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/*******************************************************************************
 * Copyright (c) 2007, 2013 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
 *     Tom Schindl - initial API and implementation
 *     											- fix in bug: 195908, 210752
 *******************************************************************************/

package org.eclipse.jface.viewers;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Item;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;

/**
 * This class is responsible to provide the concept of cells for {@link Tree}.
 * This concept is needed to provide features like editor activation with the
 * keyboard
 *
 * @since 3.3
 *
 */
public class TreeViewerFocusCellManager extends SWTFocusCellManager {
	private static final CellNavigationStrategy TREE_NAVIGATE = new CellNavigationStrategy() {
		@Override
		public void collapse(ColumnViewer viewer, ViewerCell cellToCollapse,
				Event event) {
			if (cellToCollapse != null) {
				((TreeItem) cellToCollapse.getItem()).setExpanded(false);
			}
		}

		@Override
		public void expand(ColumnViewer viewer, ViewerCell cellToExpand,
				Event event) {
			if (cellToExpand != null) {
				TreeViewer v = (TreeViewer) viewer;
				v.setExpandedState(v.getTreePathFromItem((Item) cellToExpand
						.getItem()), true);
			}
		}

		@Override
		public boolean isCollapseEvent(ColumnViewer viewer,
				ViewerCell cellToCollapse, Event event) {

			if (cellToCollapse == null) {
				return false;
			}

			return cellToCollapse != null
					&& ((TreeItem) cellToCollapse.getItem()).getExpanded()
					&& event.keyCode == SWT.ARROW_LEFT
					&& isFirstColumnCell(cellToCollapse);
		}

		@Override
		public boolean isExpandEvent(ColumnViewer viewer,
				ViewerCell cellToExpand, Event event) {

			if (cellToExpand == null) {
				return false;
			}

			return cellToExpand != null
					&& ((TreeItem) cellToExpand.getItem()).getItemCount() > 0
					&& !((TreeItem) cellToExpand.getItem()).getExpanded()
					&& event.keyCode == SWT.ARROW_RIGHT
					&& isFirstColumnCell(cellToExpand);
		}

		private boolean isFirstColumnCell(ViewerCell cell) {
			return cell.getViewerRow().getVisualIndex(cell.getColumnIndex()) == 0;
		}
	};

	/**
	 * Create a new manager using a default navigation strategy:
	 * 
	 * SWT.ARROW_UP: navigate to cell above
	 * SWT.ARROW_DOWN: navigate to cell below
	 * SWT.ARROW_RIGHT: on first column (collapses if item
	 * is expanded) else navigate to next visible cell on the right
	 * SWT.ARROW_LEFT: on first column (expands if item is
	 * collapsed) else navigate to next visible cell on the left
	 * 
	 *
	 * @param viewer
	 *            the viewer the manager is bound to
	 * @param focusDrawingDelegate
	 *            the delegate responsible to highlight selected cell
	 */
	public TreeViewerFocusCellManager(TreeViewer viewer,
			FocusCellHighlighter focusDrawingDelegate) {
		this(viewer, focusDrawingDelegate, TREE_NAVIGATE);
	}

	/**
	 * Create a new manager with a custom navigation strategy
	 *
	 * @param viewer
	 *            the viewer the manager is bound to
	 * @param focusDrawingDelegate
	 *            the delegate responsible to highlight selected cell
	 * @param navigationStrategy
	 *            the strategy used to navigate the cells
	 * @since 3.4
	 */
	public TreeViewerFocusCellManager(TreeViewer viewer,
			FocusCellHighlighter focusDrawingDelegate,
			CellNavigationStrategy navigationStrategy) {
		super(viewer, focusDrawingDelegate, navigationStrategy);
	}

	@Override
	ViewerCell getInitialFocusCell() {
		Tree tree = (Tree) getViewer().getControl();

		if (! tree.isDisposed() && tree.getItemCount() > 0 && ! tree.getTopItem().isDisposed()) {
			ViewerRow aViewerRow = getViewer().getViewerRowFromItem(tree.getTopItem());
			if (tree.getColumnCount() == 0) {
				return aViewerRow.getCell(0);
			}

			Rectangle clientArea = tree.getClientArea();
			for (int i = 0; i < tree.getColumnCount(); i++) {
				if (aViewerRow.getWidth(i) > 0 && columnInVisibleArea(clientArea,aViewerRow,i))
					return aViewerRow.getCell(i);
			}
		}

		return null;
	}

	private boolean columnInVisibleArea(Rectangle clientArea, ViewerRow row, int colIndex) {
		return row.getBounds(colIndex).x >= clientArea.x;
	}

	@Override
	public ViewerCell getFocusCell() {
		ViewerCell cell = super.getFocusCell();
		Tree t = (Tree) getViewer().getControl();

		// It is possible that the selection has changed under the hood
		if (cell != null) {
			if (t.getSelection().length == 1
					&& t.getSelection()[0] != cell.getItem()) {
				setFocusCell(getViewer().getViewerRowFromItem(
						t.getSelection()[0]).getCell(cell.getColumnIndex()));
			}
		}

		return super.getFocusCell();
	}
}