restorable: Do not record pixels if restoring is not requried

Fixes #1022

internal/graphicscommand/image.go

@@ -26,15 +26,6 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/png"
 )
 
-type lastCommand int
-
-const (
-	lastCommandNone lastCommand = iota
-	lastCommandClear
-	lastCommandDrawTriangles
-	lastCommandReplacePixels
-)
-
 // Image represents an image that is implemented with OpenGL.
 type Image struct {
 	image          driver.Image
@@ -51,8 +42,6 @@ type Image struct {
 	id int
 
 	bufferedRP []*driver.ReplacePixelsArgs
-
-	lastCommand lastCommand
 }
 
 var nextID = 1
@@ -151,12 +140,6 @@ func (i *Image) InternalSize() (int, int) {
 // If the source image is not specified, i.e., src is nil and there is no image in the uniform variables, the
 // elements for the source image are not used.
 func (i *Image) DrawTriangles(srcs [graphics.ShaderImageNum]*Image, offsets [graphics.ShaderImageNum - 1][2]float32, vertices []float32, indices []uint16, clr *affine.ColorM, mode driver.CompositeMode, filter driver.Filter, address driver.Address, sourceRegion driver.Region, shader *Shader, uniforms []interface{}) {
-	if i.lastCommand == lastCommandNone {
-		if !i.screen && mode != driver.CompositeModeClear {
-			panic("graphicscommand: the image must be cleared first")
-		}
-	}
-
 	for _, src := range srcs {
 		if src == nil {
 			continue
@@ -169,12 +152,6 @@ func (i *Image) DrawTriangles(srcs [graphics.ShaderImageNum]*Image, offsets [gra
 	i.resolveBufferedReplacePixels()
 
 	theCommandQueue.EnqueueDrawTrianglesCommand(i, srcs, offsets, vertices, indices, clr, mode, filter, address, sourceRegion, shader, uniforms)
-
-	if i.lastCommand == lastCommandNone && !i.screen {
-		i.lastCommand = lastCommandClear
-	} else {
-		i.lastCommand = lastCommandDrawTriangles
-	}
 }
 
 // Pixels returns the image's pixels.
@@ -193,12 +170,6 @@ func (i *Image) Pixels() ([]byte, error) {
 }
 
 func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
-	// ReplacePixels for a part might invalidate the current image that are drawn by DrawTriangles (#593, #738).
-	if i.lastCommand == lastCommandDrawTriangles {
-		if x != 0 || y != 0 || i.width != width || i.height != height {
-			panic("graphicscommand: ReplacePixels for a part after DrawTriangles is forbidden")
-		}
-	}
 	i.bufferedRP = append(i.bufferedRP, &driver.ReplacePixelsArgs{
 		Pixels: pixels,
 		X:      x,
@@ -206,7 +177,6 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 		Width:  width,
 		Height: height,
 	})
-	i.lastCommand = lastCommandReplacePixels
 }
 
 func (i *Image) IsInvalidated() bool {

internal/graphicscommand/image_test.go

@@ -63,11 +63,6 @@ func TestClear(t *testing.T) {
 }
 
 func TestReplacePixelsPartAfterDrawTriangles(t *testing.T) {
-	defer func() {
-		if r := recover(); r == nil {
-			t.Errorf("ReplacePixels must panic but not")
-		}
-	}()
 	const w, h = 32, 32
 	clr := NewImage(w, h)
 	src := NewImage(w/2, h/2)
@@ -77,6 +72,8 @@ func TestReplacePixelsPartAfterDrawTriangles(t *testing.T) {
 	dst.DrawTriangles([graphics.ShaderImageNum]*Image{clr}, [graphics.ShaderImageNum - 1][2]float32{}, vs, is, nil, driver.CompositeModeClear, driver.FilterNearest, driver.AddressUnsafe, driver.Region{}, nil, nil)
 	dst.DrawTriangles([graphics.ShaderImageNum]*Image{src}, [graphics.ShaderImageNum - 1][2]float32{}, vs, is, nil, driver.CompositeModeSourceOver, driver.FilterNearest, driver.AddressUnsafe, driver.Region{}, nil, nil)
 	dst.ReplacePixels(make([]byte, 4), 0, 0, 1, 1)
+
+	// TODO: Check the result.
 }
 
 func TestShader(t *testing.T) {

internal/restorable/image.go

@@ -153,6 +153,18 @@ func NewImage(width, height int, volatile bool) *Image {
 	return i
 }
 
+func newImageWithColor(width, height int, volatile bool, clr color.RGBA) *Image {
+	i := &Image{
+		image:    graphicscommand.NewImage(width, height),
+		width:    width,
+		height:   height,
+		volatile: volatile,
+	}
+	fillImage(i.image, clr)
+	theImages.add(i)
+	return i
+}
+
 // Extend extends the image by the given size.
 // Extend creates a new image with the given size and copies the pixels of the given source image.
 // Extend disposes itself after its call.
@@ -167,21 +179,22 @@ func (i *Image) Extend(width, height int) *Image {
 		panic(fmt.Sprintf("restorable: the original size (%d, %d) cannot be extended to (%d, %d)", i.width, i.height, width, height))
 	}
 
-	if i.stale {
+	newImg := newImageWithColor(width, height, i.volatile, i.basePixels.baseColor)
-		panic("restorable: Extend at a stale image is forbidden")
-	}
 
-	if len(i.drawTrianglesHistory) > 0 {
+	// Use DrawTriangles instead of ReplacePixels because the image i might be stale and not have its pixels
-		panic("restorable: Extend after DrawTriangles is forbidden")
+	// information.
-	}
+	srcs := [graphics.ShaderImageNum]*Image{i}
+	var offsets [graphics.ShaderImageNum - 1][2]float32
+	sw, sh := i.image.InternalSize()
+	vs := quadVertices(0, 0, float32(sw), float32(sh), 0, 0, float32(sw), float32(sh), 1, 1, 1, 1)
+	is := graphics.QuadIndices()
+	newImg.DrawTriangles(srcs, offsets, vs, is, nil, driver.CompositeModeCopy, driver.FilterNearest, driver.AddressUnsafe, driver.Region{}, nil, nil)
 
-	newImg := NewImage(width, height, i.volatile)
+	// Overwrite the history as if the image newImg is created only by ReplacePixels. Now drawTrianglesHistory
-	i.basePixels.Apply(newImg.image)
+	// and basePixels cannot be mixed.
-
+	newImg.drawTrianglesHistory = nil
-	if i.basePixels.baseColor != (color.RGBA{}) {
-		panic("restorable: baseColor must be empty at Extend")
-	}
 	newImg.basePixels = i.basePixels
+	newImg.stale = i.stale
 
 	i.Dispose()
 
@@ -312,6 +325,11 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 		i.image.ReplacePixels(make([]byte, 4*width*height), x, y, width, height)
 	}
 
+	if !needsRestoring() || i.screen || i.volatile {
+		i.makeStale()
+		return
+	}
+
 	if x == 0 && y == 0 && width == w && height == h {
 		if pixels != nil {
 			i.basePixels.AddOrReplace(pixels, 0, 0, w, h)
@@ -323,9 +341,7 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 		return
 	}
 
-	// It looked like ReplacePixels on a part of image deletes other region that are rendered by DrawTriangles
+	// drawTrianglesHistory and basePixels cannot be mixed.
-	// (#593, #758).
-
 	if len(i.drawTrianglesHistory) > 0 {
 		panic("restorable: ReplacePixels for a part after DrawTriangles is forbidden")
 	}