Use transformations in svg context

also few minor changes in to svg transformation functions

draw2dsvg/converters.go

@@ -13,7 +13,11 @@ import (
 
 func toSvgRGBA(c color.Color) string {
 	r, g, b, a := c.RGBA()
-	return fmt.Sprintf("rgba(%v, %v, %v, %.3f)", r>>8, g>>8, b>>8, float64(a>>8)/255)
+	r, g, b, a = r>>8, g>>8, b>>8, a>>8
+	if a == 255 {
+		return fmt.Sprintf("#%02X%02X%02X", r, g, b)
+	}
+	return fmt.Sprintf("rgba(%v,%v,%v,%.3f)", r, g, b, float64(a)/255)
 }
 
 func toSvgLength(l float64) string {
@@ -84,10 +88,7 @@ func toSvgPathDesc(p *draw2d.Path) string {
 
 			// rx ry x-axis-rotation large-arc-flag sweep-flag x y
 			parts[i] = fmt.Sprintf("A %.4f %.4f %v %v %v %.4f %.4f",
-				rx, ry,
-				0,
-				large, sweep,
-				x, y,
+				rx, ry, 0, large, sweep, x, y,
 			)
 			ps = ps[6:]
 		case draw2d.CloseCmp:
@@ -96,3 +97,16 @@ func toSvgPathDesc(p *draw2d.Path) string {
 	}
 	return strings.Join(parts, " ")
 }
+
+func toSvgTransform(mat draw2d.Matrix) string {
+	if mat.IsIdentity() {
+		return ""
+	}
+	if mat.IsTranslation() {
+		x, y := mat.GetTranslation()
+		return fmt.Sprintf("translate(%f,%f)", x, y)
+	}
+	return fmt.Sprintf("matrix(%f,%f,%f,%f,%f,%f)",
+		mat[0], mat[1], mat[2], mat[3], mat[4], mat[5],
+	)
+}

draw2dsvg/gc.go

@@ -70,38 +70,45 @@ func (gc *GraphicContext) FillStroke(paths ...*draw2d.Path) {
 }
 
 func (gc *GraphicContext) drawPaths(drawType drawType, paths ...*draw2d.Path) {
-	paths = append(paths, gc.Current.Path)
-
+	// create elements
 	svgPath := Path{}
 	group := Group{}
 
-	svgPathsDesc := make([]string, len(paths))
-
-	// multiple pathes has to be joined to single svg path description
-	// because fill-rule wont work for whole group
-	for i, path := range paths {
-		svgPathsDesc[i] = toSvgPathDesc(path)
-	}
-	svgPath.Desc = strings.Join(svgPathsDesc, " ")
-
-	if drawType&stroked == stroked {
-		group.Stroke = toSvgRGBA(gc.Current.StrokeColor)
-		group.StrokeWidth = toSvgLength(gc.Current.LineWidth)
-		group.StrokeLinecap = gc.Current.Cap.String()
-		group.StrokeLinejoin = gc.Current.Join.String()
-		if len(gc.Current.Dash) > 0 {
-			group.StrokeDasharray = toSvgArray(gc.Current.Dash)
-			group.StrokeDashoffset = toSvgLength(gc.Current.DashOffset)
+	// set attrs to path
+	{
+		paths = append(paths, gc.Current.Path)
+		svgPathsDesc := make([]string, len(paths))
+		// multiple pathes has to be joined to single svg path description
+		// because fill-rule wont work for whole group as excepted
+		for i, path := range paths {
+			svgPathsDesc[i] = toSvgPathDesc(path)
 		}
+		svgPath.Desc = strings.Join(svgPathsDesc, " ")
 	}
 
-	if drawType&filled == filled {
-		group.Fill = toSvgRGBA(gc.Current.FillColor)
-		group.FillRule = toSvgFillRule(gc.Current.FillRule)
+	// set attrs to group
+	{
+		if drawType&stroked == stroked {
+			group.Stroke = toSvgRGBA(gc.Current.StrokeColor)
+			group.StrokeWidth = toSvgLength(gc.Current.LineWidth)
+			group.StrokeLinecap = gc.Current.Cap.String()
+			group.StrokeLinejoin = gc.Current.Join.String()
+			if len(gc.Current.Dash) > 0 {
+				group.StrokeDasharray = toSvgArray(gc.Current.Dash)
+				group.StrokeDashoffset = toSvgLength(gc.Current.DashOffset)
+			}
+		}
+
+		if drawType&filled == filled {
+			group.Fill = toSvgRGBA(gc.Current.FillColor)
+			group.FillRule = toSvgFillRule(gc.Current.FillRule)
+		}
+
+		group.Transform = toSvgTransform(gc.Current.Tr)
 	}
 
+	// link elements
 	group.Paths = []Path{svgPath}
-
 	gc.svg.Groups = append(gc.svg.Groups, group)
 }
 
@@ -130,12 +137,14 @@ func (gc *GraphicContext) DrawImage(image image.Image) {
 
 // Save the context and push it to the context stack
 func (gc *GraphicContext) Save() {
-
+	gc.StackGraphicContext.Save()
+	// TODO use common transformation group for multiple elements
 }
 
 // Restore remove the current context and restore the last one
 func (gc *GraphicContext) Restore() {
-
+	gc.StackGraphicContext.Restore()
+	// TODO use common transformation group for multiple elements
 }
 
 // ClearRect fills the specified rectangle with a default transparent color

draw2dsvg/svg.go

@@ -18,9 +18,10 @@ type Svg struct {
 
 type Group struct {
 	FillStroke
-	Groups []Group `xml:"g"`
-	Paths  []Path  `xml:"path"`
-	Texts  []Text  `xml:"text"`
+	Transform string  `xml:"transform,attr,omitempty"`
+	Groups    []Group `xml:"g"`
+	Paths     []Path  `xml:"path"`
+	Texts     []Text  `xml:"text"`
 }
 
 type Path struct {