86 lines
1.8 KiB
Go
86 lines
1.8 KiB
Go
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// Copyright 2016 Minho. All rights reserved.
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// Copyright 2021 Flamego. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package captchautil
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import (
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"crypto/rand"
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"image/color"
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"math"
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"math/big"
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)
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func randomDeepColor() color.RGBA {
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randColor := randomColor()
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increase := float64(30 + r.Intn(255))
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red := math.Abs(math.Min(float64(randColor.R)-increase, 255))
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green := math.Abs(math.Min(float64(randColor.G)-increase, 255))
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blue := math.Abs(math.Min(float64(randColor.B)-increase, 255))
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return color.RGBA{
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R: uint8(red),
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G: uint8(green),
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B: uint8(blue),
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A: uint8(255),
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}
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}
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func randomColor() color.RGBA {
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red := r.Intn(255)
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green := r.Intn(255)
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blue := 0
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if (red + green) <= 400 {
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blue = 400 - green - red
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}
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if blue > 255 {
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blue = 255
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}
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return color.RGBA{
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R: uint8(red),
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G: uint8(green),
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B: uint8(blue),
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A: uint8(255),
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}
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}
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// RandomLightColor returns a random light color.
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func RandomLightColor() color.RGBA {
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red := r.Intn(55) + 200
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green := r.Intn(55) + 200
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blue := r.Intn(55) + 200
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return color.RGBA{
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R: uint8(red),
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G: uint8(green),
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B: uint8(blue),
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A: uint8(255),
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}
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}
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// RandomText returns a generated string in given number of random characters.
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func RandomText(n int) (string, error) {
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const alphanum = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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randomInt := func(max *big.Int) (int, error) {
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r, err := rand.Int(rand.Reader, max)
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if err != nil {
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return 0, err
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}
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return int(r.Int64()), nil
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}
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buffer := make([]byte, n)
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max := big.NewInt(int64(len(alphanum)))
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for i := 0; i < n; i++ {
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index, err := randomInt(max)
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if err != nil {
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return "", err
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}
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buffer[i] = alphanum[index]
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}
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return string(buffer), nil
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}
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