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<?php
/**
* @author Joas Schilling <nickvergessen@owncloud.com>
* @author Morris Jobke <hey@morrisjobke.de>
* @author Olivier Paroz <github@oparoz.com>
* @author Thomas Müller <thomas.mueller@tmit.eu>
*
* @copyright Copyright (c) 2016, ownCloud, Inc.
* @license AGPL-3.0
*
* This code is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License, version 3,
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
*/
namespace OC\Preview;
use Imagick;
/**
* Creates a PNG preview using ImageMagick via the PECL extension
*
* @package OC\Preview
*/
abstract class Bitmap extends Provider {
/**
* {@inheritDoc}
*/
public function getThumbnail($path, $maxX, $maxY, $scalingup, $fileview) {
$tmpPath = $fileview->toTmpFile($path);
if (!$tmpPath) {
return false;
}
// Creates \Imagick object from bitmap or vector file
try {
$bp = $this->getResizedPreview($tmpPath, $maxX, $maxY);
} catch (\Exception $e) {
\OCP\Util::writeLog('core', 'ImageMagick says: ' . $e->getmessage(), \OCP\Util::ERROR);
return false;
}
unlink($tmpPath);
//new bitmap image object
$image = new \OC_Image();
$image->loadFromData($bp);
//check if image object is valid
return $image->valid() ? $image : false;
}
/**
* Returns a preview of maxX times maxY dimensions in PNG format
*
* * The default resolution is already 72dpi, no need to change it for a bitmap output
* * It's possible to have proper colour conversion using profileimage().
* ICC profiles are here: http://www.color.org/srgbprofiles.xalter
* * It's possible to Gamma-correct an image via gammaImage()
*
* @param string $tmpPath the location of the file to convert
* @param int $maxX
* @param int $maxY
*
* @return \Imagick
*/
private function getResizedPreview($tmpPath, $maxX, $maxY) {
$bp = new Imagick();
// Layer 0 contains either the bitmap or a flat representation of all vector layers
$bp->readImage($tmpPath . '[0]');
$bp = $this->resize($bp, $maxX, $maxY);
$bp->setImageFormat('png');
return $bp;
}
/**
* Returns a resized \Imagick object
*
* If you want to know more on the various methods available to resize an
* image, check out this link : @link https://stackoverflow.com/questions/8517304/what-the-difference-of-sample-resample-scale-resize-adaptive-resize-thumbnail-im
*
* @param \Imagick $bp
* @param int $maxX
* @param int $maxY
*
* @return \Imagick
*/
private function resize($bp, $maxX, $maxY) {
list($previewWidth, $previewHeight) = array_values($bp->getImageGeometry());
// We only need to resize a preview which doesn't fit in the maximum dimensions
if ($previewWidth > $maxX || $previewHeight > $maxY) {
// TODO: LANCZOS is the default filter, CATROM could bring similar results faster
$bp->resizeImage($maxX, $maxY, imagick::FILTER_LANCZOS, 1, true);
}
return $bp;
}
}
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