Revert "restorable: Merge Clear to ReplacePixels"

This reverts commit fb641d88cd.

Reason: When restoring the image where ReplacePixels is called,
dummyImage might not be restored since there is no record of
relationships between this image and dummyImage. Now pixels is not
nil when reverting by chance, but this would cause problems in the
future.

internal/restorable/image.go

@@ -89,10 +89,18 @@ func newImageWithoutInit(width, height int, volatile bool) *Image {
 // The returned image is cleared.
 func NewImage(width, height int, volatile bool) *Image {
 	i := newImageWithoutInit(width, height, volatile)
-	i.ReplacePixels(nil, 0, 0, width, height)
+	i.Clear(0, 0, width, height)
 	return i
 }
 
+func (i *Image) Clear(x, y, width, height int) {
+	w, h := dummyImage.Size()
+	geom := (*affine.GeoM)(nil).Scale(float64(width)/float64(w), float64(height)/float64(h))
+	geom = geom.Translate(float64(x), float64(y))
+	colorm := (*affine.ColorM)(nil).Scale(0, 0, 0, 0)
+	i.DrawImage(dummyImage, 0, 0, w, h, geom, colorm, opengl.CompositeModeCopy, graphics.FilterNearest)
+}
+
 // NewScreenFramebufferImage creates a special image that framebuffer is one for the screen.
 //
 // The returned image is cleared.
@@ -104,7 +112,7 @@ func NewScreenFramebufferImage(width, height int) *Image {
 	}
 	theImages.add(i)
 	runtime.SetFinalizer(i, (*Image).Dispose)
-	i.ReplacePixels(nil, 0, 0, width, height)
+	i.Clear(0, 0, width, height)
 	return i
 }
 
@@ -131,8 +139,6 @@ func (i *Image) makeStale() {
 }
 
 // ReplacePixels replaces the image pixels with the given pixels slice.
-//
-// If pixels is nil, ReplacePixels clears the specified reagion.
 func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 	w, h := i.image.Size()
 	if width <= 0 || height <= 0 {
@@ -146,16 +152,7 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 	// For this purpuse, images should remember which part of that is used for DrawImage.
 	theImages.makeStaleIfDependingOn(i)
 
-	if pixels != nil {
-		i.image.ReplacePixels(pixels, x, y, width, height)
-	} else {
-		w, h := dummyImage.Size()
-		geom := (*affine.GeoM)(nil).Scale(float64(width)/float64(w), float64(height)/float64(h))
-		geom = geom.Translate(float64(x), float64(y))
-		colorm := (*affine.ColorM)(nil).Scale(0, 0, 0, 0)
-		vs := vertices(w, h, 0, 0, w, h, geom)
-		i.image.DrawImage(dummyImage.image, vs, colorm, opengl.CompositeModeCopy, graphics.FilterNearest)
-	}
+	i.image.ReplacePixels(pixels, x, y, width, height)
 
 	if x == 0 && y == 0 && width == w && height == h {
 		if i.basePixels == nil {
@@ -175,17 +172,9 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 		return
 	}
 	idx := 4 * (y*w + x)
-	if pixels != nil {
-		for j := 0; j < height; j++ {
-			copy(i.basePixels[idx:idx+4*width], pixels[4*j*width:4*(j+1)*width])
-			idx += 4 * w
-		}
-	} else {
-		zeros := make([]byte, 4*width)
-		for j := 0; j < height; j++ {
-			copy(i.basePixels[idx:idx+4*width], zeros)
-			idx += 4 * w
-		}
+	for j := 0; j < height; j++ {
+		copy(i.basePixels[idx:idx+4*width], pixels[4*j*width:4*(j+1)*width])
+		idx += 4 * w
 	}
 	i.stale = false
 }

internal/restorable/images_test.go

@@ -569,69 +569,4 @@ func TestDoubleResolve(t *testing.T) {
 	}
 }
 
-func TestClear(t *testing.T) {
-	pix := make([]uint8, 4*4*4)
-	for i := range pix {
-		pix[i] = 0xff
-	}
-
-	img := NewImage(4, 4, false)
-	img.ReplacePixels(pix, 0, 0, 4, 4)
-	// This doesn't make the image stale. Its base pixels are available.
-	img.ReplacePixels(nil, 1, 1, 2, 2)
-
-	cases := []struct {
-		Index int
-		Want  color.RGBA
-	}{
-		{
-			Index: 0,
-			Want:  color.RGBA{0xff, 0xff, 0xff, 0xff},
-		},
-		{
-			Index: 3,
-			Want:  color.RGBA{0xff, 0xff, 0xff, 0xff},
-		},
-		{
-			Index: 4,
-			Want:  color.RGBA{0xff, 0xff, 0xff, 0xff},
-		},
-		{
-			Index: 5,
-			Want:  color.RGBA{0, 0, 0, 0},
-		},
-		{
-			Index: 7,
-			Want:  color.RGBA{0xff, 0xff, 0xff, 0xff},
-		},
-		{
-			Index: 8,
-			Want:  color.RGBA{0xff, 0xff, 0xff, 0xff},
-		},
-		{
-			Index: 10,
-			Want:  color.RGBA{0, 0, 0, 0},
-		},
-		{
-			Index: 11,
-			Want:  color.RGBA{0xff, 0xff, 0xff, 0xff},
-		},
-		{
-			Index: 12,
-			Want:  color.RGBA{0xff, 0xff, 0xff, 0xff},
-		},
-		{
-			Index: 15,
-			Want:  color.RGBA{0xff, 0xff, 0xff, 0xff},
-		},
-	}
-	for _, c := range cases {
-		got := byteSliceToColor(img.BasePixelsForTesting(), c.Index)
-		want := c.Want
-		if got != want {
-			t.Errorf("base pixel [%d]: got %v, want %v", c.Index, got, want)
-		}
-	}
-}
-
 // TODO: How about volatile/screen images?

internal/shareable/shareable.go

@@ -189,8 +189,7 @@ func (i *Image) dispose() {
 	i.backend.page.Free(i.node)
 	if !i.backend.page.IsEmpty() {
 		// As this part can be reused, this should be cleared explicitly.
-		x0, y0, x1, y1 := i.region()
-		i.backend.restorable.ReplacePixels(nil, x0, y0, x1, y1)
+		i.backend.restorable.Clear(i.region())
 		return
 	}