1 files changed, 114 insertions, 0 deletions
diff --git a/lib/private/Preview/Bitmap.php b/lib/private/Preview/Bitmap.php
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+++ b/lib/private/Preview/Bitmap.php
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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;
+	}
+
+}