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