/**
* Tries to get tiles of a lower or higher zoom level (one or two level difference) from cache and
* use it as a placeholder until the tile has been loaded.
*/
public void loadPlaceholderFromCache(TileCache cache) {
BufferedImage tmpImage = new BufferedImage(SIZE, SIZE, BufferedImage.TYPE_INT_ARGB);
Graphics2D g = (Graphics2D) tmpImage.getGraphics();
// g.drawImage(image, 0, 0, null);
for (int zoomDiff = 1; zoomDiff < 5; zoomDiff++) {
// first we check if there are already the 2^x tiles
// of a higher detail level
int zoom_high = zoom + zoomDiff;
if (zoomDiff < 3 && zoom_high <= JMapViewer.MAX_ZOOM) {
int factor = 1 << zoomDiff;
int xtile_high = xtile << zoomDiff;
int ytile_high = ytile << zoomDiff;
double scale = 1.0 / factor;
g.setTransform(AffineTransform.getScaleInstance(scale, scale));
int paintedTileCount = 0;
for (int x = 0; x < factor; x++) {
for (int y = 0; y < factor; y++) {
Tile tile = cache.getTile(source, xtile_high + x, ytile_high + y, zoom_high);
if (tile != null && tile.isLoaded()) {
paintedTileCount++;
tile.paint(g, x * SIZE, y * SIZE);
}
}
}
if (paintedTileCount == factor * factor) {
image = tmpImage;
return;
}
}
int zoom_low = zoom - zoomDiff;
if (zoom_low >= JMapViewer.MIN_ZOOM) {
int xtile_low = xtile >> zoomDiff;
int ytile_low = ytile >> zoomDiff;
int factor = (1 << zoomDiff);
double scale = factor;
AffineTransform at = new AffineTransform();
int translate_x = (xtile % factor) * SIZE;
int translate_y = (ytile % factor) * SIZE;
at.setTransform(scale, 0, 0, scale, -translate_x, -translate_y);
g.setTransform(at);
Tile tile = cache.getTile(source, xtile_low, ytile_low, zoom_low);
if (tile != null && tile.isLoaded()) {
tile.paint(g, 0, 0);
image = tmpImage;
return;
}
}
}
}
