AppBusy.java

/*
Mjdj MIDI Morph - an extensible MIDI processor and translator.
Copyright (C) 2010 Confusionists, LLC (www.confusionists.com)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 

See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. 

You may contact the author at mjdj_midi_morph [at] confusionists.com
*/
package com.confusionists.swing;

/**
 * This is a singleton class which serves as a busy state for the whole
 * world.
 *
 * Use:
 * In your methods, use:<pre>
 * if (!AppBusy.setBusy(true))
 *     return;
 * setBusyCursor(this);
 * </pre>
 * Then, at the end of the method (MUST BE REACHABLE!) <pre>
 *     setBusy(false);
 *     setNormalCursor(this);
 *  </pre>
 *  It's a good idea to shut off the busy state in any error handlers too.
 */
public class AppBusy {

  static AppBusy me = new AppBusy();
  private boolean busy;
  private AppBusy() {}

  /**
   * This method is synchronized, if another method is setting
   * the isBusy state you gotta wait.
   * @return
   */
  public synchronized static boolean isBusy() {
    return me.busy;
  }

  /**
   * Returns true if the state was changed per request.
   * False otherwise.
   * @param busyIn
   * @return
   */
  public synchronized static boolean setBusy(boolean busyIn) {
    boolean retVal = false;
    if (busyIn && !me.busy) {
      // if we ARE NOT busy and the method wants to set a busy state, okay
      me.busy = busyIn;
      retVal = true;
    } else if (!busyIn && me.busy) {
      // if we ARE busy and the method wants to set a not busy state, okay, OR
      me.busy = busyIn;
      retVal = true;
    }
    return retVal;
  }

  public static void setBusyCursor(java.awt.Component component) {
      component.setCursor(java.awt.Cursor.getPredefinedCursor(java.awt.Cursor.WAIT_CURSOR));
  }

  public static void setNormalCursor(java.awt.Component component) {
      component.setCursor(java.awt.Cursor.getDefaultCursor());
  }

}