// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.actions.downloadtasks;
import java.util.List;
import java.util.concurrent.Future;
import org.openstreetmap.josm.data.Bounds;
import org.openstreetmap.josm.gui.progress.ProgressMonitor;
public interface DownloadTask {
/**
* Asynchronously launches the download task for a given bounding box.
*
* Set <code>progressMonitor</code> to null, if the task should create, open, and close a progress monitor.
* Set progressMonitor to {@see NullProgressMonitor#INSTANCE} if progress information is to
* be discarded.
*
* You can wait for the asynchronous download task to finish by synchronizing on the returned
* {@see Future}, but make sure not to freeze up JOSM. Example:
* <pre>
* Future<?> future = task.download(...);
* // DON'T run this on the Swing EDT or JOSM will freeze
* future.get(); // waits for the dowload task to complete
* </pre>
*
* The following example uses a pattern which is better suited if a task is launched from
* the Swing EDT:
* <pre>
* final Future<?> future = task.download(...);
* Runnable runAfterTask = new Runnable() {
* public void run() {
* // this is not strictly necessary because of the type of executor service
* // Main.worker is initialized with, but it doesn't harm either
* //
* future.get(); // wait for the download task to complete
* doSomethingAfterTheTaskCompleted();
* }
* }
* Main.worker.submit(runAfterTask);
* </pre>
*
* @param newLayer true, if the data is to be downloaded into a new layer. If false, the task
* selects one of the existing layers as download layer, preferably the active layer.
*
* @param downloadArea the area to download
* @param progressMonitor the progressMonitor
* @return the future representing the asynchronous task
*/
Future<?> download(boolean newLayer, Bounds downloadArea, ProgressMonitor progressMonitor);
/**
* Asynchronously launches the download task for a given bounding URL.
*
* Set progressMonitor to null, if the task should create, open, and close a progress monitor.
* Set progressMonitor to {@see NullProgressMonitor#INSTANCE} if progress information is to
* be discarded.
* @param newLayer newLayer true, if the data is to be downloaded into a new layer. If false, the task
* selects one of the existing layers as download layer, preferably the active layer.
* @param url the url to download from
* @param progressMonitor the progressMonitor
* @return the future representing the asynchronous task
*
* @see #download(boolean, Bounds, ProgressMonitor)
*/
Future<?> loadUrl(boolean newLayer, String url, ProgressMonitor progressMonitor);
/**
* Replies the error objects of the task. Empty list, if no error messages are available.
*
* Error objects are either {@see String}s with error messages or {@see Exception}s.
*
* @return the list of error objects
*/
List<Object> getErrorObjects();
/**
* Cancels the asynchronous download task.
*
*/
public void cancel();
}