/*******************************************************************************
* Copyright (c) 2000, 2013 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.dnd;
import org.eclipse.swt.SWTError;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Widget;
/**
*
* <code>DragSource</code> defines the source object for a drag and drop
* transfer.
*
* <p>
* IMPORTANT: This class is <em>not</em> intended to be subclassed.
* </p>
*
* <p>
* A drag source is the object which originates a drag and drop operation. For
* the specified widget, it defines the type of data that is available for
* dragging and the set of operations that can be performed on that data. The
* operations can be any bit-wise combination of DND.MOVE, DND.COPY or DND.LINK.
* The type of data that can be transferred is specified by subclasses of
* Transfer such as TextTransfer or FileTransfer. The type of data transferred
* can be a predefined system type or it can be a type defined by the
* application. For instructions on how to define your own transfer type, refer
* to <code>ByteArrayTransfer</code>.
* </p>
*
* <p>
* You may have several DragSources in an application but you can only have one
* DragSource per Control. Data dragged from this DragSource can be dropped on a
* site within this application or it can be dropped on another application such
* as an external Text editor.
* </p>
*
* <p>
* The application supplies the content of the data being transferred by
* implementing the <code>DragSourceListener</code> and associating it with the
* DragSource via DragSource#addDragListener.
* </p>
*
* <p>
* When a successful move operation occurs, the application is required to take
* the appropriate action to remove the data from its display and remove any
* associated operating system resources or internal references. Typically in a
* move operation, the drop target makes a copy of the data and the drag source
* deletes the original. However, sometimes copying the data can take a long
* time (such as copying a large file). Therefore, on some platforms, the drop
* target may actually move the data in the operating system rather than make a
* copy. This is usually only done in file transfers. In this case, the drag
* source is informed in the DragEnd event that a DROP_TARGET_MOVE was
* performed. It is the responsibility of the drag source at this point to clean
* up its displayed information. No action needs to be taken on the operating
* system resources.
* </p>
*
* <p>
* The following example shows a Label widget that allows text to be dragged
* from it.
* </p>
*
* <code><pre>
* // Enable a label as a Drag Source
* Label label = new Label(shell, SWT.NONE);
* // This example will allow text to be dragged
* Transfer[] types = new Transfer[] {TextTransfer.getInstance()};
* // This example will allow the text to be copied or moved to the drop target
* int operations = DND.DROP_MOVE | DND.DROP_COPY;
*
* DragSource source = new DragSource(label, operations);
* source.setTransfer(types);
* source.addDragListener(new DragSourceListener() {
* public void dragStart(DragSourceEvent e) {
* // Only start the drag if there is actually text in the
* // label - this text will be what is dropped on the target.
* if (label.getText().length() == 0) {
* event.doit = false;
* }
* };
* public void dragSetData(DragSourceEvent event) {
* // A drop has been performed, so provide the data of the
* // requested type.
* // (Checking the type of the requested data is only
* // necessary if the drag source supports more than
* // one data type but is shown here as an example).
* if (TextTransfer.getInstance().isSupportedType(event.dataType)){
* event.data = label.getText();
* }
* }
* public void dragFinished(DragSourceEvent event) {
* // A Move operation has been performed so remove the data
* // from the source
* if (event.detail == DND.DROP_MOVE)
* label.setText("");
* }
* });
* </pre></code>
*
*
* <dl>
* <dt><b>Styles</b></dt>
* <dd>DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK</dd>
* <dt><b>Events</b></dt>
* <dd>DND.DragStart, DND.DragSetData, DND.DragEnd</dd>
* </dl>
*
* @see <a href="http://www.eclipse.org/swt/snippets/#dnd">Drag and Drop
* snippets</a>
* @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example:
* DNDExample</a>
* @see <a href="http://www.eclipse.org/swt/">Sample code and further
* information</a>
* @noextend This class is not intended to be subclassed by clients.
*/
public class DragSource extends Widget {
/**
* Creates a new <code>DragSource</code> to handle dragging from the
* specified <code>Control</code>. Creating an instance of a DragSource may
* cause system resources to be allocated depending on the platform. It is
* therefore mandatory that the DragSource instance be disposed when no
* longer required.
*
* @param control
* the <code>Control</code> that the user clicks on to initiate
* the drag
* @param style
* the bitwise OR'ing of allowed operations; this may be a
* combination of any of DND.DROP_NONE, DND.DROP_COPY,
* DND.DROP_MOVE, DND.DROP_LINK
*
* @exception SWTException
* <ul>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the parent</li>
* <li>ERROR_INVALID_SUBCLASS - if this class is not an
* allowed subclass</li>
* </ul>
* @exception SWTError
* <ul>
* <li>ERROR_CANNOT_INIT_DRAG - unable to initiate drag
* source; this will occur if more than one drag source is
* created for a control or if the operating system will not
* allow the creation of the drag source</li>
* </ul>
*
* <p>
* NOTE: ERROR_CANNOT_INIT_DRAG should be an SWTException,
* since it is a recoverable error, but can not be changed
* due to backward compatibility.
* </p>
*
* @see Widget#dispose
* @see DragSource#checkSubclass
* @see DND#DROP_NONE
* @see DND#DROP_COPY
* @see DND#DROP_MOVE
* @see DND#DROP_LINK
*/
public DragSource(Control control, int style) {
super(control, style);
// TODO
}
/**
* Adds the listener to the collection of listeners who will be notified
* when a drag and drop operation is in progress, by sending it one of the
* messages defined in the <code>DragSourceListener</code> interface.
*
* <p>
* <ul>
* <li><code>dragStart</code> is called when the user has begun the actions
* required to drag the widget. This event gives the application the chance
* to decide if a drag should be started.
* <li><code>dragSetData</code> is called when the data is required from the
* drag source.
* <li><code>dragFinished</code> is called when the drop has successfully
* completed (mouse up over a valid target) or has been terminated (such as
* hitting the ESC key). Perform cleanup such as removing data from the
* source side on a successful move operation.
* </ul>
* </p>
*
* @param listener
* the listener which should be notified
*
* @exception IllegalArgumentException
* <ul>
* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
* </ul>
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been
* disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the receiver</li>
* </ul>
*
* @see DragSourceListener
* @see #getDragListeners
* @see #removeDragListener
* @see DragSourceEvent
*/
public void addDragListener(DragSourceListener listener) {
// TODO
}
/**
* Returns the Control which is registered for this DragSource. This is the
* control that the user clicks in to initiate dragging.
*
* @return the Control which is registered for this DragSource
*/
public Control getControl() {
// TODO
return null;
}
/**
* Returns an array of listeners who will be notified when a drag and drop
* operation is in progress, by sending it one of the messages defined in
* the <code>DragSourceListener</code> interface.
*
* @return the listeners who will be notified when a drag and drop operation
* is in progress
*
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been
* disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the receiver</li>
* </ul>
*
* @see DragSourceListener
* @see #addDragListener
* @see #removeDragListener
* @see DragSourceEvent
*
* @since 3.4
*/
public DragSourceListener[] getDragListeners() {
// TODO
return null;
}
/**
* Returns the drag effect that is registered for this DragSource. This drag
* effect will be used during a drag and drop operation.
*
* @return the drag effect that is registered for this DragSource
*
* @since 3.3
*/
public DragSourceEffect getDragSourceEffect() {
// TODO
return null;
}
/**
* Returns the list of data types that can be transferred by this
* DragSource.
*
* @return the list of data types that can be transferred by this DragSource
*/
public Transfer[] getTransfer() {
// TODO
return null;
}
/**
* Removes the listener from the collection of listeners who will be
* notified when a drag and drop operation is in progress.
*
* @param listener
* the listener which should no longer be notified
*
* @exception IllegalArgumentException
* <ul>
* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
* </ul>
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been
* disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the receiver</li>
* </ul>
*
* @see DragSourceListener
* @see #addDragListener
* @see #getDragListeners
*/
public void removeDragListener(DragSourceListener listener) {
// TODO
}
/**
* Specifies the drag effect for this DragSource. This drag effect will be
* used during a drag and drop operation.
*
* @param effect
* the drag effect that is registered for this DragSource
*
* @since 3.3
*/
public void setDragSourceEffect(DragSourceEffect effect) {
// TODO
}
/**
* Specifies the list of data types that can be transferred by this
* DragSource. The application must be able to provide data to match each of
* these types when a successful drop has occurred.
*
* @param transferAgents
* a list of Transfer objects which define the types of data that
* can be dragged from this source
*/
public void setTransfer(Transfer[] transferAgents) {
// TODO
}
}