Add emoji support

draw2dimg/ftgc.go

@@ -35,10 +35,11 @@ type GraphicContext struct {
 	painter          Painter
 	fillRasterizer   *raster.Rasterizer
 	strokeRasterizer *raster.Rasterizer
-	FontCache		 draw2d.FontCache
+	FontCache        draw2d.FontCache
 	glyphCache       draw2dbase.GlyphCache
 	glyphBuf         *truetype.GlyphBuf
 	DPI              int
+	Emojis           emoji.Table
 }
 
 // ImageFilter defines the type of filter to use
@@ -79,6 +80,7 @@ func NewGraphicContextWithPainter(img draw.Image, painter Painter) *GraphicConte
 		draw2dbase.NewGlyphCache(),
 		&truetype.GlyphBuf{},
 		dpi,
+		make(emoji.Table),
 	}
 	return gc
 }
@@ -124,6 +126,9 @@ func (gc *GraphicContext) FillString(text string) (width float64) {
 	return gc.FillStringAt(text, 0, 0)
 }
 
+const emojiSpacing = 10
+const emojiScale = 110
+
 // FillStringAt draws the text at the specified point (x, y)
 func (gc *GraphicContext) FillStringAt(text string, x, y float64) (width float64) {
 	f, err := gc.loadCurrentFont()
@@ -134,12 +139,25 @@ func (gc *GraphicContext) FillStringAt(text string, x, y float64) (width float64
 	startx := x
 	prev, hasPrev := truetype.Index(0), false
 	fontName := gc.GetFontName()
-	for _, r := range text {
+	for fragment := range gc.Emojis.Iterate(text) {
-		index := f.Index(r)
+		if fragment.IsEmoji {
+			img, err := LoadFromPngFile(fragment.Emoji.Path)
+			if err == nil {
+				gc.Save()
+				scale := gc.GetFontSize() / 100
+				gc.Translate(x+scale*emojiSpacing, y-scale*emojiScale)
+				gc.Scale(scale, scale)
+				gc.DrawImage(img)
+				gc.Restore()
+				x += scale*float64(img.Bounds().Size().X) + scale*emojiSpacing*2
+			}
+			continue
+		}
+		index := f.Index(fragment.Rune)
 		if hasPrev {
 			x += fUnitsToFloat64(f.Kern(fixed.Int26_6(gc.Current.Scale), prev, index))
 		}
-		glyph := gc.glyphCache.Fetch(gc, fontName, r)
+		glyph := gc.glyphCache.Fetch(gc, fontName, fragment.Rune)
 		x += glyph.Fill(gc, x, y)
 		prev, hasPrev = index, true
 	}