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132 lines
3.1 KiB
132 lines
3.1 KiB
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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