76 lines
1.4 KiB
Go
76 lines
1.4 KiB
Go
package downscale
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import (
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"image"
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"image/color"
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)
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type sub struct {
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image.Image
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image.Rectangle
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}
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func (sub sub) ColorModel() color.Model { return sub.Image.ColorModel() }
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func (sub sub) Bounds() image.Rectangle { return sub.Rectangle }
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func (sub sub) At(x, y int) color.Color {
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return sub.Image.At(x, y)
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}
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type GridDownscale struct {
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image.Image
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NewBounds image.Rectangle
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}
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func blend(c1, c2 color.Color) color.RGBA {
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r1, g1, b1, a1 := c1.RGBA()
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r2, g2, b2, a2 := c2.RGBA()
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r := r1/2 + r2/2
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g := g1/2 + g2/2
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b := b1/2 + b2/2
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a := a1/2 + a2/2
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return color.RGBA{
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R: uint8(r >> 8),
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G: uint8(g >> 8),
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B: uint8(b >> 8),
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A: uint8(a >> 8),
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}
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}
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func avgColor(img image.Image) (c color.Color) {
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b := img.Bounds()
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c = img.At(b.Min.X, b.Min.Y)
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for y := b.Min.Y; y < b.Max.Y; y++ {
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for x := b.Min.X + 1; x < b.Max.X; x++ {
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c = blend(c, img.At(x, y))
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}
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}
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return
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}
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func (grid GridDownscale) ColorModel() color.Model { return grid.Image.ColorModel() }
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func (grid GridDownscale) Bounds() image.Rectangle { return grid.NewBounds }
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func (grid GridDownscale) At(x, y int) color.Color {
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b := grid.Image.Bounds()
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dx, dy := b.Dx(), b.Dy()
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cellBounds := image.Rect(
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0, 0,
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dx/grid.NewBounds.Dx(),
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dy/grid.NewBounds.Dy(),
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)
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r := grid.Image.Bounds().Intersect(
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// move cell
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cellBounds.Add(
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image.Point{
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x * cellBounds.Dx(),
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y * cellBounds.Dy(),
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},
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),
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)
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println(r.Min.X, r.Min.Y)
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return avgColor(sub{grid.Image, r})
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}
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