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