bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/framelist/TreeViewerFrameSource.java

package org.eclipse.ui.views.framelist;

/**********************************************************************
Copyright (c) 2000, 2001, 2002, International Business Machines Corp and others.
All rights reserved.   This program and the accompanying materials
are made available under the terms of the Common Public License v0.5
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/cpl-v05.html
 
Contributors:
**********************************************************************/

import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.jface.viewers.*;

/** 
 * Frame source for tree viewers, which uses <code>TreeFrame</code> to capture
 * the state of the tree viewer.
 * 
 * @see TreeFrame
 */
public class TreeViewerFrameSource implements IFrameSource {

	private AbstractTreeViewer viewer;

	/**
	 * Constructs a new tree viewer frame source for the specified tree viewer.
	 * 
	 * @param viewer the tree viewer
	 */
	public TreeViewerFrameSource(AbstractTreeViewer viewer) {
		this.viewer = viewer;
	}

	/**
	 * Connects this source as a listener on the frame list,
	 * so that when the current frame changes, the viewer is updated.
	 */
	public void connectTo(FrameList frameList) {
		frameList.addPropertyChangeListener(new IPropertyChangeListener() {
			public void propertyChange(PropertyChangeEvent event) {
				TreeViewerFrameSource.this.handlePropertyChange(event);
			}
		});
	}

	/**
	 * Returns a new tree frame capturing the specified input element.
	 * 
	 * @param input the input element
	 * @return the tree frame
	 */
	protected TreeFrame createFrame(Object input) {
		return new TreeFrame(viewer, input);
	}

	/**
	 * Updates the viewer in response to the current frame changing.
	 * 
	 * @param frame the new value for the current frame
	 */
	protected void frameChanged(TreeFrame frame) {
		viewer.getControl().setRedraw(false);
		viewer.setInput(frame.getInput());
		viewer.setExpandedElements(frame.getExpandedElements());
		viewer.setSelection(frame.getSelection(), true);
		viewer.getControl().setRedraw(true);
	}

	/**
	 * Returns the current frame.
	 * 
	 * @param flags a bit-wise OR of the frame source flag constants
	 * @return the current frame
	 */
	protected Frame getCurrentFrame(int flags) {
		Object input = viewer.getInput();
		TreeFrame frame = createFrame(input);
		if ((flags & IFrameSource.FULL_CONTEXT) != 0) {
			frame.setSelection(viewer.getSelection());
			frame.setExpandedElements(viewer.getExpandedElements());
		}
		return frame;
	}

	/* (non-Javadoc)
	 * Method declared on IFrameSource.
	 */
	public Frame getFrame(int whichFrame, int flags) {
		switch (whichFrame) {
			case IFrameSource.CURRENT_FRAME :
				return getCurrentFrame(flags);
			case IFrameSource.PARENT_FRAME :
				return getParentFrame(flags);
			case IFrameSource.SELECTION_FRAME :
				return getSelectionFrame(flags);
			default :
				return null;
		}
	}

	/**
	 * Returns the parent frame, or <code>null</code> if there is no parent frame.
	 * 
	 * @param flags a bit-wise OR of the frame source flag constants
	 * @return the parent frame, or <code>null</code>
	 */
	protected Frame getParentFrame(int flags) {
		Object input = viewer.getInput();
		ITreeContentProvider provider = (ITreeContentProvider) viewer.getContentProvider();
		Object parent = provider.getParent(input);
		if (parent == null) {
			return null;
		} else {
			TreeFrame frame = createFrame(parent);
			if ((flags & IFrameSource.FULL_CONTEXT) != 0) {
				frame.setSelection(viewer.getSelection());
				// include current input in expanded set
				Object[] expanded = viewer.getExpandedElements();
				Object[] newExpanded = new Object[expanded.length + 1];
				System.arraycopy(expanded, 0, newExpanded, 0, expanded.length);
				newExpanded[newExpanded.length - 1] = input;
				frame.setExpandedElements(newExpanded);
			}
			return frame;
		}
	}

	/**
	 * Returns the frame for the selection, or <code>null</code> if there is no
	 * frame for the selection.
	 * 
	 * @param flags a bit-wise OR of the frame source flag constants
	 * @return the selection frame, or <code>null</code>
	 */
	protected Frame getSelectionFrame(int flags) {
		IStructuredSelection sel = (IStructuredSelection) viewer.getSelection();
		if (sel.size() == 1) {
			Object o = sel.getFirstElement();
			if (viewer.isExpandable(o)) {
				TreeFrame frame = createFrame(o);
				if ((flags & IFrameSource.FULL_CONTEXT) != 0) {
					frame.setSelection(viewer.getSelection());
					frame.setExpandedElements(viewer.getExpandedElements());
				}
				return frame;
			}
		}
		return null;
	}

	/**
	 * Returns the tree viewer.
	 * 
	 * @return the tree viewer
	 */
	public AbstractTreeViewer getViewer() {
		return viewer;
	}

	/**
	 * Handles a property change event from the frame list.
	 * Calls <code>frameChanged</code> when the current frame changes.
	 */
	protected void handlePropertyChange(PropertyChangeEvent event) {
		if (FrameList.P_CURRENT_FRAME.equals(event.getProperty())) {
			frameChanged((TreeFrame) event.getNewValue());
		}
	}
}