133 lines
3.1 KiB
Go
133 lines
3.1 KiB
Go
package service
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import (
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"image"
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"image/color"
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"image/draw"
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"math"
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"github.com/golang/freetype"
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"github.com/golang/freetype/truetype"
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)
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// Image Image.
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type Image struct {
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*image.RGBA
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}
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// newImage create a new image
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func newImage(width, length int) *Image {
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img := &Image{image.NewRGBA(image.Rect(0, 0, width, length))}
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return img
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}
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func (img *Image) fillBkg(c image.Image) {
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draw.Draw(img, img.Bounds(), c, image.ZP, draw.Over)
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}
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// drawCircle draw circle.
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func (img *Image) drawCircle(cx, cy, radius int, isFillColor bool, color color.Color) {
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point := img.Bounds().Size()
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// 如果圆在图片可见区域外，直接退出
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if cx+radius < 0 || cx-radius >= point.X || cy+radius < 0 || cy-radius >= point.Y {
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return
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}
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x, y, d := 0, radius, 3-2*radius
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for x <= y {
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if isFillColor {
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for yi := x; yi <= y; yi++ {
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img.drawCircle8(cx, cy, x, yi, color)
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}
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} else {
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img.drawCircle8(cx, cy, x, y, color)
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}
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if d < 0 {
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d = d + 4*x + 6
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} else {
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d = d + 4*(x-y) + 10
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y--
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}
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x++
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}
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}
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// drawLine .
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// Bresenham算法(https://zh.wikipedia.org/zh-cn/布雷森漢姆直線演算法).
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// startX,startY 起点 endX,endY终点.
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func (img *Image) drawLine(startX, startY, endX, endY int, color color.Color) {
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dx, dy, flag := int(math.Abs(float64(startY-startX))), int(math.Abs(float64(endY-startY))), false
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if dy > dx {
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flag = true
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startX, startY = startY, startX
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endX, endY = endY, endX
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dx, dy = dy, dx
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}
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ix, iy := sign(endX-startX), sign(endY-startY)
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n2dy := dy * 2
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n2dydx := (dy - dx) * 2
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d := n2dy - dx
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for startX != endX {
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if d < 0 {
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d += n2dy
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} else {
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startY += iy
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d += n2dydx
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}
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if flag {
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img.Set(startY, startX, color)
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} else {
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img.Set(startX, startY, color)
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}
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startX += ix
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}
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}
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func (img *Image) drawCircle8(xc, yc, x, y int, color color.Color) {
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img.Set(xc+x, yc+y, color)
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img.Set(xc-x, yc+y, color)
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img.Set(xc+x, yc-y, color)
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img.Set(xc-x, yc-y, color)
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img.Set(xc+y, yc+x, color)
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img.Set(xc-y, yc+x, color)
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img.Set(xc+y, yc-x, color)
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img.Set(xc-y, yc-x, color)
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}
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// drawString image draw string.
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func (img *Image) drawString(font *truetype.Font, color color.Color, str string, fontsize float64) {
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ctx := freetype.NewContext()
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// default 72dpi
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ctx.SetDst(img)
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ctx.SetClip(img.Bounds())
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ctx.SetSrc(image.NewUniform(color))
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ctx.SetFontSize(fontsize)
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ctx.SetFont(font)
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// 写入文字的位置
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pt := freetype.Pt(0, int(-fontsize/6)+ctx.PointToFixed(fontsize).Ceil())
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ctx.DrawString(str, pt)
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}
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// 水波纹, amplude=振幅, period=周期
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// copy from https://github.com/dchest/captcha/blob/master/image.go
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func (img *Image) distortTo(amplude float64, period float64) {
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w := img.Bounds().Max.X
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h := img.Bounds().Max.Y
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oldm := img.RGBA
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dx := 1.4 * math.Pi / period
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for x := 0; x < w; x++ {
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for y := 0; y < h; y++ {
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xo := amplude * math.Sin(float64(y)*dx)
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yo := amplude * math.Cos(float64(x)*dx)
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rgba := oldm.RGBAAt(x+int(xo), y+int(yo))
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if rgba.A > 0 {
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oldm.SetRGBA(x, y, rgba)
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}
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}
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}
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}
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// Rotate 旋转
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func (img *Image) rotate(angle float64) image.Image {
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return new(rotate).rotate(angle, img.RGBA).transformRGBA()
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}
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