From 99cc16d0ac8b3c21184f17a4e4b43e90103f0a8e Mon Sep 17 00:00:00 2001
From: Drahoslav <drahoslav@yo2.cz>
Date: Mon, 8 Jan 2018 00:25:25 +0100
Subject: [PATCH] Implement DrawImage in svg context

---
 draw2dsvg/converters.go | 12 ++++++++++++
 draw2dsvg/gc.go         | 18 +++++++++++++-----
 draw2dsvg/svg.go        | 11 +++++++++++
 3 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/draw2dsvg/converters.go b/draw2dsvg/converters.go
index 59d5064..70c6ace 100644
--- a/draw2dsvg/converters.go
+++ b/draw2dsvg/converters.go
@@ -4,9 +4,13 @@
 package draw2dsvg
 
 import (
+	"bytes"
+	"encoding/base64"
 	"fmt"
 	"github.com/llgcode/draw2d"
+	"image"
 	"image/color"
+	"image/png"
 	"math"
 	"strings"
 )
@@ -110,3 +114,11 @@ func toSvgTransform(mat draw2d.Matrix) string {
 		mat[0], mat[1], mat[2], mat[3], mat[4], mat[5],
 	)
 }
+
+func imageToSvgHref(image image.Image) string {
+	out := "data:image/png;base64,"
+	pngBuf := &bytes.Buffer{}
+	png.Encode(pngBuf, image)
+	out += base64.RawStdEncoding.EncodeToString(pngBuf.Bytes())
+	return out
+}
diff --git a/draw2dsvg/gc.go b/draw2dsvg/gc.go
index b4a6dca..50cc7bf 100644
--- a/draw2dsvg/gc.go
+++ b/draw2dsvg/gc.go
@@ -353,6 +353,19 @@ func (gc *GraphicContext) SetFontSize(fontSize float64) {
 	gc.recalc()
 }
 
+// DrawImage draws the raster image in the current canvas
+func (gc *GraphicContext) DrawImage(image image.Image) {
+	bounds := image.Bounds()
+
+	gc.newGroup(0).Image = &Image{
+		Href:   imageToSvgHref(image),
+		X:      bounds.Min.X,
+		Y:      bounds.Min.Y,
+		Width:  bounds.Max.X - bounds.Min.X,
+		Height: bounds.Max.Y - bounds.Min.Y,
+	}
+}
+
 ///////////////////////////////////////
 // TODO implement following methods (or remove if not neccesary)
 
@@ -362,11 +375,6 @@ func (gc *GraphicContext) GetFontName() string {
 	return fmt.Sprintf("%s:%d:%d:%d", fontData.Name, fontData.Family, fontData.Style, gc.Current.FontSize)
 }
 
-// DrawImage draws the raster image in the current canvas
-func (gc *GraphicContext) DrawImage(image image.Image) {
-	// panic("not implemented")
-}
-
 // ClearRect fills the specified rectangle with a default transparent color
 func (gc *GraphicContext) ClearRect(x1, y1, x2, y2 int) {
 	// panic("not implemented")
diff --git a/draw2dsvg/svg.go b/draw2dsvg/svg.go
index 819832e..f703052 100644
--- a/draw2dsvg/svg.go
+++ b/draw2dsvg/svg.go
@@ -42,6 +42,7 @@ type Group struct {
 	Groups    []*Group `xml:"g"`
 	Paths     []*Path  `xml:"path"`
 	Texts     []*Text  `xml:"text"`
+	Image     *Image   `xml:"image"`
 }
 
 type Path struct {
@@ -58,6 +59,16 @@ type Text struct {
 	Style      string  `xml:"style,attr,omitempty"`
 }
 
+type Image struct {
+	Href   string `xml:"href,attr"`
+	X      int    `xml:"x,attr,omitempty"`
+	Y      int    `xml:"y,attr,omitempty"`
+	Width  int    `xml:"width,attr"`
+	Height int    `xml:"height,attr"`
+}
+
+/* font related elements */
+
 type Font struct {
 	Identity
 	Face   *Face    `xml:"font-face"`