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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package draw_test
import (
"fmt"
"image"
"image/color"
"image/png"
"log"
"math"
"os"
"golang.org/x/image/draw"
"golang.org/x/image/math/f64"
)
func ExampleDraw() {
fSrc, err := os.Open("../testdata/blue-purple-pink.png")
if err != nil {
log.Fatal(err)
}
defer fSrc.Close()
src, err := png.Decode(fSrc)
if err != nil {
log.Fatal(err)
}
dst := image.NewRGBA(image.Rect(0, 0, 400, 300))
green := image.NewUniform(color.RGBA{0x00, 0x1f, 0x00, 0xff})
draw.Copy(dst, image.Point{}, green, dst.Bounds(), draw.Src, nil)
qs := []draw.Interpolator{
draw.NearestNeighbor,
draw.ApproxBiLinear,
draw.CatmullRom,
}
const cos60, sin60 = 0.5, 0.866025404
t := f64.Aff3{
+2 * cos60, -2 * sin60, 100,
+2 * sin60, +2 * cos60, 100,
}
draw.Copy(dst, image.Point{20, 30}, src, src.Bounds(), draw.Over, nil)
for i, q := range qs {
q.Scale(dst, image.Rect(200+10*i, 100*i, 600+10*i, 150+100*i), src, src.Bounds(), draw.Over, nil)
}
draw.NearestNeighbor.Transform(dst, t, src, src.Bounds(), draw.Over, nil)
red := image.NewNRGBA(image.Rect(0, 0, 16, 16))
for y := 0; y < 16; y++ {
for x := 0; x < 16; x++ {
red.SetNRGBA(x, y, color.NRGBA{
R: uint8(x * 0x11),
A: uint8(y * 0x11),
})
}
}
red.SetNRGBA(0, 0, color.NRGBA{0xff, 0xff, 0x00, 0xff})
red.SetNRGBA(15, 15, color.NRGBA{0xff, 0xff, 0x00, 0xff})
ops := []draw.Op{
draw.Over,
draw.Src,
}
for i, op := range ops {
dr := image.Rect(120+10*i, 150+60*i, 170+10*i, 200+60*i)
draw.NearestNeighbor.Scale(dst, dr, red, red.Bounds(), op, nil)
t := f64.Aff3{
+cos60, -sin60, float64(190 + 10*i),
+sin60, +cos60, float64(140 + 50*i),
}
draw.NearestNeighbor.Transform(dst, t, red, red.Bounds(), op, nil)
}
dr := image.Rect(0, 0, 128, 128)
checkerboard := image.NewAlpha(dr)
for y := dr.Min.Y; y < dr.Max.Y; y++ {
for x := dr.Min.X; x < dr.Max.X; x++ {
if (x/20)%2 == (y/20)%2 {
checkerboard.SetAlpha(x, y, color.Alpha{0xff})
}
}
}
sr := image.Rect(0, 0, 16, 16)
circle := image.NewAlpha(sr)
for y := sr.Min.Y; y < sr.Max.Y; y++ {
for x := sr.Min.X; x < sr.Max.X; x++ {
dx, dy := x-10, y-8
if d := 32 * math.Sqrt(float64(dx*dx)+float64(dy*dy)); d < 0xff {
circle.SetAlpha(x, y, color.Alpha{0xff - uint8(d)})
}
}
}
cyan := image.NewUniform(color.RGBA{0x00, 0xff, 0xff, 0xff})
draw.NearestNeighbor.Scale(dst, dr, cyan, sr, draw.Over, &draw.Options{
DstMask: checkerboard,
SrcMask: circle,
})
// Change false to true to write the resultant image to disk.
if false {
fDst, err := os.Create("out.png")
if err != nil {
log.Fatal(err)
}
defer fDst.Close()
err = png.Encode(fDst, dst)
if err != nil {
log.Fatal(err)
}
}
fmt.Printf("dst has bounds %v.\n", dst.Bounds())
// Output:
// dst has bounds (0,0)-(400,300).
}
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