server/lib/private/preview/bitmap.php

<?php
/**
 * Copyright (c) 2013-2014 Georg Ehrke georg@ownCloud.com
 * This file is licensed under the Affero General Public License version 3 or
 * later.
 * See the COPYING-README file.
 */

namespace OC\Preview;

abstract class Bitmap extends Provider {
	/**
	 * {@inheritDoc}
	 */
	public function getThumbnail($path, $maxX, $maxY, $scalingup, $fileview) {
		$tmpPath = $fileview->toTmpFile($path);

		//create imagick object from bitmap or vector file
		try {
			// Layer 0 contains either the bitmap or
			// a flat representation of all vector layers
			$bp = new \Imagick($tmpPath . '[0]');

			$bp->setImageFormat('png');
		} catch (\Exception $e) {
			\OC_Log::write('core', $e->getmessage(), \OC_Log::ERROR);
			return false;
		}

		unlink($tmpPath);

		//new bitmap image object
		$image = new \OC_Image($bp);
		//check if image object is valid
		return $image->valid() ? $image : false;
	}
}