change Picture receiver to pointer

graphics.go

@@ -80,14 +80,14 @@ func (g *Group) Do(sub func(pixelgl.Context)) {
 // Usually you use this type only indirectly throught other specific shapes (sprites, polygons, ...) embedding it.
 type Shape struct {
 	parent    pixelgl.Doer
-	picture   Picture
+	picture   *Picture
 	color     color.Color
 	transform Transform
 	va        *pixelgl.VertexArray
 }
 
 // NewShape creates a new shape with specified parent, picture, color, transform and vertex array.
-func NewShape(parent pixelgl.Doer, picture Picture, c color.Color, transform Transform, va *pixelgl.VertexArray) *Shape {
+func NewShape(parent pixelgl.Doer, picture *Picture, c color.Color, transform Transform, va *pixelgl.VertexArray) *Shape {
 	return &Shape{
 		parent:    parent,
 		picture:   picture,
@@ -98,12 +98,12 @@ func NewShape(parent pixelgl.Doer, picture Picture, c color.Color, transform Tra
 }
 
 // SetPicture changes the picture of a shape.
-func (s *Shape) SetPicture(picture Picture) {
+func (s *Shape) SetPicture(picture *Picture) {
 	s.picture = picture
 }
 
 // Picture returns the current picture of a shape.
-func (s *Shape) Picture() Picture {
+func (s *Shape) Picture() *Picture {
 	return s.picture
 }
 
@@ -145,7 +145,7 @@ func (s *Shape) Draw(t ...Transform) {
 		ctx.Shader().SetUniformAttr(maskColorVec4, mgl32.Vec4{r, g, b, a})
 		ctx.Shader().SetUniformAttr(transformMat3, mat)
 
-		if s.picture.Texture() != nil {
+		if s.picture != nil {
 			s.picture.Texture().Do(func(pixelgl.Context) {
 				s.va.Draw()
 			})
@@ -169,12 +169,12 @@ type MultiShape struct {
 //
 // If two of the supplied shapes have different pictures, this function panics.
 func NewMultiShape(parent pixelgl.Doer, shapes ...*Shape) *MultiShape {
-	var picture Picture
+	var picture *Picture
 	for _, shape := range shapes {
-		if picture.IsNil() {
+		if picture == nil {
 			picture = shape.Picture()
 		} else {
-			if shape.Picture().IsNil() && shape.Picture() != picture {
+			if shape.Picture() == nil && shape.Picture().Texture() != picture.Texture() {
 				panic(errors.New("failed to create multishape: shapes have different pictures"))
 			}
 		}
@@ -256,7 +256,7 @@ type Sprite struct {
 
 // NewSprite creates a new sprite with the supplied picture. The sprite's size is the size of the supplied picture.
 // If you want to change the sprite's size, change it's transform.
-func NewSprite(parent pixelgl.Doer, picture Picture) *Sprite {
+func NewSprite(parent pixelgl.Doer, picture *Picture) *Sprite {
 	var va *pixelgl.VertexArray
 
 	parent.Do(func(ctx pixelgl.Context) {
@@ -317,7 +317,7 @@ func NewLineColor(parent pixelgl.Doer, c color.Color, a, b Vec, width float64) *
 		va.SetVertexAttr(i, texCoordVec2, mgl32.Vec2{-1, -1})
 	}
 
-	lc := &LineColor{NewShape(parent, Picture{}, c, Position(0), va), a, b, width}
+	lc := &LineColor{NewShape(parent, nil, c, Position(0), va), a, b, width}
 	lc.setPoints()
 	return lc
 }
@@ -398,7 +398,7 @@ func NewPolygonColor(parent pixelgl.Doer, c color.Color, points ...Vec) *Polygon
 		va.SetVertexAttr(i, texCoordVec2, mgl32.Vec2{-1, -1})
 	}
 
-	return &PolygonColor{NewShape(parent, Picture{}, c, Position(0), va), points}
+	return &PolygonColor{NewShape(parent, nil, c, Position(0), va), points}
 }
 
 // PointNum returns the number of points in a polygon.
@@ -474,7 +474,7 @@ func NewEllipseColor(parent pixelgl.Doer, c color.Color, radius Vec, fill float6
 		va.SetVertexAttr(j, texCoordVec2, mgl32.Vec2{-1, -1})
 	}
 
-	return &EllipseColor{NewShape(parent, Picture{}, c, Position(0), va), radius, fill}
+	return &EllipseColor{NewShape(parent, nil, c, Position(0), va), radius, fill}
 }
 
 // Radius returns the radius of an ellipse.

picture.go

@@ -18,7 +18,7 @@ type Picture struct {
 }
 
 // NewPicture creates a new picture from an image.Image.
-func NewPicture(img image.Image) Picture {
+func NewPicture(img image.Image) *Picture {
 	// convert the image to RGBA format
 	rgba := image.NewRGBA(image.Rect(0, 0, img.Bounds().Dx(), img.Bounds().Dy()))
 	draw.Draw(rgba, rgba.Bounds(), img, img.Bounds().Min, draw.Src)
@@ -33,21 +33,16 @@ func NewPicture(img image.Image) Picture {
 		panic(errors.Wrap(err, "failed to create picture"))
 	}
 
-	return Picture{
+	return &Picture{
 		texture: texture,
 		bounds:  R(0, 0, float64(texture.Width()), float64(texture.Height())),
 	}
 }
 
-// IsNil returns true if a picture is no picture.
-func (p Picture) IsNil() bool {
-	return p.texture == nil
-}
-
 // Texture returns a pointer to the underlying OpenGL texture of a picture.
 //
 // Note, that the parent of this texture is pixelgl.NoOpDoer.
-func (p Picture) Texture() *pixelgl.Texture {
+func (p *Picture) Texture() *pixelgl.Texture {
 	return p.texture
 }
 
@@ -56,8 +51,8 @@ func (p Picture) Texture() *pixelgl.Texture {
 //
 // For example, suppose we have a 100x200 pixels picture. If we slice it with rectangle (50, 100, 50, 100), we get
 // the upper-right quadrant of the original picture.
-func (p Picture) Slice(slice Rect) Picture {
-	return Picture{
+func (p *Picture) Slice(slice Rect) *Picture {
+	return &Picture{
 		texture: p.texture,
 		bounds:  Rect{p.bounds.Pos + slice.Pos, slice.Size},
 	}
@@ -66,6 +61,6 @@ func (p Picture) Slice(slice Rect) Picture {
 // Bounds returns the bounding rectangle of this picture relative to the most original picture.
 //
 // If the original picture gets sliced with the return value of this method, this picture will be obtained.
-func (p Picture) Bounds() Rect {
+func (p *Picture) Bounds() Rect {
 	return p.bounds
 }

pixelgl/shader.go

@@ -120,10 +120,8 @@ func NewShader(parent Doer, vertexFmt, uniformFmt AttrFormat, vertexShader, frag
 }
 
 func (s *Shader) delete() {
-	s.parent.Do(func(ctx Context) {
-		DoNoBlock(func() {
-			gl.DeleteProgram(s.program.obj)
-		})
+	DoNoBlock(func() {
+		gl.DeleteProgram(s.program.obj)
 	})
 }
 

pixelgl/texture.go

@@ -52,10 +52,8 @@ func NewTexture(parent Doer, width, height int, pixels []uint8) (*Texture, error
 }
 
 func (t *Texture) delete() {
-	t.parent.Do(func(ctx Context) {
-		DoNoBlock(func() {
-			gl.DeleteTextures(1, &t.tex.obj)
-		})
+	DoNoBlock(func() {
+		gl.DeleteTextures(1, &t.tex.obj)
 	})
 }
 

pixelgl/vertex.go

@@ -115,12 +115,10 @@ func NewVertexArray(parent Doer, format AttrFormat, vertexNum int, indices []int
 }
 
 func (va *VertexArray) delete() {
-	va.parent.Do(func(ctx Context) {
-		DoNoBlock(func() {
-			gl.DeleteVertexArrays(1, &va.vao.obj)
-			gl.DeleteBuffers(1, &va.vbo.obj)
-			gl.DeleteBuffers(1, &va.ebo.obj)
-		})
+	DoNoBlock(func() {
+		gl.DeleteVertexArrays(1, &va.vao.obj)
+		gl.DeleteBuffers(1, &va.vbo.obj)
+		gl.DeleteBuffers(1, &va.ebo.obj)
 	})
 }