org.eclipse.swt.snippets.Snippet226.java Source code

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Here is the source code for org.eclipse.swt.snippets.Snippet226.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: draw a custom gradient selection for tree
 *
 * 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 3.3
 */
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

public class Snippet226 {

    public static void main(String[] args) {
        final Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("Custom gradient selection for Tree");
        shell.setLayout(new FillLayout());
        final 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.
         */
        tree.addListener(SWT.EraseItem, event -> {
            event.detail &= ~SWT.HOT;
            if ((event.detail & SWT.SELECTED) != 0) {
                GC gc = event.gc;
                Rectangle area = tree.getClientArea();
                /*
                 * If you wish to paint the selection beyond the end of
                 * last column, you must change the clipping region.
                 */
                int columnCount1 = tree.getColumnCount();
                if (event.index == columnCount1 - 1 || columnCount1 == 0) {
                    int width = area.x + area.width - event.x;
                    if (width > 0) {
                        Region region = new Region();
                        gc.getClipping(region);
                        region.add(event.x, event.y, width, event.height);
                        gc.setClipping(region);
                        region.dispose();
                    }
                }
                gc.setAdvanced(true);
                if (gc.getAdvanced())
                    gc.setAlpha(127);
                Rectangle rect = event.getBounds();
                Color foreground = gc.getForeground();
                Color background = gc.getBackground();
                gc.setForeground(display.getSystemColor(SWT.COLOR_RED));
                gc.setBackground(display.getSystemColor(SWT.COLOR_LIST_BACKGROUND));
                gc.fillGradientRectangle(0, rect.y, 500, rect.height, false);
                // restore colors for subsequent drawing
                gc.setForeground(foreground);
                gc.setBackground(background);
                event.detail &= ~SWT.SELECTED;
            }
        });
        for (int i = 0; i < columnCount; i++) {
            tree.getColumn(i).pack();
        }
        tree.setSelection(tree.getItem(0));
        shell.setSize(500, 200);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }
}