/**
* Returns a greyscale copy of an image
*
* @param WideImage_Image $image
* @return WideImage_Image
*/
function execute($image)
{
$palette = !$image->isTrueColor();
$transparent = $image->isTransparent();
if ($palette && $transparent) {
$tcrgb = $image->getTransparentColorRGB();
}
$new = $image->asTrueColor();
if (!imagefilter($new->getHandle(), IMG_FILTER_NEGATE)) {
throw new WideImage_GDFunctionResultException("imagefilter() returned false");
}
if ($palette) {
$new = $new->asPalette();
if ($transparent) {
$irgb = array('red' => 255 - $tcrgb['red'], 'green' => 255 - $tcrgb['green'], 'blue' => 255 - $tcrgb['blue'], 'alpha' => 127);
// needs imagecolorexactalpha instead of imagecolorexact, otherwise doesn't work on some transparent GIF images
$new_tci = imagecolorexactalpha($new->getHandle(), $irgb['red'], $irgb['green'], $irgb['blue'], 127);
$new->setTransparentColor($new_tci);
}
}
return $new;
}
