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57 lines
1.3 KiB
57 lines
1.3 KiB
package webp
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import "image"
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// YUVAImage represents a image of YUV colors with alpha channel image.
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//
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// We can not insert WebP planer image into image.YCbCr,
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// because image.YCbCr is not compatible with ITU-R BT.601, but JFIF/JPEG one.
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//
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// See: http://en.wikipedia.org/wiki/YCbCr
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type YUVAImage struct {
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Y, Cb, Cr, A []uint8
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YStride int
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CStride int
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AStride int
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ColorSpace ColorSpace
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Rect image.Rectangle
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}
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// NewYUVAImage creates and allocates image buffer.
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func NewYUVAImage(r image.Rectangle, c ColorSpace) (image *YUVAImage) {
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yw, yh := r.Dx(), r.Dx()
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cw, ch := ((r.Max.X+1)/2 - r.Min.X/2), ((r.Max.Y+1)/2 - r.Min.Y/2)
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switch c {
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case YUV420:
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b := make([]byte, yw*yh+2*cw*ch)
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image = &YUVAImage{
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Y: b[:yw*yh],
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Cb: b[yw*yh+0*cw*ch : yw*yh+1*cw*ch],
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Cr: b[yw*yh+1*cw*ch : yw*yh+2*cw*ch],
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A: nil,
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YStride: yw,
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CStride: cw,
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AStride: 0,
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ColorSpace: c,
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Rect: r,
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}
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case YUV420A:
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b := make([]byte, 2*yw*yh+2*cw*ch)
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image = &YUVAImage{
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Y: b[:yw*yh],
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Cb: b[yw*yh+0*cw*ch : yw*yh+1*cw*ch],
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Cr: b[yw*yh+1*cw*ch : yw*yh+2*cw*ch],
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A: b[yw*yh+2*cw*ch:],
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YStride: yw,
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CStride: cw,
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AStride: yw,
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ColorSpace: c,
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Rect: r,
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}
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}
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return
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}
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