DistanceToCenterTilePrioritizer.java

/*
 * Copyright (C) 2015 Patryk Strach
 * 
 * This file is part of Virtual Slide Viewer.
 * 
 * Virtual Slide Viewer 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 3 of the License, or (at your option) any later version.
 * 
 * Virtual Slide Viewer 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 Virtual Slide Viewer.
 * If not, see <http://www.gnu.org/licenses/>.
*/

package virtualslideviewer.imageviewing;

import java.awt.Point;
import java.awt.Rectangle;
import java.util.Collections;
import java.util.List;

import virtualslideviewer.core.BufferedVirtualSlideImage;
import virtualslideviewer.core.Tile;

/**
 * An implementation of TileLoadingPrioritizer which sorts the tiles by their distance to the center of visible portion of the image.
 * 
 * Tiles with the closest distance to the center come first.
 */
public class DistanceToCenterTilePrioritizer implements TileLoadingPrioritizer
{
	@Override
	public void sortTilesByPriority(List<Tile> tilesToSort, BufferedVirtualSlideImage image, Rectangle imageBounds)
	{
		Collections.sort(tilesToSort, (tile1, tile2) -> 
		{
			Point imageCenter = getCenter(imageBounds);
			Point tile1Center = getCenter(tile1.getBounds(image));
			Point tile2Center = getCenter(tile2.getBounds(image));
			
			return (int)(tile1Center.distanceSq(imageCenter) - tile2Center.distanceSq(imageCenter));
		});
	}
	
	private Point getCenter(Rectangle bounds)
	{
		return new Point(bounds.x + bounds.width  / 2,
		                 bounds.y + bounds.height / 2);
	}
}