Java Tutorial/SWT/SWT Drag Drop
Содержание
- 1 17. Drag and Drop: define a default operation (in this example, Copy)
 - 2 17. Drag and Drop: define my own data transfer type
 - 3 17. Drag and Drop: determine native data types available (motif only)
 - 4 17. Drag and Drop example snippet: determine data types available (win32 only)
 - 5 17. Drag and Drop inside Table
 - 6 17. Dragging and Dropping
 - 7 17. Drag leaf items in a tree
 - 8 17. Drag selected text in Text to Label
 - 9 17. Drag text between two labels
 - 10 17. Make a dropped data type depend on a target item in table
 
17. Drag and Drop: define a default operation (in this example, Copy)
/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
/*
 * Drag and Drop example snippet: define a default operation (in this example, Copy)
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
public class DragDropOperation {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    final Label label = new Label(shell, SWT.BORDER);
    label.setText("Drag Source");
    DragSource source = new DragSource(label, DND.DROP_COPY | DND.DROP_MOVE | DND.DROP_LINK);
    source.setTransfer(new Transfer[] { TextTransfer.getInstance() });
    source.addDragListener(new DragSourceAdapter() {
      public void dragSetData(DragSourceEvent event) {
        event.data = "Text Transferred";
      }
      public void dragFinished(DragSourceEvent event) {
        if (event.doit) {
          String operation = null;
          switch (event.detail) {
          case DND.DROP_MOVE:
            operation = "moved";
            break;
          case DND.DROP_COPY:
            operation = "copied";
            break;
          case DND.DROP_LINK:
            operation = "linked";
            break;
          case DND.DROP_NONE:
            operation = "disallowed";
            break;
          default:
            operation = "unknown";
            break;
          }
          label.setText("Drag Source (data " + operation + ")");
        } else {
          label.setText("Drag Source (drag cancelled)");
        }
      }
    });
    final Text text = new Text(shell, SWT.BORDER | SWT.MULTI);
    text.setText("Drop Target");
    DropTarget target = new DropTarget(text, DND.DROP_DEFAULT | DND.DROP_COPY | DND.DROP_MOVE
        | DND.DROP_LINK);
    target.setTransfer(new Transfer[] { TextTransfer.getInstance() });
    target.addDropListener(new DropTargetAdapter() {
      public void dragEnter(DropTargetEvent event) {
        if (event.detail == DND.DROP_DEFAULT)
          event.detail = DND.DROP_COPY;
      }
      public void dragOperationChanged(DropTargetEvent event) {
        if (event.detail == DND.DROP_DEFAULT)
          event.detail = DND.DROP_COPY;
      }
      public void drop(DropTargetEvent event) {
        String operation = null;
        switch (event.detail) {
        case DND.DROP_MOVE:
          operation = "moved";
          break;
        case DND.DROP_COPY:
          operation = "copied";
          break;
        case DND.DROP_LINK:
          operation = "linked";
          break;
        case DND.DROP_NONE:
          operation = "disallowed";
          break;
        default:
          operation = "unknown";
          break;
        }
        text.append("\n" + operation + (String) event.data);
      }
    });
    shell.setSize(400, 400);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
}
   
   
17. Drag and Drop: define my own data transfer type
/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
/*
 * Drag and Drop example snippet: define my own data transfer type
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 * 
 * @since 3.1
 */
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.ByteArrayTransfer;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.dnd.TransferData;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
public class DataTransfer {
  /*
   * The data being transferred is an <bold>array of type MyType</bold> where
   * MyType is define as:
   */
  static class MyType {
    String fileName;
    long fileLength;
    long lastModified;
  }
  static class MyTransfer extends ByteArrayTransfer {
    private static final String MYTYPENAME = "name_for_my_type";
    private static final int MYTYPEID = registerType(MYTYPENAME);
    private static MyTransfer _instance = new MyTransfer();
    public static MyTransfer getInstance() {
      return _instance;
    }
    public void javaToNative(Object object, TransferData transferData) {
      if (!checkMyType(object) || !isSupportedType(transferData)) {
        DND.error(DND.ERROR_INVALID_DATA);
      }
      MyType[] myTypes = (MyType[]) object;
      try {
        // write data to a byte array and then ask super to convert to pMedium
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        DataOutputStream writeOut = new DataOutputStream(out);
        for (int i = 0, length = myTypes.length; i < length; i++) {
          byte[] buffer = myTypes[i].fileName.getBytes();
          writeOut.writeInt(buffer.length);
          writeOut.write(buffer);
          writeOut.writeLong(myTypes[i].fileLength);
          writeOut.writeLong(myTypes[i].lastModified);
        }
        byte[] buffer = out.toByteArray();
        writeOut.close();
        super.javaToNative(buffer, transferData);
      } catch (IOException e) {
      }
    }
    public Object nativeToJava(TransferData transferData) {
      if (isSupportedType(transferData)) {
        byte[] buffer = (byte[]) super.nativeToJava(transferData);
        if (buffer == null)
          return null;
        MyType[] myData = new MyType[0];
        try {
          ByteArrayInputStream in = new ByteArrayInputStream(buffer);
          DataInputStream readIn = new DataInputStream(in);
          while (readIn.available() > 20) {
            MyType datum = new MyType();
            int size = readIn.readInt();
            byte[] name = new byte[size];
            readIn.read(name);
            datum.fileName = new String(name);
            datum.fileLength = readIn.readLong();
            datum.lastModified = readIn.readLong();
            MyType[] newMyData = new MyType[myData.length + 1];
            System.arraycopy(myData, 0, newMyData, 0, myData.length);
            newMyData[myData.length] = datum;
            myData = newMyData;
          }
          readIn.close();
        } catch (IOException ex) {
          return null;
        }
        return myData;
      }
      return null;
    }
    protected String[] getTypeNames() {
      return new String[] { MYTYPENAME };
    }
    protected int[] getTypeIds() {
      return new int[] { MYTYPEID };
    }
    boolean checkMyType(Object object) {
      if (object == null || !(object instanceof MyType[]) || ((MyType[]) object).length == 0) {
        return false;
      }
      MyType[] myTypes = (MyType[]) object;
      for (int i = 0; i < myTypes.length; i++) {
        if (myTypes[i] == null || myTypes[i].fileName == null || myTypes[i].fileName.length() == 0) {
          return false;
        }
      }
      return true;
    }
    protected boolean validate(Object object) {
      return checkMyType(object);
    }
  }
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    final Label label1 = new Label(shell, SWT.BORDER | SWT.WRAP);
    label1.setText("Drag Source for MyData[]");
    final Label label2 = new Label(shell, SWT.BORDER | SWT.WRAP);
    label2.setText("Drop Target for MyData[]");
    DragSource source = new DragSource(label1, DND.DROP_COPY);
    source.setTransfer(new Transfer[] { MyTransfer.getInstance() });
    source.addDragListener(new DragSourceAdapter() {
      public void dragSetData(DragSourceEvent event) {
        MyType myType1 = new MyType();
        myType1.fileName = "C:\\abc.txt";
        myType1.fileLength = 1000;
        myType1.lastModified = 12312313;
        MyType myType2 = new MyType();
        myType2.fileName = "C:\\xyz.txt";
        myType2.fileLength = 500;
        myType2.lastModified = 12312323;
        event.data = new MyType[] { myType1, myType2 };
      }
    });
    DropTarget target = new DropTarget(label2, DND.DROP_COPY | DND.DROP_DEFAULT);
    target.setTransfer(new Transfer[] { MyTransfer.getInstance() });
    target.addDropListener(new DropTargetAdapter() {
      public void dragEnter(DropTargetEvent event) {
        if (event.detail == DND.DROP_DEFAULT) {
          event.detail = DND.DROP_COPY;
        }
      }
      public void dragOperationChanged(DropTargetEvent event) {
        if (event.detail == DND.DROP_DEFAULT) {
          event.detail = DND.DROP_COPY;
        }
      }
      public void drop(DropTargetEvent event) {
        if (event.data != null) {
          MyType[] myTypes = (MyType[]) event.data;
          if (myTypes != null) {
            String string = "";
            for (int i = 0; i < myTypes.length; i++) {
              string += myTypes[i].fileName + " ";
            }
            label2.setText(string);
          }
        }
      }
    });
    shell.setSize(200, 200);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
}
   
   
17. Drag and Drop: determine native data types available (motif only)
/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
//package org.eclipse.swt.snippets;
/*
 * Drag and Drop example snippet: determine native data types available (motif only)
 * NOTE: This snippet uses internal SWT packages that are
 * subject to change without notice.
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import org.eclipse.swt.*;
import org.eclipse.swt.dnd.*;
import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.motif.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;
public class Snippet158 extends ByteArrayTransfer {
  private static Snippet158 _instance = new Snippet158();
  private int[] ids;
  private String[] names;
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    final Table control = new Table(shell, SWT.NONE);
    TableItem item = new TableItem(control, SWT.NONE);
    item.setText("Drag data over this site to see the native transfer type.");
    DropTarget target = new DropTarget(control, DND.DROP_DEFAULT | DND.DROP_COPY | DND.DROP_LINK
        | DND.DROP_MOVE);
    target.setTransfer(new Transfer[] { Snippet158.getInstance() });
    target.addDropListener(new DropTargetAdapter() {
      public void dragEnter(DropTargetEvent event) {
        String ops = "";
        if ((event.operations & DND.DROP_COPY) != 0)
          ops += "Copy;";
        if ((event.operations & DND.DROP_MOVE) != 0)
          ops += "Move;";
        if ((event.operations & DND.DROP_LINK) != 0)
          ops += "Link;";
        control.removeAll();
        TableItem item1 = new TableItem(control, SWT.NONE);
        item1.setText("Allowed Operations are " + ops);
        if (event.detail == DND.DROP_DEFAULT) {
          if ((event.operations & DND.DROP_COPY) != 0) {
            event.detail = DND.DROP_COPY;
          } else if ((event.operations & DND.DROP_LINK) != 0) {
            event.detail = DND.DROP_LINK;
          } else if ((event.operations & DND.DROP_MOVE) != 0) {
            event.detail = DND.DROP_MOVE;
          }
        }
        TransferData[] data = event.dataTypes;
        for (int i = 0; i < data.length; i++) {
          int id = data[i].type;
          String name = getNameFromId(id);
          TableItem item2 = new TableItem(control, SWT.NONE);
          item2.setText("Data type is " + id + " " + name);
        }
      }
    });
    shell.setSize(400, 400);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
  public static Snippet158 getInstance() {
    return _instance;
  }
  Snippet158() {
  }
  public void javaToNative(Object object, TransferData transferData) {
  }
  public Object nativeToJava(TransferData transferData) {
    return "Hello World";
  }
  protected String[] getTypeNames() {
    return names;
  }
  static int shellHandle;
  protected int[] getTypeIds() {
    if (ids == null) {
      Display display = Display.getCurrent();
      int widgetClass = OS.topLevelShellWidgetClass();
      shellHandle = OS.XtAppCreateShell(null, null, widgetClass, display.xDisplay, null, 0);
      OS.XtSetMappedWhenManaged(shellHandle, false);
      OS.XtRealizeWidget(shellHandle);
      ids = new int[840];
      names = new String[840];
      for (int i = 0; i < ids.length; i++) {
        ids[i] = i + i;
        names[i] = getNameFromId(i + 1);
      }
    }
    return ids;
  }
  static String getNameFromId(int id) {
    int xDisplay = OS.XtDisplay(shellHandle);
    int ptr = 0;
    try {
      ptr = OS.XmGetAtomName(xDisplay, id);
    } catch (Throwable t) {
    }
    if (ptr == 0)
      return "invalid " + id;
    int length = OS.strlen(ptr);
    byte[] nameBuf = new byte[length];
    OS.memmove(nameBuf, ptr, length);
    OS.XFree(ptr);
    return new String(Converter.mbcsToWcs(null, nameBuf)).toLowerCase();
  }
}
   
   
17. Drag and Drop example snippet: determine data types available (win32 only)
/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
//package org.eclipse.swt.snippets;
/*
 * Drag and Drop example snippet: determine data types available (win32 only)
 * NOTE: This snippet uses internal SWT packages that are
 * subject to change without notice.
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.ByteArrayTransfer;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.dnd.TransferData;
import org.eclipse.swt.internal.ole.win32.ru;
import org.eclipse.swt.internal.win32.TCHAR;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableItem;
public class Snippet83 extends ByteArrayTransfer {
  private static Snippet83 _instance = new Snippet83();
  private int[] ids;
  private String[] names;
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    final Table control = new Table(shell, SWT.NONE);
    TableItem item = new TableItem(control, SWT.NONE);
    item.setText("Drag data over this site to see the native transfer type.");
    DropTarget target = new DropTarget(control, DND.DROP_DEFAULT | DND.DROP_COPY | DND.DROP_LINK
        | DND.DROP_MOVE);
    target.setTransfer(new Transfer[] { Snippet83.getInstance() });
    target.addDropListener(new DropTargetAdapter() {
      public void dragEnter(DropTargetEvent event) {
        String ops = "";
        if ((event.operations & DND.DROP_COPY) != 0)
          ops += "Copy;";
        if ((event.operations & DND.DROP_MOVE) != 0)
          ops += "Move;";
        if ((event.operations & DND.DROP_LINK) != 0)
          ops += "Link;";
        control.removeAll();
        TableItem item1 = new TableItem(control, SWT.NONE);
        item1.setText("Allowed Operations are " + ops);
        if (event.detail == DND.DROP_DEFAULT) {
          if ((event.operations & DND.DROP_COPY) != 0) {
            event.detail = DND.DROP_COPY;
          } else if ((event.operations & DND.DROP_LINK) != 0) {
            event.detail = DND.DROP_LINK;
          } else if ((event.operations & DND.DROP_MOVE) != 0) {
            event.detail = DND.DROP_MOVE;
          }
        }
        TransferData[] data = event.dataTypes;
        for (int i = 0; i < data.length; i++) {
          int id = data[i].type;
          String name = getNameFromId(id);
          TableItem item2 = new TableItem(control, SWT.NONE);
          item2.setText("Data type is " + id + " " + name);
        }
      }
    });
    shell.setSize(400, 400);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
  public static Snippet83 getInstance() {
    return _instance;
  }
  Snippet83() {
    ids = new int[80000];
    names = new String[80000];
    for (int i = 0; i < ids.length; i++) {
      ids[i] = i;
      names[i] = getNameFromId(i);
    }
  }
  public void javaToNative(Object object, TransferData transferData) {
  }
  public Object nativeToJava(TransferData transferData) {
    return "Hello World";
  }
  protected String[] getTypeNames() {
    return names;
  }
  protected int[] getTypeIds() {
    return ids;
  }
  static String getNameFromId(int id) {
    String name = null;
    int maxSize = 128;
    TCHAR buffer = new TCHAR(0, maxSize);
    int size = COM.GetClipboardFormatName(id, buffer, maxSize);
    if (size != 0) {
      name = buffer.toString(0, size);
    } else {
      switch (id) {
      case COM.CF_HDROP:
        name = "CF_HDROP";
        break;
      case COM.CF_TEXT:
        name = "CF_TEXT";
        break;
      case COM.CF_BITMAP:
        name = "CF_BITMAP";
        break;
      case COM.CF_METAFILEPICT:
        name = "CF_METAFILEPICT";
        break;
      case COM.CF_SYLK:
        name = "CF_SYLK";
        break;
      case COM.CF_DIF:
        name = "CF_DIF";
        break;
      case COM.CF_TIFF:
        name = "CF_TIFF";
        break;
      case COM.CF_OEMTEXT:
        name = "CF_OEMTEXT";
        break;
      case COM.CF_DIB:
        name = "CF_DIB";
        break;
      case COM.CF_PALETTE:
        name = "CF_PALETTE";
        break;
      case COM.CF_PENDATA:
        name = "CF_PENDATA";
        break;
      case COM.CF_RIFF:
        name = "CF_RIFF";
        break;
      case COM.CF_WAVE:
        name = "CF_WAVE";
        break;
      case COM.CF_UNICODETEXT:
        name = "CF_UNICODETEXT";
        break;
      case COM.CF_ENHMETAFILE:
        name = "CF_ENHMETAFILE";
        break;
      case COM.CF_LOCALE:
        name = "CF_LOCALE";
        break;
      case COM.CF_MAX:
        name = "CF_MAX";
        break;
      }
    }
    return name;
  }
}
   
   
17. Drag and Drop inside Table
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;
import org.eclipse.swt.widgets.TableItem;
public class DragDropTable {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    
    Table table = new Table(shell, SWT.BORDER | SWT.H_SCROLL | SWT.V_SCROLL);
    Transfer[] types = new Transfer[] { TextTransfer.getInstance() };
    DragSource source = new DragSource(table, DND.DROP_MOVE | DND.DROP_COPY);
    source.setTransfer(types);
    
    source.addDragListener(new DragSourceAdapter() {
      public void dragSetData(DragSourceEvent event) {
        // Get the selected items in the drag source
        DragSource ds = (DragSource) event.widget;
        Table table = (Table) ds.getControl();
        TableItem[] selection = table.getSelection();
        StringBuffer buff = new StringBuffer();
        for (int i = 0, n = selection.length; i < n; i++) {
          buff.append(selection[i].getText());
        }
         event.data = buff.toString();
      }
    });
    // Create the drop target
    DropTarget target = new DropTarget(table, DND.DROP_MOVE | DND.DROP_COPY | DND.DROP_DEFAULT);
    target.setTransfer(types);
    target.addDropListener(new DropTargetAdapter() {
      public void dragEnter(DropTargetEvent event) {
        if (event.detail == DND.DROP_DEFAULT) {
          event.detail = (event.operations & DND.DROP_COPY) != 0 ? DND.DROP_COPY : DND.DROP_NONE;
        }
        // Allow dropping text only
        for (int i = 0, n = event.dataTypes.length; i < n; i++) {
          if (TextTransfer.getInstance().isSupportedType(event.dataTypes[i])) {
            event.currentDataType = event.dataTypes[i];
          }
        }
      }
      public void dragOver(DropTargetEvent event) {
         event.feedback = DND.FEEDBACK_SELECT | DND.FEEDBACK_SCROLL;
      }
      public void drop(DropTargetEvent event) {
        if (TextTransfer.getInstance().isSupportedType(event.currentDataType)) {
          // Get the dropped data
          DropTarget target = (DropTarget) event.widget;
          Table table = (Table) target.getControl();
          String data = (String) event.data;
          // Create a new item in the table to hold the dropped data
          TableItem item = new TableItem(table, SWT.NONE);
          item.setText(new String[] { data });
          table.redraw();
        }
      }
    });
    TableColumn column = new TableColumn(table, SWT.NONE);
    // Seed the table
    TableItem item = new TableItem(table, SWT.NONE);
    item.setText(new String[] { "A" });
    item = new TableItem(table, SWT.NONE);
    item.setText(new String[] { "B" });
    item = new TableItem(table, SWT.BORDER);
    item.setText(new String[] { "C" });
    column.pack();
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
    display.dispose();
  }
}
   
   
17. Dragging and Dropping
- The component you drag from is called the drag source.
 - The component you drop on is called the drop target.
 
SWT uses the DragSource class to represent drag sources. It offers a single constructor:
   
   
DragSource(Control control, int style)
   
   
17. Drag leaf items in a tree
/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
/*
 * Drag and Drop example snippet: drag leaf items in a tree
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DragSourceListener;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;
public class DragTreeLeaf {
  public static void main(String[] args) {
    final Display display = new Display();
    final Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    final Tree tree = new Tree(shell, SWT.BORDER);
    for (int i = 0; i < 3; i++) {
      TreeItem item = new TreeItem(tree, SWT.NONE);
      item.setText("item " + i);
      for (int j = 0; j < 3; j++) {
        TreeItem subItem = new TreeItem(item, SWT.NONE);
        subItem.setText("item " + i + " " + j);
        for (int k = 0; k < 3; k++) {
          TreeItem subsubItem = new TreeItem(subItem, SWT.NONE);
          subsubItem.setText("item " + i + " " + j + " " + k);
        }
      }
    }
    Transfer[] types = new Transfer[] { TextTransfer.getInstance() };
    int operations = DND.DROP_MOVE | DND.DROP_COPY | DND.DROP_LINK;
    final DragSource source = new DragSource(tree, operations);
    source.setTransfer(types);
    final TreeItem[] dragSourceItem = new TreeItem[1];
    source.addDragListener(new DragSourceListener() {
      public void dragStart(DragSourceEvent event) {
        TreeItem[] selection = tree.getSelection();
        if (selection.length > 0 && selection[0].getItemCount() == 0) {
          event.doit = true;
          dragSourceItem[0] = selection[0];
        } else {
          event.doit = false;
        }
      };
      public void dragSetData(DragSourceEvent event) {
        event.data = dragSourceItem[0].getText();
      }
      public void dragFinished(DragSourceEvent event) {
        if (event.detail == DND.DROP_MOVE)
          dragSourceItem[0].dispose();
        dragSourceItem[0] = null;
      }
    });
    DropTarget target = new DropTarget(tree, operations);
    target.setTransfer(types);
    target.addDropListener(new DropTargetAdapter() {
      public void dragOver(DropTargetEvent event) {
        event.feedback = DND.FEEDBACK_EXPAND | DND.FEEDBACK_SCROLL;
        if (event.item != null) {
          TreeItem item = (TreeItem) event.item;
          Point pt = display.map(null, tree, event.x, event.y);
          Rectangle bounds = item.getBounds();
          if (pt.y < bounds.y + bounds.height / 3) {
            event.feedback |= DND.FEEDBACK_INSERT_BEFORE;
          } else if (pt.y > bounds.y + 2 * bounds.height / 3) {
            event.feedback |= DND.FEEDBACK_INSERT_AFTER;
          } else {
            event.feedback |= DND.FEEDBACK_SELECT;
          }
        }
      }
      public void drop(DropTargetEvent event) {
        if (event.data == null) {
          event.detail = DND.DROP_NONE;
          return;
        }
        String text = (String) event.data;
        if (event.item == null) {
          TreeItem item = new TreeItem(tree, SWT.NONE);
          item.setText(text);
        } else {
          TreeItem item = (TreeItem) event.item;
          Point pt = display.map(null, tree, event.x, event.y);
          Rectangle bounds = item.getBounds();
          TreeItem parent = item.getParentItem();
          if (parent != null) {
            TreeItem[] items = parent.getItems();
            int index = 0;
            for (int i = 0; i < items.length; i++) {
              if (items[i] == item) {
                index = i;
                break;
              }
            }
            if (pt.y < bounds.y + bounds.height / 3) {
              TreeItem newItem = new TreeItem(parent, SWT.NONE, index);
              newItem.setText(text);
            } else if (pt.y > bounds.y + 2 * bounds.height / 3) {
              TreeItem newItem = new TreeItem(parent, SWT.NONE, index + 1);
              newItem.setText(text);
            } else {
              TreeItem newItem = new TreeItem(item, SWT.NONE);
              newItem.setText(text);
            }
          } else {
            TreeItem[] items = tree.getItems();
            int index = 0;
            for (int i = 0; i < items.length; i++) {
              if (items[i] == item) {
                index = i;
                break;
              }
            }
            if (pt.y < bounds.y + bounds.height / 3) {
              TreeItem newItem = new TreeItem(tree, SWT.NONE, index);
              newItem.setText(text);
            } else if (pt.y > bounds.y + 2 * bounds.height / 3) {
              TreeItem newItem = new TreeItem(tree, SWT.NONE, index + 1);
              newItem.setText(text);
            } else {
              TreeItem newItem = new TreeItem(item, SWT.NONE);
              newItem.setText(text);
            }
          }
        }
      }
    });
    shell.setSize(400, 400);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
}
   
   
17. Drag selected text in Text to Label
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
public class DragTextToLabel {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    
    Text text = new Text(shell, SWT.BORDER|SWT.SINGLE);
    Transfer[] types = new Transfer[] { TextTransfer.getInstance() };
    DragSource source = new DragSource(text, DND.DROP_MOVE | DND.DROP_COPY);
    source.setTransfer(types);
    
    source.addDragListener(new DragSourceAdapter() {
      public void dragSetData(DragSourceEvent event) {
        // Get the selected items in the drag source
        DragSource ds = (DragSource) event.widget;
        Text text = (Text) ds.getControl();
        event.data = text.getSelectionText();
      }
    });
    Label label = new Label(shell, SWT.BORDER);
    // Create the drop target
    DropTarget target = new DropTarget(label, DND.DROP_MOVE | DND.DROP_COPY | DND.DROP_DEFAULT);
    target.setTransfer(types);
    target.addDropListener(new DropTargetAdapter() {
      public void dragEnter(DropTargetEvent event) {
        if (event.detail == DND.DROP_DEFAULT) {
          event.detail = (event.operations & DND.DROP_COPY) != 0 ? DND.DROP_COPY : DND.DROP_NONE;
        }
        // Allow dropping text only
        for (int i = 0, n = event.dataTypes.length; i < n; i++) {
          if (TextTransfer.getInstance().isSupportedType(event.dataTypes[i])) {
            event.currentDataType = event.dataTypes[i];
          }
        }
      }
      public void dragOver(DropTargetEvent event) {
         event.feedback = DND.FEEDBACK_SELECT | DND.FEEDBACK_SCROLL;
      }
      public void drop(DropTargetEvent event) {
        if (TextTransfer.getInstance().isSupportedType(event.currentDataType)) {
          // Get the dropped data
          DropTarget target = (DropTarget) event.widget;
          Label label = (Label) target.getControl();
          String data = (String) event.data;
          label.setText(data);
          label.redraw();
        }
      }
    });
    text.setBounds(10,10,100,25);
    label.setBounds(10,55,100,25);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
    display.dispose();
  }
}
   
   
17. Drag text between two labels
/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
/*
 * Drag and Drop example snippet: drag text between two labels
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DragSourceListener;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
public class DragDropBetweenLabels {
  public static void main(String[] args) {
    Display display = new Display();
    final Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    final Label label1 = new Label(shell, SWT.BORDER);
    label1.setText("TEXT");
    final Label label2 = new Label(shell, SWT.BORDER);
    setDragDrop(label1);
    setDragDrop(label2);
    shell.setSize(200, 200);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
  public static void setDragDrop(final Label label) {
    Transfer[] types = new Transfer[] { TextTransfer.getInstance() };
    int operations = DND.DROP_MOVE | DND.DROP_COPY | DND.DROP_LINK;
    final DragSource source = new DragSource(label, operations);
    source.setTransfer(types);
    source.addDragListener(new DragSourceListener() {
      public void dragStart(DragSourceEvent event) {
        event.doit = (label.getText().length() != 0);
      }
      public void dragSetData(DragSourceEvent event) {
        event.data = label.getText();
      }
      public void dragFinished(DragSourceEvent event) {
        if (event.detail == DND.DROP_MOVE)
          label.setText("");
      }
    });
    DropTarget target = new DropTarget(label, operations);
    target.setTransfer(types);
    target.addDropListener(new DropTargetAdapter() {
      public void drop(DropTargetEvent event) {
        if (event.data == null) {
          event.detail = DND.DROP_NONE;
          return;
        }
        label.setText((String) event.data);
      }
    });
  }
}
   
   
17. Make a dropped data type depend on a target item in table
/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
//package org.eclipse.swt.snippets;
/*
 * Make a dropped data type depend on a target item in table
 * 
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import java.io.File;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.FileTransfer;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableItem;
public class DropTypeOnTable {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    Label label1 = new Label(shell, SWT.BORDER);
    label1.setText("Drag Source");
    final Table table = new Table(shell, SWT.BORDER);
    for (int i = 0; i < 4; i++) {
      TableItem item = new TableItem(table, SWT.NONE);
      if (i % 2 == 0)
        item.setText("Drop a file");
      if (i % 2 == 1)
        item.setText("Drop text");
    }
    DragSource dragSource = new DragSource(label1, DND.DROP_COPY);
    dragSource
        .setTransfer(new Transfer[] { TextTransfer.getInstance(), FileTransfer.getInstance() });
    dragSource.addDragListener(new DragSourceAdapter() {
      public void dragSetData(DragSourceEvent event) {
        if (FileTransfer.getInstance().isSupportedType(event.dataType)) {
          File file = new File("temp");
          event.data = new String[] { file.getAbsolutePath() };
        }
        if (TextTransfer.getInstance().isSupportedType(event.dataType)) {
          event.data = "once upon a time";
        }
      }
    });
    DropTarget dropTarget = new DropTarget(table, DND.DROP_COPY | DND.DROP_DEFAULT);
    dropTarget
        .setTransfer(new Transfer[] { TextTransfer.getInstance(), FileTransfer.getInstance() });
    dropTarget.addDropListener(new DropTargetAdapter() {
      FileTransfer fileTransfer = FileTransfer.getInstance();
      TextTransfer textTransfer = TextTransfer.getInstance();
      public void dragEnter(DropTargetEvent event) {
        if (event.detail == DND.DROP_DEFAULT)
          event.detail = DND.DROP_COPY;
      }
      public void dragOperationChanged(DropTargetEvent event) {
        if (event.detail == DND.DROP_DEFAULT)
          event.detail = DND.DROP_COPY;
      }
      public void dragOver(DropTargetEvent event) {
        event.detail = DND.DROP_NONE;
        TableItem item = (TableItem) event.item;
        if (item == null)
          return;
        int itemIndex = table.indexOf(item);
        if (itemIndex % 2 == 0) {
          int index = 0;
          while (index < event.dataTypes.length) {
            if (fileTransfer.isSupportedType(event.dataTypes[index]))
              break;
            index++;
          }
          if (index < event.dataTypes.length) {
            event.currentDataType = event.dataTypes[index];
            event.detail = DND.DROP_COPY;
            return;
          }
        } else {
          int index = 0;
          while (index < event.dataTypes.length) {
            if (textTransfer.isSupportedType(event.dataTypes[index]))
              break;
            index++;
          }
          if (index < event.dataTypes.length) {
            event.currentDataType = event.dataTypes[index];
            event.detail = DND.DROP_COPY;
            return;
          }
        }
      }
      public void drop(DropTargetEvent event) {
        TableItem item = (TableItem) event.item;
        if (item == null) {
          event.detail = DND.DROP_NONE;
          return;
        }
        if (fileTransfer.isSupportedType(event.currentDataType)) {
          String[] files = (String[]) event.data;
          if (files != null && files.length > 0) {
            item.setText(files[0]);
          }
        }
        if (textTransfer.isSupportedType(event.currentDataType)) {
          String text = (String) event.data;
          if (text != null) {
            item.setText(text);
          }
        }
      }
    });
    shell.setSize(300, 150);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
}