mirror of
https://github.com/golang/go
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143 lines
3.1 KiB
Go
143 lines
3.1 KiB
Go
// Copyright 2012 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file contains the code snippets included in "The Go image/draw package."
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package main
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import (
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"image"
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"image/color"
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"image/draw"
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)
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func main() {
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Color()
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Rect()
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RectAndScroll()
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ConvAndCircle()
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Glyph()
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}
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func Color() {
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c := color.RGBA{255, 0, 255, 255}
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r := image.Rect(0, 0, 640, 480)
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dst := image.NewRGBA(r)
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// ZERO OMIT
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// image.ZP is the zero point -- the origin.
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draw.Draw(dst, r, &image.Uniform{c}, image.ZP, draw.Src)
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// STOP OMIT
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// BLUE OMIT
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m := image.NewRGBA(image.Rect(0, 0, 640, 480))
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blue := color.RGBA{0, 0, 255, 255}
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draw.Draw(m, m.Bounds(), &image.Uniform{blue}, image.ZP, draw.Src)
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// STOP OMIT
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// RESET OMIT
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draw.Draw(m, m.Bounds(), image.Transparent, image.ZP, draw.Src)
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// STOP OMIT
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}
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func Rect() {
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dst := image.NewRGBA(image.Rect(0, 0, 640, 480))
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sr := image.Rect(0, 0, 200, 200)
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src := image.Black
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dp := image.Point{100, 100}
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// RECT OMIT
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r := image.Rectangle{dp, dp.Add(sr.Size())}
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draw.Draw(dst, r, src, sr.Min, draw.Src)
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// STOP OMIT
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}
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func RectAndScroll() {
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dst := image.NewRGBA(image.Rect(0, 0, 640, 480))
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sr := image.Rect(0, 0, 200, 200)
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src := image.Black
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dp := image.Point{100, 100}
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// RECT2 OMIT
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r := sr.Sub(sr.Min).Add(dp)
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draw.Draw(dst, r, src, sr.Min, draw.Src)
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// STOP OMIT
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m := dst
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// SCROLL OMIT
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b := m.Bounds()
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p := image.Pt(0, 20)
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// Note that even though the second argument is b,
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// the effective rectangle is smaller due to clipping.
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draw.Draw(m, b, m, b.Min.Add(p), draw.Src)
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dirtyRect := b.Intersect(image.Rect(b.Min.X, b.Max.Y-20, b.Max.X, b.Max.Y))
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// STOP OMIT
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_ = dirtyRect // noop
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}
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func ConvAndCircle() {
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src := image.NewRGBA(image.Rect(0, 0, 640, 480))
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dst := image.NewRGBA(image.Rect(0, 0, 640, 480))
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// CONV OMIT
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b := src.Bounds()
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m := image.NewRGBA(b)
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draw.Draw(m, b, src, b.Min, draw.Src)
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// STOP OMIT
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p := image.Point{100, 100}
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r := 50
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// CIRCLE2 OMIT
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draw.DrawMask(dst, dst.Bounds(), src, image.ZP, &circle{p, r}, image.ZP, draw.Over)
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// STOP OMIT
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}
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func theGlyphImageForAFont() image.Image {
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return image.NewRGBA(image.Rect(0, 0, 640, 480))
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}
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func theBoundsFor(index int) image.Rectangle {
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return image.Rect(0, 0, 32, 32)
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}
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func Glyph() {
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p := image.Point{100, 100}
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dst := image.NewRGBA(image.Rect(0, 0, 640, 480))
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glyphIndex := 42
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// GLYPH OMIT
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src := &image.Uniform{color.RGBA{0, 0, 255, 255}}
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mask := theGlyphImageForAFont()
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mr := theBoundsFor(glyphIndex)
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draw.DrawMask(dst, mr.Sub(mr.Min).Add(p), src, image.ZP, mask, mr.Min, draw.Over)
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// STOP OMIT
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}
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//CIRCLESTRUCT OMIT
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type circle struct {
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p image.Point
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r int
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}
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func (c *circle) ColorModel() color.Model {
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return color.AlphaModel
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}
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func (c *circle) Bounds() image.Rectangle {
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return image.Rect(c.p.X-c.r, c.p.Y-c.r, c.p.X+c.r, c.p.Y+c.r)
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}
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func (c *circle) At(x, y int) color.Color {
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xx, yy, rr := float64(x-c.p.X)+0.5, float64(y-c.p.Y)+0.5, float64(c.r)
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if xx*xx+yy*yy < rr*rr {
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return color.Alpha{255}
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}
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return color.Alpha{0}
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}
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//STOP OMIT
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