github.com/ccccaoqing/test@v0.0.0-20220510085219-3985d23445c0/doc/progs/image_draw.go (about)

     1  // compile
     2  
     3  // Copyright 2012 The Go Authors. All rights reserved.
     4  // Use of this source code is governed by a BSD-style
     5  // license that can be found in the LICENSE file.
     6  
     7  // This file contains the code snippets included in "The Go image/draw package."
     8  
     9  package main
    10  
    11  import (
    12  	"image"
    13  	"image/color"
    14  	"image/draw"
    15  )
    16  
    17  func main() {
    18  	Color()
    19  	Rect()
    20  	RectAndScroll()
    21  	ConvAndCircle()
    22  	Glyph()
    23  }
    24  
    25  func Color() {
    26  	c := color.RGBA{255, 0, 255, 255}
    27  	r := image.Rect(0, 0, 640, 480)
    28  	dst := image.NewRGBA(r)
    29  
    30  	// ZERO OMIT
    31  	// image.ZP is the zero point -- the origin.
    32  	draw.Draw(dst, r, &image.Uniform{c}, image.ZP, draw.Src)
    33  	// STOP OMIT
    34  
    35  	// BLUE OMIT
    36  	m := image.NewRGBA(image.Rect(0, 0, 640, 480))
    37  	blue := color.RGBA{0, 0, 255, 255}
    38  	draw.Draw(m, m.Bounds(), &image.Uniform{blue}, image.ZP, draw.Src)
    39  	// STOP OMIT
    40  
    41  	// RESET OMIT
    42  	draw.Draw(m, m.Bounds(), image.Transparent, image.ZP, draw.Src)
    43  	// STOP OMIT
    44  }
    45  
    46  func Rect() {
    47  	dst := image.NewRGBA(image.Rect(0, 0, 640, 480))
    48  	sr := image.Rect(0, 0, 200, 200)
    49  	src := image.Black
    50  	dp := image.Point{100, 100}
    51  
    52  	// RECT OMIT
    53  	r := image.Rectangle{dp, dp.Add(sr.Size())}
    54  	draw.Draw(dst, r, src, sr.Min, draw.Src)
    55  	// STOP OMIT
    56  }
    57  
    58  func RectAndScroll() {
    59  	dst := image.NewRGBA(image.Rect(0, 0, 640, 480))
    60  	sr := image.Rect(0, 0, 200, 200)
    61  	src := image.Black
    62  	dp := image.Point{100, 100}
    63  
    64  	// RECT2 OMIT
    65  	r := sr.Sub(sr.Min).Add(dp)
    66  	draw.Draw(dst, r, src, sr.Min, draw.Src)
    67  	// STOP OMIT
    68  
    69  	m := dst
    70  
    71  	// SCROLL OMIT
    72  	b := m.Bounds()
    73  	p := image.Pt(0, 20)
    74  	// Note that even though the second argument is b,
    75  	// the effective rectangle is smaller due to clipping.
    76  	draw.Draw(m, b, m, b.Min.Add(p), draw.Src)
    77  	dirtyRect := b.Intersect(image.Rect(b.Min.X, b.Max.Y-20, b.Max.X, b.Max.Y))
    78  	// STOP OMIT
    79  
    80  	_ = dirtyRect // noop
    81  }
    82  
    83  func ConvAndCircle() {
    84  	src := image.NewRGBA(image.Rect(0, 0, 640, 480))
    85  	dst := image.NewRGBA(image.Rect(0, 0, 640, 480))
    86  
    87  	// CONV OMIT
    88  	b := src.Bounds()
    89  	m := image.NewRGBA(b)
    90  	draw.Draw(m, b, src, b.Min, draw.Src)
    91  	// STOP OMIT
    92  
    93  	p := image.Point{100, 100}
    94  	r := 50
    95  
    96  	// CIRCLE2 OMIT
    97  	draw.DrawMask(dst, dst.Bounds(), src, image.ZP, &circle{p, r}, image.ZP, draw.Over)
    98  	// STOP OMIT
    99  }
   100  
   101  func theGlyphImageForAFont() image.Image {
   102  	return image.NewRGBA(image.Rect(0, 0, 640, 480))
   103  }
   104  
   105  func theBoundsFor(index int) image.Rectangle {
   106  	return image.Rect(0, 0, 32, 32)
   107  }
   108  
   109  func Glyph() {
   110  	p := image.Point{100, 100}
   111  	dst := image.NewRGBA(image.Rect(0, 0, 640, 480))
   112  	glyphIndex := 42
   113  
   114  	// GLYPH OMIT
   115  	src := &image.Uniform{color.RGBA{0, 0, 255, 255}}
   116  	mask := theGlyphImageForAFont()
   117  	mr := theBoundsFor(glyphIndex)
   118  	draw.DrawMask(dst, mr.Sub(mr.Min).Add(p), src, image.ZP, mask, mr.Min, draw.Over)
   119  	// STOP OMIT
   120  }
   121  
   122  //CIRCLESTRUCT OMIT
   123  type circle struct {
   124  	p image.Point
   125  	r int
   126  }
   127  
   128  func (c *circle) ColorModel() color.Model {
   129  	return color.AlphaModel
   130  }
   131  
   132  func (c *circle) Bounds() image.Rectangle {
   133  	return image.Rect(c.p.X-c.r, c.p.Y-c.r, c.p.X+c.r, c.p.Y+c.r)
   134  }
   135  
   136  func (c *circle) At(x, y int) color.Color {
   137  	xx, yy, rr := float64(x-c.p.X)+0.5, float64(y-c.p.Y)+0.5, float64(c.r)
   138  	if xx*xx+yy*yy < rr*rr {
   139  		return color.Alpha{255}
   140  	}
   141  	return color.Alpha{0}
   142  }
   143  
   144  //STOP OMIT