| // 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 |
