TreeEventMeasurePaintErase.java Source code

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Here is the source code for TreeEventMeasurePaintErase.java

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/*******************************************************************************
 * Copyright (c) 2000, 2006 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
 *******************************************************************************/
//package org.eclipse.swt.snippets;
/* 
 * Tree example snippet: Images on the right side of the TreeItem
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 * 
 * @since 3.2
 */

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeColumn;
import org.eclipse.swt.widgets.TreeItem;

public class TreeEventMeasurePaintErase {

    public static void main(String[] args) {
        Display display = new Display();
        final Image image = display.getSystemImage(SWT.ICON_INFORMATION);
        Shell shell = new Shell(display);
        shell.setText("Images on the right side of the TreeItem");
        shell.setLayout(new FillLayout());
        Tree tree = new Tree(shell, SWT.MULTI | SWT.FULL_SELECTION);
        tree.setHeaderVisible(true);
        tree.setLinesVisible(true);
        int columnCount = 4;
        for (int i = 0; i < columnCount; i++) {
            TreeColumn column = new TreeColumn(tree, SWT.NONE);
            column.setText("Column " + i);
        }
        int itemCount = 3;
        for (int i = 0; i < itemCount; i++) {
            TreeItem item1 = new TreeItem(tree, SWT.NONE);
            item1.setText("item " + i);
            for (int c = 1; c < columnCount; c++) {
                item1.setText(c, "item [" + i + "-" + c + "]");
            }
            for (int j = 0; j < itemCount; j++) {
                TreeItem item2 = new TreeItem(item1, SWT.NONE);
                item2.setText("item [" + i + " " + j + "]");
                for (int c = 1; c < columnCount; c++) {
                    item2.setText(c, "item [" + i + " " + j + "-" + c + "]");
                }
                for (int k = 0; k < itemCount; k++) {
                    TreeItem item3 = new TreeItem(item2, SWT.NONE);
                    item3.setText("item [" + i + " " + j + " " + k + "]");
                    for (int c = 1; c < columnCount; c++) {
                        item3.setText(c, "item [" + i + " " + j + " " + k + "-" + c + "]");
                    }
                }
            }
        }
        /*
         * NOTE: MeasureItem, PaintItem and EraseItem are called repeatedly.
         * Therefore, it is critical for performance that these methods be as
         * efficient as possible.
         */
        Listener paintListener = new Listener() {
            public void handleEvent(Event event) {
                switch (event.type) {
                case SWT.MeasureItem: {
                    Rectangle rect = image.getBounds();
                    event.width += rect.width;
                    event.height = Math.max(event.height, rect.height + 2);
                    break;
                }
                case SWT.PaintItem: {
                    int x = event.x + event.width;
                    Rectangle rect = image.getBounds();
                    int offset = Math.max(0, (event.height - rect.height) / 2);
                    event.gc.drawImage(image, x, event.y + offset);
                    break;
                }
                }
            }
        };
        tree.addListener(SWT.MeasureItem, paintListener);
        tree.addListener(SWT.PaintItem, paintListener);

        for (int i = 0; i < columnCount; i++) {
            tree.getColumn(i).pack();
        }
        shell.setSize(500, 200);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        if (image != null)
            image.dispose();
        display.dispose();
    }
}