protected void CreateDragHelper(
Drawing.Bitmap bitmap,
Point startPoint,
System.Windows.DataObject dataObject)
{
ShDragImage shdi = new ShDragImage();
Win32Size size;
size.cx = bitmap.Width;
size.cy = bitmap.Height;
shdi.sizeDragImage = size;
Win32Point wpt;
wpt.x = (int)startPoint.X;
wpt.y = (int)startPoint.Y;
shdi.ptOffset = wpt;
shdi.crColorKey = Drawing.Color.Magenta.ToArgb();
// This HBITMAP will be managed by the DragDropHelper
// as soon as we pass it to InitializeFromBitmap. If we fail
// to make the hand off, we'll delete it to prevent a mem leak.
IntPtr hbmp = bitmap.GetHbitmap();
shdi.hbmpDragImage = hbmp;
try
{
IDragSourceHelper sourceHelper = (IDragSourceHelper) new DragDropHelper();
try
{
sourceHelper.InitializeFromBitmap(ref shdi, (System.Runtime.InteropServices.ComTypes.IDataObject)dataObject);
}
catch (NotImplementedException ex)
{
throw new Exception("A NotImplementedException was caught. This could be because you forgot to construct your DataObject using a DragDropLib.DataObject", ex);
}
}
catch
{
// We failed to initialize the drag image, so the DragDropHelper
// won't be managing our memory. Release the HBITMAP we allocated.
GDI32.DeleteObject(hbmp);
}
}
/// <summary>
/// Sets the drag image.
/// </summary>
/// <param name="dataObject">The DataObject to set the drag image on.</param>
/// <param name="image">The drag image.</param>
/// <param name="cursorOffset">The location of the cursor relative to the image.</param>
public static void SetDragImage(this IDataObject dataObject, Image image, System.Drawing.Point cursorOffset)
{
ShDragImage shdi = new ShDragImage();
Win32Size size;
size.cx = image.Width;
size.cy = image.Height;
shdi.sizeDragImage = size;
Win32Point wpt;
wpt.x = cursorOffset.X;
wpt.y = cursorOffset.Y;
shdi.ptOffset = wpt;
shdi.crColorKey = Color.Magenta.ToArgb();
// This HBITMAP will be managed by the DragDropHelper
// as soon as we pass it to InitializeFromBitmap. If we fail
// to make the hand off, we'll delete it to prevent a mem leak.
IntPtr hbmp = GetHbitmapFromImage(image);
shdi.hbmpDragImage = hbmp;
try
{
IDragSourceHelper sourceHelper = (IDragSourceHelper)new DragDropHelper();
try
{
sourceHelper.InitializeFromBitmap(ref shdi, (ComIDataObject)dataObject);
}
catch (NotImplementedException ex)
{
throw new Exception("A NotImplementedException was caught. This could be because you forgot to construct your DataObject using a DragDropLib.DataObject", ex);
}
}
catch
{
DeleteObject(hbmp);
}
}
/// <summary>
/// Sets the drag image.
/// </summary>
/// <param name="dataObject">The DataObject to set the drag image on.</param>
/// <param name="image">The drag image.</param>
/// <param name="cursorOffset">The location of the cursor relative to the image.</param>
private static void SetDragImage(this IDataObject dataObject, Bitmap bitmap, Point cursorOffset)
{
ShDragImage shdi = new ShDragImage();
Win32Size size;
size.cx = bitmap.Width;
size.cy = bitmap.Height;
shdi.sizeDragImage = size;
Win32Point wpt;
wpt.x = (int)cursorOffset.X;
wpt.y = (int)cursorOffset.Y;
shdi.ptOffset = wpt;
shdi.crColorKey = DrawingColor.Magenta.ToArgb();
// This HBITMAP will be managed by the DragDropHelper
// as soon as we pass it to InitializeFromBitmap. If we fail
// to make the hand off, we'll delete it to prevent a mem leak.
IntPtr hbmp = bitmap.GetHbitmap();
shdi.hbmpDragImage = hbmp;
try
{
IDragSourceHelper sourceHelper = (IDragSourceHelper)new DragDropHelper();
try
{
sourceHelper.InitializeFromBitmap(ref shdi, (ComIDataObject)dataObject);
}
catch (NotImplementedException ex)
{
throw new Exception("A NotImplementedException was caught. This could be because you forgot to construct your DataObject using a DragDropLib.DataObject", ex);
}
}
catch
{
// We failed to initialize the drag image, so the DragDropHelper
// won't be managing our memory. Release the HBITMAP we allocated.
DeleteObject(hbmp);
}
}