Adding check for already existing Drop target or Drag source for widget

2 files changed, 23 insertions, 9 deletions

diff --git a/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DragSource.java b/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DragSource.java
index ce9835f5a9..e4c85e7315 100755
--- a/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DragSource.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DragSource.java
@@ -103,7 +103,8 @@ public class DragSource extends Widget {
 	private Listener controlListener;

 	

 	private int dataEffect;

-

+	

+	private static final String DRAGSOURCEID = "DragSource";

 /**

  * 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.  

@@ -116,6 +117,8 @@ public class DragSource extends Widget {
  * @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>

+ * @exception SWTError <ul>

+ *    <li>ERROR_CANNOT_INIT_DRAG - unable to initiate drag source</li>

  * </ul>

  *

  * @see DragSource#dispose

@@ -128,11 +131,11 @@ public class DragSource extends Widget {
 public DragSource(Control control, int style) {

 

 	super (control, checkStyle (style));

-	

 	this.control = control;

-	

+	if (control.getData(DRAGSOURCEID) != null)

+		DND.error(DND.ERROR_CANNOT_INIT_DRAG);

+	control.setData(DRAGSOURCEID, this);

 	createCOMInterfaces();

-

 	this.AddRef();

 

 	controlListener = new Listener () {

@@ -232,7 +235,8 @@ private void onDispose () {
 		control.removeListener(SWT.Dispose, controlListener);

 		control.removeListener(SWT.DragDetect, controlListener);

 	}

-	controlListener = null;	

+	controlListener = null;

+	control.setData(DRAGSOURCEID, null);	

 	control = null;

 	

 	transferAgents = null;

diff --git a/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DropTarget.java b/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DropTarget.java
index 698d0769d1..d64d99ac47 100755
--- a/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DropTarget.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DropTarget.java
@@ -7,7 +7,6 @@ package org.eclipse.swt.dnd;
  * http://www.eclipse.org/legal/cpl-v10.html

  */

 import org.eclipse.swt.*;

-import org.eclipse.swt.ole.win32.*;

 import org.eclipse.swt.internal.ole.win32.*;

 import org.eclipse.swt.graphics.*;

 import org.eclipse.swt.widgets.*;

@@ -88,6 +87,7 @@ public class DropTarget extends Widget {
 	

 	private int iDataObject;

 	

+	private static final String DROPTARGETID = "DropTarget";

 /**

  * Creates a new <code>DropTarget</code> to allow data to be dropped on the specified 

  * <code>Control</code>.

@@ -99,6 +99,13 @@ public class DropTarget extends Widget {
  * @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>

+ * @exception SWTError <ul>

+ *    <li>ERROR_CANNOT_INIT_DROP - unable to initiate drop target</li>

+ * </ul>

+ * 

  * @see DropTarget#dispose

  * @see DropTarget#checkSubclass

  * @see DND#DROP_NONE

@@ -109,11 +116,13 @@ public class DropTarget extends Widget {
 public DropTarget(Control control, int style) {

 

 	super (control, checkStyle(style));

-	

 	this.control = control;

-	

+	if (control.getData(DROPTARGETID) != null)

+		DND.error(DND.ERROR_CANNOT_INIT_DROP);

+	control.setData(DROPTARGETID, this);

 	createCOMInterfaces();

-

+	this.AddRef();

+	

 	int result = 0;

 	if ((result = COM.CoLockObjectExternal(iDropTarget.getAddress(), true, true)) != COM.S_OK)

 		DND.error(DND.ERROR_CANNOT_INIT_DROP, result);

@@ -214,6 +223,7 @@ private void onDispose () {
 	if (controlListener != null)

 		control.removeListener(SWT.Dispose, controlListener);

 	controlListener = null;

+	control.setData(DROPTARGETID, null);

 	transferAgents = null;

 	control = null;