source: osm/applications/editors/josm/plugins/slippy_map_chooser/src/OsmTile.java@ 7343

// License: GPL. Copyright 2007 by Tim Haussmann

import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;

/**
 * @author Tim Haussmann 
 */


public class OsmTile {
        
        public static final int WIDTH = 256;
        public static final int HEIGHT = 256;
        
        private int iX = 0;
        private int iY = 0;
        
        public static final int TileBackgroundColor = 0xe9d3b1;  
        
        private BufferedImage iMapImage;
        
        private int iZoomLevel = -1;
        private int iIndexY = -1;
        private int iIndexX = -1;
        
        //image does not exist
        private boolean isInvalid = false;
        
        //for a faster equals implementation
        private int iHash;
        
        public OsmTile( int aZoomLevel, int aIndexX, int aIndexY){
                        
                iZoomLevel = aZoomLevel;
                iIndexX = aIndexX;
                iIndexY = aIndexY;
                
                iX = WIDTH * iIndexX;
                iY = HEIGHT * iIndexY;
                
                iHash = toString().hashCode();
        }
        
        public int getZoomlevel(){
                return iZoomLevel;
        }
        
        public void paint(Graphics g,TileDB db){
                
                if(iMapImage != null && ! isInvalid){
                        g.drawImage( iMapImage, iX, iY, null );
                }
                else if(isInvalid){
                        //draw nothing
                }
                else{
                        // first try to interpolate tile from parent                    
                        OsmTile parent = getParent(db);
                        if (parent!=null){
                                Graphics2D g2d = (Graphics2D) g;
                                AffineTransform oldTr = g2d.getTransform();
                                Shape oldClip = g2d.getClip();
                                g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
                                
                                // since the parent will paint 4 tiles in the 
                                // current zoom level we have to clip the drawing
                                // region to the current tile
                                g2d.clipRect(iX, iY, WIDTH, HEIGHT);
                                g2d.scale(2, 2);                                
                                parent.paint(g,db);
                                
                                g2d.setTransform(oldTr);
                                g2d.setClip(oldClip);
                        }
                        else{
                                // otherwise draw placeholder
                                g.setColor(Color.RED);
                                g.drawLine(iX, iY, iX+WIDTH-1, iY+HEIGHT-1);
                                g.drawLine(iX, iY+HEIGHT-1, iX+WIDTH-1, iY);
                                g.drawRect(iX, iY, WIDTH-1, HEIGHT-1);
                        }
                }
        } 
        
        public String toString() {
                return String.valueOf(iZoomLevel) +"/" +
                String.valueOf(iIndexX) + "/" + 
                String.valueOf(iIndexY);
        }
        public static String key(int aZoomLevel, int aIndexX, int aIndexY){
                return String.valueOf(aZoomLevel) +"/" +
                String.valueOf(aIndexX) + "/" + 
                String.valueOf(aIndexY);
        }

        /**
         * Callback for the TileDB to set the Image of this tile after loading.
         * @param aImage
         */
        public void setImage(BufferedImage aImage) {
                iMapImage = aImage;
                if(iMapImage == null){
                        isInvalid = true;
                }
        }

        /**
         * @return the path of this map tile on the remote server (i.e. '/1/2/12.png')
         */
        public String getRemotePath() {
                return "/"+toString()+".png";
        }
        
        public OsmTile getParent(TileDB db){
                return iZoomLevel == 0 ? null : db.get(parentKey());
        }

        public String parentKey() {
                return key(iZoomLevel - 1,iIndexX/2,iIndexY/2);
        }
}