/*
 * @(#)AWTEvent.java	1.38 00/02/11
 *
 * Copyright 1996-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package java.awt;

import java.util.EventObject;
import java.awt.event.*;

/**
 * The root event class for all AWT events.
 * This class and its subclasses supercede the original
 * java.awt.Event class.
 * Subclasses of this root AWTEvent class defined outside of the
 * java.awt.event package should define event ID values greater than
 * the value defined by RESERVED_ID_MAX.
 * <p>
 * The event masks defined in this class are needed by Component subclasses
 * which are using Component.enableEvents() to select for event types not
 * selected by registered listeners. If a listener is registered on a
 * component, the appropriate event mask is already set internally by the
 * component.
 * <p>
 * The masks are also used to specify to which types of events an
 * AWTEventListener should listen. The masks are bitwise-ORed together
 * and passed to Toolkit.addAWTEventListener.
 * 
 * @see Component#enableEvents
 * @see Toolkit#addAWTEventListener
 *
 * @see java.awt.event.ActionEvent
 * @see java.awt.event.AdjustmentEvent
 * @see java.awt.event.ComponentEvent
 * @see java.awt.event.ContainerEvent
 * @see java.awt.event.FocusEvent
 * @see java.awt.event.InputMethodEvent
 * @see java.awt.event.InvocationEvent
 * @see java.awt.event.ItemEvent
 * @see java.awt.event.HierarchyEvent
 * @see java.awt.event.KeyEvent
 * @see java.awt.event.MouseEvent
 * @see java.awt.event.PaintEvent
 * @see java.awt.event.TextEvent
 * @see java.awt.event.WindowEvent
 *
 * @author Carl Quinn
 * @author Amy Fowler
 * @version 1.38 02/11/00
 * @since 1.1
 */
public abstract class AWTEvent extends EventObject {
    private transient long data;

	/*
	* This field contains the event's event id
	* @serial
	* @see getID()
	* @see AWTEvent())
	*/
    protected int id;

    // This field controls whether or not the event is sent back
    // down to the peer once the source has processed it -
    // false means it's sent to the peer, true means it's not.
    // Semantic events always have a 'true' value since they were
    // generated by the peer in response to a low-level event.
	/*
	* @serial
	* @see consume()
	* @see isConsumed()
	*/
    protected boolean consumed = false;

    /**
     * The event mask for selecting component events.
     */
    public final static long COMPONENT_EVENT_MASK = 0x01;

    /**
     * The event mask for selecting container events.
     */
    public final static long CONTAINER_EVENT_MASK = 0x02;

    /**
     * The event mask for selecting focus events.
     */
    public final static long FOCUS_EVENT_MASK = 0x04;

    /**
     * The event mask for selecting key events.
     */
    public final static long KEY_EVENT_MASK = 0x08;

    /**
     * The event mask for selecting mouse events.
     */
    public final static long MOUSE_EVENT_MASK = 0x10;

    /**
     * The event mask for selecting mouse motion events.
     */
    public final static long MOUSE_MOTION_EVENT_MASK = 0x20;

    /**
     * The event mask for selecting window events.
     */
    public final static long WINDOW_EVENT_MASK = 0x40;

    /**
     * The event mask for selecting action events.
     */
    public final static long ACTION_EVENT_MASK = 0x80;

    /**
     * The event mask for selecting adjustment events.
     */
    public final static long ADJUSTMENT_EVENT_MASK = 0x100;

    /**
     * The event mask for selecting item events.
     */
    public final static long ITEM_EVENT_MASK = 0x200;

    /**
     * The event mask for selecting text events.
     */
    public final static long TEXT_EVENT_MASK = 0x400;

    /**
     * The event mask for selecting input method events.
     */
    public final static long INPUT_METHOD_EVENT_MASK = 0x800;

    /**
     * The pseudo event mask for enabling input methods.
     * We're using one bit in the eventMask so we don't need
     * a separate field inputMethodsEnabled.
     */
    final static long INPUT_METHODS_ENABLED_MASK = 0x1000;

    /**
     * The event mask for selecting paint events.
     */
    public final static long PAINT_EVENT_MASK = 0x2000;

    /**
     * The event mask for selecting invocation events.
     */
    public final static long INVOCATION_EVENT_MASK = 0x4000;

    /**
     * The event mask for selecting hierarchy events.
     */
    public final static long HIERARCHY_EVENT_MASK = 0x8000;

    /**
     * The event mask for selecting hierarchy bounds events.
     */
    public final static long HIERARCHY_BOUNDS_EVENT_MASK = 0x10000;

    /**
     * The maximum value for reserved AWT event IDs. Programs defining
     * their own event IDs should use IDs greater than this value.
     */
    public final static int RESERVED_ID_MAX = 1999;

    /*
     * JDK 1.1 serialVersionUID
     */
    private static final long serialVersionUID = -1825314779160409405L;

    static {
        /* ensure that the necessary native libraries are loaded */
	Toolkit.loadLibraries();
	initIDs();
    }

    /**
     * Initialize JNI field and method IDs for fields that may be
       accessed from C.
     */
    private static native void initIDs();

    /**
     * Constructs an AWTEvent object from the parameters of a 1.0-style event.
     * @param event the old-style event
     */
    public AWTEvent(Event event) {
        this(event.target, event.id);
    }

    /**
     * Constructs an AWTEvent object with the specified source object and type.
     * @param source the object where the event originated
     * @id the event type
     */
    public AWTEvent(Object source, int id) {
        super(source);
	this.id = id;
        switch(id) {
          case ActionEvent.ACTION_PERFORMED:
          case ItemEvent.ITEM_STATE_CHANGED:
          case AdjustmentEvent.ADJUSTMENT_VALUE_CHANGED:
          case TextEvent.TEXT_VALUE_CHANGED:
            consumed = true;
            break;
          default:
        }
    }

    /**
     * Returns the event type.
     */
    public int getID() {
        return id;
    }

    public String toString() {
        String srcName = null;
        if (source instanceof Component) {
            srcName = ((Component)source).getName();
        } else if (source instanceof MenuComponent) {
            srcName = ((MenuComponent)source).getName();
        }
	return getClass().getName() + "[" + paramString() + "] on " +
            (srcName != null? srcName : source);
    }

    /**
     * Returns a string representing the state of this event. This 
     * method is intended to be used only for debugging purposes, and the 
     * content and format of the returned string may vary between 
     * implementations. The returned string may be empty but may not be 
     * <code>null</code>.
     * 
     * @return  a string representation of this event.
     */
    public String paramString() {
        return "";
    }

    protected void consume() {
        switch(id) {
          case KeyEvent.KEY_PRESSED:
          case KeyEvent.KEY_RELEASED:
          case MouseEvent.MOUSE_PRESSED:
          case MouseEvent.MOUSE_RELEASED:
          case MouseEvent.MOUSE_MOVED:
          case MouseEvent.MOUSE_DRAGGED:
          case MouseEvent.MOUSE_ENTERED:
          case MouseEvent.MOUSE_EXITED:
          case InputMethodEvent.INPUT_METHOD_TEXT_CHANGED:
          case InputMethodEvent.CARET_POSITION_CHANGED:
              consumed = true;
              break;
          default:
              // event type cannot be consumed
        }
    }

    protected boolean isConsumed() {
        return consumed;
    }

    /* Converts a new event to an old one (used for compatibility).
     * If the new event cannot be converted (because no old equivelent
     * exists) then this returns null.
     *
     * Note: this method is here instead of in each individual new
     * event class in java.awt.event because we don't want to make
     * it public and it needs to be called from java.awt.
     */
    Event convertToOld() {
        Object src = getSource();
        int newid = id;

        switch(id) {
          case KeyEvent.KEY_PRESSED:
          case KeyEvent.KEY_RELEASED:
              KeyEvent ke = (KeyEvent)this;
              if (ke.isActionKey()) {
                  newid = (id == KeyEvent.KEY_PRESSED?
                           Event.KEY_ACTION : Event.KEY_ACTION_RELEASE);
              }
              int keyCode = ke.getKeyCode();
              if (keyCode == KeyEvent.VK_SHIFT ||
                  keyCode == KeyEvent.VK_CONTROL ||
                  keyCode == KeyEvent.VK_ALT) {
                  return null;  // suppress modifier keys in old event model.
              }
              // no mask for button1 existed in old Event - strip it out
              return new Event(src, ke.getWhen(), newid, 0, 0,
                               Event.getOldEventKey(ke),
                               (ke.getModifiers() & ~InputEvent.BUTTON1_MASK));

          case MouseEvent.MOUSE_PRESSED:
          case MouseEvent.MOUSE_RELEASED:
          case MouseEvent.MOUSE_MOVED:
          case MouseEvent.MOUSE_DRAGGED:
          case MouseEvent.MOUSE_ENTERED:
          case MouseEvent.MOUSE_EXITED:
              MouseEvent me = (MouseEvent)this;
              // no mask for button1 existed in old Event - strip it out
              Event olde = new Event(src, me.getWhen(), newid,
                               me.getX(), me.getY(), 0,
                               (me.getModifiers() & ~InputEvent.BUTTON1_MASK));
              olde.clickCount = me.getClickCount();
              return olde;

          case FocusEvent.FOCUS_GAINED:
              return new Event(src, Event.GOT_FOCUS, null);

          case FocusEvent.FOCUS_LOST:
              return new Event(src, Event.LOST_FOCUS, null);

          case WindowEvent.WINDOW_CLOSING:
          case WindowEvent.WINDOW_ICONIFIED:
          case WindowEvent.WINDOW_DEICONIFIED:
              return new Event(src, newid, null);

          case ComponentEvent.COMPONENT_MOVED:
              if (src instanceof Frame || src instanceof Dialog) {
                  Point p = ((Component)src).getLocation();
                  return new Event(src, 0, Event.WINDOW_MOVED, p.x, p.y, 0, 0);
              }
              break;

          case ActionEvent.ACTION_PERFORMED:
              ActionEvent ae = (ActionEvent)this;
              String cmd;
              if (src instanceof Button) {
                  cmd = ((Button)src).getLabel();
              } else if (src instanceof MenuItem) {
                  cmd = ((MenuItem)src).getLabel();
              } else {
                  cmd = ae.getActionCommand();
              }
              return new Event(src, 0, newid, 0, 0, 0, ae.getModifiers(), cmd);

          case ItemEvent.ITEM_STATE_CHANGED:
              ItemEvent ie = (ItemEvent)this;
              Object arg;
              if (src instanceof List) {
                  newid = (ie.getStateChange() == ItemEvent.SELECTED?
                           Event.LIST_SELECT : Event.LIST_DESELECT);
                  arg = ie.getItem();
              } else {
                  newid = Event.ACTION_EVENT;
                  if (src instanceof Choice) {
                      arg = ie.getItem();

                  } else { // Checkbox
                      arg = new Boolean(ie.getStateChange() == ItemEvent.SELECTED);
                  }
              }
              return new Event(src, newid, arg);

          case AdjustmentEvent.ADJUSTMENT_VALUE_CHANGED:
              AdjustmentEvent aje = (AdjustmentEvent)this;
              switch(aje.getAdjustmentType()) {
                case AdjustmentEvent.UNIT_INCREMENT:
                  newid = Event.SCROLL_LINE_DOWN;
                  break;
                case AdjustmentEvent.UNIT_DECREMENT:
                  newid = Event.SCROLL_LINE_UP;
                  break;
                case AdjustmentEvent.BLOCK_INCREMENT:
                  newid = Event.SCROLL_PAGE_DOWN;
                  break;
                case AdjustmentEvent.BLOCK_DECREMENT:
                  newid = Event.SCROLL_PAGE_UP;
                  break;
                case AdjustmentEvent.TRACK:
                  newid = Event.SCROLL_ABSOLUTE;
                  break;
                default:
                  return null;
              }
              return new Event(src, newid, new Integer(aje.getValue()));

          default:
        }
        return null;
    }

    /**
     * "Moves" any private data into "other." The data is copied, and
     * any references data structures in this object are set to null.
     */
    void movePrivateDataInto(AWTEvent other) {
	other.data = this.data;
	data = 0;
    }

    /**
     * Copies all private data from this event into that. 
     * Space is allocated for the copied data that will be
     * freed when the that is finalized. Upon completion,
     * this event is not changed.
     */
    void copyPrivateDataInto(AWTEvent that) {
	// currently, the only private data is native
	copyDataFieldInto(that);
    }

    /**
     * Copies the "data" instance variable from this event
     * into that. Space is allocated for the data in that
     * and must be freed at some point (normally in finalize()).
     */
    private native void copyDataFieldInto(AWTEvent that);

    /**
     * frees any native data held by this object. Normally called
     * when the object is finalized.
     */
    private native void freeNativeData();
     
    protected void finalize() throws Throwable {
        freeNativeData();
        super.finalize();
    }

} // class AWTEvent