metatilemapproducer.java

电子地图服务器,搭建自己的地图服务

/* Copyright (c) 2001 - 2007 TOPP - www.openplans.org. All rights reserved.
 * This code is licensed under the GPL 2.0 license, availible at the root
 * application directory.
 */
package org.vfny.geoserver.wms.responses.map.metatile;

import java.awt.RenderingHints;
import java.awt.image.RenderedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.media.jai.JAI;
import javax.media.jai.operator.CropDescriptor;

import org.geotools.geometry.jts.ReferencedEnvelope;
import org.vfny.geoserver.ServiceException;
import org.vfny.geoserver.wms.GetMapProducer;
import org.vfny.geoserver.wms.RasterMapProducer;
import org.vfny.geoserver.wms.WMSMapContext;
import org.vfny.geoserver.wms.WmsException;
import org.vfny.geoserver.wms.requests.GetMapRequest;
import org.vfny.geoserver.wms.responses.AbstractGetMapProducer;
import org.vfny.geoserver.wms.responses.map.metatile.QuickTileCache.MetaTileKey;

/**
 * Wrapping map producer that performs on the fly meta tiling wrapping another
 * map producer. It will first peek inside a tile cache to see if the requested
 * tile has already been computed, if so, it'll encode and return that one,
 * otherwise it'll build a meta tile, split it, and finally encode just the
 * requested tile, putting the others in the tile cache.
 * 
 * @author Andrea Aime - TOPP
 * @author Simone Giannecchini - GeoSolutions
 */
public final class MetatileMapProducer extends AbstractGetMapProducer implements
		GetMapProducer {
	/** A logger for this class. */
	private static final Logger LOGGER = org.geotools.util.logging.Logging.getLogger("org.vfny.geoserver.responses.wms.map.metatile");

	/** Small number for double equality comparison */
	public static final double EPS = 1E-6;

	private GetMapRequest request;

	private RasterMapProducer delegate;

	private RenderedImage tile;

	private static QuickTileCache tileCache = new QuickTileCache();

	/**
	 * True if the request has the tiled hint, is 256x256 image, and the raw
	 * delegate is a raster one
	 * 
	 * @param request
	 * @param delegate
	 * @return
	 */
	public static boolean isRequestTiled(GetMapRequest request,
			GetMapProducer delegate) {
		if (!(request.isTiled() && (request.getTilesOrigin() != null)
				&& (request.getWidth() == 256) && (request.getHeight() == 256) && delegate instanceof RasterMapProducer)) {
			return false;
		}

		return true;
	}

	public MetatileMapProducer(GetMapRequest request, RasterMapProducer delegate) {
		this.request = request;
		this.delegate = delegate;
	}

	public void produceMap() throws WmsException {
		// get the key that identifies the meta tile. The cache will make sure
		// two threads asking
		// for the same tile will get the same key, and thus will synchronize
		// with each other
		// (the first eventually builds the meta-tile, the second finds it ready
		// to be used)
		QuickTileCache.MetaTileKey key = tileCache.getMetaTileKey(request);

		synchronized (key) {
			tile = tileCache.getTile(key, request);
			if (LOGGER.isLoggable(Level.FINER)) {
				LOGGER.finer("Looked for meta tile " + key.metaTileCoords.x
						+ ", " + key.metaTileCoords.y + "in cache: "
						+ ((tile == null) ? "hit!" : "miss"));
			}

			if (tile == null) {
				// compute the meta-tile
				if (LOGGER.isLoggable(Level.FINER)) {
					LOGGER.finer("Building meta tile " + key.metaTileCoords.x
							+ ", " + key.metaTileCoords.y);
				}

				// alter the map definition so that we build a meta-tile instead
				// of just the tile
				ReferencedEnvelope origEnv = mapContext.getAreaOfInterest();
				mapContext.setAreaOfInterest(new ReferencedEnvelope(key
						.getMetaTileEnvelope(), origEnv
						.getCoordinateReferenceSystem()));
				mapContext.setMapWidth(key.getTileSize() * key.getMetaFactor());
				mapContext
						.setMapHeight(key.getTileSize() * key.getMetaFactor());

				// generate, split and cache
				delegate.setMapContext(mapContext);
				delegate.produceMap();

				RenderedImage metaTile = delegate.getImage();
				RenderedImage[] tiles = split(key, metaTile, mapContext);
				tileCache.storeTiles(key, tiles);
				tile = tileCache.getTile(key, request, tiles);
			}
		}
	}

	// /**
	// * Splits the tile into a set of tiles, numbered from lower right and
	// going up so
	// * that first row is 0,1,2,...,metaTileFactor, and so on.
	// * In the case of a 3x3 meta-tile, the layout is as follows:
	// * <pre>
	// * 6 7 8
	// * 3 4 5
	// * 0 1 2
	// * </pre>
	// * @param key
	// * @param metaTile
	// * @param map
	// * @return
	// */
	// private BufferedImage[] split(MetaTileKey key, BufferedImage metaTile,
	// WMSMapContext map) {
	// int metaFactor = key.getMetaFactor();
	// BufferedImage[] tiles = new BufferedImage[key.getMetaFactor() *
	// key.getMetaFactor()];
	// int tileSize = key.getTileSize();
	//
	// for (int i = 0; i < metaFactor; i++) {
	// for (int j = 0; j < metaFactor; j++) {
	// // TODO: create child writable rasters instead of cloning the images
	// using
	// // graphics2d. Should be quite a bit faster and save some memory. Or
	// else,
	// // store meta-tiles in the cache directly, and extract children tiles
	// // on demand (even simpler)
	// BufferedImage tile;
	//
	// // keep the palette if necessary
	// if (metaTile.getType() == BufferedImage.TYPE_BYTE_INDEXED) {
	// tile = new BufferedImage(tileSize, tileSize,
	// BufferedImage.TYPE_BYTE_INDEXED,
	// (IndexColorModel) metaTile.getColorModel());
	// } else if (metaTile.getType() == BufferedImage.TYPE_CUSTOM) {
	// throw new RuntimeException("We don't support custom buffered image
	// tiling");
	// } else {
	// tile = new BufferedImage(tileSize, tileSize, metaTile.getType());
	// }
	//
	// Graphics2D g2d = (Graphics2D) tile.getGraphics();
	// AffineTransform at = AffineTransform.getTranslateInstance(-j * tileSize,
	// (-tileSize * (metaFactor - 1)) + (i * tileSize));
	// setupBackground(g2d, map);
	// g2d.drawRenderedImage(metaTile, at);
	// g2d.dispose();
	// tiles[(i * key.getMetaFactor()) + j] = tile;
	// }
	// }
	//
	// return tiles;
	// }

	/**
	 * Splits the tile into a set of tiles, numbered from lower right and going
	 * up so that first row is 0,1,2,...,metaTileFactor, and so on. In the case
	 * of a 3x3 meta-tile, the layout is as follows:
	 * 
	 * <pre>
	 *    6 7 8
	 *    3 4 5
	 *    0 1 2
	 * </pre>
	 * 
	 * @param key
	 * @param metaTile
	 * @param map
	 * @return
	 */
	private RenderedImage[] split(MetaTileKey key, RenderedImage metaTile,
			WMSMapContext map) {
		final int metaFactor = key.getMetaFactor();
		final RenderedImage[] tiles = new RenderedImage[key.getMetaFactor()
				* key.getMetaFactor()];
		final int tileSize = key.getTileSize();
		final RenderingHints no_cache = new RenderingHints(JAI.KEY_TILE_CACHE,
				null);

		for (int i = 0; i < metaFactor; i++) {
			for (int j = 0; j < metaFactor; j++) {
				int x = j * tileSize;
				int y = (tileSize * (metaFactor - 1)) - (i * tileSize);

				tile = CropDescriptor.create(metaTile, new Float(x), new Float(
						y), new Float(tileSize), new Float(tileSize), no_cache);
				tiles[(i * key.getMetaFactor()) + j] = tile;
			}
		}

		return tiles;
	}

	/**
	 * Have the delegate encode the tile
	 */
	public void writeTo(OutputStream out) throws ServiceException, IOException {
		delegate.formatImageOutputStream(tile, out);
	}

	public void abort() {
		delegate.abort();
	}

	public String getContentDisposition() {
		return delegate.getContentDisposition();
	}

	public String getContentType() throws IllegalStateException {
		return delegate.getContentType();
	}
}