public static bool TryGetData <T>(this IDataObject dataObject, string format, out T data)
where T : struct
{
var formatEtc = OleConverter.CreateFormat(format);
formatEtc.tymed = TYMED.TYMED_HGLOBAL;
if (0 == dataObject.QueryGetData(ref formatEtc))
{
STGMEDIUM medium;
dataObject.GetData(ref formatEtc, out medium);
try
{
data = (T)Marshal.PtrToStructure(medium.unionmember, typeof(T));
return(true);
}
finally
{
ReleaseStgMedium(ref medium);
}
}
data = default(T);
return(false);
}
public static void SetData <T>(this IDataObject dataObject, string format, T data)
where T : struct
{
var formatEtc = OleConverter.CreateFormat(format);
formatEtc.tymed = TYMED.TYMED_HGLOBAL;
// We need to set the drop description as an HGLOBAL.
// Allocate space ...
var unmanagedPtr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(T)));
try
{
// ... and marshal the data
Marshal.StructureToPtr(data, unmanagedPtr, false);
// The medium wraps the HGLOBAL
STGMEDIUM medium;
medium.pUnkForRelease = null;
medium.tymed = TYMED.TYMED_HGLOBAL;
medium.unionmember = unmanagedPtr;
// Set the data
dataObject.SetData(ref formatEtc, ref medium, true);
}
catch
{
// If we failed, we need to free the HGLOBAL memory
Marshal.FreeHGlobal(unmanagedPtr);
throw;
}
}
public void SetData(string format, Type type, bool autoConvert, object data)
{
var tymed = GetCompatibleFormat(format, type);
if (tymed != TYMED.TYMED_NULL)
{
var formatEtc = OleConverter.CreateFormat(format);
formatEtc.tymed = tymed;
// Set data on an empty DataObject instance
var conv = new DataObject();
conv.SetData(format, true, data);
// Now retrieve the data, using the COM interface.
// This will perform a managed to unmanaged conversion for us.
STGMEDIUM medium;
((IComDataObject)conv).GetData(ref formatEtc, out medium);
try
{
// Now set the data on our data object
SetData(ref formatEtc, ref medium, true);
}
catch
{
// On exceptions, release the medium
ReleaseStgMedium(ref medium);
throw;
}
}
else
{
m_managedStorage[format] = data;
}
}
/// <summary>
/// Begins a drag-and-drop operation, with an image attached.
/// </summary>
/// <param name="data">The data to drag.</param>
/// <param name="allowedEffects">One of the DragDropEffects values.</param>
/// <param name="dragImage">The image to attach to the cursor</param>
/// <param name="cursorOffset">The offset within the image that the cursor attaches to.</param>
/// <returns>A value from the DragDropEffects enumeration that represents the final effect that was performed during the drag-and-drop operation.</returns>
public DragDropEffects DoDragDrop(object data, DragDropEffects allowedEffects, Bitmap dragImage, Point cursorOffset)
{
var adviseConnection = 0;
try
{
DragDropHelper.SetFlags(1);
// Create IDataObject
m_dragData = new DragDropDataObject();
// attach image if we have one.
if (dragImage != null)
{
DragDropHelper.InitializeFromBitmap(m_dragData, dragImage, cursorOffset);
}
// We need to listen for drop description changes. If a drop target
// changes the drop description, we shouldn't provide a default one.
var formatEtc = OleConverter.CreateFormat("DropDescription");
var hr = m_dragData.DAdvise(ref formatEtc, 0, new AdviseSink(m_dragData), out adviseConnection);
if (hr != 0)
{
Marshal.ThrowExceptionForHR(hr);
}
// associate data with it.
m_dragData.SetData("DragDropExtender", this);
m_dragData.SetData(data);
m_owner.GiveFeedback += OnGiveFeedback;
m_owner.QueryContinueDrag += OnQueryContinueDrag;
return(m_owner.DoDragDrop(m_dragData, allowedEffects));
}
finally
{
m_owner.GiveFeedback -= OnGiveFeedback;
m_owner.QueryContinueDrag -= OnQueryContinueDrag;
if (m_dragData != null)
{
// Stop listening to drop description changes
m_dragData.DUnadvise(adviseConnection);
m_dragData.Dispose();
m_dragData = null;
}
}
}
public bool GetDataPresent(string format, bool autoConvert)
{
if (m_managedStorage.ContainsKey(format))
{
return(true);
}
var formatEtc = OleConverter.CreateFormat(format);
if (QueryGetData(ref formatEtc) == 0)
{
return(true);
}
return(false);
}
public object GetData(string format, bool autoConvert)
{
object obj;
if (m_managedStorage.TryGetValue(format, out obj))
{
return(obj);
}
var formatEtc = OleConverter.CreateFormat(format);
if (QueryGetData(ref formatEtc) == 0)
{
STGMEDIUM medium;
GetData(ref formatEtc, out medium);
return(OleConverter.Convert(format, ref medium));
}
return(null);
}
