private BufferedImage requestImage(MercatorTextureTile tile, String mimeType)
throws URISyntaxException {
String pathBase = tile.getPath().substring(0, tile.getPath().lastIndexOf("."));
String suffix = WWIO.makeSuffixForMimeType(mimeType);
String path = pathBase + suffix;
URL url = WorldWind.getDataFileStore().findFile(path, false);
if (url == null) // image is not local
return null;
if (WWIO.isFileOutOfDate(url, tile.getLevel().getExpiryTime())) {
// The file has expired. Delete it.
WorldWind.getDataFileStore().removeFile(url);
String message = Logging.getMessage("generic.DataFileExpired", url);
Logging.logger().fine(message);
} else {
try {
File imageFile = new File(url.toURI());
BufferedImage image = ImageIO.read(imageFile);
if (image == null) {
String message = Logging.getMessage("generic.ImageReadFailed", imageFile);
throw new RuntimeException(message);
}
this.levels.unmarkResourceAbsent(tile);
return image;
} catch (IOException e) {
// Assume that something's wrong with the file and delete it.
gov.nasa.worldwind.WorldWind.getDataFileStore().removeFile(url);
this.levels.markResourceAbsent(tile);
String message = Logging.getMessage("generic.DeletedCorruptDataFile", url);
Logging.logger().info(message);
}
}
return null;
}
private void addTileOrDescendants(DrawContext dc, MercatorTextureTile tile) {
if (this.meetsRenderCriteria(dc, tile)) {
this.addTile(dc, tile);
return;
}
// The incoming tile does not meet the rendering criteria, so it must be subdivided and those
// subdivisions tested against the criteria.
// All tiles that meet the selection criteria are drawn, but some of those tiles will not have
// textures associated with them either because their texture isn't loaded yet or because they
// are finer grain than the layer has textures for. In these cases the tiles use the texture of
// the closest ancestor that has a texture loaded. This ancestor is called the
// currentResourceTile.
// A texture transform is applied during rendering to align the sector's texture coordinates
// with the
// appropriate region of the ancestor's texture.
MercatorTextureTile ancestorResource = null;
try {
// TODO: Revise this to reflect that the parent layer is only requested while the algorithm
// continues
// to search for the layer matching the criteria.
// At this point the tile does not meet the render criteria but it may have its texture in
// memory.
// If so, register this tile as the resource tile. If not, then this tile will be the next
// level
// below a tile with texture in memory. So to provide progressive resolution increase, add
// this tile
// to the draw list. That will cause the tile to be drawn using its parent tile's texture, and
// it will
// cause it's texture to be requested. At some future call to this method the tile's texture
// will be in
// memory, it will not meet the render criteria, but will serve as the parent to a tile that
// goes
// through this same process as this method recurses. The result of all this is that a tile
// isn't rendered
// with its own texture unless all its parents have their textures loaded. In addition to
// causing
// progressive resolution increase, this ensures that the parents are available as the user
// zooms out, and
// therefore the layer remains visible until the user is zoomed out to the point the layer is
// no longer
// active.
if (tile.isTextureInMemory(dc.getTextureCache()) || tile.getLevelNumber() == 0) {
ancestorResource = this.currentResourceTile;
this.currentResourceTile = tile;
} else if (!tile.getLevel().isEmpty()) {
// this.addTile(dc, tile);
// return;
// Issue a request for the parent before descending to the children.
if (tile.getLevelNumber() < this.levels.getNumLevels()) {
// Request only tiles with data associated at this level
if (!this.levels.isResourceAbsent(tile)) this.requestTexture(dc, tile);
}
}
MercatorTextureTile[] subTiles =
tile.createSubTiles(this.levels.getLevel(tile.getLevelNumber() + 1));
for (MercatorTextureTile child : subTiles) {
if (this.isTileVisible(dc, child)) this.addTileOrDescendants(dc, child);
}
} finally {
if (ancestorResource != null) // Pop this tile as the currentResource ancestor
this.currentResourceTile = ancestorResource;
}
}