Join multiple PNG Images into a single one PNG using PHP

Question

I´m trying to make custom sprites based on my own PNGs using PHP, but I got two problems:

1. Output Image it´s a collection of stacked PNGs... in other words: source PNGs are one over other.
2. I need a transparent background for the output image!

This is the code that I used:

$width = 210;
$height = 190;

$layers = array();
$layers[] = imagecreatefrompng("copy.png");
$layers[] = imagecreatefrompng("cut.png");

$image = imagecreatetruecolor($width, $height);

// to make background transparent?
imagealphablending($image, false);
$transparency = imagecolorallocatealpha($image, 0, 0, 0, 127);
imagefill($image, 0, 0, $transparency);
imagesavealpha($image, true);

imagealphablending($image, true);
for ($i = 0; $i < count($layers); $i++) {
    imagecopy($image, $layers[$i], 0, 0, 0, 0, $width, $height);
}
imagealphablending($image, false);
imagesavealpha($image, true);

imagepng($image, 'final_img.png'); 

Answer 1

After one hour trying to do the Job using only PHP GD I decided to give a chance to this Library called "ImageWorkshop" which is accessible from here:

http://phpimageworkshop.com/

The result is AWESOME, with less of 10 lines of code I solve the situation. Here is How:

(Obviously, first you have to download ImageWorkshop)

NOTE: I will use a little bit descriptive code to ensure everybody understanding :)

require_once('libs/PHPImageWorkshop/ImageWorkshop.php');

/*The Empty Layer have 100x100... And is TRANSPARENT!!*/ 
$emptyLayer = ImageWorkshop::initVirginLayer(100, 100); 

$cut = ImageWorkshop::initFromPath(__DIR__ . '/icons/copy.png');
$copy = ImageWorkshop::initFromPath(__DIR__ . '/icons/cut.png');

/*Set the position of "cut" and "copy" icons inside the emptyLayer*/
$emptyLayer->addLayerOnTop($cut, 20, 10, 'LT');
$emptyLayer->addLayerOnTop($copy, 20, 30, 'LT');

// Saving the result
$dirPath = __DIR__ . "/icons/";
$filename = "output.png";
$createFolders = true; //will create the folder if not exist
$backgroundColor = null; // transparent, only for PNG (otherwise it will be white if set null)
$imageQuality = 100; // useless for GIF, usefull for PNG and JPEG (0 to 100%)

$emptyLayer->save($dirPath, $filename, $createFolders, $backgroundColor, $imageQuality);

Thats all!

By the way this small Library uses the PHP GD library.