1 files changed, 142 insertions, 0 deletions
diff --git a/doc/progs/image_draw.go b/doc/progs/image_draw.go
new file mode 100644
index 000000000..f3400b601
--- /dev/null
+++ b/doc/progs/image_draw.go
@@ -0,0 +1,142 @@
+// 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(image.Rect(0, 0, b.Dx(), b.Dy()))
+	draw.Draw(m, m.Bounds(), 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
+}
+
+//CIRCLE 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