362 lines
12 KiB
Java
362 lines
12 KiB
Java
/* LightweightDispatcher.java -- Dispatches mouse events to lightweights
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Copyright (C) 2006 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.awt;
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import java.awt.event.InputEvent;
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import java.awt.event.MouseEvent;
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import java.awt.event.MouseWheelEvent;
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import java.awt.peer.LightweightPeer;
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import java.util.WeakHashMap;
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/**
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* Redispatches mouse events to lightweight components. The native peers know
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* nothing about the lightweight components and thus mouse events are always
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* targetted at Windows or heavyweight components. This class listenes directly
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* on the eventqueue and dispatches mouse events to lightweight components.
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*
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* @author Roman Kennke (kennke@aicas.com)
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*/
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final class LightweightDispatcher
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{
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/**
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* Maps thread groups to lightweight dispatcher instances. We need to
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* have one instance per thread group so that 2 or more applets or otherwise
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* separated applications (like in OSGI) do not interfer with each other.
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*/
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private static WeakHashMap instances = new WeakHashMap();
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/**
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* The last mouse event target. If the target changes, additional
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* MOUSE_ENTERED and MOUSE_EXITED events must be dispatched.
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*/
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private Component lastTarget;
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/**
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* The current mouseEventTarget.
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*/
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private Component mouseEventTarget;
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/**
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* Returns an instance of LightweightDispatcher for the current thread's
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* thread group.
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*
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* @return an instance of LightweightDispatcher for the current thread's
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* thread group
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*/
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static LightweightDispatcher getInstance()
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{
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Thread t = Thread.currentThread();
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ThreadGroup tg = t.getThreadGroup();
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LightweightDispatcher instance = (LightweightDispatcher) instances.get(tg);
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if (instance == null)
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{
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instance = new LightweightDispatcher();
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instances.put(tg, instance);
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}
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return instance;
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}
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/**
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* Creates a new LightweightDispatcher. This is private to prevent access
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* from outside. Use {@link #getInstance()} instead.
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*/
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private LightweightDispatcher()
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{
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// Nothing to do here.
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}
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/**
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* Receives notification if a mouse event passes along the eventqueue.
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*
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* @param event the event
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*/
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public boolean dispatchEvent(final AWTEvent event)
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{
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if (event instanceof MouseEvent)
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{
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MouseEvent mouseEvent = (MouseEvent) event;
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return handleMouseEvent(mouseEvent);
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}
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return false;
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}
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/**
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* Handles all mouse events that are targetted at toplevel containers
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* (Window instances) and dispatches them to the correct lightweight child.
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*
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* @param ev the mouse event
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* @return whether or not we found a lightweight that handled the event.
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*/
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private boolean handleMouseEvent(final MouseEvent ev)
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{
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Container container = (Container) ev.getSource();
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Component target = findTarget(container, ev.getX(), ev.getY());
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trackEnterExit(target, ev);
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int id = ev.getID();
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// Dont update the mouseEventTarget when dragging. Also, MOUSE_CLICKED
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// must be dispatched to the original target of MOUSE_PRESSED, so don't
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// update in this case either.
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if (! isDragging(ev) && id != MouseEvent.MOUSE_CLICKED)
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mouseEventTarget = (target != container) ? target : null;
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if (mouseEventTarget != null)
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{
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switch (id)
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{
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case MouseEvent.MOUSE_ENTERED:
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case MouseEvent.MOUSE_EXITED:
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// This is already handled in trackEnterExit().
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break;
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case MouseEvent.MOUSE_PRESSED:
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case MouseEvent.MOUSE_RELEASED:
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case MouseEvent.MOUSE_MOVED:
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redispatch(ev, mouseEventTarget, id);
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break;
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case MouseEvent.MOUSE_CLICKED:
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// MOUSE_CLICKED must be dispatched to the original target of
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// MOUSE_PRESSED.
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if (target == mouseEventTarget)
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redispatch(ev, mouseEventTarget, id);
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break;
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case MouseEvent.MOUSE_DRAGGED:
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if (isDragging(ev))
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redispatch(ev, mouseEventTarget, id);
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break;
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case MouseEvent.MOUSE_WHEEL:
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redispatch(ev, mouseEventTarget, id);
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}
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ev.consume();
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}
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return ev.isConsumed();
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}
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/**
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* Finds the actual target for a mouseevent, starting at <code>c</code>.
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* This searches through the children of the container and finds the first
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* one which is showing, at the location from the mouse event and has
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* a MouseListener or MouseMotionListener attached. If no such child component
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* is found, null is returned.
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*
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* @param c the container to search through
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* @param loc the mouse event point
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*
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* @return the actual receiver of the mouse event, or null, if no such
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* component has been found
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*/
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private Component findTarget(final Container c, final int x, final int y)
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{
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Component target = null;
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// First we check the children of the container.
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// Note: It is important that we use the package private Container
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// fields ncomponents and component here. There are applications
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// that override getComponentCount()
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// and getComponent() to hide internal components, which makes
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// the LightweightDispatcher not work correctly in these cases.
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// As a positive sideeffect this is slightly more efficient.
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int nChildren = c.ncomponents;
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for (int i = 0; i < nChildren && target == null; i++)
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{
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Component child = c.component[i];
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int childX = x - child.x;
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int childY = y - child.y;
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if (child != null && child.visible
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&& child.peer instanceof LightweightPeer
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&& child.contains(childX, childY))
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{
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// Check if there's a deeper possible target.
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if (child instanceof Container)
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{
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Component deeper = findTarget((Container) child,
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childX, childY);
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if (deeper != null)
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target = deeper;
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}
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// Check if the child itself is interested in mouse events.
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else if (isMouseListening(child))
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target = child;
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}
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}
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// Check the container itself, if we didn't find a target yet.
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if (target == null && c.contains(x, y) && isMouseListening(c))
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target = c;
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return target;
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}
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/**
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* Checks if the specified component would be interested in a mouse event.
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*
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* @param c the component to check
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*
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* @return <code>true</code> if the component has mouse listeners installed,
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* <code>false</code> otherwise
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*/
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private boolean isMouseListening(final Component c)
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{
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// Note: It is important to NOT check if the component is listening
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// for a specific event (for instance, mouse motion events). The event
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// gets dispatched to the component if the component is listening
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// for ANY mouse event, even when the component is not listening for the
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// specific type of event. There are applications that depend on this
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// (sadly).
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return c.mouseListener != null
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|| c.mouseMotionListener != null
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|| c.mouseWheelListener != null
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|| (c.eventMask & AWTEvent.MOUSE_EVENT_MASK) != 0
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|| (c.eventMask & AWTEvent.MOUSE_MOTION_EVENT_MASK) != 0
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|| (c.eventMask & AWTEvent.MOUSE_WHEEL_EVENT_MASK) != 0;
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}
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/**
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* Tracks MOUSE_ENTERED and MOUSE_EXIT as well as MOUSE_MOVED and
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* MOUSE_DRAGGED and creates synthetic MOUSE_ENTERED and MOUSE_EXITED for
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* lightweight component.s
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*
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* @param target the current mouse event target
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* @param ev the mouse event
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*/
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private void trackEnterExit(final Component target, final MouseEvent ev)
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{
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int id = ev.getID();
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if (target != lastTarget)
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{
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if (lastTarget != null)
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redispatch(ev, lastTarget, MouseEvent.MOUSE_EXITED);
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if (id == MouseEvent.MOUSE_EXITED)
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ev.consume();
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if (target != null)
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redispatch(ev, target, MouseEvent.MOUSE_ENTERED);
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if (id == MouseEvent.MOUSE_ENTERED)
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ev.consume();
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lastTarget = target;
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}
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}
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/**
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* Redispatches the specified mouse event to the specified target with the
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* specified id.
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*
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* @param ev the mouse event
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* @param target the new target
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* @param id the new id
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*/
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private void redispatch(MouseEvent ev, Component target, int id)
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{
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Component source = ev.getComponent();
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if (target != null)
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{
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// Translate coordinates.
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int x = ev.getX();
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int y = ev.getY();
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for (Component c = target; c != null && c != source; c = c.getParent())
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{
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x -= c.x;
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y -= c.y;
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}
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// Retarget event.
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MouseEvent retargeted;
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if (id == MouseEvent.MOUSE_WHEEL)
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{
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MouseWheelEvent mwe = (MouseWheelEvent) ev;
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retargeted = new MouseWheelEvent(target, id, ev.getWhen(),
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ev.getModifiers()
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| ev.getModifiersEx(), x, y,
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ev.getClickCount(),
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ev.isPopupTrigger(),
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mwe.getScrollType(),
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mwe.getScrollAmount(),
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mwe.getWheelRotation());
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}
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else
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{
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retargeted = new MouseEvent(target, id, ev.getWhen(),
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ev.getModifiers() | ev.getModifiersEx(),
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x, y, ev.getClickCount(),
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ev.isPopupTrigger(), ev.getButton());
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}
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if (target == source)
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((Container) target).dispatchNoLightweight(retargeted);
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else
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target.dispatchEvent(retargeted);
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}
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}
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/**
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* Determines if we are in the middle of a drag operation, that is, if
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* any of the buttons is held down.
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*
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* @param ev the mouse event to check
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*
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* @return <code>true</code> if we are in the middle of a drag operation,
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* <code>false</code> otherwise
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*/
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private boolean isDragging(MouseEvent ev)
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{
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int mods = ev.getModifiersEx();
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int id = ev.getID();
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if (id == MouseEvent.MOUSE_PRESSED || id == MouseEvent.MOUSE_RELEASED)
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{
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switch (ev.getButton())
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{
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case MouseEvent.BUTTON1:
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mods ^= InputEvent.BUTTON1_DOWN_MASK;
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break;
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case MouseEvent.BUTTON2:
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mods ^= InputEvent.BUTTON2_DOWN_MASK;
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break;
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case MouseEvent.BUTTON3:
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mods ^= InputEvent.BUTTON3_DOWN_MASK;
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break;
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}
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}
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return (mods & (InputEvent.BUTTON1_DOWN_MASK
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| InputEvent.BUTTON2_DOWN_MASK
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| InputEvent.BUTTON3_DOWN_MASK)) != 0;
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}
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}
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