Unify RenderTarget and Image into Image (#34)

ebitenutil/debugprint.go

@@ -24,18 +24,18 @@ import (
 )
 
 type debugPrintState struct {
-	textTexture            *ebiten.Image
+	textImage              *ebiten.Image
-	debugPrintRenderTarget *ebiten.RenderTarget
+	debugPrintRenderTarget *ebiten.Image
 	y                      int
 }
 
 var defaultDebugPrintState = new(debugPrintState)
 
-func DebugPrint(r *ebiten.RenderTarget, str string) {
+func DebugPrint(r *ebiten.Image, str string) {
 	defaultDebugPrintState.DebugPrint(r, str)
 }
 
-func (d *debugPrintState) drawText(rt *ebiten.RenderTarget, str string, x, y int, c color.Color) {
+func (d *debugPrintState) drawText(rt *ebiten.Image, str string, x, y int, c color.Color) {
 	parts := []ebiten.ImagePart{}
 	locationX, locationY := 0, 0
 	for _, c := range str {
@@ -57,16 +57,16 @@ func (d *debugPrintState) drawText(rt *ebiten.RenderTarget, str string, x, y int
 	geo := ebiten.TranslateGeometry(float64(x)+1, float64(y))
 	r, g, b, a := internal.RGBA(c)
 	clr := ebiten.ScaleColor(r, g, b, a)
-	rt.DrawImage(d.textTexture, parts, geo, clr)
+	rt.DrawImage(d.textImage, parts, geo, clr)
 }
 
-func (d *debugPrintState) DebugPrint(r *ebiten.RenderTarget, str string) {
+func (d *debugPrintState) DebugPrint(r *ebiten.Image, str string) {
-	if d.textTexture == nil {
+	if d.textImage == nil {
 		img, err := assets.TextImage()
 		if err != nil {
 			panic(err)
 		}
-		d.textTexture, err = ebiten.NewImage(img, ebiten.FilterNearest)
+		d.textImage, err = ebiten.NewImageFromImage(img, ebiten.FilterNearest)
 		if err != nil {
 			panic(err)
 		}
@@ -74,7 +74,7 @@ func (d *debugPrintState) DebugPrint(r *ebiten.RenderTarget, str string) {
 	if d.debugPrintRenderTarget == nil {
 		width, height := 256, 256
 		var err error
-		d.debugPrintRenderTarget, err = ebiten.NewRenderTarget(width, height, ebiten.FilterNearest)
+		d.debugPrintRenderTarget, err = ebiten.NewImage(width, height, ebiten.FilterNearest)
 		if err != nil {
 			panic(err)
 		}

ebitenutil/image.go

@@ -32,9 +32,9 @@ func NewImageFromFile(path string, filter ebiten.Filter) (*ebiten.Image, image.I
 	if err != nil {
 		return nil, nil, err
 	}
-	texture, err := ebiten.NewImage(img, filter)
+	img2, err := ebiten.NewImageFromImage(img, filter)
 	if err != nil {
 		return nil, nil, err
 	}
-	return texture, img, err
+	return img2, img, err
 }

example/alphablending/main.go

@@ -31,11 +31,11 @@ const (
 
 type Game struct {
 	count           int
-	tmpRenderTarget *ebiten.RenderTarget
+	tmpRenderTarget *ebiten.Image
 	ebitenImage     *ebiten.Image
 }
 
-func (g *Game) Update(r *ebiten.RenderTarget) error {
+func (g *Game) Update(r *ebiten.Image) error {
 	g.count++
 	g.count %= 600
 	diff := float64(g.count) * 0.2
@@ -62,7 +62,7 @@ func (g *Game) Update(r *ebiten.RenderTarget) error {
 	for i := 0; i < 10; i++ {
 		geo := ebiten.TranslateGeometry(0, float64(i)*(diff))
 		clr := ebiten.ColorMatrixI()
-		if err := ebiten.DrawWholeImage(r, g.tmpRenderTarget.Image(), geo, clr); err != nil {
+		if err := ebiten.DrawWholeImage(r, g.tmpRenderTarget, geo, clr); err != nil {
 			return err
 		}
 	}
@@ -76,7 +76,7 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	g.tmpRenderTarget, err = ebiten.NewRenderTarget(screenWidth, screenHeight, ebiten.FilterNearest)
+	g.tmpRenderTarget, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
 	if err != nil {
 		log.Fatal(err)
 	}

example/blocks/blocks/field.go

@@ -112,7 +112,7 @@ func (f *Field) flushLine(j int) bool {
 	return true
 }
 
-func (f *Field) Draw(r *ebiten.RenderTarget, images *Images, geo ebiten.GeometryMatrix) {
+func (f *Field) Draw(r *ebiten.Image, images *Images, geo ebiten.GeometryMatrix) {
 	blocks := make([][]BlockType, len(f.blocks))
 	for i, blockCol := range f.blocks {
 		blocks[i] = make([]BlockType, len(blockCol))

example/blocks/blocks/font.go

@@ -33,7 +33,7 @@ func textWidth(str string) int {
 	return charWidth * len(str)
 }
 
-func drawText(rt *ebiten.RenderTarget, images *Images, str string, ox, oy, scale int, c color.Color) {
+func drawText(rt *ebiten.Image, images *Images, str string, ox, oy, scale int, c color.Color) {
 	fontImageId := images.GetImage("font")
 	parts := []ebiten.ImagePart{}
 
@@ -66,7 +66,7 @@ func drawText(rt *ebiten.RenderTarget, images *Images, str string, ox, oy, scale
 	rt.DrawImage(fontImageId, parts, geo, clr)
 }
 
-func drawTextWithShadow(rt *ebiten.RenderTarget, images *Images, str string, x, y, scale int, clr color.Color) {
+func drawTextWithShadow(rt *ebiten.Image, images *Images, str string, x, y, scale int, clr color.Color) {
 	drawText(rt, images, str, x+1, y+1, scale, color.NRGBA{0, 0, 0, 0x80})
 	drawText(rt, images, str, x, y, scale, clr)
 }

example/blocks/blocks/game.go

@@ -70,7 +70,7 @@ func (game *Game) isInitialized() bool {
 	return true
 }
 
-func (game *Game) Update(r *ebiten.RenderTarget) error {
+func (game *Game) Update(r *ebiten.Image) error {
 	game.once.Do(func() {
 		game.images = NewImages()
 		for name, path := range imagePaths {

example/blocks/blocks/gamescene.go

@@ -109,7 +109,7 @@ func (s *GameScene) Update(state *GameState) {
 	}
 }
 
-func (s *GameScene) Draw(r *ebiten.RenderTarget, images *Images) {
+func (s *GameScene) Draw(r *ebiten.Image, images *Images) {
 	r.Fill(color.White)
 
 	field := images.GetImage("empty")

example/blocks/blocks/images.go

@@ -38,7 +38,7 @@ type Images struct {
 	imagePaths        chan namePath
 	renderTargetSizes chan nameSize
 	images            map[string]*ebiten.Image
-	renderTargets     map[string]*ebiten.RenderTarget
+	renderTargets     map[string]*ebiten.Image
 	sync.RWMutex
 }
 
@@ -47,7 +47,7 @@ func NewImages() *Images {
 		imagePaths:        make(chan namePath),
 		renderTargetSizes: make(chan nameSize),
 		images:            map[string]*ebiten.Image{},
-		renderTargets:     map[string]*ebiten.RenderTarget{},
+		renderTargets:     map[string]*ebiten.Image{},
 	}
 	go func() {
 		for {
@@ -81,7 +81,7 @@ func (i *Images) loopMain() {
 			if err != nil {
 				panic(err)
 			}
-			id, err := ebiten.NewImage(img, ebiten.FilterNearest)
+			id, err := ebiten.NewImageFromImage(img, ebiten.FilterNearest)
 			if err != nil {
 				panic(err)
 			}
@@ -93,7 +93,7 @@ func (i *Images) loopMain() {
 		name := s.name
 		size := s.size
 		go func() {
-			id, err := ebiten.NewRenderTarget(size.Width, size.Height, ebiten.FilterNearest)
+			id, err := ebiten.NewImage(size.Width, size.Height, ebiten.FilterNearest)
 			if err != nil {
 				panic(err)
 			}
@@ -129,7 +129,7 @@ func (i *Images) GetImage(name string) *ebiten.Image {
 	return i.images[name]
 }
 
-func (i *Images) GetRenderTarget(name string) *ebiten.RenderTarget {
+func (i *Images) GetRenderTarget(name string) *ebiten.Image {
 	i.RLock()
 	defer i.RUnlock()
 	return i.renderTargets[name]

example/blocks/blocks/piece.go

@@ -138,7 +138,7 @@ const blockHeight = 10
 const fieldBlockNumX = 10
 const fieldBlockNumY = 20
 
-func drawBlocks(r *ebiten.RenderTarget, images *Images, blocks [][]BlockType, geo ebiten.GeometryMatrix) {
+func drawBlocks(r *ebiten.Image, images *Images, blocks [][]BlockType, geo ebiten.GeometryMatrix) {
 	parts := []ebiten.ImagePart{}
 	for i, blockCol := range blocks {
 		for j, block := range blockCol {
@@ -213,7 +213,7 @@ func (p *Piece) AbsorbInto(field *Field, x, y int, angle Angle) {
 	}
 }
 
-func (p *Piece) Draw(r *ebiten.RenderTarget, images *Images, fieldX, fieldY int, pieceX, pieceY int, angle Angle) {
+func (p *Piece) Draw(r *ebiten.Image, images *Images, fieldX, fieldY int, pieceX, pieceY int, angle Angle) {
 	size := len(p.blocks)
 	blocks := make([][]BlockType, size)
 	for i := range p.blocks {

example/blocks/blocks/scenemanager.go

@@ -29,7 +29,7 @@ func init() {
 
 type Scene interface {
 	Update(state *GameState)
-	Draw(r *ebiten.RenderTarget, images *Images)
+	Draw(r *ebiten.Image, images *Images)
 }
 
 const transitionMaxCount = 20
@@ -60,7 +60,7 @@ func (s *SceneManager) Update(state *GameState) {
 	}
 }
 
-func (s *SceneManager) Draw(r *ebiten.RenderTarget, images *Images) {
+func (s *SceneManager) Draw(r *ebiten.Image, images *Images) {
 	if s.transitionCount == -1 {
 		s.current.Draw(r, images)
 		return
@@ -74,11 +74,11 @@ func (s *SceneManager) Draw(r *ebiten.RenderTarget, images *Images) {
 	s.next.Draw(to, images)
 
 	color := ebiten.ColorMatrixI()
-	ebiten.DrawWholeImage(r, from.Image(), ebiten.GeometryMatrixI(), color)
+	ebiten.DrawWholeImage(r, from, ebiten.GeometryMatrixI(), color)
 
 	alpha := float64(s.transitionCount) / float64(transitionMaxCount)
 	color.Elements[3][3] = alpha
-	ebiten.DrawWholeImage(r, to.Image(), ebiten.GeometryMatrixI(), color)
+	ebiten.DrawWholeImage(r, to, ebiten.GeometryMatrixI(), color)
 }
 
 func (s *SceneManager) GoTo(scene Scene) {

example/blocks/blocks/titlescene.go

@@ -40,7 +40,7 @@ func (s *TitleScene) Update(state *GameState) {
 	}
 }
 
-func (s *TitleScene) Draw(r *ebiten.RenderTarget, images *Images) {
+func (s *TitleScene) Draw(r *ebiten.Image, images *Images) {
 	drawTitleBackground(r, images, s.count)
 	drawLogo(r, images, "BLOCKS")
 
@@ -50,7 +50,7 @@ func (s *TitleScene) Draw(r *ebiten.RenderTarget, images *Images) {
 	drawTextWithShadow(r, images, message, x, y, 1, color.NRGBA{0x80, 0, 0, 0xff})
 }
 
-func drawTitleBackground(r *ebiten.RenderTarget, images *Images, c int) {
+func drawTitleBackground(r *ebiten.Image, images *Images, c int) {
 	const imageWidth = 32
 	const imageHeight = 32
 
@@ -73,7 +73,7 @@ func drawTitleBackground(r *ebiten.RenderTarget, images *Images, c int) {
 	r.DrawImage(backgroundImage, parts, geo, clr)
 }
 
-func drawLogo(r *ebiten.RenderTarget, images *Images, str string) {
+func drawLogo(r *ebiten.Image, images *Images, str string) {
 	scale := 4
 	textWidth := textWidth(str) * scale
 	x := (ScreenWidth - textWidth) / 2

example/image/main.go

@@ -36,7 +36,7 @@ type Game struct {
 	gophersImage    *ebiten.Image
 }
 
-func (g *Game) Update(r *ebiten.RenderTarget) error {
+func (g *Game) Update(r *ebiten.Image) error {
 	g.count++
 	if ebiten.IsKeyPressed(ebiten.KeyLeft) {
 		g.horizontalCount--
@@ -60,7 +60,9 @@ func (g *Game) Update(r *ebiten.RenderTarget) error {
 	geo.Concat(ebiten.TranslateGeometry(screenWidth/2, screenHeight/2))
 	//clr := ebiten.RotateHue(float64(g.count%180) * 2 * math.Pi / 180)
 	clr := ebiten.ColorMatrixI()
-	ebiten.DrawWholeImage(r, g.gophersImage, geo, clr)
+	if err := ebiten.DrawWholeImage(r, g.gophersImage, geo, clr); err != nil {
+		return err
+	}
 	return nil
 }
 

example/mosaic/main.go

@@ -32,15 +32,15 @@ const mosaicRatio = 16
 
 type Game struct {
 	gophersImage        *ebiten.Image
-	gophersRenderTarget *ebiten.RenderTarget
+	gophersRenderTarget *ebiten.Image
 }
 
-func (g *Game) Update(r *ebiten.RenderTarget) error {
+func (g *Game) Update(r *ebiten.Image) error {
 	geo := ebiten.ScaleGeometry(1.0/mosaicRatio, 1.0/mosaicRatio)
 	ebiten.DrawWholeImage(g.gophersRenderTarget, g.gophersImage, geo, ebiten.ColorMatrixI())
 
 	geo = ebiten.ScaleGeometry(mosaicRatio/2.0, mosaicRatio/2.0)
-	ebiten.DrawWholeImage(r, g.gophersRenderTarget.Image(), geo, ebiten.ColorMatrixI())
+	ebiten.DrawWholeImage(r, g.gophersRenderTarget, geo, ebiten.ColorMatrixI())
 	return nil
 }
 
@@ -52,7 +52,7 @@ func main() {
 		log.Fatal(err)
 	}
 	w, h := g.gophersImage.Size()
-	g.gophersRenderTarget, err = ebiten.NewRenderTarget(w/mosaicRatio, h/mosaicRatio, ebiten.FilterNearest)
+	g.gophersRenderTarget, err = ebiten.NewImage(w/mosaicRatio, h/mosaicRatio, ebiten.FilterNearest)
 	if err != nil {
 		log.Fatal(err)
 	}

example/paint/main.go

@@ -33,11 +33,11 @@ const (
 type Game struct {
 	inited             bool
 	count              int
-	brushRenderTarget  *ebiten.RenderTarget
+	brushRenderTarget  *ebiten.Image
-	canvasRenderTarget *ebiten.RenderTarget
+	canvasRenderTarget *ebiten.Image
 }
 
-func (g *Game) Update(r *ebiten.RenderTarget) error {
+func (g *Game) Update(r *ebiten.Image) error {
 	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
 		g.count++
 	}
@@ -54,10 +54,10 @@ func (g *Game) Update(r *ebiten.RenderTarget) error {
 		clr := ebiten.ScaleColor(1.0, 0.25, 0.25, 1.0)
 		theta := 2.0 * math.Pi * float64(g.count%60) / 60.0
 		clr.Concat(ebiten.RotateHue(theta))
-		ebiten.DrawWholeImage(g.canvasRenderTarget, g.brushRenderTarget.Image(), geo, clr)
+		ebiten.DrawWholeImage(g.canvasRenderTarget, g.brushRenderTarget, geo, clr)
 	}
 
-	ebiten.DrawWholeImage(r, g.canvasRenderTarget.Image(), ebiten.GeometryMatrixI(), ebiten.ColorMatrixI())
+	ebiten.DrawWholeImage(r, g.canvasRenderTarget, ebiten.GeometryMatrixI(), ebiten.ColorMatrixI())
 
 	ebitenutil.DebugPrint(r, fmt.Sprintf("(%d, %d)", mx, my))
 	return nil
@@ -66,11 +66,11 @@ func (g *Game) Update(r *ebiten.RenderTarget) error {
 func main() {
 	g := new(Game)
 	var err error
-	g.brushRenderTarget, err = ebiten.NewRenderTarget(1, 1, ebiten.FilterNearest)
+	g.brushRenderTarget, err = ebiten.NewImage(1, 1, ebiten.FilterNearest)
 	if err != nil {
 		log.Fatal(err)
 	}
-	g.canvasRenderTarget, err = ebiten.NewRenderTarget(screenWidth, screenHeight, ebiten.FilterNearest)
+	g.canvasRenderTarget, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
 	if err != nil {
 		log.Fatal(err)
 	}

example/perspective/main.go

@@ -32,7 +32,7 @@ type Game struct {
 	gophersImage *ebiten.Image
 }
 
-func (g *Game) Update(r *ebiten.RenderTarget) error {
+func (g *Game) Update(r *ebiten.Image) error {
 	parts := []ebiten.ImagePart{}
 	w, h := g.gophersImage.Size()
 	for i := 0; i < h; i++ {

gamecontext.go

@@ -47,12 +47,12 @@ func glFilter(f Filter) int {
 	}
 }
 
-// NewRenderTarget returns a new RenderTarget.
+// NewImage returns an empty image.
-func NewRenderTarget(width, height int, filter Filter) (*RenderTarget, error) {
+func NewImage(width, height int, filter Filter) (*Image, error) {
-	return currentUI.newRenderTarget(width, height, glFilter(filter))
+	return currentUI.newImage(width, height, glFilter(filter))
 }
 
-// NewImage returns a new image.
+// NewImage creates a new image with the given image (img).
-func NewImage(img image.Image, filter Filter) (*Image, error) {
+func NewImageFromImage(img image.Image, filter Filter) (*Image, error) {
-	return currentUI.newImage(img, glFilter(filter))
+	return currentUI.newImageFromImage(img, glFilter(filter))
 }

graphics.go

@@ -16,10 +16,6 @@ limitations under the License.
 
 package ebiten
 
-import (
-	"github.com/hajimehoshi/ebiten/internal/opengl"
-)
-
 // A Rect represents a rectangle.
 type Rect struct {
 	X      float64
@@ -35,7 +31,7 @@ type ImagePart struct {
 }
 
 // DrawWholeImage draws the whole image.
-func DrawWholeImage(r *RenderTarget, image *Image, geo GeometryMatrix, color ColorMatrix) error {
+func DrawWholeImage(r *Image, image *Image, geo GeometryMatrix, color ColorMatrix) error {
 	w, h := image.Size()
 	parts := []ImagePart{
 		{Rect{0, 0, float64(w), float64(h)}, Rect{0, 0, float64(w), float64(h)}},
@@ -51,14 +47,3 @@ const (
 	FilterNearest Filter = iota
 	FilterLinear
 )
-
-// An Image represents an image to be rendered.
-// An image's pixels are stored as non alpha-premultiplied.
-type Image struct {
-	glTexture *opengl.Texture
-}
-
-// Size returns the size of the image.
-func (i *Image) Size() (width int, height int) {
-	return i.glTexture.Size()
-}

graphicscontext.go

@@ -27,12 +27,17 @@ func newGraphicsContext(screenWidth, screenHeight, screenScale int) (*graphicsCo
 		return nil, err
 	}
 
-	screen, err := newInnerRenderTarget(screenWidth, screenHeight, gl.NEAREST)
+	texture, err := opengl.NewTexture(screenWidth, screenHeight, gl.NEAREST)
 	if err != nil {
 		return nil, err
 	}
+	screen, err := newInnerImage(texture, gl.NEAREST)
+	if err != nil {
+		return nil, err
+	}
+
 	c := &graphicsContext{
-		defaultR:    &innerRenderTarget{r, nil},
+		defaultR:    &innerImage{r, nil},
 		screen:      screen,
 		screenScale: screenScale,
 	}
@@ -40,15 +45,15 @@ func newGraphicsContext(screenWidth, screenHeight, screenScale int) (*graphicsCo
 }
 
 type graphicsContext struct {
-	screen      *innerRenderTarget
+	screen      *innerImage
-	defaultR    *innerRenderTarget
+	defaultR    *innerImage
 	screenScale int
 }
 
 func (c *graphicsContext) dispose() {
 	// NOTE: Now this method is not used anywhere.
 	glRenderTarget := c.screen.glRenderTarget
-	glTexture := c.screen.image.glTexture
+	glTexture := c.screen.glTexture
 
 	glRenderTarget.Dispose()
 	glTexture.Dispose()
@@ -64,11 +69,11 @@ func (c *graphicsContext) postUpdate() error {
 	scale := float64(c.screenScale)
 	geo := ScaleGeometry(scale, scale)
 	clr := ColorMatrixI()
-	w, h := c.screen.image.Size()
+	w, h := c.screen.size()
 	parts := []ImagePart{
 		{Rect{0, 0, float64(w), float64(h)}, Rect{0, 0, float64(w), float64(h)}},
 	}
-	if err := c.defaultR.DrawImage(c.screen.image, parts, geo, clr); err != nil {
+	if err := c.defaultR.drawImage(c.screen, parts, geo, clr); err != nil {
 		return err
 	}
 

image.go

@@ -24,35 +24,29 @@ import (
 	"image/color"
 )
 
-type innerRenderTarget struct {
+type innerImage struct {
-	glRenderTarget *opengl.RenderTarget
+	// TODO: Rename them later.
-	image          *Image
+	glRenderTarget *opengl.Image
+	glTexture      *opengl.Texture
 }
 
-func newInnerRenderTarget(width, height int, filter int) (*innerRenderTarget, error) {
+func newInnerImage(glTexture *opengl.Texture, filter int) (*innerImage, error) {
-	glTexture, err := opengl.NewTexture(width, height, filter)
-	if err != nil {
-		return nil, err
-	}
-
 	glRenderTarget, err := opengl.NewRenderTargetFromTexture(glTexture)
 	if err != nil {
 		return nil, err
 	}
-
+	return &innerImage{glRenderTarget, glTexture}, nil
-	image := &Image{glTexture}
-	return &innerRenderTarget{glRenderTarget, image}, nil
 }
 
-func (r *innerRenderTarget) size() (width, height int) {
+func (r *innerImage) size() (width, height int) {
 	return r.glRenderTarget.Size()
 }
 
-func (r *innerRenderTarget) Clear() error {
+func (r *innerImage) Clear() error {
 	return r.Fill(color.Transparent)
 }
 
-func (r *innerRenderTarget) Fill(clr color.Color) error {
+func (r *innerImage) Fill(clr color.Color) error {
 	if err := r.glRenderTarget.SetAsViewport(); err != nil {
 		return err
 	}
@@ -62,20 +56,19 @@ func (r *innerRenderTarget) Fill(clr color.Color) error {
 	return nil
 }
 
-func (r *innerRenderTarget) DrawImage(image *Image, parts []ImagePart, geo GeometryMatrix, color ColorMatrix) error {
+func (r *innerImage) drawImage(image *innerImage, parts []ImagePart, geo GeometryMatrix, color ColorMatrix) error {
 	if err := r.glRenderTarget.SetAsViewport(); err != nil {
 		return err
 	}
-	glTexture := image.glTexture
+	w, h := image.glTexture.Size()
-	w, h := glTexture.Size()
 	quads := textureQuads(parts, w, h)
 	targetNativeTexture := gl.Texture(0)
-	if r.image != nil {
+	if r.glTexture != nil {
-		targetNativeTexture = r.image.glTexture.Native()
+		targetNativeTexture = r.glTexture.Native()
 	}
 	w2, h2 := r.size()
 	projectionMatrix := r.glRenderTarget.ProjectionMatrix()
-	shader.DrawTexture(glTexture.Native(), targetNativeTexture, w2, h2, projectionMatrix, quads, &geo, &color)
+	shader.DrawTexture(image.glTexture.Native(), targetNativeTexture, w2, h2, projectionMatrix, quads, &geo, &color)
 	return nil
 }
 
@@ -108,36 +101,36 @@ type syncer interface {
 	Sync(func())
 }
 
-type RenderTarget struct {
+type Image struct {
 	syncer syncer
-	inner  *innerRenderTarget
+	inner  *innerImage
 }
 
-func (r *RenderTarget) Image() *Image {
+func (r *Image) Size() (width, height int) {
-	return r.inner.image
-}
-
-func (r *RenderTarget) Size() (width, height int) {
 	return r.inner.size()
 }
 
-func (r *RenderTarget) Clear() (err error) {
+func (r *Image) Clear() (err error) {
 	r.syncer.Sync(func() {
 		err = r.inner.Clear()
 	})
 	return
 }
 
-func (r *RenderTarget) Fill(clr color.Color) (err error) {
+func (r *Image) Fill(clr color.Color) (err error) {
 	r.syncer.Sync(func() {
 		err = r.inner.Fill(clr)
 	})
 	return
 }
 
-func (r *RenderTarget) DrawImage(image *Image, parts []ImagePart, geo GeometryMatrix, color ColorMatrix) (err error) {
+func (r *Image) DrawImage(image *Image, parts []ImagePart, geo GeometryMatrix, color ColorMatrix) (err error) {
+	return r.drawImage(image.inner, parts, geo, color)
+}
+
+func (r *Image) drawImage(image *innerImage, parts []ImagePart, geo GeometryMatrix, color ColorMatrix) (err error) {
 	r.syncer.Sync(func() {
-		err = r.inner.DrawImage(image, parts, geo, color)
+		err = r.inner.drawImage(image, parts, geo, color)
 	})
 	return
 }

internal/opengl/rendertarget.go

@@ -37,15 +37,15 @@ func orthoProjectionMatrix(left, right, bottom, top int) [4][4]float64 {
 	}
 }
 
-type RenderTarget struct {
+type Image struct {
 	framebuffer gl.Framebuffer
 	width       int
 	height      int
 	flipY       bool
 }
 
-func NewZeroRenderTarget(width, height int) (*RenderTarget, error) {
+func NewZeroRenderTarget(width, height int) (*Image, error) {
-	r := &RenderTarget{
+	r := &Image{
 		width:  width,
 		height: height,
 		flipY:  true,
@@ -53,24 +53,24 @@ func NewZeroRenderTarget(width, height int) (*RenderTarget, error) {
 	return r, nil
 }
 
-func NewRenderTargetFromTexture(texture *Texture) (*RenderTarget, error) {
+func NewRenderTargetFromTexture(texture *Texture) (*Image, error) {
 	framebuffer, err := createFramebuffer(texture.Native())
 	if err != nil {
 		return nil, err
 	}
 	w, h := texture.Size()
-	return &RenderTarget{
+	return &Image{
 		framebuffer: framebuffer,
 		width:       w,
 		height:      h,
 	}, nil
 }
 
-func (r *RenderTarget) Size() (width, height int) {
+func (r *Image) Size() (width, height int) {
 	return r.width, r.height
 }
 
-func (r *RenderTarget) Dispose() {
+func (r *Image) Dispose() {
 	r.framebuffer.Delete()
 }
 
@@ -83,13 +83,10 @@ func createFramebuffer(nativeTexture gl.Texture) (gl.Framebuffer, error) {
 		return 0, errors.New("creating framebuffer failed")
 	}
 
-	gl.ClearColor(0, 0, 0, 0)
-	gl.Clear(gl.COLOR_BUFFER_BIT)
-
 	return framebuffer, nil
 }
 
-func (r *RenderTarget) SetAsViewport() error {
+func (r *Image) SetAsViewport() error {
 	gl.Flush()
 	r.framebuffer.Bind()
 	err := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
@@ -106,7 +103,7 @@ func (r *RenderTarget) SetAsViewport() error {
 	return nil
 }
 
-func (r *RenderTarget) ProjectionMatrix() [4][4]float64 {
+func (r *Image) ProjectionMatrix() [4][4]float64 {
 	width := internal.NextPowerOf2Int(r.width)
 	height := internal.NextPowerOf2Int(r.height)
 	m := orthoProjectionMatrix(0, width, 0, height)

run.go

@@ -17,8 +17,11 @@ limitations under the License.
 package ebiten
 
 // Run runs the game.
+// f is a function which is called at every frame.
+// The argument (*Image) is the render target that represents the screen.
+//
 // This function must be called from the main thread.
-func Run(f func(*RenderTarget) error, width, height, scale int, title string) error {
+func Run(f func(*Image) error, width, height, scale int, title string) error {
 	err := startUI(width, height, scale, title)
 	if err != nil {
 		return err

ui.go

@@ -110,14 +110,14 @@ func (u *ui) Sync(f func()) {
 	u.use(f)
 }
 
-func (u *ui) draw(f func(*RenderTarget) error) (err error) {
+func (u *ui) draw(f func(*Image) error) (err error) {
 	u.use(func() {
 		err = u.graphicsContext.preUpdate()
 	})
 	if err != nil {
 		return
 	}
-	err = f(&RenderTarget{syncer: u, inner: u.graphicsContext.screen})
+	err = f(&Image{syncer: u, inner: u.graphicsContext.screen})
 	if err != nil {
 		return
 	}
@@ -131,26 +131,39 @@ func (u *ui) draw(f func(*RenderTarget) error) (err error) {
 	return
 }
 
-func (u *ui) newImage(img image.Image, filter int) (*Image, error) {
+func (u *ui) newImageFromImage(img image.Image, filter int) (*Image, error) {
-	var i *Image
+	var innerImage *innerImage
 	var err error
 	u.use(func() {
-		glTexture, err := opengl.NewTextureFromImage(img, filter)
+		var texture *opengl.Texture
+		texture, err = opengl.NewTextureFromImage(img, filter)
 		if err != nil {
 			return
 		}
-		i = &Image{glTexture}
+		innerImage, err = newInnerImage(texture, filter)
 	})
-	return i, err
+	if err != nil {
+		return nil, err
+	}
+	return &Image{u, innerImage}, nil
 }
 
-func (u *ui) newRenderTarget(width, height int, filter int) (*RenderTarget, error) {
+func (u *ui) newImage(width, height int, filter int) (*Image, error) {
-	var innerRenderTarget *innerRenderTarget
+	var innerImage *innerImage
 	var err error
 	u.use(func() {
-		innerRenderTarget, err = newInnerRenderTarget(width, height, filter)
+		var texture *opengl.Texture
+		texture, err = opengl.NewTexture(width, height, filter)
+		if err != nil {
+			return
+		}
+		innerImage, err = newInnerImage(texture, filter)
+		innerImage.Clear()
 	})
-	return &RenderTarget{u, innerRenderTarget}, err
+	if err != nil {
+		return nil, err
+	}
+	return &Image{u, innerImage}, nil
 }
 
 func (u *ui) run() {