org.eclipse.swt.snippets.Snippet220.java Source code

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Here is the source code for org.eclipse.swt.snippets.Snippet220.java

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/*******************************************************************************
 * Copyright (c) 2000, 2016 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * 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 detailed explanation of this snippet see
 * http://www.eclipse.org/articles/Article-CustomDrawingTableAndTreeItems/customDraw.htm#_example5
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 *
 * @since 3.2
 */

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

public class Snippet220 {

    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("Snippet 220");
        shell.setBounds(10, 10, 350, 200);
        Image xImage = new Image(display, 16, 16);
        GC gc = new GC(xImage);
        gc.setForeground(display.getSystemColor(SWT.COLOR_RED));
        gc.drawLine(1, 1, 14, 14);
        gc.drawLine(1, 14, 14, 1);
        gc.drawOval(2, 2, 11, 11);
        gc.dispose();
        final int IMAGE_MARGIN = 2;
        final Tree tree = new Tree(shell, SWT.CHECK);
        tree.setBounds(10, 10, 300, 150);
        TreeItem item = new TreeItem(tree, SWT.NONE);
        item.setText("root item");
        for (int i = 0; i < 4; i++) {
            TreeItem newItem = new TreeItem(item, SWT.NONE);
            newItem.setText("descendent " + i);
            if (i % 2 == 0)
                newItem.setData(xImage);
            item.setExpanded(true);
            item = newItem;
        }

        /*
         * NOTE: MeasureItem and PaintItem are called repeatedly.  Therefore it is
         * critical for performance that these methods be as efficient as possible.
         */
        tree.addListener(SWT.MeasureItem, event -> {
            TreeItem item1 = (TreeItem) event.item;
            Image trailingImage = (Image) item1.getData();
            if (trailingImage != null) {
                event.width += trailingImage.getBounds().width + IMAGE_MARGIN;
            }
        });
        tree.addListener(SWT.PaintItem, event -> {
            TreeItem item1 = (TreeItem) event.item;
            Image trailingImage = (Image) item1.getData();
            if (trailingImage != null) {
                int x = event.x + event.width + IMAGE_MARGIN;
                int itemHeight = tree.getItemHeight();
                int imageHeight = trailingImage.getBounds().height;
                int y = event.y + (itemHeight - imageHeight) / 2;
                event.gc.drawImage(trailingImage, x, y);
            }
        });

        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        xImage.dispose();
        display.dispose();
    }
}