panorama.php

<?php

function panorama($file_name, $water_mark = false, $r = 255, $g = 255, $b = 255)
{
    list($width_x, $size) = getimagesize($file_name);

    if ($width_x < $size) {
        throw new Exception('The panorama must be horizontal');
    }

    if (($src_im = imagecreatefromjpeg($file_name)) === false) {
        if (($src_im = imagecreatefrompng($file_name)) === false) {
            if (($src_im = imagecreatefromgif($file_name)) === false) {
                throw new Exception('Undefined format');
            }
        }
    }

    var_dump($src_im);

    $sections = intval(ceil($width_x / $size));
    $diff     = ($sections * $size - $width_x) / 2;

    for ($i = 0; $i < $sections; $i++) {
        $dst_im   = imagecreatetruecolor($size, $size);
        $bg_color = imagecolorallocate($dst_im, $r, $g, $b);
        imagefilledrectangle($dst_im, 0, 0, $size, $size, $bg_color);

        $dst_x = $diff * ( ! boolval($i));
        $dst_y = 0;
        $src_x = ($size * $i) - $diff * (boolval($i));
        $src_y = 0;
        $src_w = $size - (( ! boolval($i) || $i + 1 == $sections) ? $diff : 0);
        $src_h = $size;

        imagecopy($dst_im, $src_im, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h);

        if ($water_mark && $i + 1 == $sections) {
            $water_mark = imagecreatefrompng($water_mark);
            list($water_mark_x, $water_mark_y) = getimagesize($water_mark);
            $k1 = $size / 2 / $water_mark_y;
            $w_x = ($k1 * $water_mark_x);
            $w_y = ($k1 * $water_mark_y);

            $dst_x = $size - $w_x + 1;
            $dst_y = $size - $w_y + 1;
            $src_x = 0;
            $src_y = 0;
            $dst_w = $w_x;
            $dst_h = $w_y;
            $src_w = $water_mark_x;
            $src_h = $water_mark_y;

            imagecopyresized($dst_im, $water_mark, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h);
        }

        header('Content-Type: image/png');
        imagepng($dst_im, 'panorama_'.($i + 1).'.png', 0);
        imagedestroy($dst_im);
    }
}

//  panorama('IMG_9115.JPG');
//  panorama('IMG_9115.PNG');
//  panorama('IMG_9115.GIF');

// output ./panorama_(\d+).png