added function to create an image pattern

backend/backendbase/base.go

@@ -13,6 +13,7 @@ type Backend interface {
 	Size() (int, int)
 
 	LoadImage(img image.Image) (Image, error)
+	LoadImagePattern(data ImagePatternData) ImagePattern
 	LoadLinearGradient(data Gradient) LinearGradient
 	LoadRadialGradient(data Gradient) RadialGradient
 
@@ -43,7 +44,7 @@ type FillStyle struct {
 		RadFrom float64
 		RadTo   float64
 	}
-	Image Image
+	ImagePattern ImagePattern
 }
 
 type Gradient []GradientStop
@@ -104,3 +105,12 @@ type Image interface {
 	Delete()
 	Replace(src image.Image) error
 }
+
+type ImagePatternData struct {
+	Image Image
+}
+
+type ImagePattern interface {
+	Delete()
+	Replace(data ImagePatternData)
+}

backend/gogl/gogl.go

@@ -441,8 +441,8 @@ func (b *GoGLBackend) useShader(style *backendbase.FillStyle) (vertexLoc uint32)
 		gl.Uniform1f(b.rgr.GlobalAlpha, float32(style.Color.A)/255)
 		return b.rgr.Vertex
 	}
-	if img := style.Image; img != nil {
+	if ip := style.ImagePattern; ip != nil {
-		img := img.(*Image)
+		img := ip.(*ImagePattern).data.Image.(*Image)
 		gl.UseProgram(b.ipr.ID)
 		gl.ActiveTexture(gl.TEXTURE0)
 		gl.BindTexture(gl.TEXTURE_2D, img.tex)
@@ -498,8 +498,8 @@ func (b *GoGLBackend) useAlphaShader(style *backendbase.FillStyle, alphaTexSlot
 		gl.Uniform1f(b.rgar.GlobalAlpha, float32(style.Color.A)/255)
 		return b.rgar.Vertex, b.rgar.AlphaTexCoord
 	}
-	if img := style.Image; img != nil {
+	if ip := style.ImagePattern; ip != nil {
-		img := img.(*Image)
+		img := ip.(*ImagePattern).data.Image.(*Image)
 		gl.UseProgram(b.ipar.ID)
 		gl.ActiveTexture(gl.TEXTURE0)
 		gl.BindTexture(gl.TEXTURE_2D, img.tex)

backend/gogl/images.go

@@ -239,3 +239,18 @@ func (b *GoGLBackend) DrawImage(dimg backendbase.Image, sx, sy, sw, sh float64,
 
 	gl.StencilFunc(gl.ALWAYS, 0, 0xFF)
 }
+
+type ImagePattern struct {
+	b    *GoGLBackend
+	data backendbase.ImagePatternData
+}
+
+func (b *GoGLBackend) LoadImagePattern(data backendbase.ImagePatternData) backendbase.ImagePattern {
+	return &ImagePattern{
+		b:    b,
+		data: data,
+	}
+}
+
+func (ip *ImagePattern) Delete()                                   {}
+func (ip *ImagePattern) Replace(data backendbase.ImagePatternData) { ip.data = data }

backend/xmobile/images.go

@@ -241,3 +241,18 @@ func (b *XMobileBackend) DrawImage(dimg backendbase.Image, sx, sy, sw, sh float6
 
 	b.glctx.StencilFunc(gl.ALWAYS, 0, 0xFF)
 }
+
+type ImagePattern struct {
+	b    *XMobileBackend
+	data backendbase.ImagePatternData
+}
+
+func (b *XMobileBackend) LoadImagePattern(data backendbase.ImagePatternData) backendbase.ImagePattern {
+	return &ImagePattern{
+		b:    b,
+		data: data,
+	}
+}
+
+func (ip *ImagePattern) Delete()                                   {}
+func (ip *ImagePattern) Replace(data backendbase.ImagePatternData) { ip.data = data }

backend/xmobile/xmobile.go

@@ -434,8 +434,8 @@ func (b *XMobileBackend) useShader(style *backendbase.FillStyle) (vertexLoc gl.A
 		b.glctx.Uniform1f(b.rgr.GlobalAlpha, float32(style.Color.A)/255)
 		return b.rgr.Vertex
 	}
-	if img := style.Image; img != nil {
+	if ip := style.ImagePattern; ip != nil {
-		img := img.(*Image)
+		img := ip.(*ImagePattern).data.Image.(*Image)
 		b.glctx.UseProgram(b.ipr.ID)
 		b.glctx.ActiveTexture(gl.TEXTURE0)
 		b.glctx.BindTexture(gl.TEXTURE_2D, img.tex)
@@ -491,8 +491,8 @@ func (b *XMobileBackend) useAlphaShader(style *backendbase.FillStyle, alphaTexSl
 		b.glctx.Uniform1f(b.rgar.GlobalAlpha, float32(style.Color.A)/255)
 		return b.rgar.Vertex, b.rgar.AlphaTexCoord
 	}
-	if img := style.Image; img != nil {
+	if ip := style.ImagePattern; ip != nil {
-		img := img.(*Image)
+		img := ip.(*ImagePattern).data.Image.(*Image)
 		b.glctx.UseProgram(b.ipar.ID)
 		b.glctx.ActiveTexture(gl.TEXTURE0)
 		b.glctx.BindTexture(gl.TEXTURE_2D, img.tex)

canvas.go

@@ -74,7 +74,7 @@ type drawStyle struct {
 	color          color.RGBA
 	radialGradient *RadialGradient
 	linearGradient *LinearGradient
-	image          *Image
+	imagePattern   *ImagePattern
 }
 
 type lineJoin uint8
@@ -202,6 +202,8 @@ func (cv *Canvas) SetStrokeStyle(value ...interface{}) {
 	cv.state.stroke = cv.parseStyle(value...)
 }
 
+var imagePatterns = make(map[interface{}]*ImagePattern)
+
 func (cv *Canvas) parseStyle(value ...interface{}) drawStyle {
 	var style drawStyle
 	if len(value) == 1 {
@@ -220,7 +222,12 @@ func (cv *Canvas) parseStyle(value ...interface{}) drawStyle {
 	} else if len(value) == 1 {
 		switch v := value[0].(type) {
 		case *Image, string:
-			style.image = cv.getImage(v)
+			if _, ok := imagePatterns[v]; !ok {
+				imagePatterns[v] = cv.CreatePattern(v, "")
+			}
+			style.imagePattern = imagePatterns[v]
+		case *ImagePattern:
+			style.imagePattern = v
 		}
 	}
 	return style
@@ -249,8 +256,12 @@ func (cv *Canvas) backendFillStyle(s *drawStyle, alpha float64) backendbase.Fill
 		stl.Gradient.RadFrom = rg.radFrom
 		stl.Gradient.RadTo = rg.radTo
 		stl.RadialGradient = rg.grad
-	} else if img := s.image; img != nil {
+	} else if ip := s.imagePattern; ip != nil {
-		stl.Image = img.img
+		if ip.ip == nil {
+			stl.Color = color.RGBA{}
+		} else {
+			stl.ImagePattern = ip.ip
+		}
 	} else {
 		alpha *= float64(s.color.A) / 255
 	}

images.go

@@ -183,3 +183,30 @@ func (cv *Canvas) GetImageData(x, y, w, h int) *image.RGBA {
 func (cv *Canvas) PutImageData(img *image.RGBA, x, y int) {
 	cv.b.PutImageData(img, x, y)
 }
+
+// ImagePattern is an image pattern that can be used for any
+// fill call
+type ImagePattern struct {
+	cv  *Canvas
+	img *Image
+	ip  backendbase.ImagePattern
+}
+
+func (ip *ImagePattern) data() backendbase.ImagePatternData {
+	return backendbase.ImagePatternData{
+		Image: ip.img.img,
+	}
+}
+
+// CreatePattern creates a new image pattern with the specified
+// image and repetition
+func (cv *Canvas) CreatePattern(src interface{}, repetition string) *ImagePattern {
+	ip := &ImagePattern{
+		cv:  cv,
+		img: cv.getImage(src),
+	}
+	if ip.img != nil {
+		ip.ip = cv.b.LoadImagePattern(ip.data())
+	}
+	return ip
+}