FB2CoverImage.java

/*
 * Copyright (C) 2010-2011 Geometer Plus <contact@geometerplus.com>
 *
 * This program 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 2 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

package org.geometerplus.fbreader.formats.fb2;

import java.util.*;

import org.geometerplus.zlibrary.core.constants.XMLNamespaces;
import org.geometerplus.zlibrary.core.constants.MimeTypes;
import org.geometerplus.zlibrary.core.filesystem.ZLFile;
import org.geometerplus.zlibrary.core.image.ZLSingleImage;
import org.geometerplus.zlibrary.core.image.ZLImageProxy;
import org.geometerplus.zlibrary.core.xml.*;

class FB2CoverImage extends ZLImageProxy {
	private final ZLFile myFile;

	FB2CoverImage(ZLFile file) {
		myFile = file;
	}

	@Override
	public ZLSingleImage getRealImage() {
		return new BackgroundReader().readCover(myFile);
	}

	@Override
	public int sourceType() {
		return SourceType.DISK;
	}

	@Override
	public String getId() {
		return myFile.getPath();
	}

	private static class BackgroundReader extends ZLXMLReaderAdapter {
		private boolean myReadCoverPage;
		private String myImageReference;
		private Base64EncodedImage myImage;

		Base64EncodedImage readCover(ZLFile file) {
			myReadCoverPage = false;
			myImageReference = null;
			read(file);
			return myImage;
		}

		@Override
		public boolean processNamespaces() {
			return true;
		}

		@Override
		public boolean startElementHandler(String tagName, ZLStringMap attributes) {
			switch (FB2Tag.getTagByName(tagName)) {
			case FB2Tag.COVERPAGE:
				myReadCoverPage = true;
				break;
			case FB2Tag.IMAGE:
				if (myReadCoverPage) {
					final String href = getAttributeValue(attributes, XMLNamespaces.XLink, "href");
					if (href != null && href.length() > 1 && href.charAt(0) == '#') {
						myImageReference = href.substring(1);
					}
				}
				break;
			case FB2Tag.BINARY:
				if (myImageReference != null) {
					final String id = attributes.getValue("id");
					final String contentType = attributes.getValue("content-type");
					if (id != null && contentType != null && myImageReference.equals(id)) {
						// FIXME: make different Base64EncodedImage constructor to use another cache for covers
						myImage = new Base64EncodedImage((contentType != null) ? contentType : MimeTypes.MIME_IMAGE_AUTO);
					}
				}
				break;
			}
			return false;
		}

		@Override
		public boolean endElementHandler(String tag) {
			switch (FB2Tag.getTagByName(tag)) {
			case FB2Tag.COVERPAGE:
				myReadCoverPage = false;
				break;
			case FB2Tag.DESCRIPTION:
				if (myImageReference == null) {
					return true;
				}
				break;
			case FB2Tag.BINARY:
				if (myImage != null) {
					myImage.close();
					return true;
				}
				break;
			}	
			return false;
		}

		@Override
		public void characterDataHandler(char[] data, int start, int length) {
			if (length > 0 && myImage != null) {
				myImage.addData(data, start, length);
			}
		}
	}
}