/**
* Returns a list of tiles constructed from the given array of files. Every file in the given
* array must exist, be a valid image and have a valid <cite>World File</cite>, i.e. a file of the
* same name in the same directory then the image file, but with an extension like {@code ".tfw"}
* (for TIFF images) or {@code ".jgw"} (for JPEG images).
*
* <p>This method loads the World Files and fetches the image sizes immediately. The world file
* applies to the first image in the file. If the file contains more than one image, then each
* additional image is assumed to represent the same data than the first image at a different
* resolution.
*
* <p>{@section Customization} If the files contain many images but those images are
* <strong>not</strong> overviews of the first image at different resolution, then subclasses can
* use only a specific image by overriding this method as below, where {@code imageIndex} is the
* index of the image to use (typically 0):
*
* <p>{@preformat java public List<Tile> listTiles(final ImageReaderSpi provider, final Path...
* inputs) throws IOException { final List<Tile> tiles = new ArrayList<Tile>(inputs.length); for
* (final Path input : inputs) { tiles.add(new Tile(provider, input, imageIndex)); } return tiles;
* } }
*
* <p>This method is invoked by {@link #create(Path, PathMatcher, ImageReaderSpi)}, so it can be
* overridden for controlling the tiles to be built when {@code TileManagerFactory} scans a
* directory.
*
* @param provider The image reader provider to use. If {@code null}, the provider will be
* inferred from each input. If it can't be inferred, then an exception is thrown.
* @param inputs The image files.
* @return The tiles constructed from the image files.
* @throws IOException If no <cite>World File</cite> were found for a given image file, or if an
* error occurred while reading a file.
* @see Tile#Tile(ImageReaderSpi, File, int)
* @since 3.18
*/
public List<Tile> listTiles(final ImageReaderSpi provider, final Path... inputs)
throws IOException {
try (final TileReaderPool readers = new TileReaderPool()) {
final Set<ImageReaderSpi> providers = new HashSet<>();
final List<Tile> tiles = new ArrayList<>(inputs.length);
for (final Path input : inputs) {
tiles.addAll(toTiles(provider, readers, providers, input));
}
readers.dispose();
return tiles;
}
}
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;
}