KjwImage.php

<?php // vim:ts=4:sw=4:noet
/*====================================================================== 
Copyright (C) 2006-2009, Walter Doekes
This file is part of KjwLib-php45.
 
KjwLib-php45 is free software: you can redistribute it and/or modify 
it under the terms of the GNU General Public License as published by 
the Free Software Foundation, either version 3 of the License, or 
(at your option) any later version. 

KjwLib-php45 is distributed in the hope that it will be useful, 
but WITHOUT ANY WARRANTY; without even the implied warranty of 
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
GNU General Public License for more details. 

You should have received a copy of the GNU General Public License 
along with KjwLib-php45.  If not, see <http://www.gnu.org/licenses/>. 
======================================================================*/

function kjwimage_create_thumbnail($infile, $outfile, $outx, $outy,
                &$characteristics = array()) {
        assert('strrpos($outfile, ".") !== false');
        $outext = strtolower(substr($outfile, strrpos($outfile, '.') + 1));
        if ($outext == 'jpeg')
                $outext = 'jpg';
        assert('$outext == "gif" || $outext == "jpg" || $outext == "png"');

        // Return-characteristics
        $characteristics = array();

        // Open image
        if (($inimg = @imagecreatefrompng($infile))) {
                $inext = 'png';
        } elseif (($inimg = @imagecreatefromjpeg($infile))) {
                $inext = 'jpg';
        } elseif (($inimg = @imagecreatefromgif($infile))) {
                $inext = 'gif';
        } else {
                return null;
        }

        // Image type
        $characteristics['input.extension'] = $inext;

        // Select scale (if $outx or $outy is null, we use inscale as outscale)
        $inx = imagesx($inimg);
        $iny = imagesy($inimg);
        $inscale = (float)$inx / (float)$iny;
        if ($outx !== null && $outy !== null) {
                $outscale = (float)$outx / (float)$outy;
        } elseif ($outx !== null && $outy === null) {
                $outscale = $inscale;
                $outy = $outx / $outscale;
        } elseif ($outx === null && $outy !== null) {
                $outscale = $inscale;
                $outx = $outy * $outscale;
        } else {
                assert(0);
        }

        // Create new image
        if (!($outimg = @imagecreatetruecolor($outx, $outy))) {
                imagedestroy($inimg);
                return null;
        }

        // In case we save as png, we use a transparent background, otherwise we use a white one.
        if ($outext == 'png') {
                imagesavealpha($outimg, true);
                imagealphablending($outimg, false);
                imagefill($outimg, 0, 0, imagecolorallocatealpha($outimg, 0xff, 0x00, 0xff, 127));
        } else {
                imagefill($outimg, 0, 0, imagecolorallocate($outimg, 0xff, 0xff, 0xff));
        }

        // Image size
        $characteristics['input.width'] = $inx;
        $characteristics['input.height'] = $iny;

        // If small scale difference, use full image and stretch it a bit.
        if (abs($outscale - $inscale) < 0.1) {
                $success = imagecopyresampled($outimg, $inimg, 0, 0, 0, 0, $outx, $outy, $inx, $iny);
        // If the image is too high, add space on the sides.
        } elseif ($outscale < $inscale) {
                $newy = (int)((float)$outx / $inscale);
                $success = imagecopyresampled($outimg, $inimg, 0, (int)(($outy - $newy) / 2), 0, 0, $outx, $newy, $inx, $iny);
        // If the image is too wide, add space on top/bottom.
        } else {
                $newx = (int)((float)$outy * $inscale);
                $success = imagecopyresampled($outimg, $inimg, (int)(($outx - $newx) / 2), 0, 0, 0, $newx, $outy, $inx, $iny);
        }

        imagedestroy($inimg); // Free memory early :)
        
        // Write image
        if ($success) {
                if ($outext == 'jpg') {
                        $success = imagejpeg($outimg, $outfile);
                } elseif ($outext == 'png') {
                        $success = imagepng($outimg, $outfile);
                } elseif ($outext == 'gif') {
                        $success = imagegif($outimg, $outfile);
                } else {
                        assert('false');
                }
        }

        imagedestroy($outimg); // Free more
        return $success;
}

?>

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