Introduce MonochromePainter and GammaCorrectionPainter. R=r, rsc CC=golang-dev http://codereview.appspot.com/904041
85 lines
2 KiB
Go
85 lines
2 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,
|
|
// 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.Fixed(x * 256), raster.Fixed(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.New(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.AlphaSrcPainter(mask)
|
|
gammas := []float64{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.GammaCorrectionPainter(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.")
|
|
}
|