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// Copyright 2010 The Freetype-Go Authors. All rights reserved.
// Use of this source code is governed by your choice of either the
// FreeType License or the GNU General Public License version 2 (or
// any later version), both of which can be found in the LICENSE file.
// +build example
//
// This build tag means that "go install github.com/golang/freetype/..."
// doesn't install this example program. Use "go run main.go" to run it or "go
// install -tags=example" to install it.
package main
import (
"bufio"
"fmt"
"image"
"image/color"
"image/draw"
"image/png"
"log"
"os"
"github.com/golang/freetype/raster"
"golang.org/x/image/math/fixed"
)
type node struct {
x, y, degree int
}
// These contours "outside" and "inside" are from the 'A' glyph from the Droid
// Serif Regular font.
var outside = []node{
node{414, 489, 1},
node{336, 274, 2},
node{327, 250, 0},
node{322, 226, 2},
node{317, 203, 0},
node{317, 186, 2},
node{317, 134, 0},
node{350, 110, 2},
node{384, 86, 0},
node{453, 86, 1},
node{500, 86, 1},
node{500, 0, 1},
node{0, 0, 1},
node{0, 86, 1},
node{39, 86, 2},
node{69, 86, 0},
node{90, 92, 2},
node{111, 99, 0},
node{128, 117, 2},
node{145, 135, 0},
node{160, 166, 2},
node{176, 197, 0},
node{195, 246, 1},
node{649, 1462, 1},
node{809, 1462, 1},
node{1272, 195, 2},
node{1284, 163, 0},
node{1296, 142, 2},
node{1309, 121, 0},
node{1326, 108, 2},
node{1343, 96, 0},
node{1365, 91, 2},
node{1387, 86, 0},
node{1417, 86, 1},
node{1444, 86, 1},
node{1444, 0, 1},
node{881, 0, 1},
node{881, 86, 1},
node{928, 86, 2},
node{1051, 86, 0},
node{1051, 184, 2},
node{1051, 201, 0},
node{1046, 219, 2},
node{1042, 237, 0},
node{1034, 260, 1},
node{952, 489, 1},
node{414, 489, -1},
}
var inside = []node{
node{686, 1274, 1},
node{453, 592, 1},
node{915, 592, 1},
node{686, 1274, -1},
}
func p(n node) fixed.Point26_6 {
x, y := 20+n.x/4, 380-n.y/4
return fixed.Point26_6{
X: fixed.Int26_6(x << 6),
Y: fixed.Int26_6(y << 6),
}
}
func contour(r *raster.Rasterizer, ns []node) {
if len(ns) == 0 {
return
}
i := 0
r.Start(p(ns[i]))
for {
switch ns[i].degree {
case -1:
// -1 signifies end-of-contour.
return
case 1:
i += 1
r.Add1(p(ns[i]))
case 2:
i += 2
r.Add2(p(ns[i-1]), p(ns[i]))
default:
panic("bad degree")
}
}
}
func showNodes(m *image.RGBA, ns []node) {
for _, n := range ns {
p := p(n)
x, y := int(p.X)/64, int(p.Y)/64
if !(image.Point{x, y}).In(m.Bounds()) {
continue
}
var c color.Color
switch n.degree {
case 0:
c = color.RGBA{0, 255, 255, 255}
case 1:
c = color.RGBA{255, 0, 0, 255}
case 2:
c = color.RGBA{255, 0, 0, 255}
}
if c != nil {
m.Set(x, y, c)
}
}
}
func main() {
// Rasterize the contours to a mask image.
const (
w = 400
h = 400
)
r := raster.NewRasterizer(w, h)
contour(r, outside)
contour(r, inside)
mask := image.NewAlpha(image.Rect(0, 0, w, h))
p := raster.NewAlphaSrcPainter(mask)
r.Rasterize(p)
// Draw the mask image (in gray) onto an RGBA image.
rgba := image.NewRGBA(image.Rect(0, 0, w, h))
gray := image.NewUniform(color.Alpha{0x1f})
draw.Draw(rgba, rgba.Bounds(), image.Black, image.ZP, draw.Src)
draw.DrawMask(rgba, rgba.Bounds(), gray, image.ZP, mask, image.ZP, draw.Over)
showNodes(rgba, outside)
showNodes(rgba, inside)
// Save that RGBA image to disk.
outFile, err := os.Create("out.png")
if err != nil {
log.Println(err)
os.Exit(1)
}
defer outFile.Close()
b := bufio.NewWriter(outFile)
err = png.Encode(b, rgba)
if err != nil {
log.Println(err)
os.Exit(1)
}
err = b.Flush()
if err != nil {
log.Println(err)
os.Exit(1)
}
fmt.Println("Wrote out.png OK.")
}
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