Attachment 239388 Details for Bug 426773 – WidgetMethodHandler

WidgetMethodHandler

WidgetMethodHandler.java (text/plain), 7.24 KB, created by Sebastien Pennec

on 2014-01-28 09:00:08 EST

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Creator: Sebastien Pennec

Created: 2014-01-28 09:00:08 EST

Size: 7.24 KB

patch

obsolete

>package com.lodh.administrator.rcp.commands;
>
>import java.lang.reflect.InvocationTargetException;
>import java.lang.reflect.Method;
>
>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;
>
>/**
> * 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 {
>
>	/**
>	 * Track this base class enabled state.
>	 * 
>	 * @since 3.4
>	 */
>	private boolean baseEnabled = true;
>	
>	/**
>	 * 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() {
>	}
>
>	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;
>
>	/**
>	 * 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", null); //$NON-NLS-1$
>			final Object keyboardFocusManager = keyboardFocusManagerGetCurrentKeyboardFocusManagerMethod.invoke(
>					keyboardFocusManagerClass, null);
>			final Method keyboardFocusManagerGetFocusOwner = keyboardFocusManagerClass.getMethod("getFocusOwner", null); //$NON-NLS-1$
>			final Object focusComponent = keyboardFocusManagerGetFocusOwner.invoke(keyboardFocusManager, null);
>			return focusComponent;
>		}
>		// Use JRE 1.3 API
>		final Class focusManagerClass = Class.forName("javax.swing.FocusManager"); //$NON-NLS-1$
>		final Method focusManagerGetCurrentManagerMethod = focusManagerClass.getMethod("getCurrentManager", null); //$NON-NLS-1$
>		final Object focusManager = focusManagerGetCurrentManagerMethod.invoke(focusManagerClass, null);
>		final Method focusManagerGetFocusOwner = focusManagerClass.getMethod("getFocusOwner", null); //$NON-NLS-1$
>		final Object focusComponent = focusManagerGetFocusOwner.invoke(focusManager, null);
>		return focusComponent;
>
>	}
>
>	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;
>	}
>
>	/*
>	 * (non-Javadoc)
>	 * 
>	 * @see org.eclipse.core.commands.AbstractHandler#dispose()
>	 */
>	public void dispose() {
>		if (display != null && !display.isDisposed()) {
>			display.removeFilter(SWT.FocusIn, focusListener);
>		}
>		display = null;
>		focusListener = null;
>	}
>	
>	/**
>	 * Whether this handler is capable of executing at this time. Subclasses may
>	 * override this method. If clients override this method they should also
>	 * consider overriding {@link #setEnabled(Object)} so they can be notified
>	 * about framework execution contexts.
>	 * 
>	 * @return <code>true</code>
>	 * @see #setEnabled(Object)
>	 * @see #setBaseEnabled(boolean)
>	 */
>	public boolean isEnabled() {
>		return baseEnabled;
>	}
>
>	/**
>	 * Allow the default {@link #isEnabled()} to answer our enabled state. It
>	 * will fire a HandlerEvent if necessary. If clients use this method they
>	 * should also consider overriding {@link #setEnabled(Object)} so they can
>	 * be notified about framework execution contexts.
>	 * 
>	 * @param state
>	 *            the enabled state
>	 * @since 3.4
>	 */
>	protected void setBaseEnabled(boolean state) {
>		if (baseEnabled == state) {
>			return;
>		}
>		baseEnabled = state;
>	}
>}

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Attachments on bug 426773: 239387 | 239388