/*******************************************************************************
* Copyright (c) 2000, 2015 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
* Bruno Haible haible@ilog.fr - bug 228890
*******************************************************************************/
package org.eclipse.ui.internal.handlers;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExecutableExtension;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.ui.internal.ExceptionHandler;
/**
* Handles the cut command in both dialogs and windows. This handler is enabled
* if the focus control supports the "cut" method.
*
* @since 3.0
*/
public class WidgetMethodHandler extends AbstractHandler implements
IExecutableExtension {
/**
* The parameters to pass to the method this handler invokes. This handler
* always passes no parameters.
*/
protected static final Class[] NO_PARAMETERS = new Class[0];
public WidgetMethodHandler() {
display = Display.getCurrent();
if (display != null) {
focusListener = event -> updateEnablement();
display.addFilter(SWT.FocusIn, focusListener);
}
}
void updateEnablement() {
boolean rc = isHandled();
if (rc != isEnabled()) {
setBaseEnabled(rc);
}
}
/**
* The name of the method to be invoked by this handler. This value should
* never be <code>null</code>.
*/
protected String methodName;
private Listener focusListener;
private Display display;
@Override
public Object execute(final ExecutionEvent event) throws ExecutionException {
final Method methodToExecute = getMethodToExecute();
if (methodToExecute != null) {
try {
final Control focusControl = Display.getCurrent()
.getFocusControl();
if ((focusControl instanceof Composite)
&& ((((Composite) focusControl).getStyle() & SWT.EMBEDDED) != 0)) {
/*
* Okay. Have a seat. Relax a while. This is going to be a
* bumpy ride. If it is an embedded widget, then it *might*
* be a Swing widget. At the point where this handler is
* executing, the key event is already bound to be
* swallowed. If I don't do something, then the key will be
* gone for good. So, I will try to forward the event to the
* Swing widget. Unfortunately, we can't even count on the
* Swing libraries existing, so I need to use reflection
* everywhere. And, to top it off, I need to dispatch the
* event on the Swing event queue, which means that it will
* be carried out asynchronously to the SWT event queue.
*/
try {
final Object focusComponent = getFocusComponent();
if (focusComponent != null) {
Runnable methodRunnable = () -> {
try {
methodToExecute.invoke(focusComponent);
} catch (final IllegalAccessException e1) {
// The method is protected, so do
// nothing.
} catch (final InvocationTargetException e2) {
/*
* I would like to log this exception --
* and possibly show a dialog to the
* user -- but I have to go back to the
* SWT event loop to do this. So, back
* we go....
*/
focusControl.getDisplay().asyncExec(
() -> ExceptionHandler
.getInstance()
.handleException(
new ExecutionException(
"An exception occurred while executing " //$NON-NLS-1$
+ methodToExecute
.getName(),
e2
.getTargetException())));
}
};
swingInvokeLater(methodRunnable);
}
} catch (final ClassNotFoundException e) {
// There is no Swing support, so do nothing.
} catch (final NoSuchMethodException e) {
// The API has changed, which seems amazingly unlikely.
throw new Error("Something is seriously wrong here"); //$NON-NLS-1$
}
} else {
methodToExecute.invoke(focusControl);
}
} catch (IllegalAccessException e) {
// The method is protected, so do nothing.
} catch (InvocationTargetException e) {
throw new ExecutionException(
"An exception occurred while executing " //$NON-NLS-1$
+ methodToExecute.getName(), e
.getTargetException());
}
}
return null;
}
/**
* Invoke a runnable on the swing EDT.
*
* @param methodRunnable
* @throws ClassNotFoundException
* @throws NoSuchMethodException
* @throws IllegalAccessException
* @throws InvocationTargetException
*/
protected void swingInvokeLater(Runnable methodRunnable)
throws ClassNotFoundException, NoSuchMethodException,
IllegalAccessException, InvocationTargetException {
final Class swingUtilitiesClass = Class
.forName("javax.swing.SwingUtilities"); //$NON-NLS-1$
final Method swingUtilitiesInvokeLaterMethod = swingUtilitiesClass
.getMethod("invokeLater", //$NON-NLS-1$
new Class[] { Runnable.class });
swingUtilitiesInvokeLaterMethod.invoke(swingUtilitiesClass,
new Object[] { methodRunnable });
}
/**
* Find the swing focus component, if it is available.
*
* @return Hopefully, the swing focus component, but it can return
* <code>null</code>.
* @throws ClassNotFoundException
* @throws NoSuchMethodException
* @throws IllegalAccessException
* @throws InvocationTargetException
*/
protected Object getFocusComponent() throws ClassNotFoundException,
NoSuchMethodException, IllegalAccessException,
InvocationTargetException {
/*
* Before JRE 1.4, one has to use
* javax.swing.FocusManager.getCurrentManager().getFocusOwner(). Since
* JRE 1.4, one has to use
* java.awt.KeyboardFocusManager.getCurrentKeyboardFocusManager
* ().getFocusOwner(); the use of the older API would install a
* LegacyGlueFocusTraversalPolicy which causes endless recursions in
* some situations.
*/
Class keyboardFocusManagerClass = null;
try {
keyboardFocusManagerClass = Class
.forName("java.awt.KeyboardFocusManager"); //$NON-NLS-1$
} catch (ClassNotFoundException e) {
// switch to the old guy
}
if (keyboardFocusManagerClass != null) {
// Use JRE 1.4 API
final Method keyboardFocusManagerGetCurrentKeyboardFocusManagerMethod = keyboardFocusManagerClass
.getMethod("getCurrentKeyboardFocusManager"); //$NON-NLS-1$
final Object keyboardFocusManager = keyboardFocusManagerGetCurrentKeyboardFocusManagerMethod
.invoke(keyboardFocusManagerClass);
final Method keyboardFocusManagerGetFocusOwner = keyboardFocusManagerClass
.getMethod("getFocusOwner"); //$NON-NLS-1$
final Object focusComponent = keyboardFocusManagerGetFocusOwner
.invoke(keyboardFocusManager);
return focusComponent;
}
// Use JRE 1.3 API
final Class focusManagerClass = Class
.forName("javax.swing.FocusManager"); //$NON-NLS-1$
final Method focusManagerGetCurrentManagerMethod = focusManagerClass
.getMethod("getCurrentManager"); //$NON-NLS-1$
final Object focusManager = focusManagerGetCurrentManagerMethod
.invoke(focusManagerClass);
final Method focusManagerGetFocusOwner = focusManagerClass
.getMethod("getFocusOwner"); //$NON-NLS-1$
final Object focusComponent = focusManagerGetFocusOwner
.invoke(focusManager);
return focusComponent;
}
@Override
public final boolean isHandled() {
return getMethodToExecute() != null;
}
/**
* Looks up the method on the focus control.
*
* @return The method on the focus control; <code>null</code> if none.
*/
protected Method getMethodToExecute() {
Display display = Display.getCurrent();
if (display == null)
return null;
final Control focusControl = display.getFocusControl();
Method method = null;
if (focusControl != null) {
final Class clazz = focusControl.getClass();
try {
method = clazz.getMethod(methodName, NO_PARAMETERS);
} catch (NoSuchMethodException e) {
// Fall through...
}
}
if ((method == null)
&& (focusControl instanceof Composite)
&& ((((Composite) focusControl).getStyle() & SWT.EMBEDDED) != 0)) {
/*
* We couldn't find the appropriate method on the current focus
* control. It is possible that the current focus control is an
* embedded SWT composite, which could be containing some Swing
* components. If this is the case, then we should try to pass
* through to the underlying Swing component hierarchy. Insha'allah,
* this will work.
*/
try {
final Object focusComponent = getFocusComponent();
if (focusComponent != null) {
final Class clazz = focusComponent.getClass();
try {
method = clazz.getMethod(methodName, NO_PARAMETERS);
} catch (NoSuchMethodException e) {
// Do nothing.
}
}
} catch (final ClassNotFoundException e) {
// There is no Swing support, so do nothing.
} catch (final NoSuchMethodException e) {
// The API has changed, which seems amazingly unlikely.
throw new Error("Something is seriously wrong here"); //$NON-NLS-1$
} catch (IllegalAccessException e) {
// The API has changed, which seems amazingly unlikely.
throw new Error("Something is seriously wrong here"); //$NON-NLS-1$
} catch (InvocationTargetException e) {
// The API has changed, which seems amazingly unlikely.
throw new Error("Something is seriously wrong here"); //$NON-NLS-1$
}
}
return method;
}
@Override
public void setInitializationData(IConfigurationElement config,
String propertyName, Object data) {
// The data is really just a string (i.e., the method name).
methodName = data.toString();
}
@Override
public void dispose() {
if (display!=null && !display.isDisposed()) {
display.removeFilter(SWT.FocusIn, focusListener);
}
display = null;
focusListener = null;
}
}