, clr0.B, clr0.A)
+	img0.Fill(clr0.R, clr0.G, clr0.B, clr0.A)
 	ResolveStaleImages()
 	if err := Restore(); err != nil {
 		t.Fatal(err)
 	}
 	want := clr0
-	got := byteSliceToColor(img0.BasePixelsForTesting(), 0)
+	got := pixelsToColor(img0.BasePixelsForTesting(), 0)
 	if !sameColors(got, want, 1) {
 		t.Errorf("got %v, want %v", got, want)
 	}
@@ -110,7 +98,7 @@ func TestRestoreWithoutDraw(t *testing.T) {
 
 	for i := 0; i < 1024*1024; i++ {
 		want := color.RGBA{0x00, 0x00, 0x00, 0x00}
-		got := byteSliceToColor(img0.BasePixelsForTesting(), i)
+		got := pixelsToColor(img0.BasePixelsForTesting(), i)
 		if !sameColors(got, want, 0) {
 			t.Errorf("got %v, want %v", got, want)
 		}
@@ -130,7 +118,7 @@ func TestRestoreChain(t *testing.T) {
 		}
 	}()
 	clr := color.RGBA{0x00, 0x00, 0x00, 0xff}
-	fill(imgs[0], clr.R, clr.G, clr.B, clr.A)
+	imgs[0].Fill(clr.R, clr.G, clr.B, clr.A)
 	for i := 0; i < num-1; i++ {
 		w, h := imgs[i].Size()
 		vs := graphics.QuadVertices(w, h, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1)
@@ -143,7 +131,7 @@ func TestRestoreChain(t *testing.T) {
 	}
 	want := clr
 	for i, img := range imgs {
-		got := byteSliceToColor(img.BasePixelsForTesting(), 0)
+		got := pixelsToColor(img.BasePixelsForTesting(), 0)
 		if !sameColors(got, want, 1) {
 			t.Errorf("%d: got %v, want %v", i, got, want)
 		}
@@ -168,11 +156,11 @@ func TestRestoreChain2(t *testing.T) {
 	}()
 
 	clr0 := color.RGBA{0xff, 0x00, 0x00, 0xff}
-	fill(imgs[0], clr0.R, clr0.G, clr0.B, clr0.A)
+	imgs[0].Fill(clr0.R, clr0.G, clr0.B, clr0.A)
 	clr7 := color.RGBA{0x00, 0xff, 0x00, 0xff}
-	fill(imgs[7], clr7.R, clr7.G, clr7.B, clr7.A)
+	imgs[7].Fill(clr7.R, clr7.G, clr7.B, clr7.A)
 	clr8 := color.RGBA{0x00, 0x00, 0xff, 0xff}
-	fill(imgs[8], clr8.R, clr8.G, clr8.B, clr8.A)
+	imgs[8].Fill(clr8.R, clr8.G, clr8.B, clr8.A)
 
 	vs := graphics.QuadVertices(w, h, 0, 0, w, h, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1)
 	is := graphics.QuadIndices()
@@ -191,7 +179,7 @@ func TestRestoreChain2(t *testing.T) {
 		if i == 8 || i == 9 {
 			want = clr7
 		}
-		got := byteSliceToColor(img.BasePixelsForTesting(), 0)
+		got := pixelsToColor(img.BasePixelsForTesting(), 0)
 		if !sameColors(got, want, 1) {
 			t.Errorf("%d: got %v, want %v", i, got, want)
 		}
@@ -215,12 +203,12 @@ func TestRestoreOverrideSource(t *testing.T) {
 	}()
 	clr0 := color.RGBA{0x00, 0x00, 0x00, 0xff}
 	clr1 := color.RGBA{0x00, 0x00, 0x01, 0xff}
-	fill(img1, clr0.R, clr0.G, clr0.B, clr0.A)
+	img1.Fill(clr0.R, clr0.G, clr0.B, clr0.A)
 	vs := graphics.QuadVertices(w, h, 0, 0, w, h, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1)
 	is := graphics.QuadIndices()
 	img2.DrawImage(img1, vs, is, nil, graphics.CompositeModeSourceOver, graphics.FilterNearest, graphics.AddressClampToZero)
 	img3.DrawImage(img2, vs, is, nil, graphics.CompositeModeSourceOver, graphics.FilterNearest, graphics.AddressClampToZero)
-	fill(img0, clr1.R, clr1.G, clr1.B, clr1.A)
+	img0.Fill(clr1.R, clr1.G, clr1.B, clr1.A)
 	img1.DrawImage(img0, vs, is, nil, graphics.CompositeModeSourceOver, graphics.FilterNearest, graphics.AddressClampToZero)
 	ResolveStaleImages()
 	if err := Restore(); err != nil {
@@ -234,22 +222,22 @@ func TestRestoreOverrideSource(t *testing.T) {
 		{
 			"0",
 			clr1,
-			byteSliceToColor(img0.BasePixelsForTesting(), 0),
+			pixelsToColor(img0.BasePixelsForTesting(), 0),
 		},
 		{
 			"1",
 			clr1,
-			byteSliceToColor(img1.BasePixelsForTesting(), 0),
+			pixelsToColor(img1.BasePixelsForTesting(), 0),
 		},
 		{
 			"2",
 			clr0,
-			byteSliceToColor(img2.BasePixelsForTesting(), 0),
+			pixelsToColor(img2.BasePixelsForTesting(), 0),
 		},
 		{
 			"3",
 			clr0,
-			byteSliceToColor(img3.BasePixelsForTesting(), 0),
+			pixelsToColor(img3.BasePixelsForTesting(), 0),
 		},
 	}
 	for _, c := range testCases {
@@ -371,7 +359,7 @@ func TestRestoreComplexGraph(t *testing.T) {
 			if c.out[i] == '*' {
 				want = color.RGBA{0xff, 0xff, 0xff, 0xff}
 			}
-			got := byteSliceToColor(c.image.BasePixelsForTesting(), i)
+			got := pixelsToColor(c.image.BasePixelsForTesting(), i)
 			if !sameColors(got, want, 1) {
 				t.Errorf("%s[%d]: got %v, want %v", c.name, i, got, want)
 			}
@@ -433,7 +421,7 @@ func TestRestoreRecursive(t *testing.T) {
 			if c.out[i] == '*' {
 				want = color.RGBA{0xff, 0xff, 0xff, 0xff}
 			}
-			got := byteSliceToColor(c.image.BasePixelsForTesting(), i)
+			got := pixelsToColor(c.image.BasePixelsForTesting(), i)
 			if !sameColors(got, want, 1) {
 				t.Errorf("%s[%d]: got %v, want %v", c.name, i, got, want)
 			}
@@ -601,7 +589,7 @@ func TestClear(t *testing.T) {
 		},
 	}
 	for _, c := range cases {
-		got := byteSliceToColor(img.BasePixelsForTesting(), c.Index)
+		got := pixelsToColor(img.BasePixelsForTesting(), c.Index)
 		want := c.Want
 		if got != want {
 			t.Errorf("base pixel [%d]: got %v, want %v", c.Index, got, want)
@@ -634,7 +622,7 @@ func TestReplacePixelsOnly(t *testing.T) {
 		case i%5 == 0:
 			want = color.RGBA{1, 2, 3, 4}
 		}
-		got := byteSliceToColor(img0.BasePixelsForTesting(), i)
+		got := pixelsToColor(img0.BasePixelsForTesting(), i)
 		if !sameColors(got, want, 0) {
 			t.Errorf("got %v, want %v", got, want)
 		}
@@ -645,7 +633,7 @@ func TestReplacePixelsOnly(t *testing.T) {
 		t.Fatal(err)
 	}
 	want := color.RGBA{1, 2, 3, 4}
-	got := byteSliceToColor(img1.BasePixelsForTesting(), 0)
+	got := pixelsToColor(img1.BasePixelsForTesting(), 0)
 	if !sameColors(got, want, 0) {
 		t.Errorf("got %v, want %v", got, want)
 	}
@@ -664,7 +652,7 @@ func TestReadPixelsFromVolatileImage(t *testing.T) {
 	dst.ReplacePixels(make([]byte, 4*w*h), 0, 0, w, h)
 
 	// Second, draw src to dst. If the implementation is correct, dst becomes stale.
-	fill(src, 0xff, 0xff, 0xff, 0xff)
+	src.Fill(0xff, 0xff, 0xff, 0xff)
 	vs := graphics.QuadVertices(w, h, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1)
 	is := graphics.QuadIndices()
 	dst.DrawImage(src, vs, is, nil, graphics.CompositeModeCopy, graphics.FilterNearest, graphics.AddressClampToZero)