org.eclipse.swt.snippets.Snippet257.java Source code

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Here is the source code for org.eclipse.swt.snippets.Snippet257.java

Source

/*******************************************************************************
 * Copyright (c) 2007, 2017 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;

/*
 * Drag text selection within a StyledText widget
 *
 * 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.custom.*;
import org.eclipse.swt.dnd.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

public class Snippet257 {

    static String string1 = "A drag source is the provider of data in a Drag and Drop data transfer as well as "
            + "the originator of the Drag and Drop operation. The data provided by the drag source "
            + "may be transferred to another location in the same widget, to a different widget "
            + "within the same application, or to a different application altogether. For example, "
            + "you can drag text from your application and drop it on an email application, or you "
            + "could drag an item in a tree and drop it below a different node in the same tree.";

    static String DRAG_START_DATA = "DRAG_START_DATA";

    public static void main(String[] args) {
        final Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("Snippet 257");
        shell.setLayout(new FillLayout());
        shell.setSize(100, 300);
        int style = SWT.MULTI | SWT.WRAP | SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER;
        final StyledText text = new StyledText(shell, style);
        text.setText(string1);
        final DragSource source = new DragSource(text, DND.DROP_COPY | DND.DROP_MOVE);
        source.setDragSourceEffect(new DragSourceEffect(text) {
            @Override
            public void dragStart(DragSourceEvent event) {
                event.image = display.getSystemImage(SWT.ICON_WARNING);
            }
        });
        source.setTransfer(TextTransfer.getInstance());
        source.addDragListener(new DragSourceAdapter() {
            Point selection;

            @Override
            public void dragStart(DragSourceEvent event) {
                selection = text.getSelection();
                event.doit = selection.x != selection.y;
                text.setData(DRAG_START_DATA, selection);
            }

            @Override
            public void dragSetData(DragSourceEvent e) {
                e.data = text.getText(selection.x, selection.y - 1);
            }

            @Override
            public void dragFinished(DragSourceEvent event) {
                if (event.detail == DND.DROP_MOVE) {
                    Point newSelection = text.getSelection();
                    int length = selection.y - selection.x;
                    int delta = 0;
                    if (newSelection.x < selection.x)
                        delta = length;
                    text.replaceTextRange(selection.x + delta, length, "");
                }
                selection = null;
                text.setData(DRAG_START_DATA, null);
            }
        });

        DropTarget target = new DropTarget(text, DND.DROP_DEFAULT | DND.DROP_MOVE | DND.DROP_COPY | DND.DROP_LINK);
        target.setTransfer(TextTransfer.getInstance());
        target.addDropListener(new DropTargetAdapter() {
            @Override
            public void dragEnter(DropTargetEvent event) {
                if (event.detail == DND.DROP_DEFAULT) {
                    if (text.getData(DRAG_START_DATA) == null)
                        event.detail = DND.DROP_COPY;
                    else
                        event.detail = DND.DROP_MOVE;
                }
            }

            @Override
            public void dragOperationChanged(DropTargetEvent event) {
                if (event.detail == DND.DROP_DEFAULT) {
                    if (text.getData(DRAG_START_DATA) == null)
                        event.detail = DND.DROP_COPY;
                    else
                        event.detail = DND.DROP_MOVE;
                }
            }

            @Override
            public void dragOver(DropTargetEvent event) {
                event.feedback = DND.FEEDBACK_SCROLL | DND.FEEDBACK_SELECT;
            }

            @Override
            public void drop(DropTargetEvent event) {
                if (event.detail != DND.DROP_NONE) {
                    Point selection = (Point) text.getData(DRAG_START_DATA);
                    int insertPos = text.getCaretOffset();
                    if (event.detail == DND.DROP_MOVE && selection != null && selection.x <= insertPos
                            && insertPos <= selection.y
                            || event.detail == DND.DROP_COPY && selection != null && selection.x < insertPos
                                    && insertPos < selection.y) {
                        text.setSelection(selection);
                        event.detail = DND.DROP_COPY; // prevent source from deleting selection
                    } else {
                        String string = (String) event.data;
                        text.insert(string);
                        if (selection != null)
                            text.setSelectionRange(insertPos, string.length());
                    }
                }
            }
        });
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }

}