org.eclipse.swt.snippets.Snippet221.java Source code

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Here is the source code for org.eclipse.swt.snippets.Snippet221.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;
/*
 * example snippet: Scroll tree when mouse at top or bottom
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */

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

public class Snippet221 {
    static Runnable Heartbeat;
    static boolean Tracking;
    static int ScrollSpeed = 40;

    public static void main(String[] args) {
        final Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("Snippet 221");
        shell.setLayout(new FillLayout());
        final Tree tree = new Tree(shell, SWT.FULL_SELECTION | SWT.BORDER);
        tree.setHeaderVisible(true);
        TreeColumn column0 = new TreeColumn(tree, SWT.LEFT);
        column0.setText("Column 0");
        TreeColumn column1 = new TreeColumn(tree, SWT.LEFT);
        column1.setText("Column 1");
        TreeColumn column2 = new TreeColumn(tree, SWT.LEFT);
        column2.setText("Column 2");
        for (int i = 0; i < 9; i++) {
            TreeItem item = new TreeItem(tree, SWT.NONE);
            item.setText("item " + i);
            item.setText(1, "column 1 - " + i);
            item.setText(2, "column 2 - " + i);
            for (int j = 0; j < 9; j++) {
                TreeItem subItem = new TreeItem(item, SWT.NONE);
                subItem.setText("item " + i + " " + j);
                subItem.setText(1, "column 1 - " + i + " " + j);
                subItem.setText(2, "column 2 - " + i + " " + j);
                for (int k = 0; k < 9; k++) {
                    TreeItem subsubItem = new TreeItem(subItem, SWT.NONE);
                    subsubItem.setText("item " + i + " " + j + " " + k);
                    subsubItem.setText(1, "column 1 - " + i + " " + j + " " + k);
                    subsubItem.setText(2, "column 2 - " + i + " " + j + " " + k);
                }
            }
        }
        column0.pack();
        column1.pack();
        column2.pack();

        Heartbeat = () -> {
            if (!Tracking || tree.isDisposed())
                return;
            Point cursor = display.getCursorLocation();
            cursor = display.map(null, tree, cursor);
            Scroll(tree, cursor.x, cursor.y);
            display.timerExec(ScrollSpeed, Heartbeat);
        };
        Listener listener = event -> {
            switch (event.type) {
            case SWT.MouseEnter:
                Tracking = true;
                display.timerExec(0, Heartbeat);
                break;
            case SWT.MouseExit:
                Tracking = false;
                break;
            }
        };
        tree.addListener(SWT.MouseEnter, listener);
        tree.addListener(SWT.MouseExit, listener);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }

    static void Scroll(Tree tree, int x, int y) {
        TreeItem item = tree.getItem(new Point(x, y));
        if (item == null)
            return;
        Rectangle area = tree.getClientArea();
        int headerHeight = tree.getHeaderHeight();
        int itemHeight = tree.getItemHeight();
        TreeItem nextItem = null;
        if (y < area.y + headerHeight + 2 * itemHeight) {
            nextItem = PreviousItem(tree, item);
        }
        if (y > area.y + area.height - 2 * itemHeight) {
            nextItem = NextItem(tree, item);
        }
        if (nextItem != null)
            tree.showItem(nextItem);
    }

    static TreeItem PreviousItem(Tree tree, TreeItem item) {
        if (item == null)
            return null;
        TreeItem childItem = item;
        TreeItem parentItem = childItem.getParentItem();
        int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
        if (index == 0) {
            return parentItem;
        } else {
            TreeItem nextItem = parentItem == null ? tree.getItem(index - 1) : parentItem.getItem(index - 1);
            int count = nextItem.getItemCount();
            while (count > 0 && nextItem.getExpanded()) {
                nextItem = nextItem.getItem(count - 1);
                count = nextItem.getItemCount();
            }
            return nextItem;
        }
    }

    static TreeItem NextItem(Tree tree, TreeItem item) {
        if (item == null)
            return null;
        if (item.getExpanded()) {
            return item.getItem(0);
        } else {
            TreeItem childItem = item;
            TreeItem parentItem = childItem.getParentItem();
            int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
            int count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
            while (true) {
                if (index + 1 < count) {
                    return parentItem == null ? tree.getItem(index + 1) : parentItem.getItem(index + 1);
                } else {
                    if (parentItem == null) {
                        return null;
                    } else {
                        childItem = parentItem;
                        parentItem = childItem.getParentItem();
                        index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
                        count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
                    }
                }
            }
        }
    }
}