Merge pull request #118 from redstarcoder/text_cache_upstream

Seamless Glyph Cache

draw2dbase/stack_gc.go

@@ -4,6 +4,7 @@
 package draw2dbase
 
 import (
+	"fmt"
 	"image"
 	"image/color"
 
@@ -195,3 +196,8 @@ func (gc *StackGraphicContext) Restore() {
 		oldContext.Previous = nil
 	}
 }
+
+func (gc *StackGraphicContext) GetFontName() string {
+	fontData := gc.Current.FontData
+	return fmt.Sprintf("%s:%d:%d:%d", fontData.Name, fontData.Family, fontData.Style, gc.Current.FontSize)
+}

draw2dbase/text.go

@@ -0,0 +1,68 @@
+package draw2dbase
+
+import "github.com/llgcode/draw2d"
+
+var glyphCache map[string]map[rune]*Glyph
+
+func init() {
+	glyphCache = make(map[string]map[rune]*Glyph)
+}
+
+// FetchGlyph fetches a glyph from the cache, calling renderGlyph first if it doesn't already exist
+func FetchGlyph(gc draw2d.GraphicContext, fontName string, chr rune) *Glyph {
+	if glyphCache[fontName] == nil {
+		glyphCache[fontName] = make(map[rune]*Glyph, 60)
+	}
+	if glyphCache[fontName][chr] == nil {
+		glyphCache[fontName][chr] = renderGlyph(gc, fontName, chr)
+	}
+	return glyphCache[fontName][chr].Copy()
+}
+
+// renderGlyph renders a glyph then caches and returns it
+func renderGlyph(gc draw2d.GraphicContext, fontName string, chr rune) *Glyph {
+	gc.Save()
+	defer gc.Restore()
+	gc.BeginPath()
+	width := gc.CreateStringPath(string(chr), 0, 0)
+	path := gc.GetPath()
+	return &Glyph{
+		path:  &path,
+		Width: width,
+	}
+}
+
+// Glyph represents a rune which has been converted to a Path and width
+type Glyph struct {
+	// path represents a glyph, it is always at (0, 0)
+	path *draw2d.Path
+	// Width of the glyph
+	Width float64
+}
+
+func (g *Glyph) Copy() *Glyph {
+	return &Glyph{
+		path:  g.path.Copy(),
+		Width: g.Width,
+	}
+}
+
+// Fill copies a glyph from the cache, and fills it
+func (g *Glyph) Fill(gc draw2d.GraphicContext, x, y float64) float64 {
+	gc.Save()
+	gc.BeginPath()
+	gc.Translate(x, y)
+	gc.Fill(g.path)
+	gc.Restore()
+	return g.Width
+}
+
+// Stroke fetches a glyph from the cache, and strokes it
+func (g *Glyph) Stroke(gc draw2d.GraphicContext, x, y float64) float64 {
+	gc.Save()
+	gc.BeginPath()
+	gc.Translate(x, y)
+	gc.Stroke(g.path)
+	gc.Restore()
+	return g.Width
+}

draw2dgl/gc.go

@@ -197,10 +197,20 @@ func (gc *GraphicContext) CreateStringPath(s string, x, y float64) float64 {
 	return x - startx
 }
 
+// FillString draws the text at point (0, 0)
+func (gc *GraphicContext) FillString(text string) (width float64) {
+	return gc.FillStringAt(text, 0, 0)
+}
+
+// FillStringAt draws the text at the specified point (x, y)
 func (gc *GraphicContext) FillStringAt(text string, x, y float64) (width float64) {
-	width = gc.CreateStringPath(text, x, y)
-	gc.Fill()
-	return width
+	xorig := x
+	fontName := gc.GetFontName()
+	for _, r := range text {
+		glyph := draw2dbase.FetchGlyph(gc, fontName, r)
+		x += glyph.Fill(gc, x, y)
+	}
+	return x - xorig
 }
 
 // GetStringBounds returns the approximate pixel bounds of the string s at x, y.
@@ -242,14 +252,20 @@ func (gc *GraphicContext) GetStringBounds(s string) (left, top, right, bottom fl
 	return left, top, right, bottom
 }
 
+// StrokeString draws the contour of the text at point (0, 0)
 func (gc *GraphicContext) StrokeString(text string) (width float64) {
 	return gc.StrokeStringAt(text, 0, 0)
 }
 
+// StrokeStringAt draws the contour of the text at point (x, y)
 func (gc *GraphicContext) StrokeStringAt(text string, x, y float64) (width float64) {
-	width = gc.CreateStringPath(text, x, y)
-	gc.Stroke()
-	return width
+	xorig := x
+	fontName := gc.GetFontName()
+	for _, r := range text {
+		glyph := draw2dbase.FetchGlyph(gc, fontName, r)
+		x += glyph.Stroke(gc, x, y)
+	}
+	return x - xorig
 }
 
 // recalc recalculates scale and bounds values from the font size, screen
@@ -293,10 +309,6 @@ func (gc *GraphicContext) DrawImage(img image.Image) {
 	panic("not implemented")
 }
 
-func (gc *GraphicContext) FillString(text string) (cursor float64) {
-	return gc.FillStringAt(text, 0, 0)
-}
-
 func (gc *GraphicContext) paint(rasterizer *raster.Rasterizer, color color.Color) {
 	gc.painter.SetColor(color)
 	rasterizer.Rasterize(gc.painter)

draw2dimg/ftgc.go

@@ -117,27 +117,35 @@ func (gc *GraphicContext) DrawImage(img image.Image) {
 }
 
 // FillString draws the text at point (0, 0)
-func (gc *GraphicContext) FillString(text string) (cursor float64) {
+func (gc *GraphicContext) FillString(text string) (width float64) {
 	return gc.FillStringAt(text, 0, 0)
 }
 
 // FillStringAt draws the text at the specified point (x, y)
-func (gc *GraphicContext) FillStringAt(text string, x, y float64) (cursor float64) {
-	width := gc.CreateStringPath(text, x, y)
-	gc.Fill()
-	return width
+func (gc *GraphicContext) FillStringAt(text string, x, y float64) (width float64) {
+	xorig := x
+	fontName := gc.GetFontName()
+	for _, r := range text {
+		glyph := draw2dbase.FetchGlyph(gc, fontName, r)
+		x += glyph.Fill(gc, x, y)
+	}
+	return x - xorig
 }
 
 // StrokeString draws the contour of the text at point (0, 0)
-func (gc *GraphicContext) StrokeString(text string) (cursor float64) {
+func (gc *GraphicContext) StrokeString(text string) (width float64) {
 	return gc.StrokeStringAt(text, 0, 0)
 }
 
 // StrokeStringAt draws the contour of the text at point (x, y)
-func (gc *GraphicContext) StrokeStringAt(text string, x, y float64) (cursor float64) {
-	width := gc.CreateStringPath(text, x, y)
-	gc.Stroke()
-	return width
+func (gc *GraphicContext) StrokeStringAt(text string, x, y float64) (width float64) {
+	xorig := x
+	fontName := gc.GetFontName()
+	for _, r := range text {
+		glyph := draw2dbase.FetchGlyph(gc, fontName, r)
+		x += glyph.Stroke(gc, x, y)
+	}
+	return x - xorig
 }
 
 func (gc *GraphicContext) loadCurrentFont() (*truetype.Font, error) {

gc.go

@@ -50,6 +50,8 @@ type GraphicContext interface {
 	SetFontData(fontData FontData)
 	// GetFontData gets the current FontData
 	GetFontData() FontData
+	// GetFontName gets the current FontData as a string
+	GetFontName() string
 	// DrawImage draws the raster image in the current canvas
 	DrawImage(image image.Image)
 	// Save the context and push it to the context stack