restorable: Refactoring: Use ReplacePixels(nil, ...) for clearing an image

image.go

@@ -97,6 +97,12 @@ func (i *Image) Fill(clr color.Color) error {
 }
 
 func (i *Image) fill(r, g, b, a uint8) {
+	if r == 0 && g == 0 && b == 0 && a == 0 {
+		i.shareableImages[0].ReplacePixels(nil)
+		i.disposeMipmaps()
+		return
+	}
+
 	wd, hd := i.Size()
 
 	if wd*hd <= 256 {
@@ -126,7 +132,7 @@ func (i *Image) fill(r, g, b, a uint8) {
 	}
 	op.CompositeMode = CompositeModeCopy
 	op.Filter = FilterNearest
-	i.drawImage(emptyImage, op, r == 0 && g == 0 && b == 0 && a == 0)
+	i.drawImage(emptyImage, op)
 }
 
 func (i *Image) disposeMipmaps() {
@@ -170,11 +176,11 @@ func (i *Image) disposeMipmaps() {
 //
 // DrawImage always returns nil as of 1.5.0-alpha.
 func (i *Image) DrawImage(img *Image, options *DrawImageOptions) error {
-	i.drawImage(img, options, false)
+	i.drawImage(img, options)
 	return nil
 }
 
-func (i *Image) drawImage(img *Image, options *DrawImageOptions, clear bool) {
+func (i *Image) drawImage(img *Image, options *DrawImageOptions) {
 	i.copyCheck()
 	if img.isDisposed() {
 		panic("ebiten: the given image to DrawImage must not be disposed")
@@ -316,9 +322,6 @@ func (i *Image) drawImage(img *Image, options *DrawImageOptions, clear bool) {
 		is := graphicsutil.QuadIndices()
 		i.shareableImages[0].DrawImage(src, vs, is, options.ColorM.impl, mode, filter)
 	}
-	if clear {
-		i.shareableImages[0].ClearRestorableState()
-	}
 	i.disposeMipmaps()
 }
 

internal/restorable/image.go

@@ -155,7 +155,7 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 	if pixels != nil {
 		i.image.ReplacePixels(pixels, x, y, width, height)
 	} else {
-		// There is not 'drawImageHistoryItem' for this image and dummyImage.
+		// There are not 'drawImageHistoryItem's for this image and dummyImage (in clear).
 		// This means dummyImage might not be restored yet when this image is restored.
 		// However, that's ok since this image will be stale or have updated pixel data
 		// and this image can be restored without dummyImage.
@@ -216,17 +216,6 @@ func (i *Image) DrawImage(img *Image, vertices []float32, indices []uint16, colo
 	i.image.DrawImage(img.image, vertices, indices, colorm, mode, filter)
 }
 
-// ClearState clears the internal state. This is useful when it is known that the image is cleared and not stale.
-//
-// TODO: This is a tricky function since it is hard to determine when to call ClearState.
-// Refactor this.
-func (i *Image) ClearState() {
-	// TODO: Ensure i.image is already cleared?
-	i.basePixels = nil
-	i.drawImageHistory = nil
-	i.stale = false
-}
-
 // appendDrawImageHistory appends a draw-image history item to the image.
 func (i *Image) appendDrawImageHistory(image *Image, vertices []float32, indices []uint16, colorm *affine.ColorM, mode opengl.CompositeMode, filter graphics.Filter) {
 	if i.stale || i.volatile || i.screen {

internal/shareable/shareable.go

@@ -232,22 +232,6 @@ func (i *Image) DrawImage(img *Image, vertices []float32, indices []uint16, colo
 	// }
 }
 
-func (i *Image) ClearRestorableState() {
-	backendsM.Lock()
-	defer backendsM.Unlock()
-
-	if i.disposed {
-		panic("shareable: the image must not be disposed")
-	}
-	if i.backend == nil {
-		panic("shareable: the image must have backend")
-	}
-	if i.isShared() {
-		panic("shareable: the image must not be shared")
-	}
-	i.backend.restorable.ClearState()
-}
-
 func (i *Image) ReplacePixels(p []byte) {
 	backendsM.Lock()
 	defer backendsM.Unlock()
@@ -259,13 +243,18 @@ func (i *Image) replacePixels(p []byte) {
 		panic("shareable: the image must not be disposed")
 	}
 	if i.backend == nil {
+		if p == nil {
+			return
+		}
 		i.allocate(true)
 	}
 
 	x, y, w, h := i.region()
+	if p != nil {
 		if l := 4 * w * h; len(p) != l {
 			panic(fmt.Sprintf("shareable: len(p) was %d but must be %d", len(p), l))
 		}
+	}
 	i.backend.restorable.ReplacePixels(p, x, y, w, h)
 }