add path adder for comparing with freetype decomposition algorithm

draw2d/src/pkg/draw2d/arc.go

@@ -2,6 +2,10 @@
 // created: 21/11/2010 by Laurent Le Goff
 package draw2d
 
+import (
+	"freetype-go.googlecode.com/hg/freetype/raster"
+)
+
 func arc(t VertexConverter, x, y, rx, ry, start, angle, scale float) (lastX, lastY float) {
 	end := start + angle
 	clockWise := true
@@ -30,3 +34,34 @@ func arc(t VertexConverter, x, y, rx, ry, start, angle, scale float) (lastX, las
 	}
 	return curX, curY
 }
+
+
+func arcAdder(adder raster.Adder, x, y, rx, ry, start, angle, scale float) (raster.Point) {
+        end := start + angle
+        clockWise := true
+        if angle < 0 {
+                clockWise = false
+        }
+        ra := (fabs(rx) + fabs(ry)) / 2
+        da := acos(ra/(ra+0.125/scale)) * 2
+        //normalize
+        if !clockWise {
+                da = -da
+        }
+        angle = start + da
+        var curX, curY float
+        for {
+                if (angle < end-da/4) != clockWise {
+                        curX = x + cos(end)*rx
+                        curY = y + sin(end)*ry
+                        return floatToPoint(curX, curY)
+                }
+                curX = x + cos(angle)*rx
+                curY = y + sin(angle)*ry
+
+                angle += da
+                adder.Add1(floatToPoint(curX, curY))
+        }
+	return floatToPoint(curX, curY)
+}
+

draw2d/src/pkg/draw2d/path_adder.go

@@ -34,3 +34,55 @@ func (vertexAdder *VertexAdder) Vertex(x, y float) {
 	}
 	vertexAdder.command = VertexNoCommand
 }
+
+
+type PathAdder struct {
+	adder   raster.Adder
+	lastPoint raster.Point
+	ApproximationScale float
+}
+
+func NewPathAdder(adder raster.Adder) (* PathAdder) {
+	return &PathAdder{adder, raster.Point{0,0}, 1}
+}
+
+
+func (pathAdder *PathAdder) Convert(paths ...*PathStorage) {
+        for _, path := range paths {
+                j := 0
+                for _, cmd := range path.commands {
+                        j = j + pathAdder.ConvertCommand(cmd, path.vertices[j:]...)
+                }
+        }
+}
+
+
+func (pathAdder *PathAdder) ConvertCommand(cmd PathCmd, vertices ...float) int {
+        switch cmd {
+        case MoveTo:
+		pathAdder.lastPoint = floatToPoint(vertices[0], vertices[1])
+                pathAdder.adder.Start(pathAdder.lastPoint)
+                return 2
+        case LineTo:
+		pathAdder.lastPoint = floatToPoint(vertices[0], vertices[1])
+                pathAdder.adder.Add1(pathAdder.lastPoint)
+                return 2
+        case QuadCurveTo:
+		pathAdder.lastPoint = floatToPoint(vertices[2], vertices[3])
+                pathAdder.adder.Add2(floatToPoint(vertices[0], vertices[1]), pathAdder.lastPoint)
+                return 4
+        case CubicCurveTo:
+		pathAdder.lastPoint = floatToPoint(vertices[4], vertices[5])
+		pathAdder.adder.Add3(floatToPoint(vertices[0], vertices[1]), floatToPoint(vertices[2], vertices[3]), pathAdder.lastPoint)
+                return 6
+        case ArcTo:
+		pathAdder.lastPoint = arcAdder(pathAdder.adder,vertices[0], vertices[1], vertices[2], vertices[3], vertices[4], vertices[5], pathAdder.ApproximationScale)
+		pathAdder.adder.Add1(pathAdder.lastPoint)
+                return 6
+        case Close:
+		pathAdder.adder.Add1(pathAdder.lastPoint)
+                return 0
+        }
+        return 0
+}
+