How to merge multiple images together using GD library?

Question

I have removed my original question as I have managed to partially get this working, what I have is 7 images,

https://dl.dropboxusercontent.com/u/58586640/layer1.png https://dl.dropboxusercontent.com/u/58586640/layer2.png https://dl.dropboxusercontent.com/u/58586640/layer3.png https://dl.dropboxusercontent.com/u/58586640/layer4.png https://dl.dropboxusercontent.com/u/58586640/layer5.png https://dl.dropboxusercontent.com/u/58586640/layer6.png https://dl.dropboxusercontent.com/u/58586640/layer7.png

Each of these images when placed over the top of each other should create one image that slots together perfectly.

The current result i have is,

https://dl.dropboxusercontent.com/u/58586640/Screen%20Shot%202013-12-11%20at%2018.31.57.png

As you can see it works nearly perfectly but 2 of the layers are either not being copied or are not getting the alphas saved correctly. I am not sure what I am doing wrong, as all the other layers seem to working fine, the images that are coming in as black are,

https://dl.dropboxusercontent.com/u/58586640/layer3.png https://dl.dropboxusercontent.com/u/58586640/layer4.png

Here is my current code,

    <?php

$images = array('img/layer1.png', 'img/layer2.png', 'img/layer3.png', 'img/layer4.png', 'img/layer5.png', 'img/layer6.png', 'img/layer7.png');

// foreach($images as $i) {
//  var_dump(file_exists($i));
// }

// Allocate new image

$img = imagecreatetruecolor(704, 469);

// Make alpha channels work

imagealphablending($img, true);
imagesavealpha($img, true);

foreach($images as $fn) {

    // Load image
    $cur = imagecreatefrompng($fn);
    imagealphablending($cur, true);
    imagesavealpha($cur, true);

    // Copy over image
    imagecopy($img, $cur, 0,0,0,0, 704, 469);

    // Free memory
    imagedestroy($cur);

}

header('Content-Type: image/png');
imagepng($img);

As you can see I have checked to make sure that the files exist, and they do so it must be GD problem, anyone have ideas?

Answer 1

Funny I did exactly this yesterday here's how I did it using a static background layer and a QR code which is generated prior to the combine.

$template = imagecreatefrompng("./images/asset_barcode_template.png");
//QR created fine assemble final image
$qrimage = imagecreatefrompng($this->qrfilename);
//final image assembled just fine
imagecopy($template, $qrimage, 230, 6, 0, 0, 106, 106);
imagepng($template,$filename,0,PNG_NO_FILTER);