/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.custom;


import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.events.*;

/**
*
* A TreeEditor is a manager for a Control that appears above a cell in a Tree and tracks with the
* moving and resizing of that cell.  It can be used to display a text widget above a cell
* in a Tree so that the user can edit the contents of that cell.  It can also be used to display
* a button that can launch a dialog for modifying the contents of the associated cell.
*
* <p> Here is an example of using a TreeEditor:
* <code><pre>
*	final Tree tree = new Tree(shell, SWT.BORDER);
*	for (int i = 0; i &lt 3; i++) {
*		TreeItem item = new TreeItem(tree, SWT.NONE);
*		item.setText("item " + i);
*		for (int j = 0; j &lt 3; j++) {
*			TreeItem subItem = new TreeItem(item, SWT.NONE);
*			subItem.setText("item " + i + " " + j);
*		}
*	}
*	
*	final TreeEditor editor = new TreeEditor(tree);
*	//The editor must have the same size as the cell and must
*	//not be any smaller than 50 pixels.
*	editor.horizontalAlignment = SWT.LEFT;
*	editor.grabHorizontal = true;
*	editor.minimumWidth = 50;
*	
*	tree.addSelectionListener(new SelectionAdapter() {
*		public void widgetSelected(SelectionEvent e) {
*			// Clean up any previous editor control
*			Control oldEditor = editor.getEditor();
*			if (oldEditor != null) oldEditor.dispose();
*	
*			// Identify the selected row
*			TreeItem item = (TreeItem)e.item;
*			if (item == null) return;
*	
*			// The control that will be the editor must be a child of the Table
*			Text newEditor = new Text(tree, SWT.NONE);
*			newEditor.setText(item.getText());
*			newEditor.addModifyListener(new ModifyListener() {
*				public void modifyText(ModifyEvent e) {
*					Text text = (Text)editor.getEditor();
*					editor.getItem().setText(text.getText());
*				}
*			});
*			newEditor.selectAll();
*			newEditor.setFocus();
*			editor.setEditor(newEditor, item);
*		}
*	});
* </pre></code>
*/
public class TreeEditor extends ControlEditor {	
	Tree tree;
	TreeItem item;
	TreeListener treeListener;
/**
* Creates a TreeEditor for the specified Tree.
*
* @param tree the Tree Control above which this editor will be displayed
*
*/
public TreeEditor (Tree tree) {
	super(tree);
	this.tree = tree;

	treeListener = new TreeListener () {
		final Runnable runnable = new Runnable() {
			public void run() {
				if (TreeEditor.this.tree.isDisposed() || editor == null) return;
				resize();
				if (editor == null || editor.isDisposed()) return;
				editor.setVisible(true);
			}
		};
		public void treeCollapsed(TreeEvent e) {
			if (editor == null || editor.isDisposed ()) return;
			editor.setVisible(false);
			Display display = TreeEditor.this.tree.getDisplay();
			display.asyncExec(runnable);
		}
		public void treeExpanded(TreeEvent e) {
			if (editor == null || editor.isDisposed ()) return;
			editor.setVisible(false);
			Display display = TreeEditor.this.tree.getDisplay();
			display.asyncExec(runnable);
		}
	};
	tree.addTreeListener(treeListener);
	
	// To be consistent with older versions of SWT, grabVertical defaults to true
	grabVertical = true;
}
Rectangle computeBounds () {
	if (item == null || item.isDisposed()) return new Rectangle(0, 0, 0, 0);
	Rectangle cell = item.getBounds();
	Rectangle area = tree.getClientArea();
	if (cell.x < area.x + area.width) {
		if (cell.x + cell.width > area.x + area.width) {
			cell.width = area.x + area.width - cell.x;
		}
	}
	Rectangle editorRect = new Rectangle(cell.x, cell.y, minimumWidth, minimumHeight);

	if (grabHorizontal) {
		// Bounds of tree item only include the text area - stretch out to include 
		// entire client area
		cell.width = area.x + area.width - cell.x;
		editorRect.width = Math.max(cell.width, minimumWidth);
	}
	
	if (grabVertical) {
		editorRect.height = Math.max(cell.height, minimumHeight);
	}
	
	if (horizontalAlignment == SWT.RIGHT) {
		editorRect.x += cell.width - editorRect.width;
	} else if (horizontalAlignment == SWT.LEFT) {
		// do nothing - cell.x is the right answer
	} else { // default is CENTER
		editorRect.x += (cell.width - editorRect.width)/2;
	}
	// don't let the editor overlap with the +/- of the tree
	editorRect.x = Math.max(cell.x, editorRect.x);
	
	if (verticalAlignment == SWT.BOTTOM) {
		editorRect.y += cell.height - editorRect.height;
	} else if (verticalAlignment == SWT.TOP) {
		// do nothing - cell.y is the right answer
	} else { // default is CENTER
		editorRect.y += (cell.height - editorRect.height)/2;
	}
	return editorRect;
}
/**
 * Removes all associations between the TreeEditor and the row in the tree.  The
 * tree and the editor Control are <b>not</b> disposed.
 */
public void dispose () {
	if (treeListener != null) 
		tree.removeTreeListener(treeListener);
	treeListener = null;
	tree = null;
	item = null;
	super.dispose();
}
/**
* Returns the TreeItem for the row of the cell being tracked by this editor.
*
* @return the TreeItem for the row of the cell being tracked by this editor
*/
public TreeItem getItem () {
	return item;
}
public void setItem (TreeItem item) {
	this.item = item;
	resize();
}

/**
* Specify the Control that is to be displayed and the cell in the tree that it is to be positioned above.
*
* <p>Note: The Control provided as the editor <b>must</b> be created with its parent being the Tree control
* specified in the TreeEditor constructor.
* 
* @param editor the Control that is displayed above the cell being edited
* @param item the TreeItem for the row of the cell being tracked by this editor
* @param column the zero based index of the column of the cell being tracked by this editor
*/
public void setEditor (Control editor, TreeItem item) {
	setItem(item);
	setEditor(editor);
}
void resize () {
	if (tree.isDisposed()) return;
	if (item == null || item.isDisposed()) return;	
	super.resize();
}
}