Merge pull request #69 from stanim/master

add transparency support to pdf backend

draw2dpdf/gc.go

@@ -190,7 +190,9 @@ func (gc *GraphicContext) StrokeStringAt(text string, x, y float64) (cursor floa
 
 // Stroke strokes the paths with the color specified by SetStrokeColor
 func (gc *GraphicContext) Stroke(paths ...*draw2d.PathStorage) {
-	gc.draw("D", paths...)
+	_, _, _, alphaS := gc.Current.StrokeColor.RGBA()
+	gc.draw("D", alphaS, paths...)
+	gc.Current.Path = draw2d.NewPathStorage()
 }
 
 // Fill fills the paths with the color specified by SetFillColor
@@ -199,27 +201,43 @@ func (gc *GraphicContext) Fill(paths ...*draw2d.PathStorage) {
 	if !gc.Current.FillRule.UseNonZeroWinding() {
 		style += "*"
 	}
-	gc.draw(style, paths...)
+	_, _, _, alphaF := gc.Current.FillColor.RGBA()
+	gc.draw(style, alphaF, paths...)
+	gc.Current.Path = draw2d.NewPathStorage()
 }
 
 // FillStroke first fills the paths and than strokes them
 func (gc *GraphicContext) FillStroke(paths ...*draw2d.PathStorage) {
-	style := "FD"
+	var rule string
 	if !gc.Current.FillRule.UseNonZeroWinding() {
-		style += "*"
+		rule = "*"
 	}
-	gc.draw(style, paths...)
+	_, _, _, alphaS := gc.Current.StrokeColor.RGBA()
+	_, _, _, alphaF := gc.Current.FillColor.RGBA()
+	if alphaS == alphaF {
+		gc.draw("FD"+rule, alphaF, paths...)
+	} else {
+		gc.draw("F"+rule, alphaF, paths...)
+		gc.draw("S", alphaS, paths...)
+	}
+	gc.Current.Path = draw2d.NewPathStorage()
 }
 
 var logger = log.New(os.Stdout, "", log.Lshortfile)
 
+const alphaMax = float64(0xFFFF)
+
 // draw fills and/or strokes paths
-func (gc *GraphicContext) draw(style string, paths ...*draw2d.PathStorage) {
+func (gc *GraphicContext) draw(style string, alpha uint32, paths ...*draw2d.PathStorage) {
 	paths = append(paths, gc.Current.Path)
 	pathConverter := NewPathConverter(gc.pdf)
 	pathConverter.Convert(paths...)
+	a := float64(alpha) / alphaMax
+	current, blendMode := gc.pdf.GetAlpha()
+	if a != current {
+		gc.pdf.SetAlpha(a, blendMode)
+	}
 	gc.pdf.DrawPath(style)
-	gc.Current.Path = draw2d.NewPathStorage()
 }
 
 // overwrite StackGraphicContext methods

samples/geometry/geometry.go

@@ -80,7 +80,6 @@ func CurveRectangle(gc draw2d.GraphicContext, x0, y0,
 		}
 	}
 	gc.Close()
-
 	gc.SetStrokeColor(stroke)
 	gc.SetFillColor(fill)
 	gc.SetLineWidth(10.0)
@@ -125,9 +124,8 @@ func Arc(gc draw2d.GraphicContext, xc, yc, width, height float64) {
 	gc.SetFillColor(color.NRGBA{255, 0x33, 0x33, 0x80})
 	gc.SetLineWidth(width / 20)
 
-	gc.MoveTo(xc, yc)
+	gc.MoveTo(xc+math.Cos(startAngle)*radiusX, yc+math.Sin(startAngle)*radiusY)
-	gc.LineTo(xc+math.Cos(startAngle)*radiusX, yc+math.Sin(startAngle)*radiusY)
+	gc.LineTo(xc, yc)
-	gc.MoveTo(xc, yc)
 	gc.LineTo(xc-radiusX, yc)
 	gc.Stroke()
 
@@ -154,9 +152,8 @@ func ArcNegative(gc draw2d.GraphicContext, xc, yc, width, height float64) {
 	gc.SetFillColor(color.NRGBA{255, 0x33, 0x33, 0x80})
 	gc.SetLineWidth(width / 20)
 
-	gc.MoveTo(xc, yc)
+	gc.MoveTo(xc+math.Cos(startAngle)*radiusX, yc+math.Sin(startAngle)*radiusY)
-	gc.LineTo(xc+math.Cos(startAngle)*radiusX, yc+math.Sin(startAngle)*radiusY)
+	gc.LineTo(xc, yc)
-	gc.MoveTo(xc, yc)
 	gc.LineTo(xc-radiusX, yc)
 	gc.Stroke()
 
@@ -205,7 +202,7 @@ func FillString(gc draw2d.GraphicContext, x, y, width, height float64) {
 		Name:   "luxi",
 		Family: draw2d.FontFamilyMono,
 		Style:  draw2d.FontStyleBold | draw2d.FontStyleItalic})
-	w := gc.FillString("cou")
+	w := gc.FillString("Hug")
 	gc.Translate(w+sx, 0)
 	left, top, right, bottom := gc.GetStringBounds("cou")
 	gc.SetStrokeColor(color.NRGBA{255, 0x33, 0x33, 0x80})
@@ -215,7 +212,7 @@ func FillString(gc draw2d.GraphicContext, x, y, width, height float64) {
 	gc.SetFillColor(color.NRGBA{0x33, 0x33, 0xff, 0xff})
 	gc.SetStrokeColor(color.NRGBA{0x33, 0x33, 0xff, 0xff})
 	gc.SetLineWidth(height / 100)
-	gc.StrokeString("cou")
+	gc.StrokeString("Hug")
 	gc.Restore()
 }
 

samples/gopher2/gopher2.go

@@ -21,7 +21,7 @@ func Main(gc draw2d.GraphicContext, ext string) (string, error) {
 	gc.SetFillColor(image.White)
 	gc.Save()
 	// Draw a (partial) gopher
-	gc.Translate(-65, 65)
+	gc.Translate(-60, 65)
 	gc.Rotate(-30 * (math.Pi / 180.0))
 	Draw(gc, 48, 48, 240, 72)
 	gc.Restore()
@@ -41,13 +41,13 @@ func Draw(gc draw2d.GraphicContext, x, y, w, h float64) {
 	brb := color.RGBA{0x8B, 0x45, 0x13, 0xBB} // brown transparant
 
 	// round head top
-	gc.MoveTo(x, y+h)
+	gc.MoveTo(x, y+h*1.002)
-	gc.CubicCurveTo(x, y+h*1.05, x+w/2, y-h, x+w, y+h*1.05)
+	gc.CubicCurveTo(x+w/4, y-h/3, x+3*w/4, y-h/3, x+w, y+h*1.002)
 	gc.Close()
 	gc.SetFillColor(brb)
 	gc.Fill()
 	// rectangle head bottom
-	draw2d.RoundRect(gc, x, y+h, x+w, y+h+h, w/5, h/5)
+	draw2d.RoundRect(gc, x, y+h, x+w, y+h+h, h/5, h/5)
 	gc.Fill()
 	// left ear outside
 	draw2d.Circle(gc, x, y+h, w/12)