freetype/example/gamma/main.go
Nigel Tao 2af394dab9 freetype: clarify that the GPL licence is "version 2 or later", not
just version 2. The FTL (Freetype Licence) is still available. This
matches the original Freetype library (written in C).

This only expands and does not further restrict the licensing options
available to users of the freetype-go library.

R=adg
CC=golang-dev
http://codereview.appspot.com/1731049
2010-08-03 11:07:23 +10:00

85 lines
2.1 KiB
Go

// 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.
package main
import (
"bufio"
"exp/draw"
"fmt"
"image"
"image/png"
"log"
"os"
"freetype-go.googlecode.com/hg/freetype/raster"
)
func p(x, y int) raster.Point {
return raster.Point{raster.Fix32(x * 256), raster.Fix32(y * 256)}
}
func clear(m *image.Alpha) {
for y := 0; y < m.Height(); y++ {
for x := 0; x < m.Width(); x++ {
m.Pixel[y][x] = image.AlphaColor{0}
}
}
}
func main() {
// Draw a rounded corner that is one pixel wide.
r := raster.NewRasterizer(50, 50)
r.Start(p(5, 5))
r.Add1(p(5, 25))
r.Add2(p(5, 45), p(25, 45))
r.Add1(p(45, 45))
r.Add1(p(45, 44))
r.Add1(p(26, 44))
r.Add2(p(6, 44), p(6, 24))
r.Add1(p(6, 5))
r.Add1(p(5, 5))
// Rasterize that curve multiple times at different gammas.
const (
w = 600
h = 200
)
rgba := image.NewRGBA(w, h)
draw.Draw(rgba, draw.Rect(0, 0, w, h/2), image.Black, draw.ZP)
draw.Draw(rgba, draw.Rect(0, h/2, w, h), image.White, draw.ZP)
mask := image.NewAlpha(50, 50)
painter := raster.NewAlphaPainter(mask)
painter.Op = draw.Src
gammas := []float{1.0 / 10.0, 1.0 / 3.0, 1.0 / 2.0, 2.0 / 3.0, 4.0 / 5.0, 1.0, 5.0 / 4.0, 3.0 / 2.0, 2.0, 3.0, 10.0}
for i, g := range gammas {
clear(mask)
r.Rasterize(raster.NewGammaCorrectionPainter(painter, g))
x, y := 50*i+25, 25
draw.DrawMask(rgba, draw.Rect(x, y, x+50, y+50), image.White, draw.ZP, mask, draw.ZP, draw.Over)
y += 100
draw.DrawMask(rgba, draw.Rect(x, y, x+50, y+50), image.Black, draw.ZP, mask, draw.ZP, draw.Over)
}
// Save that RGBA image to disk.
f, err := os.Open("out.png", os.O_CREAT|os.O_WRONLY, 0600)
if err != nil {
log.Stderr(err)
os.Exit(1)
}
defer f.Close()
b := bufio.NewWriter(f)
err = png.Encode(b, rgba)
if err != nil {
log.Stderr(err)
os.Exit(1)
}
err = b.Flush()
if err != nil {
log.Stderr(err)
os.Exit(1)
}
fmt.Println("Wrote out.png OK.")
}