X-Git-Url: https://gitweb.fperrin.net/?p=GpsPrune.git;a=blobdiff_plain;f=src%2Ftim%2Fprune%2Fgui%2Fmap%2FMemTileCacher.java;fp=src%2Ftim%2Fprune%2Fgui%2Fmap%2FMemTileCacher.java;h=20d7a213a1a0c1b76001272f862739cec19f5051;hp=0000000000000000000000000000000000000000;hb=ce6f2161b8596f7018d6a76bff79bc9e571f35fd;hpb=2d8cb72e84d5cc1089ce77baf1e34ea3ea2f8465

diff --git a/src/tim/prune/gui/map/MemTileCacher.java b/src/tim/prune/gui/map/MemTileCacher.java
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+++ b/src/tim/prune/gui/map/MemTileCacher.java
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+package tim.prune.gui.map;
+
+import java.awt.Image;
+
+/**
+ * Class to act as a memory-based map tile cache
+ * For caching of tiles on disk, see the DiskTileCacher class.
+ */
+public class MemTileCacher
+{
+	/** 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;
+
+	/** Grid size */
+	private static final int GRID_SIZE = 15;
+
+	/**
+	 * 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)
+	{
+		int shift = Math.max(Math.abs(inTileX-_tileX), Math.abs(inTileY - _tileY));
+		if (shift == 0) {return;}
+		// Clear cache if either zoom has changed or map has jumped too far
+		if (inZoom != _zoom || shift > GRID_SIZE/2)
+		{
+			_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[getArrayIndexNoWrap(_tileX + GRID_SIZE/2 + 1, _tileY + i - GRID_SIZE/2)] = null;
+			_tiles[getArrayIndexNoWrap(_tileX + i - GRID_SIZE/2, _tileY + GRID_SIZE/2 + 1)] = null;
+		}
+	}
+
+	/**
+	 * 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;
+	}
+
+	/**
+	 * Get the array index for the given coordinates, including regular lon wrapping
+	 * @param inX x coord of tile
+	 * @param inY y coord of tile
+	 * @return array index
+	 */
+	private int getArrayIndex(int inX, int inY)
+	{
+		final int tileSpan = 1 << _zoom;
+		int deltaX = (inX - _tileX);
+		while (deltaX > (tileSpan/2))  {deltaX -= tileSpan;}
+		while (deltaX < (-tileSpan/2)) {deltaX += tileSpan;}
+
+		int x = getCacheCoordinate(deltaX + _gridCentreX);
+		int y = getCacheCoordinate(inY - _tileY + _gridCentreY);
+		return (x + y * GRID_SIZE);
+	}
+
+	/**
+	 * Get the array index for the given coordinates, without wrapping x coords
+	 * (used for deletion to avoid deleting the wrong tile)
+	 * @param inX x coord of tile
+	 * @param inY y coord of tile
+	 * @return array index
+	 */
+	private int getArrayIndexNoWrap(int inX, int inY)
+	{
+		int x = getCacheCoordinate(inX - _tileX + _gridCentreX);
+		int y = getCacheCoordinate(inY - _tileY + _gridCentreY);
+		return (x + y * GRID_SIZE);
+	}
+
+	/**
+	 * Clear all the cached images
+	 */
+	public void clearAll()
+	{
+		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)
+	{
+		return _tiles[getArrayIndex(inX, inY)];
+	}
+
+	/**
+	 * Save the specified tile at the given coordinates
+	 * @param inTile image to save
+	 * @param inX x coordinate of tile
+	 * @param inY y coordinate of tile
+	 * @param inZoom zoom level
+	 */
+	public void setTile(Image inTile, int inX, int inY, int inZoom)
+	{
+		// Ignore images received for a different zoom level
+		if (inZoom == _zoom) {
+			_tiles[getArrayIndex(inX, inY)] = inTile;
+		}
+	}
+}