JsonTileDataSource.java

/*
 * Copyright 2014 Hannes Janetzek
 *
 * This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
 *
 * This program is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.oscim.tiling.source;

import static org.oscim.tiling.ITileDataSink.QueryResult.FAILED;
import static org.oscim.tiling.ITileDataSink.QueryResult.SUCCESS;

import java.io.InputStream;

import org.oscim.layers.tile.MapTile;
import org.oscim.layers.tile.MapTile.State;
import org.oscim.tiling.ITileDataSink;
import org.oscim.tiling.ITileDataSource;
import org.oscim.tiling.source.geojson.GeoJsonTileDecoder;
import org.oscim.tiling.source.geojson.GeoJsonTileSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.gwt.core.client.JavaScriptObject;
import com.google.gwt.jsonp.client.JsonpRequest;
import com.google.gwt.jsonp.client.JsonpRequestBuilder;
import com.google.gwt.user.client.rpc.AsyncCallback;

public class JsonTileDataSource implements ITileDataSource {
	static final Logger log = LoggerFactory.getLogger(JsonTileDataSource.class);

	protected final GeoJsonTileDecoder mTileDecoder;
	protected final UrlTileSource mTileSource;

	public JsonTileDataSource(GeoJsonTileSource tileSource) {
		mTileSource = tileSource;
		mTileDecoder = new GeoJsonTileDecoder(tileSource);
	}

	UrlTileSource getTileSource() {
		return mTileSource;
	}

	private ITileDataSink mSink;
	private MapTile mTile;

	@Override
	public void query(MapTile tile, ITileDataSink sink) {
		mTile = tile;
		mSink = sink;

		try {
			doGet(mTileSource.getTileUrl(tile));
		} catch (Exception e) {
			e.printStackTrace();
			sink.completed(FAILED);
		}
	}

	public void process(InputStream is) {
	}

	boolean mFinished;

	@Override
	public void dispose() {
		mFinished = true;
	}

	@Override
	public void cancel() {
		mFinished = true;
	}

	JsonpRequest<JavaScriptObject> mRequestHandle;

	void doGet(final String url) {
		JsonpRequestBuilder builder = new JsonpRequestBuilder();
		//builder.setCallbackParam("json_callback");

		mRequestHandle = builder.requestObject(url, new AsyncCallback<JavaScriptObject>() {
			public void onFailure(Throwable caught) {

				mSink.completed(FAILED);
				log.debug("fail! {} {}", mRequestHandle, caught.getMessage());
				//mRequestHandle.cancel();
			}

			public void onSuccess(JavaScriptObject jso) {
				if (mTile.state(State.NONE)) {
					log.debug("tile cleared {}", url);
					mSink.completed(FAILED);
					return;
				}

				if (jso == null) {
					log.debug("Couldn't retrieve JSON for {}", url);
					mSink.completed(FAILED);
					return;
				}

				try {
					if (mTileDecoder.decode(mTile, mSink, jso)) {
						mSink.completed(SUCCESS);
						return;
					}
				} catch (Exception e) {
					log.debug("Couldn't retrieve JSON for {} {}" + url, e);
					// FIXME need to check where it might be thrown
					mSink.completed(FAILED);
				}
			}
		});
	}
}