/**
* Returns an image with only specified channels copied
*
* @param WideImage_PaletteImage $img
* @param array $channels
* @return WideImage_PaletteImage
*/
function execute($img, $channels)
{
$blank = array('red' => 0, 'green' => 0, 'blue' => 0);
if (isset($channels['alpha'])) {
unset($channels['alpha']);
}
$width = $img->getWidth();
$height = $img->getHeight();
$copy = WideImage_PaletteImage::create($width, $height);
if ($img->isTransparent()) {
$otci = $img->getTransparentColor();
$TRGB = $img->getColorRGB($otci);
$tci = $copy->allocateColor($TRGB);
} else {
$otci = null;
$tci = null;
}
for ($x = 0; $x < $width; $x++) {
for ($y = 0; $y < $height; $y++) {
$ci = $img->getColorAt($x, $y);
if ($ci === $otci) {
$copy->setColorAt($x, $y, $tci);
continue;
}
$RGB = $img->getColorRGB($ci);
$newRGB = $blank;
foreach ($channels as $channel) {
$newRGB[$channel] = $RGB[$channel];
}
$color = $copy->getExactColor($newRGB);
if ($color == -1) {
$color = $copy->allocateColor($newRGB);
}
$copy->setColorAt($x, $y, $color);
}
}
if ($img->isTransparent()) {
$copy->setTransparentColor($tci);
}
return $copy;
}
