152 lines
3.8 KiB
Go
152 lines
3.8 KiB
Go
package qr
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import (
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"image"
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"image/color"
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)
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// average convert the sums to averages and returns the result.
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func average(sum []uint64, w, h int, n uint64) *image.RGBA {
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ret := image.NewRGBA(image.Rect(0, 0, w, h))
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for y := 0; y < h; y++ {
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for x := 0; x < w; x++ {
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index := 4 * (y*w + x)
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pix := ret.Pix[y*ret.Stride+x*4:]
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pix[0] = uint8(sum[index+0] / n)
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pix[1] = uint8(sum[index+1] / n)
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pix[2] = uint8(sum[index+2] / n)
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pix[3] = uint8(sum[index+3] / n)
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}
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}
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return ret
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}
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// ResizeRGBA returns a scaled copy of the RGBA image slice r of m.
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// The returned image has width w and height h.
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func ResizeRGBA(m *image.RGBA, r image.Rectangle, w, h int) *image.RGBA {
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ww, hh := uint64(w), uint64(h)
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dx, dy := uint64(r.Dx()), uint64(r.Dy())
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// See comment in Resize.
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n, sum := dx*dy, make([]uint64, 4*w*h)
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for y := r.Min.Y; y < r.Max.Y; y++ {
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pix := m.Pix[(y-r.Min.Y)*m.Stride:]
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for x := r.Min.X; x < r.Max.X; x++ {
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// Get the source pixel.
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p := pix[(x-r.Min.X)*4:]
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r64 := uint64(p[0])
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g64 := uint64(p[1])
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b64 := uint64(p[2])
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a64 := uint64(p[3])
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// Spread the source pixel over 1 or more destination rows.
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py := uint64(y) * hh
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for remy := hh; remy > 0; {
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qy := dy - (py % dy)
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if qy > remy {
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qy = remy
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}
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// Spread the source pixel over 1 or more destination columns.
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px := uint64(x) * ww
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index := 4 * ((py/dy)*ww + (px / dx))
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for remx := ww; remx > 0; {
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qx := dx - (px % dx)
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if qx > remx {
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qx = remx
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}
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qxy := qx * qy
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sum[index+0] += r64 * qxy
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sum[index+1] += g64 * qxy
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sum[index+2] += b64 * qxy
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sum[index+3] += a64 * qxy
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index += 4
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px += qx
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remx -= qx
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}
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py += qy
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remy -= qy
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}
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}
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}
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return average(sum, w, h, (uint64)(n))
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}
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// ResizeNRGBA returns a scaled copy of the RGBA image slice r of m.
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// The returned image has width w and height h.
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func ResizeNRGBA(m *image.NRGBA, r image.Rectangle, w, h int) *image.RGBA {
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ww, hh := uint64(w), uint64(h)
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dx, dy := uint64(r.Dx()), uint64(r.Dy())
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// See comment in Resize.
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n, sum := dx*dy, make([]uint64, 4*w*h)
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for y := r.Min.Y; y < r.Max.Y; y++ {
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pix := m.Pix[(y-r.Min.Y)*m.Stride:]
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for x := r.Min.X; x < r.Max.X; x++ {
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// Get the source pixel.
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p := pix[(x-r.Min.X)*4:]
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r64 := uint64(p[0])
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g64 := uint64(p[1])
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b64 := uint64(p[2])
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a64 := uint64(p[3])
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r64 = (r64 * a64) / 255
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g64 = (g64 * a64) / 255
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b64 = (b64 * a64) / 255
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// Spread the source pixel over 1 or more destination rows.
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py := uint64(y) * hh
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for remy := hh; remy > 0; {
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qy := dy - (py % dy)
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if qy > remy {
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qy = remy
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}
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// Spread the source pixel over 1 or more destination columns.
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px := uint64(x) * ww
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index := 4 * ((py/dy)*ww + (px / dx))
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for remx := ww; remx > 0; {
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qx := dx - (px % dx)
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if qx > remx {
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qx = remx
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}
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qxy := qx * qy
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sum[index+0] += r64 * qxy
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sum[index+1] += g64 * qxy
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sum[index+2] += b64 * qxy
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sum[index+3] += a64 * qxy
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index += 4
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px += qx
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remx -= qx
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}
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py += qy
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remy -= qy
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}
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}
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}
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return average(sum, w, h, (uint64)(n))
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}
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// Resample returns a resampled copy of the image slice r of m.
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// The returned image has width w and height h.
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func Resample(m image.Image, r image.Rectangle, w, h int) *image.RGBA {
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if w < 0 || h < 0 {
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return nil
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}
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if w == 0 || h == 0 || r.Dx() <= 0 || r.Dy() <= 0 {
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return image.NewRGBA(image.Rect(0, 0, w, h))
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}
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curw, curh := r.Dx(), r.Dy()
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img := image.NewRGBA(image.Rect(0, 0, w, h))
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for y := 0; y < h; y++ {
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for x := 0; x < w; x++ {
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// Get a source pixel.
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subx := x * curw / w
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suby := y * curh / h
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r32, g32, b32, a32 := m.At(subx, suby).RGBA()
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r := uint8(r32 >> 8)
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g := uint8(g32 >> 8)
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b := uint8(b32 >> 8)
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a := uint8(a32 >> 8)
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img.SetRGBA(x, y, color.RGBA{r, g, b, a})
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}
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}
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return img
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}
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