private List<Tile> toTiles(
ImageReaderSpi provider, TileReaderPool readers, Set<ImageReaderSpi> providers, Path input)
throws IOException {
// Creates the tile for the first image, which usually have the maximal resolution.
// The Tile constructor will read the TFW file and infer a provider if the given
// 'provider' argument is null. If this is a new provider, then we need to declare
// it to the pool of image readers before to use it.
final List<Tile> tiles = new ArrayList<>();
final Tile root = new Tile(provider, input, 0);
if (providers.add(root.getImageReaderSpi())) {
readers.setProviders(providers);
}
final AffineTransform scaledGridToCRS = new AffineTransform();
final AffineTransform gridToCRS = root.getPendingGridToCRS(false);
final ImageReader reader = root.getImageReader(readers, true, true);
final int numImages = reader.getNumImages(false); // Result may be -1.
for (int index = 0; index != numImages; index++) { // Intentional use of !=, not <.
final int width, height;
try {
width = reader.getWidth(index);
height = reader.getHeight(index);
} catch (IndexOutOfBoundsException e) {
// As explained in ImageReader javadoc, this approach is sometime
// more efficient than invoking reader.getNumImages(true) first.
break;
}
final Tile tile;
if (index == 0) {
tile = root;
} else {
final Rectangle region = root.getRegion();
scaledGridToCRS.setTransform(new AffineTransform(gridToCRS));
scaledGridToCRS.scale(region.width / (double) width, region.height / (double) height);
tile = new Tile(root.getImageReaderSpi(), input, index, region, scaledGridToCRS);
}
tile.setSize(width, height);
tiles.add(tile);
}
reader.dispose();
return tiles;
}
