IMyxProgressMonitor.java

/*******************************************************************************
 * Copyright (c) 2000, 2007 IBM Corporation and others. All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0 which accompanies this distribution, and is
 * available at http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors: IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.archstudio.myx.fw;

/**
 * The <code>IProgressMonitor</code> interface is implemented by objects that monitor the progress of an activity; the
 * methods in this interface are invoked by code that performs the activity.
 * <p>
 * All activity is broken down into a linear sequence of tasks against which progress is reported. When a task begins, a
 * <code>beginTask(String, int)
 * </code> notification is reported, followed by any number and mixture of progress reports (<code>worked()</code>) and
 * subtask notifications ( <code>subTask(String)</code>). When the task is eventually completed, a <code>done()</code>
 * notification is reported. After the <code>done()</code> notification, the progress monitor cannot be reused; i.e.,
 * <code>
 * beginTask(String, int)</code> cannot be called again after the call to <code>done()</code>.
 * </p>
 * <p>
 * A request to cancel an operation can be signaled using the <code>setCanceled</code> method. Operations taking a
 * progress monitor are expected to poll the monitor (using <code>isCanceled</code>) periodically and abort at their
 * earliest convenience. Operation can however choose to ignore cancelation requests.
 * </p>
 * <p>
 * Since notification is synchronous with the activity itself, the listener should provide a fast and robust
 * implementation. If the handling of notifications would involve blocking operations, or operations which might throw
 * uncaught exceptions, the notifications should be queued, and the actual processing deferred (or perhaps delegated to
 * a separate thread).
 * </p>
 * <p>
 * This interface can be used without OSGi running.
 * </p>
 * <p>
 * Clients may implement this interface.
 * </p>
 */
public interface IMyxProgressMonitor {

	/**
	 * Constant indicating an unknown amount of work.
	 */
	public final static int UNKNOWN = -1;

	/**
	 * Notifies that the main task is beginning. This must only be called once on a given progress monitor instance.
	 * 
	 * @param name
	 *            the name (or description) of the main task
	 * @param totalWork
	 *            the total number of work units into which the main task is been subdivided. If the value is
	 *            <code>UNKNOWN</code> the implementation is free to indicate progress in a way which doesn't require
	 *            the total number of work units in advance.
	 */
	public void beginTask(String name, int totalWork);

	/**
	 * Notifies that the work is done; that is, either the main task is completed or the user canceled it. This method
	 * may be called more than once (implementations should be prepared to handle this case).
	 */
	public void done();

	/**
	 * Internal method to handle scaling correctly. This method must not be called by a client. Clients should always
	 * use the method </code>worked(int)</code>.
	 * 
	 * @param work
	 *            the amount of work done
	 */
	public void internalWorked(double work);

	/**
	 * Returns whether cancelation of current operation has been requested. Long-running operations should poll to see
	 * if cancelation has been requested.
	 * 
	 * @return <code>true</code> if cancellation has been requested, and <code>false</code> otherwise
	 * @see #setCanceled(boolean)
	 */
	public boolean isCanceled();

	/**
	 * Sets the cancel state to the given value.
	 * 
	 * @param value
	 *            <code>true</code> indicates that cancelation has been requested (but not necessarily acknowledged);
	 *            <code>false</code> clears this flag
	 * @see #isCanceled()
	 */
	public void setCanceled(boolean value);

	/**
	 * Sets the task name to the given value. This method is used to restore the task label after a nested operation was
	 * executed. Normally there is no need for clients to call this method.
	 * 
	 * @param name
	 *            the name (or description) of the main task
	 * @see #beginTask(java.lang.String, int)
	 */
	public void setTaskName(String name);

	/**
	 * Notifies that a subtask of the main task is beginning. Subtasks are optional; the main task might not have
	 * subtasks.
	 * 
	 * @param name
	 *            the name (or description) of the subtask
	 */
	public void subTask(String name);

	/**
	 * Notifies that a given number of work unit of the main task has been completed. Note that this amount represents
	 * an installment, as opposed to a cumulative amount of work done to date.
	 * 
	 * @param work
	 *            a non-negative number of work units just completed
	 */
	public void worked(int work);
}