org.eclipse.swt.snippets.Snippet322.java Source code

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Here is the source code for org.eclipse.swt.snippets.Snippet322.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;

/*
 * ScrolledComposite snippet: use a ScrolledComposite to scroll a disabled
 * control.  Note that this goes against conventional UI behaviour, where
 * disabling a control typically disables its scrollbars as well.
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import static org.eclipse.swt.events.SelectionListener.*;

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

public class Snippet322 {

    public static void main(String[] args) {
        final Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("Snippet 322");
        shell.setBounds(10, 10, 300, 300);
        final ScrolledComposite sc = new ScrolledComposite(shell, SWT.VERTICAL);
        sc.setBounds(10, 10, 280, 200);
        final int clientWidth = sc.getClientArea().width;

        final Tree tree = new Tree(sc, SWT.NONE);
        for (int i = 0; i < 99; i++) {
            TreeItem item = new TreeItem(tree, SWT.NONE);
            item.setText("item " + i);
            new TreeItem(item, SWT.NONE).setText("child");
        }
        sc.setContent(tree);
        int prefHeight = tree.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
        tree.setSize(clientWidth, prefHeight);
        /*
         * The following listener ensures that the Tree is always large
         * enough to not need to show its own vertical scrollbar.
         */
        tree.addTreeListener(new TreeListener() {
            @Override
            public void treeExpanded(TreeEvent e) {
                int prefHeight = tree.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
                tree.setSize(clientWidth, prefHeight);
            }

            @Override
            public void treeCollapsed(TreeEvent e) {
                int prefHeight = tree.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
                tree.setSize(clientWidth, prefHeight);
            }
        });
        /*
         * The following listener ensures that a newly-selected item
         * in the Tree is always visible.
         */
        tree.addSelectionListener(widgetSelectedAdapter(e -> {
            TreeItem[] selectedItems = tree.getSelection();
            if (selectedItems.length > 0) {
                Rectangle itemRect = selectedItems[0].getBounds();
                Rectangle area = sc.getClientArea();
                Point origin = sc.getOrigin();
                if (itemRect.x < origin.x || itemRect.y < origin.y
                        || itemRect.x + itemRect.width > origin.x + area.width
                        || itemRect.y + itemRect.height > origin.y + area.height) {
                    sc.setOrigin(itemRect.x, itemRect.y);
                }
            }
        }));
        /*
         * The following listener scrolls the Tree one item at a time
         * in response to MouseWheel events.
         */
        tree.addListener(SWT.MouseWheel, event -> {
            Point origin = sc.getOrigin();
            if (event.count < 0) {
                origin.y = Math.min(origin.y + tree.getItemHeight(), tree.getSize().y);
            } else {
                origin.y = Math.max(origin.y - tree.getItemHeight(), 0);
            }
            sc.setOrigin(origin);
        });

        Button disableButton = new Button(shell, SWT.PUSH);
        disableButton.setBounds(10, 220, 120, 30);
        disableButton.setText("Disable");
        disableButton.addListener(SWT.Selection, event -> tree.setEnabled(false));
        Button enableButton = new Button(shell, SWT.PUSH);
        enableButton.setBounds(140, 220, 120, 30);
        enableButton.setText("Enable");
        enableButton.addListener(SWT.Selection, event -> tree.setEnabled(true));

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