205 lines
6.5 KiB
Go
205 lines
6.5 KiB
Go
package captcha
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import (
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"bytes"
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"context"
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"crypto/rand"
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"encoding/base64"
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"fmt"
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"image"
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"image/color"
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"image/draw"
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"image/png"
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"math/big"
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"photowall/pkg/redis"
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"strings"
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"time"
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)
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const chars = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789"
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// Generate 生成图形验证码，返回 captcha_id 和 base64 图片
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func Generate() (id string, imgBase64 string) {
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code := randomCode(4)
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id = randomID()
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// 存入 Redis，5分钟过期
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redis.Set(context.Background(), "captcha:"+id, code, 5*time.Minute)
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img := drawImage(code)
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imgBase64 = encodeToBase64(img)
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return id, "data:image/png;base64," + imgBase64
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}
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// Verify 校验验证码，校验成功后立即删除（一次性）
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// 开发万能码：888888（任意 captcha_id 均可通过，仅用于开发测试）
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func Verify(id, code string) bool {
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if code == "888888" {
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return true
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}
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if id == "" || code == "" {
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return false
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}
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stored, err := redis.Get(context.Background(), "captcha:"+id)
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if err != nil {
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return false
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}
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redis.Del(context.Background(), "captcha:"+id) // 一次性
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return strings.EqualFold(stored, code)
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}
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func randomCode(length int) string {
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b := make([]byte, length)
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for i := range b {
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n, _ := rand.Int(rand.Reader, big.NewInt(int64(len(chars))))
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b[i] = chars[n.Int64()]
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}
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return string(b)
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}
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func randomID() string {
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b := make([]byte, 16)
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rand.Read(b)
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return fmt.Sprintf("%x", b)
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}
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// ============ 图片绘制 ============
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func drawImage(code string) image.Image {
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width, height := 120, 40
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img := image.NewRGBA(image.Rect(0, 0, width, height))
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bg := color.RGBA{240, 245, 255, 255}
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draw.Draw(img, img.Bounds(), &image.Uniform{bg}, image.Point{}, draw.Src)
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for i := 0; i < 3; i++ {
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x1, _ := rand.Int(rand.Reader, big.NewInt(int64(width)))
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y1, _ := rand.Int(rand.Reader, big.NewInt(int64(height)))
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x2, _ := rand.Int(rand.Reader, big.NewInt(int64(width)))
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y2, _ := rand.Int(rand.Reader, big.NewInt(int64(height)))
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drawLine(img, int(x1.Int64()), int(y1.Int64()), int(x2.Int64()), int(y2.Int64()), randomColor())
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}
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for i := 0; i < 25; i++ {
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x, _ := rand.Int(rand.Reader, big.NewInt(int64(width)))
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y, _ := rand.Int(rand.Reader, big.NewInt(int64(height)))
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img.Set(int(x.Int64()), int(y.Int64()), randomColor())
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}
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// 字符居中绘制：字符高 21px (7*3)，画布高 40px，垂直居中起始 y 约 9px；4 字符总宽 90px，水平居中起始 x 为 15px
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for i, ch := range code {
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offsetY, _ := rand.Int(rand.Reader, big.NewInt(3))
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charY := 8 + int(offsetY.Int64()) // 8..10px，垂直完美居中
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drawChar(img, 15+i*25, charY, string(ch), randomDarkColor())
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}
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return img
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}
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func drawChar(img *image.RGBA, x, y int, ch string, c color.Color) {
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font := map[rune][7]string{
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'0': {"01110", "10001", "10011", "10101", "11001", "10001", "01110"},
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'1': {"00100", "01100", "00100", "00100", "00100", "00100", "01110"},
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'2': {"01110", "10001", "00001", "00010", "00100", "01000", "11111"},
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'3': {"11110", "00001", "00001", "01110", "00001", "00001", "11110"},
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'4': {"00010", "00110", "01010", "10010", "11111", "00010", "00010"},
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'5': {"11111", "10000", "11110", "00001", "00001", "10001", "01110"},
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'6': {"00110", "01000", "10000", "11110", "10001", "10001", "01110"},
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'7': {"11111", "00001", "00010", "00100", "01000", "01000", "01000"},
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'8': {"01110", "10001", "10001", "01110", "10001", "10001", "01110"},
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'9': {"01110", "10001", "10001", "01111", "00001", "00010", "01100"},
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'A': {"01110", "10001", "10001", "11111", "10001", "10001", "10001"},
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'B': {"11110", "10001", "10001", "11110", "10001", "10001", "11110"},
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'C': {"01111", "10000", "10000", "10000", "10000", "10000", "01111"},
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'D': {"11110", "10001", "10001", "10001", "10001", "10001", "11110"},
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'E': {"11111", "10000", "10000", "11110", "10000", "10000", "11111"},
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'F': {"11111", "10000", "10000", "11110", "10000", "10000", "10000"},
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'G': {"01111", "10000", "10000", "10111", "10001", "10001", "01110"},
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'H': {"10001", "10001", "10001", "11111", "10001", "10001", "10001"},
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'J': {"00001", "00001", "00001", "00001", "00001", "10001", "01110"},
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'K': {"10001", "10010", "10100", "11000", "10100", "10010", "10001"},
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'L': {"10000", "10000", "10000", "10000", "10000", "10000", "11111"},
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'M': {"10001", "11011", "10101", "10101", "10001", "10001", "10001"},
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'N': {"10001", "11001", "10101", "10011", "10001", "10001", "10001"},
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'P': {"11110", "10001", "10001", "11110", "10000", "10000", "10000"},
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'Q': {"01110", "10001", "10001", "10001", "10101", "10010", "01101"},
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'R': {"11110", "10001", "10001", "11110", "10100", "10010", "10001"},
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'S': {"01111", "10000", "10000", "01110", "00001", "00001", "11110"},
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'T': {"11111", "00100", "00100", "00100", "00100", "00100", "00100"},
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'U': {"10001", "10001", "10001", "10001", "10001", "10001", "01110"},
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'V': {"10001", "10001", "10001", "10001", "10001", "01010", "00100"},
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'W': {"10001", "10001", "10001", "10101", "10101", "11011", "10001"},
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'X': {"10001", "10001", "01010", "00100", "01010", "10001", "10001"},
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'Y': {"10001", "10001", "01010", "00100", "00100", "00100", "00100"},
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'Z': {"11111", "00001", "00010", "00100", "01000", "10000", "11111"},
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}
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pattern, ok := font[rune(ch[0])]
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if !ok {
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pattern = font['0']
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}
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scale := 3
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for row, line := range pattern {
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for col, px := range line {
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if px == '1' {
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for dy := 0; dy < scale; dy++ {
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for dx := 0; dx < scale; dx++ {
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img.Set(x+col*scale+dx, y+row*scale+dy, c)
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}
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}
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}
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}
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}
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}
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func drawLine(img *image.RGBA, x1, y1, x2, y2 int, c color.Color) {
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dx := abs(x2 - x1)
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dy := abs(y2 - y1)
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sx, sy := 1, -1
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if x1 > x2 {
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sx = -1
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}
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if y1 < y2 {
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sy = 1
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}
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err := dx - dy
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for {
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img.Set(x1, y1, c)
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if x1 == x2 && y1 == y2 {
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break
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}
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e2 := 2 * err
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if e2 > -dy {
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err -= dy
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x1 += sx
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}
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if e2 < dx {
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err += dx
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y1 += sy
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}
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}
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}
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func abs(x int) int {
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if x < 0 {
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return -x
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}
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return x
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}
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func randomColor() color.RGBA {
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r, _ := rand.Int(rand.Reader, big.NewInt(200))
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g, _ := rand.Int(rand.Reader, big.NewInt(200))
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b, _ := rand.Int(rand.Reader, big.NewInt(200))
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return color.RGBA{uint8(r.Int64() + 55), uint8(g.Int64() + 55), uint8(b.Int64() + 55), 255}
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}
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func randomDarkColor() color.RGBA {
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r, _ := rand.Int(rand.Reader, big.NewInt(100))
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g, _ := rand.Int(rand.Reader, big.NewInt(100))
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b, _ := rand.Int(rand.Reader, big.NewInt(150))
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return color.RGBA{uint8(r.Int64()), uint8(g.Int64()), uint8(b.Int64() + 50), 255}
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}
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func encodeToBase64(img image.Image) string {
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var buf bytes.Buffer
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enc := base64.NewEncoder(base64.StdEncoding, &buf)
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_ = png.Encode(enc, img)
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_ = enc.Close()
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return buf.String()
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}
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