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Add palette option

This commit is contained in:
Weilin Shi 2018-08-14 14:27:29 +08:00
parent fc4a5d0dfc
commit 1b36f64f5d
1 changed files with 14 additions and 2 deletions
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16
captcha.go
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@ -50,6 +50,8 @@ type Options struct {
// A noise dot is drawn for every 28 pixel by default. // A noise dot is drawn for every 28 pixel by default.
// The default is 1.0. // The default is 1.0.
Noise float64 Noise float64
// Palette is the set of colors to chose from
Palette color.Palette
width int width int
height int height int
@ -64,6 +66,7 @@ func newDefaultOption(width, height int) *Options {
FontDPI: 72.0, FontDPI: 72.0,
FontScale: 1.0, FontScale: 1.0,
Noise: 1.0, Noise: 1.0,
Palette: []color.Color{},
width: width, width: width,
height: height, height: height,
} }
@ -212,7 +215,7 @@ func drawSineCurve(img *image.NRGBA, opts *Options) {
if rng.Intn(2) == 0 { if rng.Intn(2) == 0 {
yFlip = -1.0 yFlip = -1.0
} }
curveColor := randomInvertColor(opts.BackgroundColor) curveColor := randomColorFromOptions(opts)
for x1 := xStart; x1 <= xEnd; x1++ { for x1 := xStart; x1 <= xEnd; x1++ {
y := math.Sin(math.Pi*angle*float64(x1)/float64(opts.width)) * curveHeight * yFlip y := math.Sin(math.Pi*angle*float64(x1)/float64(opts.width)) * curveHeight * yFlip
@ -235,7 +238,7 @@ func drawText(text string, img *image.NRGBA, opts *Options) error {
fontScale := 0.8 + rng.Float64()*0.4 fontScale := 0.8 + rng.Float64()*0.4
fontSize := float64(opts.height) / fontScale * opts.FontScale fontSize := float64(opts.height) / fontScale * opts.FontScale
ctx.SetFontSize(fontSize) ctx.SetFontSize(fontSize)
ctx.SetSrc(image.NewUniform(randomInvertColor(opts.BackgroundColor))) ctx.SetSrc(image.NewUniform(randomColorFromOptions(opts)))
x := fontSpacing*idx + fontOffset x := fontSpacing*idx + fontOffset
y := opts.height/6 + rng.Intn(opts.height/3) + int(fontSize/2) y := opts.height/6 + rng.Intn(opts.height/3) + int(fontSize/2)
pt := freetype.Pt(x, y) pt := freetype.Pt(x, y)
@ -247,6 +250,15 @@ func drawText(text string, img *image.NRGBA, opts *Options) error {
return nil return nil
} }
func randomColorFromOptions(opts *Options) color.Color {
length := len(opts.Palette)
if length == 0 {
return randomInvertColor(opts.BackgroundColor)
}
return opts.Palette[rng.Intn(length)]
}
func randomInvertColor(base color.Color) color.Color { func randomInvertColor(base color.Color) color.Color {
baseLightness := getLightness(base) baseLightness := getLightness(base)
var value float64 var value float64