implemented clearRect

README.md

@@ -112,6 +112,7 @@ These features *should* work just like their HTML5 counterparts, but there are l
 - drawImage
 - getImageData
 - putImageData
+- clearRect
 
 # Missing features
 
@@ -120,7 +121,6 @@ These features *should* work just like their HTML5 counterparts, but there are l
 - miterLimit
 - shadows
 - textBaseline
-- clearRect
 - getLineDash
 - isPointInPath
 - isPointInStroke

glimpl/android/glandroidimpl.go

@@ -64,6 +64,9 @@ func (_ GLImpl) BufferData(target uint32, size int, data unsafe.Pointer, usage u
 func (_ GLImpl) Clear(mask uint32) {
 	C.glClear(C.uint(mask))
 }
+func (_ GLImpl) ClearColor(red float32, green float32, blue float32, alpha float32) {
+	C.glClearColor(C.float(red), C.float(green), C.float(blue), C.float(alpha))
+}
 func (_ GLImpl) ColorMask(red bool, green bool, blue bool, alpha bool) {
 	var r, g, b, a C.uchar
 	if red {
@@ -95,6 +98,9 @@ func (_ GLImpl) DeleteShader(shader uint32) {
 func (_ GLImpl) DeleteTextures(n int32, textures *uint32) {
 	C.glDeleteTextures(C.int(n), (*C.uint)(textures))
 }
+func (_ GLImpl) Disable(cap uint32) {
+	C.glDisable(C.uint(cap))
+}
 func (_ GLImpl) DisableVertexAttribArray(index uint32) {
 	C.glDisableVertexAttribArray(C.uint(index))
 }

glimpl/gogl/goglimpl.go

@@ -36,6 +36,9 @@ func (_ GLImpl) BufferData(target uint32, size int, data unsafe.Pointer, usage u
 func (_ GLImpl) Clear(mask uint32) {
 	gl.Clear(mask)
 }
+func (_ GLImpl) ClearColor(red float32, green float32, blue float32, alpha float32) {
+	gl.ClearColor(red, green, blue, alpha)
+}
 func (_ GLImpl) ColorMask(red bool, green bool, blue bool, alpha bool) {
 	gl.ColorMask(red, green, blue, alpha)
 }
@@ -54,6 +57,9 @@ func (_ GLImpl) DeleteShader(shader uint32) {
 func (_ GLImpl) DeleteTextures(n int32, textures *uint32) {
 	gl.DeleteTextures(n, textures)
 }
+func (_ GLImpl) Disable(cap uint32) {
+	gl.Disable(cap)
+}
 func (_ GLImpl) DisableVertexAttribArray(index uint32) {
 	gl.DisableVertexAttribArray(index)
 }

glimpl/ios/gliosimpl.go

@@ -64,6 +64,9 @@ func (_ GLImpl) BufferData(target uint32, size int, data unsafe.Pointer, usage u
 func (_ GLImpl) Clear(mask uint32) {
 	C.glClear(C.GLbitfield(mask))
 }
+func (_ GLImpl) ClearColor(red float32, green float32, blue float32, alpha float32) {
+	C.glClearColor(C.GLfloat(red), C.GLfloat(green), C.GLfloat(blue), C.GLfloat(alpha))
+}
 func (_ GLImpl) ColorMask(red bool, green bool, blue bool, alpha bool) {
 	var r, g, b, a C.GLboolean
 	if red {
@@ -95,6 +98,9 @@ func (_ GLImpl) DeleteShader(shader uint32) {
 func (_ GLImpl) DeleteTextures(n int32, textures *uint32) {
 	C.glDeleteTextures(C.GLsizei(n), (*C.GLuint)(textures))
 }
+func (_ GLImpl) Disable(cap uint32) {
+	C.glDisable(C.GLenum(cap))
+}
 func (_ GLImpl) DisableVertexAttribArray(index uint32) {
 	C.glDisableVertexAttribArray(C.GLuint(index))
 }

openglinterface.go

@@ -801,12 +801,14 @@ type GL interface {
 	BlendFunc(sfactor uint32, dfactor uint32)
 	BufferData(target uint32, size int, data unsafe.Pointer, usage uint32)
 	Clear(mask uint32)
+	ClearColor(red float32, green float32, blue float32, alpha float32)
 	ColorMask(red bool, green bool, blue bool, alpha bool)
 	CompileShader(shader uint32)
 	CreateProgram() uint32
 	CreateShader(xtype uint32) uint32
 	DeleteShader(shader uint32)
 	DeleteTextures(n int32, textures *uint32)
+	Disable(cap uint32)
 	DisableVertexAttribArray(index uint32)
 	DrawArrays(mode uint32, first int32, count int32)
 	Enable(cap uint32)

paths.go

@@ -714,3 +714,43 @@ func (cv *Canvas) FillRect(x, y, w, h float64) {
 
 	gli.StencilFunc(gl_ALWAYS, 0, 0xFF)
 }
+
+// ClearRect sets the color of the rectangle to transparent black
+func (cv *Canvas) ClearRect(x, y, w, h float64) {
+	cv.activate()
+
+	if cv.state.transform == matIdentity() {
+		gli.Scissor(int32(x+0.5), int32(cv.fh-y-h+0.5), int32(w+0.5), int32(h+0.5))
+		gli.ClearColor(0, 0, 0, 0)
+		gli.Clear(gl_COLOR_BUFFER_BIT)
+		cv.applyScissor()
+		return
+	}
+
+	gli.UseProgram(sr.id)
+	gli.Uniform2f(sr.canvasSize, float32(cv.fw), float32(cv.fh))
+	gli.Uniform4f(sr.color, 0, 0, 0, 0)
+	gli.Uniform1f(sr.globalAlpha, 1)
+
+	gli.Disable(gl_BLEND)
+
+	p0 := cv.tf(vec{x, y})
+	p1 := cv.tf(vec{x, y + h})
+	p2 := cv.tf(vec{x + w, y + h})
+	p3 := cv.tf(vec{x + w, y})
+
+	gli.BindBuffer(gl_ARRAY_BUFFER, buf)
+	data := [8]float32{float32(p0[0]), float32(p0[1]), float32(p1[0]), float32(p1[1]), float32(p2[0]), float32(p2[1]), float32(p3[0]), float32(p3[1])}
+	gli.BufferData(gl_ARRAY_BUFFER, len(data)*4, unsafe.Pointer(&data[0]), gl_STREAM_DRAW)
+
+	gli.StencilFunc(gl_EQUAL, 0, 0xFF)
+
+	gli.VertexAttribPointer(sr.vertex, 2, gl_FLOAT, false, 0, 0)
+	gli.EnableVertexAttribArray(sr.vertex)
+	gli.DrawArrays(gl_TRIANGLE_FAN, 0, 4)
+	gli.DisableVertexAttribArray(sr.vertex)
+
+	gli.StencilFunc(gl_ALWAYS, 0, 0xFF)
+
+	gli.Enable(gl_BLEND)
+}