org.eclipse.swt.snippets.Snippet319.java Source code

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Here is the source code for org.eclipse.swt.snippets.Snippet319.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;

/*
 * Drag and Drop example snippet: drag and drop an object with a
 * custom data transfer type from SWT to AWT/Swing
 *
 * Note that JRE 1.6 or newer is required on Linux.
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.dnd.*;
import java.awt.dnd.DropTarget;
import java.awt.dnd.DropTargetAdapter;
import java.awt.dnd.DropTargetListener;
import java.io.*;
import java.util.*;

import javax.swing.*;

import org.eclipse.swt.*;
import org.eclipse.swt.awt.*;
import org.eclipse.swt.dnd.*;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Label;

public class Snippet319 {

    /* The data flavor must be MIME type-like */
    static final String MIME_TYPE = "custom/myType"; // $NON-NLS-1$

    /* The object being transferred is defined as: */
    static class MyType {
        String name;
        long time;
    }

    public static void main(String[] args) {
        new Snippet319().go();
    }

    public void go() {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("Snippet 319");
        shell.setBounds(10, 10, 600, 200);

        /* Create SWT controls and add drag source */
        final Label swtLabel = new Label(shell, SWT.BORDER);
        swtLabel.setBounds(10, 10, 580, 50);
        swtLabel.setText("SWT drag source");
        DragSource dragSource = new DragSource(swtLabel, DND.DROP_COPY);
        dragSource.setTransfer(new MyTypeTransfer());
        dragSource.addDragListener(new DragSourceAdapter() {
            @Override
            public void dragSetData(DragSourceEvent event) {
                MyType object = new MyType();
                object.name = "content dragged from SWT";
                object.time = System.currentTimeMillis();
                event.data = object;
            }
        });

        /* Create AWT/Swing controls */
        Composite embeddedComposite = new Composite(shell, SWT.EMBEDDED);
        embeddedComposite.setBounds(10, 100, 580, 50);
        embeddedComposite.setLayout(new FillLayout());
        Frame frame = SWT_AWT.new_Frame(embeddedComposite);
        final JLabel jLabel = new JLabel("AWT/Swing drop target");
        frame.add(jLabel);

        /* Register the custom data flavour */
        final DataFlavor flavor = new DataFlavor(MIME_TYPE, "MyType custom flavor");
        /*
         * Note that according to jre/lib/flavormap.properties, the preferred way to
         * augment the default system flavor map is to specify the AWT.DnD.flavorMapFileURL
         * property in an awt.properties file.
         *
         * This snippet uses the alternate approach below in order to provide a simple
         * stand-alone snippet that demonstrates the functionality.  This implementation
         * works well, but if the instanceof check below fails for some reason when used
         * in a different context then the drop will not be accepted.
         */
        FlavorMap map = SystemFlavorMap.getDefaultFlavorMap();
        if (map instanceof SystemFlavorMap) {
            SystemFlavorMap systemMap = (SystemFlavorMap) map;
            systemMap.addFlavorForUnencodedNative(MIME_TYPE, flavor);
        }

        /* add drop target */
        DropTargetListener dropTargetListener = new DropTargetAdapter() {
            @Override
            public void drop(DropTargetDropEvent dropTargetDropEvent) {
                try {
                    dropTargetDropEvent.acceptDrop(DnDConstants.ACTION_COPY);
                    ByteArrayInputStream inStream = (ByteArrayInputStream) dropTargetDropEvent.getTransferable()
                            .getTransferData(flavor);
                    int available = inStream.available();
                    byte[] bytes = new byte[available];
                    inStream.read(bytes);
                    MyType object = restoreFromByteArray(bytes);
                    String string = object.name + ": " + new Date(object.time).toString();
                    jLabel.setText(string);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        };
        new DropTarget(jLabel, dropTargetListener);

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

    /* SWT custom data transfer implementation */

    class MyTypeTransfer extends ByteArrayTransfer {

        final int MIME_TYPE_ID = registerType(MIME_TYPE);

        @Override
        protected int[] getTypeIds() {
            return new int[] { MIME_TYPE_ID };
        }

        @Override
        protected String[] getTypeNames() {
            return new String[] { MIME_TYPE };
        }

        @Override
        public void javaToNative(Object object, TransferData transferData) {
            if (!checkMyType(object) || !isSupportedType(transferData)) {
                DND.error(DND.ERROR_INVALID_DATA);
            }
            MyType myType = (MyType) object;
            byte[] bytes = convertToByteArray(myType);
            if (bytes != null) {
                super.javaToNative(bytes, transferData);
            }
        }

        @Override
        public Object nativeToJava(TransferData transferData) {
            if (!isSupportedType(transferData))
                return null;
            byte[] bytes = (byte[]) super.nativeToJava(transferData);
            return bytes == null ? null : restoreFromByteArray(bytes);
        }

        boolean checkMyType(Object object) {
            if (object == null)
                return false;
            MyType myType = (MyType) object;
            return myType != null && myType.name != null && myType.name.length() > 0 && myType.time > 0;
        }

        @Override
        protected boolean validate(Object object) {
            return checkMyType(object);
        }
    }

    /* shared methods for converting instances of MyType <-> byte[] */

    static byte[] convertToByteArray(MyType type) {
        DataOutputStream dataOutStream = null;
        try {
            ByteArrayOutputStream byteOutStream = new ByteArrayOutputStream();
            dataOutStream = new DataOutputStream(byteOutStream);
            byte[] bytes = type.name.getBytes();
            dataOutStream.writeInt(bytes.length);
            dataOutStream.write(bytes);
            dataOutStream.writeLong(type.time);
            return byteOutStream.toByteArray();
        } catch (IOException e) {
            return null;
        } finally {
            if (dataOutStream != null) {
                try {
                    dataOutStream.close();
                } catch (IOException e) {
                }
            }
        }
    }

    static MyType restoreFromByteArray(byte[] bytes) {
        DataInputStream dataInStream = null;
        try {
            ByteArrayInputStream byteInStream = new ByteArrayInputStream(bytes);
            dataInStream = new DataInputStream(byteInStream);
            int size = dataInStream.readInt();
            byte[] name = new byte[size];
            dataInStream.read(name);
            MyType result = new MyType();
            result.name = new String(name);
            result.time = dataInStream.readLong();
            return result;
        } catch (IOException ex) {
            return null;
        } finally {
            if (dataInStream != null) {
                try {
                    dataInStream.close();
                } catch (IOException e) {
                }
            }
        }
    }

}