zorldo

image.go (20447B)

---

 // Copyright 2018 The Ebiten Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 package atlas
 
 import (
 	"fmt"
 	"image"
 	"runtime"
 	"sync"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/affine"
 	"github.com/hajimehoshi/ebiten/v2/internal/driver"
 	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
 	"github.com/hajimehoshi/ebiten/v2/internal/hooks"
 	"github.com/hajimehoshi/ebiten/v2/internal/packing"
 	"github.com/hajimehoshi/ebiten/v2/internal/restorable"
 )
 
 const (
 	// paddingSize represents the size of padding around an image.
 	// Every image or node except for a screen image has its padding.
 	paddingSize = 1
 )
 
 var (
 	minSize = 0
 	maxSize = 0
 )
 
 type temporaryPixels struct {
 	pixels           []byte
 	pos              int
 	notFullyUsedTime int
 }
 
 var theTemporaryPixels temporaryPixels
 
 func temporaryPixelsByteSize(size int) int {
 	l := 16
 	for l < size {
 		l *= 2
 	}
 	return l
 }
 
 // alloc allocates the pixels and reutrns it.
 // Be careful that the returned pixels might not be zero-cleared.
 func (t *temporaryPixels) alloc(size int) []byte {
 	if len(t.pixels) < t.pos+size {
 		t.pixels = make([]byte, temporaryPixelsByteSize(t.pos+size))
 		t.pos = 0
 	}
 	pix := t.pixels[t.pos : t.pos+size]
 	t.pos += size
 	return pix
 }
 
 func (t *temporaryPixels) resetAtFrameEnd() {
 	const maxNotFullyUsedTime = 60
 
 	if temporaryPixelsByteSize(t.pos) < len(t.pixels) {
 		if t.notFullyUsedTime < maxNotFullyUsedTime {
 			t.notFullyUsedTime++
 		}
 	} else {
 		t.notFullyUsedTime = 0
 	}
 
 	// Let the pixels GCed if this is not used for a while.
 	if t.notFullyUsedTime == maxNotFullyUsedTime && len(t.pixels) > 0 {
 		t.pixels = nil
 	}
 
 	// Reset the position and reuse the allocated bytes.
 	// t.pixels should already be sent to GPU, then this can be reused.
 	t.pos = 0
 }
 
 func max(a, b int) int {
 	if a > b {
 		return a
 	}
 	return b
 }
 
 func min(a, b int) int {
 	if a < b {
 		return a
 	}
 	return b
 }
 
 func init() {
 	hooks.AppendHookOnBeforeUpdate(func() error {
 		backendsM.Lock()
 		defer backendsM.Unlock()
 
 		resolveDeferred()
 		return putImagesOnAtlas()
 	})
 }
 
 func resolveDeferred() {
 	deferredM.Lock()
 	fs := deferred
 	deferred = nil
 	deferredM.Unlock()
 
 	for _, f := range fs {
 		f()
 	}
 }
 
 // baseCountToPutOnAtlas represents the base time duration when the image can be put onto an atlas.
 // Actual time duration is increased in an exponential way for each usages as a rendering target.
 const baseCountToPutOnAtlas = 10
 
 func putImagesOnAtlas() error {
 	for i := range imagesToPutOnAtlas {
 		i.usedAsSourceCount++
 		if i.usedAsSourceCount >= baseCountToPutOnAtlas*(1<<uint(min(i.isolatedCount, 31))) {
 			if err := i.putOnAtlas(); err != nil {
 				return err
 			}
 			i.usedAsSourceCount = 0
 			delete(imagesToPutOnAtlas, i)
 		}
 	}
 
 	// Reset the images. The images will be registered again when it is used as a rendering source.
 	for k := range imagesToPutOnAtlas {
 		delete(imagesToPutOnAtlas, k)
 	}
 	return nil
 }
 
 type backend struct {
 	// restorable is an atlas on which there might be multiple images.
 	restorable *restorable.Image
 
 	// page is an atlas map. Each part is called a node.
 	// If page is nil, the backend's image is isolated and not on an atlas.
 	page *packing.Page
 }
 
 func (b *backend) tryAlloc(width, height int) (*packing.Node, bool) {
 	// If the region is allocated without any extension, that's fine.
 	if n := b.page.Alloc(width, height); n != nil {
 		return n, true
 	}
 
 	nExtended := 1
 	var n *packing.Node
 	for {
 		if !b.page.Extend(nExtended) {
 			// The page can't be extended any more. Return as failure.
 			return nil, false
 		}
 		nExtended++
 		n = b.page.Alloc(width, height)
 		if n != nil {
 			b.page.CommitExtension()
 			break
 		}
 		b.page.RollbackExtension()
 	}
 
 	s := b.page.Size()
 	b.restorable = b.restorable.Extend(s, s)
 
 	if n == nil {
 		panic("atlas: Alloc result must not be nil at TryAlloc")
 	}
 	return n, true
 }
 
 var (
 	// backendsM is a mutex for critical sections of the backend and packing.Node objects.
 	backendsM sync.Mutex
 
 	initOnce sync.Once
 
 	// theBackends is a set of atlases.
 	theBackends = []*backend{}
 
 	imagesToPutOnAtlas = map[*Image]struct{}{}
 
 	deferred []func()
 
 	// deferredM is a mutext for the slice operations. This must not be used for other usages.
 	deferredM sync.Mutex
 )
 
 func init() {
 	// Lock the mutex before a frame begins.
 	//
 	// In each frame, restoring images and resolving images happen respectively:
 	//
 	//   [Restore -> Resolve] -> [Restore -> Resolve] -> ...
 	//
 	// Between each frame, any image operations are not permitted, or stale images would remain when restoring
 	// (#913).
 	backendsM.Lock()
 }
 
 // Image is a renctangle pixel set that might be on an atlas.
 type Image struct {
 	width    int
 	height   int
 	disposed bool
 	volatile bool
 	screen   bool
 
 	backend *backend
 
 	node *packing.Node
 
 	// usedAsSourceCount represents how long the image is used as a rendering source and kept not modified with
 	// DrawTriangles.
 	// In the current implementation, if an image is being modified by DrawTriangles, the image is separated from
 	// a restorable image on an atlas by ensureIsolated.
 	//
 	// usedAsSourceCount is increased if the image is used as a rendering source, or set to 0 if the image is
 	// modified.
 	//
 	// ReplacePixels doesn't affect this value since ReplacePixels can be done on images on an atlas.
 	usedAsSourceCount int
 
 	// isolatedCount represents how many times the image on a texture atlas is changed into an isolated image.
 	// isolatedCount affects the calculation when to put the image onto a texture atlas again.
 	isolatedCount int
 }
 
 // moveTo moves its content to the given image dst.
 // After moveTo is called, the image i is no longer available.
 //
 // moveTo is smilar to C++'s move semantics.
 func (i *Image) moveTo(dst *Image) {
 	dst.dispose(false)
 	*dst = *i
 
 	// i is no longer available but Dispose must not be called
 	// since i and dst have the same values like node.
 	runtime.SetFinalizer(i, nil)
 }
 
 func (i *Image) isOnAtlas() bool {
 	return i.node != nil
 }
 
 func (i *Image) resetUsedAsSourceCount() {
 	i.usedAsSourceCount = 0
 	delete(imagesToPutOnAtlas, i)
 }
 
 func (i *Image) ensureIsolated() {
 	i.resetUsedAsSourceCount()
 
 	if i.backend == nil {
 		i.allocate(false)
 		return
 	}
 
 	if !i.isOnAtlas() {
 		return
 	}
 
 	ox, oy, w, h := i.regionWithPadding()
 	dx0 := float32(0)
 	dy0 := float32(0)
 	dx1 := float32(w)
 	dy1 := float32(h)
 	sx0 := float32(ox)
 	sy0 := float32(oy)
 	sx1 := float32(ox + w)
 	sy1 := float32(oy + h)
 	newImg := restorable.NewImage(w, h)
 	newImg.SetVolatile(i.volatile)
 	vs := []float32{
 		dx0, dy0, sx0, sy0, 1, 1, 1, 1,
 		dx1, dy0, sx1, sy0, 1, 1, 1, 1,
 		dx0, dy1, sx0, sy1, 1, 1, 1, 1,
 		dx1, dy1, sx1, sy1, 1, 1, 1, 1,
 	}
 	is := graphics.QuadIndices()
 	srcs := [graphics.ShaderImageNum]*restorable.Image{i.backend.restorable}
 	var offsets [graphics.ShaderImageNum - 1][2]float32
 	dstRegion := driver.Region{
 		X:      paddingSize,
 		Y:      paddingSize,
 		Width:  float32(w - 2*paddingSize),
 		Height: float32(h - 2*paddingSize),
 	}
 	newImg.DrawTriangles(srcs, offsets, vs, is, affine.ColorMIdentity{}, driver.CompositeModeCopy, driver.FilterNearest, driver.AddressUnsafe, dstRegion, driver.Region{}, nil, nil, false)
 
 	i.dispose(false)
 	i.backend = &backend{
 		restorable: newImg,
 	}
 
 	i.isolatedCount++
 }
 
 func (i *Image) putOnAtlas() error {
 	if i.backend == nil {
 		i.allocate(true)
 		return nil
 	}
 
 	if i.isOnAtlas() {
 		return nil
 	}
 
 	if !i.canBePutOnAtlas() {
 		panic("atlas: putOnAtlas cannot be called on a image that cannot be on an atlas")
 	}
 
 	newI := NewImage(i.width, i.height)
 	newI.SetVolatile(i.volatile)
 
 	if restorable.NeedsRestoring() {
 		// If the underlying graphics driver requires restoring from the context lost, the pixel data is
 		// needed. A image on an atlas must have its complete pixel data in this case.
 		pixels := make([]byte, 4*i.width*i.height)
 		for y := 0; y < i.height; y++ {
 			for x := 0; x < i.width; x++ {
 				r, g, b, a, err := i.at(x+paddingSize, y+paddingSize)
 				if err != nil {
 					return err
 				}
 				pixels[4*(i.width*y+x)] = r
 				pixels[4*(i.width*y+x)+1] = g
 				pixels[4*(i.width*y+x)+2] = b
 				pixels[4*(i.width*y+x)+3] = a
 			}
 		}
 		newI.replacePixels(pixels)
 	} else {
 		// If the underlying graphics driver doesn't require restoring from the context lost, just a regular
 		// rendering works.
 		w, h := float32(i.width), float32(i.height)
 		vs := graphics.QuadVertices(0, 0, w, h, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1)
 		is := graphics.QuadIndices()
 		dr := driver.Region{
 			X:      0,
 			Y:      0,
 			Width:  w,
 			Height: h,
 		}
 		newI.drawTriangles([graphics.ShaderImageNum]*Image{i}, vs, is, affine.ColorMIdentity{}, driver.CompositeModeCopy, driver.FilterNearest, driver.AddressUnsafe, dr, driver.Region{}, [graphics.ShaderImageNum - 1][2]float32{}, nil, nil, false, true)
 	}
 
 	newI.moveTo(i)
 	i.usedAsSourceCount = 0
 	return nil
 }
 
 func (i *Image) regionWithPadding() (x, y, width, height int) {
 	if i.backend == nil {
 		panic("atlas: backend must not be nil: not allocated yet?")
 	}
 	if !i.isOnAtlas() {
 		return 0, 0, i.width + 2*paddingSize, i.height + 2*paddingSize
 	}
 	return i.node.Region()
 }
 
 func (i *Image) processSrc(src *Image) {
 	if src == nil {
 		return
 	}
 	if src.disposed {
 		panic("atlas: the drawing source image must not be disposed (DrawTriangles)")
 	}
 	if src.backend == nil {
 		src.allocate(true)
 	}
 
 	// Compare i and source images after ensuring i is not on an atlas, or
 	// i and a source image might share the same atlas even though i != src.
 	if i.backend.restorable == src.backend.restorable {
 		panic("atlas: Image.DrawTriangles: source must be different from the receiver")
 	}
 }
 
 // DrawTriangles draws triangles with the given image.
 //
 // The vertex floats are:
 //
 //   0: Destination X in pixels
 //   1: Destination Y in pixels
 //   2: Source X in pixels (the upper-left is (0, 0))
 //   3: Source Y in pixels
 //   4: Color R [0.0-1.0]
 //   5: Color G
 //   6: Color B
 //   7: Color Y
 func (i *Image) DrawTriangles(srcs [graphics.ShaderImageNum]*Image, vertices []float32, indices []uint16, colorm affine.ColorM, mode driver.CompositeMode, filter driver.Filter, address driver.Address, dstRegion, srcRegion driver.Region, subimageOffsets [graphics.ShaderImageNum - 1][2]float32, shader *Shader, uniforms []interface{}, evenOdd bool) {
 	backendsM.Lock()
 	defer backendsM.Unlock()
 	i.drawTriangles(srcs, vertices, indices, colorm, mode, filter, address, dstRegion, srcRegion, subimageOffsets, shader, uniforms, evenOdd, false)
 }
 
 func (i *Image) drawTriangles(srcs [graphics.ShaderImageNum]*Image, vertices []float32, indices []uint16, colorm affine.ColorM, mode driver.CompositeMode, filter driver.Filter, address driver.Address, dstRegion, srcRegion driver.Region, subimageOffsets [graphics.ShaderImageNum - 1][2]float32, shader *Shader, uniforms []interface{}, evenOdd bool, keepOnAtlas bool) {
 	if i.disposed {
 		panic("atlas: the drawing target image must not be disposed (DrawTriangles)")
 	}
 	if keepOnAtlas {
 		if i.backend == nil {
 			i.allocate(true)
 		}
 	} else {
 		i.ensureIsolated()
 	}
 
 	for _, src := range srcs {
 		i.processSrc(src)
 	}
 
 	cr := float32(1)
 	cg := float32(1)
 	cb := float32(1)
 	ca := float32(1)
 	if !colorm.IsIdentity() && colorm.ScaleOnly() {
 		cr = colorm.At(0, 0)
 		cg = colorm.At(1, 1)
 		cb = colorm.At(2, 2)
 		ca = colorm.At(3, 3)
 		colorm = affine.ColorMIdentity{}
 	}
 
 	var dx, dy float32
 	// A screen image doesn't have its padding.
 	if !i.screen {
 		x, y, _, _ := i.regionWithPadding()
 		dx = float32(x) + paddingSize
 		dy = float32(y) + paddingSize
 		// TODO: Check if dstRegion does not to violate the region.
 	}
 	dstRegion.X += dx
 	dstRegion.Y += dy
 
 	var oxf, oyf float32
 	if srcs[0] != nil {
 		ox, oy, _, _ := srcs[0].regionWithPadding()
 		ox += paddingSize
 		oy += paddingSize
 		oxf, oyf = float32(ox), float32(oy)
 		n := len(vertices)
 		for i := 0; i < n; i += graphics.VertexFloatNum {
 			vertices[i] += dx
 			vertices[i+1] += dy
 			vertices[i+2] += oxf
 			vertices[i+3] += oyf
 			vertices[i+4] *= cr
 			vertices[i+5] *= cg
 			vertices[i+6] *= cb
 			vertices[i+7] *= ca
 		}
 		// srcRegion can be delibarately empty when this is not needed in order to avoid unexpected
 		// performance issue (#1293).
 		if srcRegion.Width != 0 && srcRegion.Height != 0 {
 			srcRegion.X += oxf
 			srcRegion.Y += oyf
 		}
 	} else {
 		n := len(vertices)
 		for i := 0; i < n; i += graphics.VertexFloatNum {
 			vertices[i] += dx
 			vertices[i+1] += dy
 			vertices[i+4] *= cr
 			vertices[i+5] *= cg
 			vertices[i+6] *= cb
 			vertices[i+7] *= ca
 		}
 	}
 
 	var offsets [graphics.ShaderImageNum - 1][2]float32
 	var s *restorable.Shader
 	var imgs [graphics.ShaderImageNum]*restorable.Image
 	if shader == nil {
 		// Fast path for rendering without a shader (#1355).
 		imgs[0] = srcs[0].backend.restorable
 	} else {
 		for i, subimageOffset := range subimageOffsets {
 			src := srcs[i+1]
 			if src == nil {
 				continue
 			}
 			ox, oy, _, _ := src.regionWithPadding()
 			offsets[i][0] = float32(ox) + paddingSize - oxf + subimageOffset[0]
 			offsets[i][1] = float32(oy) + paddingSize - oyf + subimageOffset[1]
 		}
 		s = shader.shader
 		for i, src := range srcs {
 			if src == nil {
 				continue
 			}
 			imgs[i] = src.backend.restorable
 		}
 	}
 
 	i.backend.restorable.DrawTriangles(imgs, offsets, vertices, indices, colorm, mode, filter, address, dstRegion, srcRegion, s, uniforms, evenOdd)
 
 	for _, src := range srcs {
 		if src == nil {
 			continue
 		}
 		if !src.isOnAtlas() && src.canBePutOnAtlas() {
 			// src might already registered, but assiging it again is not harmful.
 			imagesToPutOnAtlas[src] = struct{}{}
 		}
 	}
 }
 
 func (i *Image) ReplacePixels(pix []byte) {
 	backendsM.Lock()
 	defer backendsM.Unlock()
 	i.replacePixels(pix)
 }
 
 func (i *Image) replacePixels(pix []byte) {
 	if i.disposed {
 		panic("atlas: the image must not be disposed at replacePixels")
 	}
 
 	i.resetUsedAsSourceCount()
 
 	if i.backend == nil {
 		if pix == nil {
 			return
 		}
 		i.allocate(true)
 	}
 
 	x, y, w, h := i.regionWithPadding()
 	if pix == nil {
 		i.backend.restorable.ReplacePixels(nil, x, y, w, h)
 		return
 	}
 
 	ow, oh := w-2*paddingSize, h-2*paddingSize
 	if l := 4 * ow * oh; len(pix) != l {
 		panic(fmt.Sprintf("atlas: len(p) must be %d but %d", l, len(pix)))
 	}
 
 	pixb := theTemporaryPixels.alloc(4 * w * h)
 
 	// Clear the edges. pixb might not be zero-cleared.
 	rowPixels := 4 * w
 	for i := 0; i < rowPixels; i++ {
 		pixb[i] = 0
 	}
 	for j := 1; j < h-1; j++ {
 		pixb[rowPixels*j] = 0
 		pixb[rowPixels*j+1] = 0
 		pixb[rowPixels*j+2] = 0
 		pixb[rowPixels*j+3] = 0
 		pixb[rowPixels*(j+1)-4] = 0
 		pixb[rowPixels*(j+1)-3] = 0
 		pixb[rowPixels*(j+1)-2] = 0
 		pixb[rowPixels*(j+1)-1] = 0
 	}
 	for i := 0; i < rowPixels; i++ {
 		pixb[rowPixels*(h-1)+i] = 0
 	}
 
 	// Copy the content.
 	for j := 0; j < oh; j++ {
 		copy(pixb[4*((j+paddingSize)*w+paddingSize):], pix[4*j*ow:4*(j+1)*ow])
 	}
 
 	i.backend.restorable.ReplacePixels(pixb, x, y, w, h)
 }
 
 func (img *Image) Pixels(x, y, width, height int) ([]byte, error) {
 	backendsM.Lock()
 	defer backendsM.Unlock()
 
 	x += paddingSize
 	y += paddingSize
 
 	bs := make([]byte, 4*width*height)
 	idx := 0
 	for j := y; j < y+height; j++ {
 		for i := x; i < x+width; i++ {
 			r, g, b, a, err := img.at(i, j)
 			if err != nil {
 				return nil, err
 			}
 			bs[4*idx] = r
 			bs[4*idx+1] = g
 			bs[4*idx+2] = b
 			bs[4*idx+3] = a
 			idx++
 		}
 	}
 	return bs, nil
 }
 
 func (i *Image) at(x, y int) (byte, byte, byte, byte, error) {
 	if i.backend == nil {
 		return 0, 0, 0, 0, nil
 	}
 
 	ox, oy, w, h := i.regionWithPadding()
 	if x < 0 || y < 0 || x >= w || y >= h {
 		return 0, 0, 0, 0, nil
 	}
 
 	return i.backend.restorable.At(x+ox, y+oy)
 }
 
 // MarkDisposed marks the image as disposed. The actual operation is deferred.
 // MarkDisposed can be called from finalizers.
 //
 // A function from finalizer must not be blocked, but disposing operation can be blocked.
 // Defer this operation until it becomes safe. (#913)
 func (i *Image) MarkDisposed() {
 	deferredM.Lock()
 	deferred = append(deferred, func() {
 		i.dispose(true)
 	})
 	deferredM.Unlock()
 }
 
 func (i *Image) dispose(markDisposed bool) {
 	defer func() {
 		if markDisposed {
 			i.disposed = true
 		}
 		i.backend = nil
 		i.node = nil
 		if markDisposed {
 			runtime.SetFinalizer(i, nil)
 		}
 	}()
 
 	i.resetUsedAsSourceCount()
 
 	if i.disposed {
 		return
 	}
 
 	if i.backend == nil {
 		// Not allocated yet.
 		return
 	}
 
 	if !i.isOnAtlas() {
 		i.backend.restorable.Dispose()
 		return
 	}
 
 	i.backend.page.Free(i.node)
 	if !i.backend.page.IsEmpty() {
 		// As this part can be reused, this should be cleared explicitly.
 		i.backend.restorable.ClearPixels(i.regionWithPadding())
 		return
 	}
 
 	i.backend.restorable.Dispose()
 	index := -1
 	for idx, sh := range theBackends {
 		if sh == i.backend {
 			index = idx
 			break
 		}
 	}
 	if index == -1 {
 		panic("atlas: backend not found at an image being disposed")
 	}
 	theBackends = append(theBackends[:index], theBackends[index+1:]...)
 }
 
 func NewImage(width, height int) *Image {
 	// Actual allocation is done lazily, and the lock is not needed.
 	return &Image{
 		width:  width,
 		height: height,
 	}
 }
 
 func (i *Image) SetVolatile(volatile bool) {
 	i.volatile = volatile
 	if i.backend == nil {
 		return
 	}
 	if i.volatile {
 		i.ensureIsolated()
 	}
 	i.backend.restorable.SetVolatile(i.volatile)
 }
 
 func (i *Image) canBePutOnAtlas() bool {
 	if minSize == 0 || maxSize == 0 {
 		panic("atlas: minSize or maxSize must be initialized")
 	}
 	if i.volatile {
 		return false
 	}
 	if i.screen {
 		return false
 	}
 	return i.width+2*paddingSize <= maxSize && i.height+2*paddingSize <= maxSize
 }
 
 func (i *Image) allocate(putOnAtlas bool) {
 	if i.backend != nil {
 		panic("atlas: the image is already allocated")
 	}
 
 	runtime.SetFinalizer(i, (*Image).MarkDisposed)
 
 	if i.screen {
 		// A screen image doesn't have a padding.
 		i.backend = &backend{
 			restorable: restorable.NewScreenFramebufferImage(i.width, i.height),
 		}
 		return
 	}
 
 	if !putOnAtlas || !i.canBePutOnAtlas() {
 		i.backend = &backend{
 			restorable: restorable.NewImage(i.width+2*paddingSize, i.height+2*paddingSize),
 		}
 		i.backend.restorable.SetVolatile(i.volatile)
 		return
 	}
 
 	for _, b := range theBackends {
 		if n, ok := b.tryAlloc(i.width+2*paddingSize, i.height+2*paddingSize); ok {
 			i.backend = b
 			i.node = n
 			return
 		}
 	}
 	size := minSize
 	for i.width+2*paddingSize > size || i.height+2*paddingSize > size {
 		if size == maxSize {
 			panic(fmt.Sprintf("atlas: the image being put on an atlas is too big: width: %d, height: %d", i.width, i.height))
 		}
 		size *= 2
 	}
 
 	b := &backend{
 		restorable: restorable.NewImage(size, size),
 		page:       packing.NewPage(size, maxSize),
 	}
 	b.restorable.SetVolatile(i.volatile)
 	theBackends = append(theBackends, b)
 
 	n := b.page.Alloc(i.width+2*paddingSize, i.height+2*paddingSize)
 	if n == nil {
 		panic("atlas: Alloc result must not be nil at allocate")
 	}
 	i.backend = b
 	i.node = n
 }
 
 func (i *Image) DumpScreenshot(path string, blackbg bool) error {
 	backendsM.Lock()
 	defer backendsM.Unlock()
 
 	return i.backend.restorable.Dump(path, blackbg, image.Rect(paddingSize, paddingSize, paddingSize+i.width, paddingSize+i.height))
 }
 
 func NewScreenFramebufferImage(width, height int) *Image {
 	// Actual allocation is done lazily.
 	i := &Image{
 		width:  width,
 		height: height,
 		screen: true,
 	}
 	return i
 }
 
 func EndFrame() error {
 	backendsM.Lock()
 
 	theTemporaryPixels.resetAtFrameEnd()
 
 	return restorable.ResolveStaleImages()
 }
 
 func BeginFrame() error {
 	defer backendsM.Unlock()
 
 	var err error
 	initOnce.Do(func() {
 		err = restorable.InitializeGraphicsDriverState()
 		if err != nil {
 			return
 		}
 		if len(theBackends) != 0 {
 			panic("atlas: all the images must be not on an atlas before the game starts")
 		}
 		minSize = 1024
 		maxSize = restorable.MaxImageSize()
 	})
 	if err != nil {
 		return err
 	}
 
 	return restorable.RestoreIfNeeded()
 }
 
 func DumpImages(dir string) error {
 	backendsM.Lock()
 	defer backendsM.Unlock()
 	return restorable.DumpImages(dir)
 }