diff options
Diffstat (limited to 'vendor/github.com/mattermost/rsc/qr/web/resize/resize.go')
| -rw-r--r-- | vendor/github.com/mattermost/rsc/qr/web/resize/resize.go | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/vendor/github.com/mattermost/rsc/qr/web/resize/resize.go b/vendor/github.com/mattermost/rsc/qr/web/resize/resize.go new file mode 100644 index 000000000..02c8b0040 --- /dev/null +++ b/vendor/github.com/mattermost/rsc/qr/web/resize/resize.go @@ -0,0 +1,152 @@ +// Copyright 2011 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package resize + +import ( + "image" + "image/color" +) + +// average convert the sums to averages and returns the result. +func average(sum []uint64, w, h int, n uint64) *image.RGBA { + ret := image.NewRGBA(image.Rect(0, 0, w, h)) + for y := 0; y < h; y++ { + for x := 0; x < w; x++ { + index := 4 * (y*w + x) + pix := ret.Pix[y*ret.Stride+x*4:] + pix[0] = uint8(sum[index+0] / n) + pix[1] = uint8(sum[index+1] / n) + pix[2] = uint8(sum[index+2] / n) + pix[3] = uint8(sum[index+3] / n) + } + } + return ret +} + +// ResizeRGBA returns a scaled copy of the RGBA image slice r of m. +// The returned image has width w and height h. +func ResizeRGBA(m *image.RGBA, r image.Rectangle, w, h int) *image.RGBA { + ww, hh := uint64(w), uint64(h) + dx, dy := uint64(r.Dx()), uint64(r.Dy()) + // See comment in Resize. + n, sum := dx*dy, make([]uint64, 4*w*h) + for y := r.Min.Y; y < r.Max.Y; y++ { + pix := m.Pix[(y-r.Min.Y)*m.Stride:] + for x := r.Min.X; x < r.Max.X; x++ { + // Get the source pixel. + p := pix[(x-r.Min.X)*4:] + r64 := uint64(p[0]) + g64 := uint64(p[1]) + b64 := uint64(p[2]) + a64 := uint64(p[3]) + // Spread the source pixel over 1 or more destination rows. + py := uint64(y) * hh + for remy := hh; remy > 0; { + qy := dy - (py % dy) + if qy > remy { + qy = remy + } + // Spread the source pixel over 1 or more destination columns. + px := uint64(x) * ww + index := 4 * ((py/dy)*ww + (px / dx)) + for remx := ww; remx > 0; { + qx := dx - (px % dx) + if qx > remx { + qx = remx + } + qxy := qx * qy + sum[index+0] += r64 * qxy + sum[index+1] += g64 * qxy + sum[index+2] += b64 * qxy + sum[index+3] += a64 * qxy + index += 4 + px += qx + remx -= qx + } + py += qy + remy -= qy + } + } + } + return average(sum, w, h, n) +} + +// ResizeNRGBA returns a scaled copy of the RGBA image slice r of m. +// The returned image has width w and height h. +func ResizeNRGBA(m *image.NRGBA, r image.Rectangle, w, h int) *image.RGBA { + ww, hh := uint64(w), uint64(h) + dx, dy := uint64(r.Dx()), uint64(r.Dy()) + // See comment in Resize. + n, sum := dx*dy, make([]uint64, 4*w*h) + for y := r.Min.Y; y < r.Max.Y; y++ { + pix := m.Pix[(y-r.Min.Y)*m.Stride:] + for x := r.Min.X; x < r.Max.X; x++ { + // Get the source pixel. + p := pix[(x-r.Min.X)*4:] + r64 := uint64(p[0]) + g64 := uint64(p[1]) + b64 := uint64(p[2]) + a64 := uint64(p[3]) + r64 = (r64 * a64) / 255 + g64 = (g64 * a64) / 255 + b64 = (b64 * a64) / 255 + // Spread the source pixel over 1 or more destination rows. + py := uint64(y) * hh + for remy := hh; remy > 0; { + qy := dy - (py % dy) + if qy > remy { + qy = remy + } + // Spread the source pixel over 1 or more destination columns. + px := uint64(x) * ww + index := 4 * ((py/dy)*ww + (px / dx)) + for remx := ww; remx > 0; { + qx := dx - (px % dx) + if qx > remx { + qx = remx + } + qxy := qx * qy + sum[index+0] += r64 * qxy + sum[index+1] += g64 * qxy + sum[index+2] += b64 * qxy + sum[index+3] += a64 * qxy + index += 4 + px += qx + remx -= qx + } + py += qy + remy -= qy + } + } + } + return average(sum, w, h, n) +} + +// Resample returns a resampled copy of the image slice r of m. +// The returned image has width w and height h. +func Resample(m image.Image, r image.Rectangle, w, h int) *image.RGBA { + if w < 0 || h < 0 { + return nil + } + if w == 0 || h == 0 || r.Dx() <= 0 || r.Dy() <= 0 { + return image.NewRGBA(image.Rect(0, 0, w, h)) + } + curw, curh := r.Dx(), r.Dy() + img := image.NewRGBA(image.Rect(0, 0, w, h)) + for y := 0; y < h; y++ { + for x := 0; x < w; x++ { + // Get a source pixel. + subx := x * curw / w + suby := y * curh / h + r32, g32, b32, a32 := m.At(subx, suby).RGBA() + r := uint8(r32 >> 8) + g := uint8(g32 >> 8) + b := uint8(b32 >> 8) + a := uint8(a32 >> 8) + img.SetRGBA(x, y, color.RGBA{r, g, b, a}) + } + } + return img +} |