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// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net>
package images
import (
"fmt"
)
var _ = fmt.Print
func reverse_row(bytes_per_pixel int, pix []uint8) {
if len(pix) <= bytes_per_pixel {
return
}
i := 0
j := len(pix) - bytes_per_pixel
for i < j {
pi := pix[i : i+bytes_per_pixel : i+bytes_per_pixel]
pj := pix[j : j+bytes_per_pixel : j+bytes_per_pixel]
for x := 0; x < bytes_per_pixel; x++ {
pi[x], pj[x] = pj[x], pi[x]
}
i += bytes_per_pixel
j -= bytes_per_pixel
}
}
func (self *Context) FlipPixelsH(bytes_per_pixel, width, height int, pix []uint8) {
stride := bytes_per_pixel * width
self.Parallel(0, height, func(ys <-chan int) {
for y := range ys {
i := y * stride
reverse_row(bytes_per_pixel, pix[i:i+stride])
}
})
}
func (self *Context) FlipPixelsV(bytes_per_pixel, width, height int, pix []uint8) {
stride := bytes_per_pixel * width
num := height / 2
self.Parallel(0, num, func(ys <-chan int) {
for y := range ys {
upper := y
lower := height - 1 - y
a := upper * stride
b := lower * stride
as := pix[a : a+stride : a+stride]
bs := pix[b : b+stride : b+stride]
for i := range as {
as[i], bs[i] = bs[i], as[i]
}
}
})
}
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