84 lines
1.7 KiB
Go
84 lines
1.7 KiB
Go
package captcha
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import (
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"image"
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"image/color"
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"image/png"
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"io"
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"math/rand"
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"time"
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)
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const charPreset = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
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type Options struct {
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BackgroundColor color.RGBA
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CharPreset string
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TxtLength int
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width int
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height int
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}
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func newDefaultOption(width, height int) *Options {
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return &Options{
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CharPreset: charPreset,
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TxtLength: 4,
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width: width,
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height: height,
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}
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}
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type Option func(*Options)
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type Data struct {
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Text string
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img *image.NRGBA
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}
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func (data *Data) WriteTo(w io.Writer) error {
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return png.Encode(w, data.img)
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}
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func New(width int, height int, option ...Option) *Data {
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options := newDefaultOption(width, height)
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for _, setOption := range option {
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setOption(options)
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}
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text := randomText(options)
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img := image.NewNRGBA(image.Rect(0, 0, width, height))
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drawNoise(img, options)
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return &Data{Text: text, img: img}
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}
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func randomText(opts *Options) (text string) {
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n := len(opts.CharPreset)
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rng := rand.New(rand.NewSource(time.Now().UnixNano()))
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for i := 0; i < opts.TxtLength; i++ {
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text += string(opts.CharPreset[rng.Intn(n)])
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}
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return text
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}
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func drawNoise(img *image.NRGBA, opts *Options) {
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rng := rand.New(rand.NewSource(time.Now().UnixNano()))
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noiseCount := (opts.width * opts.height) / 18
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for i := 0; i < noiseCount; i++ {
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x := rng.Intn(opts.width)
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y := rng.Intn(opts.height)
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img.Set(x, y, randomColor())
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}
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}
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func randomColor() color.RGBA {
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rng := rand.New(rand.NewSource(time.Now().UnixNano()))
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red := rng.Intn(255)
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green := rng.Intn(255)
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blue := rng.Intn(255)
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return color.RGBA{R: uint8(red), G: uint8(green), B: uint8(blue), A: uint8(255)}
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}
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