PhotoUtil.java

/*
 * Copyright (c) 2006-2009 by Dirk Riehle, http://dirkriehle.com
 *
 * This file is part of the Wahlzeit photo rating application.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * 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 along with this program. If not, see
 * <http://www.gnu.org/licenses/>.
 */

package org.wahlzeit.model;

import com.google.appengine.api.images.Image;
import com.google.appengine.api.images.ImagesService;
import com.google.appengine.api.images.ImagesServiceFactory;
import com.google.appengine.api.images.Transform;
import org.wahlzeit.services.LogBuilder;

import java.util.logging.Logger;

/**
 * PhotoUtil provides a set of utility functions to create defined images.
 * Images are created from a source in different sizes as needed by the app.
 */
public class PhotoUtil {

	private static final Logger log = Logger.getLogger(PhotoUtil.class.getName());

	/**
	 * @methodtype creation
	 */
	public static Photo createPhoto(String filename, PhotoId id, Image uploadedImage) throws Exception {
		Photo result = PhotoFactory.getInstance().createPhoto(id);
		result.setEnding(filename.substring(filename.lastIndexOf(".") + 1));

		createImageFiles(uploadedImage, result);

		int sourceWidth = uploadedImage.getWidth();
		int sourceHeight = uploadedImage.getHeight();
		result.setWidthAndHeight(sourceWidth, sourceHeight);

		return result;
	}

	/**
	 *
	 */
	public static void createImageFiles(Image source, Photo photo) throws Exception {
		assertIsValidImage(source);

		int sourceWidth = source.getWidth();
		int sourceHeight = source.getHeight();
		assertHasValidSize(sourceWidth, sourceHeight);

		for (PhotoSize size : PhotoSize.values()) {
			if (!size.isWiderAndHigher(sourceWidth, sourceHeight)) {
				scaleImage(ImagesServiceFactory.makeImage(source.getImageData()), size, photo);
			}
		}
	}

	/**
	 * @methodtype assertion
	 */
	protected static void assertIsValidImage(Image image) {
		if (image == null) {
			throw new IllegalArgumentException("Image = null!");
		}
	}

	/**
	 *
	 */
	protected static void assertHasValidSize(int cw, int ch) {
		if (PhotoSize.THUMB.isWiderAndHigher(cw, ch)) {
			throw new IllegalArgumentException("Photo too small!");
		}
	}

	/**
	 * @methodtype command Scale the source picture to the given size, store it in the datastore and reference it in the
	 * photo.
	 */
	protected static void scaleImage(Image source, PhotoSize size, Photo photo) throws Exception {
		int sourceWidth = source.getWidth();
		int sourceHeight = source.getHeight();

		int targetWidth = size.calcAdjustedWidth(sourceWidth, sourceHeight);
		int targetHeight = size.calcAdjustedHeight(sourceWidth, sourceHeight);

		ImagesService imagesService = ImagesServiceFactory.getImagesService();
		Transform resize = ImagesServiceFactory.makeResize(targetWidth, targetHeight);
		Image newImage = imagesService.applyTransform(resize, source);

		photo.setImage(size, newImage);

		log.config(LogBuilder.createSystemMessage().addParameter("Scaled image to size", size.asString()).toString());
	}

}