org.eclipse.swt.snippets.Snippet240.java Source code

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Here is the source code for org.eclipse.swt.snippets.Snippet240.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 snippet: Text that spans multiple columns
 *
 * For more info on custom-drawing TableItem and TreeItem content see
 * http://www.eclipse.org/articles/article.php?file=Article-CustomDrawingTableAndTreeItems/index.html
 *
 * 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.layout.*;
import org.eclipse.swt.widgets.*;

public class Snippet240 {

    public static void main(String[] args) {
        final Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("Text spans two columns in a TreeItem");
        shell.setLayout(new FillLayout());
        final Tree tree = new Tree(shell, SWT.MULTI | SWT.FULL_SELECTION);
        tree.setHeaderVisible(true);
        int columnCount = 4;
        for (int i = 0; i < columnCount; i++) {
            TreeColumn column = new TreeColumn(tree, SWT.NONE);
            column.setText("Column " + i);
        }
        int itemCount = 8;
        for (int i = 0; i < itemCount; i++) {
            TreeItem item = new TreeItem(tree, SWT.NONE);
            item.setText(0, "item " + i + " a");
            item.setText(3, "item " + i + " d");
            for (int j = 0; j < 3; j++) {
                TreeItem subItem = new TreeItem(item, SWT.NONE);
                subItem.setText(0, "subItem " + i + "-" + j + " a");
                subItem.setText(3, "subItem " + i + "-" + j + " d");
            }
        }
        /*
         * NOTE: MeasureItem, PaintItem and EraseItem are called repeatedly.
         * Therefore, it is critical for performance that these methods be
         * as efficient as possible.
         */
        final String string = "text that spans two columns";
        GC gc = new GC(tree);
        final Point extent = gc.stringExtent(string);
        gc.dispose();
        final Color red = display.getSystemColor(SWT.COLOR_RED);
        Listener paintListener = event -> {
            switch (event.type) {
            case SWT.MeasureItem: {
                if (event.index == 1 || event.index == 2) {
                    event.width = extent.x / 2;
                    event.height = Math.max(event.height, extent.y + 2);
                }
                break;
            }
            case SWT.PaintItem: {
                if (event.index == 1 || event.index == 2) {
                    int offset = 0;
                    if (event.index == 2) {
                        TreeColumn column1 = tree.getColumn(1);
                        offset = column1.getWidth();
                    }
                    event.gc.setForeground(red);
                    int y = event.y + (event.height - extent.y) / 2;
                    event.gc.drawString(string, event.x - offset, y, true);
                }
                break;
            }
            }
        };
        tree.addListener(SWT.MeasureItem, paintListener);
        tree.addListener(SWT.PaintItem, paintListener);
        for (int i = 0; i < columnCount; i++) {
            tree.getColumn(i).pack();
        }
        shell.pack();
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }
}