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431 lines
10 KiB
Go
431 lines
10 KiB
Go
// Go implementation of the StackBlur algorithm
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// http://incubator.quasimondo.com/processing/fast_blur_deluxe.php
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package caire
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import (
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"errors"
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"image"
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"image/color"
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)
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// blurStack is a linked list containing the color value and a pointer to the next struct.
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type blurStack struct {
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r, g, b, a uint32
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next *blurStack
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}
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var mulTable = []uint32{
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512, 512, 456, 512, 328, 456, 335, 512, 405, 328, 271, 456, 388, 335, 292, 512,
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454, 405, 364, 328, 298, 271, 496, 456, 420, 388, 360, 335, 312, 292, 273, 512,
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482, 454, 428, 405, 383, 364, 345, 328, 312, 298, 284, 271, 259, 496, 475, 456,
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437, 420, 404, 388, 374, 360, 347, 335, 323, 312, 302, 292, 282, 273, 265, 512,
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497, 482, 468, 454, 441, 428, 417, 405, 394, 383, 373, 364, 354, 345, 337, 328,
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320, 312, 305, 298, 291, 284, 278, 271, 265, 259, 507, 496, 485, 475, 465, 456,
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446, 437, 428, 420, 412, 404, 396, 388, 381, 374, 367, 360, 354, 347, 341, 335,
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329, 323, 318, 312, 307, 302, 297, 292, 287, 282, 278, 273, 269, 265, 261, 512,
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505, 497, 489, 482, 475, 468, 461, 454, 447, 441, 435, 428, 422, 417, 411, 405,
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399, 394, 389, 383, 378, 373, 368, 364, 359, 354, 350, 345, 341, 337, 332, 328,
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324, 320, 316, 312, 309, 305, 301, 298, 294, 291, 287, 284, 281, 278, 274, 271,
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268, 265, 262, 259, 257, 507, 501, 496, 491, 485, 480, 475, 470, 465, 460, 456,
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451, 446, 442, 437, 433, 428, 424, 420, 416, 412, 408, 404, 400, 396, 392, 388,
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385, 381, 377, 374, 370, 367, 363, 360, 357, 354, 350, 347, 344, 341, 338, 335,
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332, 329, 326, 323, 320, 318, 315, 312, 310, 307, 304, 302, 299, 297, 294, 292,
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289, 287, 285, 282, 280, 278, 275, 273, 271, 269, 267, 265, 263, 261, 259,
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}
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var shgTable = []uint32{
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9, 11, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17,
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17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19,
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19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20,
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20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21,
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21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
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21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22,
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22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
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22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23,
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23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
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23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
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23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
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23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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}
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// Stackblur takes the source image and returns it's blurred version by applying the blur radius defined as parameter. The destination image must be a image.NRGBA.
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func Stackblur(dst, src image.Image, radius uint32) error {
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// Limit the maximum blur radius to 255 to avoid overflowing the multable.
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if int(radius) >= len(mulTable) {
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radius = uint32(len(mulTable) - 1)
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}
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if radius < 1 {
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return errors.New("blur radius must be greater than 0")
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}
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img, ok := dst.(*image.NRGBA)
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if !ok {
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return errors.New("the destination image must be image.NRGBA")
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}
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process(img, src, radius)
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return nil
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}
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func process(dst *image.NRGBA, src image.Image, radius uint32) {
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srcBounds := src.Bounds()
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srcMinX := srcBounds.Min.X
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srcMinY := srcBounds.Min.Y
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dstBounds := srcBounds.Sub(srcBounds.Min)
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dstW := dstBounds.Dx()
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dstH := dstBounds.Dy()
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switch src0 := src.(type) {
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case *image.NRGBA:
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rowSize := srcBounds.Dx() * 4
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for dstY := 0; dstY < dstH; dstY++ {
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di := src0.PixOffset(0, dstY)
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si := src0.PixOffset(srcMinX, srcMinY+dstY)
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for dstX := 0; dstX < dstW; dstX++ {
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copy(dst.Pix[di:di+rowSize], src0.Pix[si:si+rowSize])
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}
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}
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case *image.YCbCr:
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for dstY := 0; dstY < dstH; dstY++ {
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di := dst.PixOffset(0, dstY)
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for dstX := 0; dstX < dstW; dstX++ {
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srcX := srcMinX + dstX
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srcY := srcMinY + dstY
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siy := src0.YOffset(srcX, srcY)
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sic := src0.COffset(srcX, srcY)
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r, g, b := color.YCbCrToRGB(src0.Y[siy], src0.Cb[sic], src0.Cr[sic])
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dst.Pix[di+0] = r
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dst.Pix[di+1] = g
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dst.Pix[di+2] = b
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dst.Pix[di+3] = 0xff
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di += 4
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}
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}
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default:
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for dstY := 0; dstY < dstH; dstY++ {
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di := dst.PixOffset(0, dstY)
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for dstX := 0; dstX < dstW; dstX++ {
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c := color.NRGBAModel.Convert(src.At(srcMinX+dstX, srcMinY+dstY)).(color.NRGBA)
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dst.Pix[di+0] = c.R
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dst.Pix[di+1] = c.G
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dst.Pix[di+2] = c.B
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dst.Pix[di+3] = c.A
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di += 4
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}
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}
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}
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blurImage(dst, radius)
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}
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func blurImage(src *image.NRGBA, radius uint32) {
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var (
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stackEnd *blurStack
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stackIn *blurStack
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stackOut *blurStack
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)
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var width, height = uint32(src.Bounds().Dx()), uint32(src.Bounds().Dy())
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var (
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div, widthMinus1, heightMinus1, radiusPlus1, sumFactor uint32
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x, y, i, p, yp, yi, yw,
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rSum, gSum, bSum, aSum,
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rOutSum, gOutSum, bOutSum, aOutSum,
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rInSum, gInSum, bInSum, aInSum,
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pr, pg, pb, pa uint32
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)
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div = radius + radius + 1
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widthMinus1 = width - 1
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heightMinus1 = height - 1
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radiusPlus1 = radius + 1
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sumFactor = radiusPlus1 * (radiusPlus1 + 1) / 2
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stackStart := new(blurStack)
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stack := stackStart
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for i = 1; i < div; i++ {
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stack.next = new(blurStack)
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stack = stack.next
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if i == radiusPlus1 {
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stackEnd = stack
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}
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}
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stack.next = stackStart
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mulSum := mulTable[radius]
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shgSum := shgTable[radius]
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for y = 0; y < height; y++ {
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rInSum, gInSum, bInSum, aInSum, rSum, gSum, bSum, aSum = 0, 0, 0, 0, 0, 0, 0, 0
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pr = uint32(src.Pix[yi])
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pg = uint32(src.Pix[yi+1])
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pb = uint32(src.Pix[yi+2])
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pa = uint32(src.Pix[yi+3])
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rOutSum = radiusPlus1 * pr
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gOutSum = radiusPlus1 * pg
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bOutSum = radiusPlus1 * pb
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aOutSum = radiusPlus1 * pa
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rSum += sumFactor * pr
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gSum += sumFactor * pg
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bSum += sumFactor * pb
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aSum += sumFactor * pa
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stack = stackStart
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for i = 0; i < radiusPlus1; i++ {
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stack.r = pr
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stack.g = pg
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stack.b = pb
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stack.a = pa
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stack = stack.next
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}
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for i = 1; i < radiusPlus1; i++ {
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var diff uint32
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if widthMinus1 < i {
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diff = widthMinus1
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} else {
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diff = i
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}
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p = yi + (diff << 2)
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pr = uint32(src.Pix[p])
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pg = uint32(src.Pix[p+1])
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pb = uint32(src.Pix[p+2])
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pa = uint32(src.Pix[p+3])
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stack.r = pr
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stack.g = pg
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stack.b = pb
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stack.a = pa
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rSum += stack.r * (radiusPlus1 - i)
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gSum += stack.g * (radiusPlus1 - i)
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bSum += stack.b * (radiusPlus1 - i)
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aSum += stack.a * (radiusPlus1 - i)
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rInSum += pr
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gInSum += pg
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bInSum += pb
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aInSum += pa
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stack = stack.next
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}
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stackIn = stackStart
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stackOut = stackEnd
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for x = 0; x < width; x++ {
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pa = (aSum * mulSum) >> shgSum
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src.Pix[yi+3] = uint8(pa)
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if pa != 0 {
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src.Pix[yi] = uint8((rSum * mulSum) >> shgSum)
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src.Pix[yi+1] = uint8((gSum * mulSum) >> shgSum)
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src.Pix[yi+2] = uint8((bSum * mulSum) >> shgSum)
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} else {
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src.Pix[yi] = 0
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src.Pix[yi+1] = 0
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src.Pix[yi+2] = 0
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}
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rSum -= rOutSum
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gSum -= gOutSum
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bSum -= bOutSum
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aSum -= aOutSum
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rOutSum -= stackIn.r
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gOutSum -= stackIn.g
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bOutSum -= stackIn.b
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aOutSum -= stackIn.a
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p = x + radius + 1
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if p > widthMinus1 {
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p = widthMinus1
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}
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p = (yw + p) << 2
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stackIn.r = uint32(src.Pix[p])
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stackIn.g = uint32(src.Pix[p+1])
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stackIn.b = uint32(src.Pix[p+2])
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stackIn.a = uint32(src.Pix[p+3])
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rInSum += stackIn.r
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gInSum += stackIn.g
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bInSum += stackIn.b
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aInSum += stackIn.a
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rSum += rInSum
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gSum += gInSum
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bSum += bInSum
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aSum += aInSum
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stackIn = stackIn.next
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pr = stackOut.r
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pg = stackOut.g
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pb = stackOut.b
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pa = stackOut.a
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rOutSum += pr
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gOutSum += pg
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bOutSum += pb
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aOutSum += pa
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rInSum -= pr
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gInSum -= pg
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bInSum -= pb
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aInSum -= pa
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stackOut = stackOut.next
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yi += 4
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}
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yw += width
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}
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for x = 0; x < width; x++ {
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rInSum, gInSum, bInSum, aInSum, rSum, gSum, bSum, aSum = 0, 0, 0, 0, 0, 0, 0, 0
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yi = x << 2
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pr = uint32(src.Pix[yi])
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pg = uint32(src.Pix[yi+1])
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pb = uint32(src.Pix[yi+2])
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pa = uint32(src.Pix[yi+3])
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rOutSum = radiusPlus1 * pr
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gOutSum = radiusPlus1 * pg
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bOutSum = radiusPlus1 * pb
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aOutSum = radiusPlus1 * pa
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rSum += sumFactor * pr
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gSum += sumFactor * pg
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bSum += sumFactor * pb
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aSum += sumFactor * pa
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stack = stackStart
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for i = 0; i < radiusPlus1; i++ {
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stack.r = pr
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stack.g = pg
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stack.b = pb
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stack.a = pa
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stack = stack.next
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}
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yp = width
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for i = 1; i <= radius; i++ {
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yi = (yp + x) << 2
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pr = uint32(src.Pix[yi])
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pg = uint32(src.Pix[yi+1])
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pb = uint32(src.Pix[yi+2])
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pa = uint32(src.Pix[yi+3])
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stack.r = pr
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stack.g = pg
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stack.b = pb
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stack.a = pa
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rSum += stack.r * (radiusPlus1 - i)
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gSum += stack.g * (radiusPlus1 - i)
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bSum += stack.b * (radiusPlus1 - i)
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aSum += stack.a * (radiusPlus1 - i)
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rInSum += pr
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gInSum += pg
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bInSum += pb
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aInSum += pa
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stack = stack.next
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if i < heightMinus1 {
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yp += width
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}
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}
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yi = x
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stackIn = stackStart
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stackOut = stackEnd
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for y = 0; y < height; y++ {
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p = yi << 2
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pa = (aSum * mulSum) >> shgSum
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src.Pix[p+3] = uint8(pa)
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if pa > 0 {
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src.Pix[p] = uint8((rSum * mulSum) >> shgSum)
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src.Pix[p+1] = uint8((gSum * mulSum) >> shgSum)
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src.Pix[p+2] = uint8((bSum * mulSum) >> shgSum)
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} else {
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src.Pix[p] = 0
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src.Pix[p+1] = 0
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src.Pix[p+2] = 0
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}
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rSum -= rOutSum
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gSum -= gOutSum
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bSum -= bOutSum
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aSum -= aOutSum
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rOutSum -= stackIn.r
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gOutSum -= stackIn.g
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bOutSum -= stackIn.b
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aOutSum -= stackIn.a
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p = y + radiusPlus1
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if p > heightMinus1 {
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p = heightMinus1
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}
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p = (x + (p * width)) << 2
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stackIn.r = uint32(src.Pix[p])
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stackIn.g = uint32(src.Pix[p+1])
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stackIn.b = uint32(src.Pix[p+2])
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stackIn.a = uint32(src.Pix[p+3])
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rInSum += stackIn.r
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gInSum += stackIn.g
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bInSum += stackIn.b
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aInSum += stackIn.a
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rSum += rInSum
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gSum += gInSum
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bSum += bInSum
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aSum += aInSum
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stackIn = stackIn.next
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pr = stackOut.r
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pg = stackOut.g
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pb = stackOut.b
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pa = stackOut.a
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rOutSum += pr
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gOutSum += pg
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bOutSum += pb
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aOutSum += pa
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rInSum -= pr
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gInSum -= pg
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bInSum -= pb
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aInSum -= pa
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stackOut = stackOut.next
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yi += width
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}
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}
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}
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