1: package main
2:
3: import (
4: "fmt"
5: "image"
6: "image/color"
7: "image/png"
8: "log"
9: "os"
10: )
11:
12: // Putpixel describes a function expected to draw a point on a bitmap at (x, y) coordinates.
13: type Putpixel func(x, y int)
14:
15: // 求绝对值
16: func abs(x int) int {
17: if x >= 0 {
18: return x
19: }
20: return -x
21: }
22:
23: // Bresenham's algorithm, http://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm
24: // https://github.com/akavel/polyclip-go/blob/9b07bdd6e0a784f7e5d9321bff03425ab3a98beb/polyutil/draw.go
25: // TODO: handle int overflow etc.
26: func drawline(x0, y0, x1, y1 int, brush Putpixel) {
27: dx := abs(x1 - x0)
28: dy := abs(y1 - y0)
29: sx, sy := 1, 1
30: if x0 >= x1 {
31: sx = -1
32: }
33: if y0 >= y1 {
34: sy = -1
35: }
36: err := dx - dy
37:
38: for {
39: brush(x0, y0)
40: if x0 == x1 && y0 == y1 {
41: return
42: }
43: e2 := err * 2
44: if e2 > -dy {
45: err -= dy
46: x0 += sx
47: }
48: if e2 < dx {
49: err += dx
50: y0 += sy
51: }
52: }
53: }
54:
55: func main() {
56:
57: const (
58: dx = 300
59: dy = 500
60: )
61:
62: // 需要保存的文件
63:
64: // 新建一个 指定大小的 RGBA位图
65: img := image.NewNRGBA(image.Rect(0, 0, dx, dy))
66:
67: drawline(5, 5, dx-8, dy-10, func(x, y int) {
68: img.Set(x, y, color.RGBA{uint8(x), uint8(y), 0, 255})
69: })
70:
71: // 左右都画一条竖线
72: for i := 0; i < dy; i++ {
73: img.Set(0, i, color.Black)
74: img.Set(dx-1, i, color.Black)
75: }
76:
77: imgcounter := 250
78: imgfile, _ := os.Create(fmt.Sprintf("%03d.png", imgcounter))
79: defer imgfile.Close()
80:
81: // 以PNG格式保存文件
82: err := png.Encode(imgfile, img)
83: if err != nil {
84: log.Fatal(err)
85: }
86: }
