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; }