80 lines
1.9 KiB
Go
80 lines
1.9 KiB
Go
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package imageproc
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import (
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"image"
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"image/color"
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xdraw "golang.org/x/image/draw"
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)
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func Crop(src image.Image, rect image.Rectangle) image.Image {
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b := src.Bounds()
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rect = rect.Intersect(b)
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if rect.Empty() {
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rect = b
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}
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dst := image.NewRGBA(image.Rect(0, 0, rect.Dx(), rect.Dy()))
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for y := rect.Min.Y; y < rect.Max.Y; y++ {
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for x := rect.Min.X; x < rect.Max.X; x++ {
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dst.Set(x-rect.Min.X, y-rect.Min.Y, src.At(x, y))
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}
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}
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return dst
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}
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func ResizeToMax(src image.Image, maxDim int) image.Image {
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if maxDim <= 0 {
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return src
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}
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b := src.Bounds()
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w, h := b.Dx(), b.Dy()
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if w <= maxDim && h <= maxDim {
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return normalizeRGBA(src)
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}
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nw, nh := w, h
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if w >= h {
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nw = maxDim
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nh = max(1, h*maxDim/w)
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} else {
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nh = maxDim
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nw = max(1, w*maxDim/h)
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}
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dst := image.NewRGBA(image.Rect(0, 0, nw, nh))
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xdraw.CatmullRom.Scale(dst, dst.Bounds(), src, b, xdraw.Over, nil)
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return dst
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}
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func ResizeToFill(src image.Image, width, height int) image.Image {
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if width <= 0 || height <= 0 {
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return normalizeRGBA(src)
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}
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b := src.Bounds()
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srcRatio := float64(b.Dx()) / float64(b.Dy())
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dstRatio := float64(width) / float64(height)
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crop := b
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if srcRatio > dstRatio {
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cropW := int(float64(b.Dy()) * dstRatio)
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x0 := b.Min.X + (b.Dx()-cropW)/2
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crop = image.Rect(x0, b.Min.Y, x0+cropW, b.Max.Y)
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} else if srcRatio < dstRatio {
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cropH := int(float64(b.Dx()) / dstRatio)
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y0 := b.Min.Y + (b.Dy()-cropH)/2
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crop = image.Rect(b.Min.X, y0, b.Max.X, y0+cropH)
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}
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dst := image.NewRGBA(image.Rect(0, 0, width, height))
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xdraw.CatmullRom.Scale(dst, dst.Bounds(), src, crop, xdraw.Over, nil)
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return dst
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}
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func normalizeRGBA(src image.Image) image.Image {
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b := src.Bounds()
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dst := image.NewRGBA(image.Rect(0, 0, b.Dx(), b.Dy()))
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xdraw.Draw(dst, dst.Bounds(), src, b.Min, xdraw.Src)
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return dst
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}
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func rgba8(c color.Color) (int, int, int) {
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r, g, b, _ := c.RGBA()
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return int(r >> 8), int(g >> 8), int(b >> 8)
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}
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