public function algorithm($callback)
{
if (!$callback instanceof imagealgorithm) {
throw new ImageException("Callback is no class implementing " . "interface 'imagealgorithm'.");
}
if ($callback->option("newimg")) {
$new = new self();
$new->createtruecolor($this->width(), $this->height());
$new->preparecopy($this);
}
$callback->setoriginalimage($this);
if ($callback->option("newimg") && method_exists($callback, "setnewimage")) {
$callback->setnewimage($new);
}
for ($x = 0; $x < $this->width(); $x++) {
for ($y = 0; $y < $this->height(); $y++) {
$color = $callback->algorithm($x, $y);
if (!$callback->option("newimg") || $color == false || $color == self::undefined) {
continue;
}
if (is_numeric($color)) {
$color = min(255, max(0, $color));
$new->setpixelrgb($x, $y, array("red" => $color, "green" => $color, "blue" => $color));
continue;
}
foreach ($color as $key => $val) {
$color[$key] = min(255, max(0, $val));
}
$new->setpixelrgb($x, $y, $color);
}
}
if ($callback->option("newimg")) {
$this->sethandle($new->handle());
$this->setpixelcache($new->getpixelcache());
$new->close();
}
if ($callback->option("return")) {
return $callback->return();
}
return $this;
}
