--- /dev/null
+package tim.prune.gui.map;
+
+import java.awt.Image;
+import java.awt.Toolkit;
+import java.awt.image.ImageObserver;
+import java.net.MalformedURLException;
+import java.net.URL;
+
+
+/**
+ * Class to handle the caching of map tiles from openstreetmap
+ */
+public class MapTileCacher implements ImageObserver
+{
+ /** Parent to be informed of updates */
+ private MapCanvas _parent = null;
+ /** Default grid size */
+ private static final int GRID_SIZE = 11;
+ /** Array of images to hold tiles */
+ private Image[] _tiles = new Image[GRID_SIZE * GRID_SIZE];
+ /** Current zoom level */
+ private int _zoom = -1;
+ /** X coordinate of central tile */
+ private int _tileX = -1;
+ /** Y coordinate of central tile */
+ private int _tileY = -1;
+ /** X coord of grid centre */
+ private int _gridCentreX = 0;
+ /** Y coord of grid centre */
+ private int _gridCentreY = 0;
+
+
+ /**
+ * Constructor
+ * @param inParent parent canvas to be informed of updates
+ */
+ public MapTileCacher(MapCanvas inParent)
+ {
+ _parent = inParent;
+ }
+
+ /**
+ * Recentre the map and clear the cache
+ * @param inZoom zoom level
+ * @param inTileX x coord of central tile
+ * @param inTileY y coord of central tile
+ */
+ public void centreMap(int inZoom, int inTileX, int inTileY)
+ {
+ if (inZoom != _zoom)
+ {
+ _zoom = inZoom;
+ clearAll();
+ }
+ _gridCentreX = getCacheCoordinate(_gridCentreX + inTileX - _tileX);
+ _gridCentreY = getCacheCoordinate(_gridCentreY + inTileY - _tileY);
+ _tileX = inTileX;
+ _tileY = inTileY;
+ // Mark boundaries as invalid
+ for (int i=0; i<GRID_SIZE; i++)
+ {
+ _tiles[getArrayIndex(_tileX + GRID_SIZE/2 + 1, _tileY + i - GRID_SIZE/2)] = null;
+ _tiles[getArrayIndex(_tileX + i - GRID_SIZE/2, _tileY + GRID_SIZE/2 + 1)] = null;
+ }
+ }
+
+ /**
+ * Clear all the cached images
+ */
+ public void clearAll()
+ {
+ // Clear all images if zoom changed
+ for (int i=0; i<_tiles.length; i++) {
+ _tiles[i] = null;
+ }
+ }
+
+ /**
+ * @param inX x index of tile
+ * @param inY y index of tile
+ * @return selected tile if already loaded, or null otherwise
+ */
+ public Image getTile(int inX, int inY)
+ {
+ int arrayIndex = getArrayIndex(inX, inY);
+ Image image = _tiles[arrayIndex];
+ if (image != null)
+ {
+ // image already finished loading so return it
+ return image;
+ }
+
+ // Trigger load if not already triggered
+ // Work out tile coords for URL
+ int urlX = getUrlCoordinate(inX, _zoom);
+ int urlY = getUrlCoordinate(inY, _zoom);
+ try
+ {
+ String url = "http://tile.openstreetmap.org/" + _zoom + "/" + urlX + "/" + urlY + ".png";
+ // Load image asynchronously, using observer
+ image = Toolkit.getDefaultToolkit().createImage(new URL(url));
+ _tiles[arrayIndex] = image;
+ if (image.getWidth(this) > 0) {return image;}
+ }
+ catch (MalformedURLException urle) {} // ignore
+ return null;
+ }
+
+
+ /**
+ * Get the array index for the given coordinates
+ * @param inX x coord of tile
+ * @param inY y coord of tile
+ * @return array index
+ */
+ private int getArrayIndex(int inX, int inY)
+ {
+ //System.out.println("Getting array index for (" + inX + ", " + inY + ") where the centre is at (" + _tileX + ", " + _tileY
+ // + ") and grid coords (" + _gridCentreX + ", " + _gridCentreY + ")");
+ int x = getCacheCoordinate(inX - _tileX + _gridCentreX);
+ int y = getCacheCoordinate(inY - _tileY + _gridCentreY);
+ //System.out.println("Transformed to (" + x + ", " + y + ")");
+ return (x + y * GRID_SIZE);
+ }
+
+ /**
+ * Transform a coordinate from map tiles to array coordinates
+ * @param inTile coordinate of tile
+ * @return coordinate in array (wrapping around cache grid)
+ */
+ private static int getCacheCoordinate(int inTile)
+ {
+ int tile = inTile;
+ while (tile >= GRID_SIZE) {tile -= GRID_SIZE;}
+ while (tile < 0) {tile += GRID_SIZE;}
+ return tile;
+ }
+
+ /**
+ * Make sure a url coordinate is within range
+ * @param inTile coordinate of tile in map system
+ * @param inZoom zoom factor
+ * @return coordinate for url (either vertical or horizontal)
+ */
+ private static int getUrlCoordinate(int inTile, int inZoom)
+ {
+ int mapSize = 1 << inZoom;
+ int coord = inTile;
+ while (coord >= mapSize) {coord -= mapSize;}
+ while (coord < 0) {coord += mapSize;}
+ // coord is now between 0 and mapsize
+ return coord;
+ }
+
+ /**
+ * Convert to string for debug
+ * @see java.lang.Object#toString()
+ */
+ public String toString()
+ {
+ StringBuffer result = new StringBuffer("Grid centre (" + _gridCentreX + "," + _gridCentreY + ") - (" + _tileX + "," + _tileY + ")\n");
+ for (int i=0; i<GRID_SIZE; i++)
+ {
+ for (int j=0; j<GRID_SIZE; j++) {
+ if (i == _gridCentreY && j == _gridCentreX) {
+ result.append(_tiles[j + i*GRID_SIZE] == null?"c":"C");
+ }
+ else {
+ result.append(_tiles[j + i*GRID_SIZE] == null?".":"*");
+ }
+ }
+ result.append("\n");
+ }
+ return result.toString();
+ }
+
+ /**
+ * Method called by image loader to inform of updates to the tiles
+ * @param img the image
+ * @param infoflags flags describing how much of the image is known
+ * @param x ignored
+ * @param y ignored
+ * @param width ignored
+ * @param height ignored
+ * @return false to carry on loading, true to stop
+ */
+ public boolean imageUpdate(Image img, int infoflags, int x, int y, int width, int height)
+ {
+ boolean loaded = (infoflags & ImageObserver.ALLBITS) > 0;
+ boolean error = (infoflags & ImageObserver.ERROR) > 0;
+ if (loaded || error) {
+ _parent.tilesUpdated(loaded);
+ }
+ return !loaded;
+ }
+}
projects / GpsPrune.git / blobdiff