/// <summary>
/// Gets the current DropDescription's drop image type.
/// </summary>
/// <param name="dataObject">The DataObject.</param>
/// <returns>The current drop image type.</returns>
private static DropImageType GetDropImageType(IDataObject dataObject)
{
object data = ComDataObjectExtensions.GetDropDescription((System.Runtime.InteropServices.ComTypes.IDataObject)dataObject);
if (data is DropDescription)
{
return((DropImageType)((DropDescription)data).type);
}
return(DropImageType.Invalid);
}
/// <summary>
/// Checks if the current drop description, if any, is valid.
/// </summary>
/// <param name="dataObject">The DataObject from which to get the drop description.</param>
/// <returns>True if the drop description is set, and the
/// DropImageType is not DropImageType.Invalid.</returns>
private static bool IsDropDescriptionValid(IDataObject dataObject)
{
object data = ComDataObjectExtensions.GetDropDescription((Runtime.InteropServices.ComTypes.IDataObject)dataObject);
if (data is DropDescription)
{
return((DropImageType)((DropDescription)data).type != DropImageType.Invalid);
}
return(false);
}
/// <summary>
/// Handles DataChanged events from a COM IDataObject.
/// </summary>
/// <param name="format">The data format that had a change.</param>
/// <param name="stgmedium">The data value.</param>
public void OnDataChange(ref FORMATETC format, ref STGMEDIUM stgmedium)
{
// We listen to DropDescription changes, so that we can unset the IsDefault
// drop description flag.
object odd = ComDataObjectExtensions.GetDropDescription((System.Runtime.InteropServices.ComTypes.IDataObject)data);
if (odd != null)
{
SetDropDescriptionIsDefault(data, false);
}
}
/// <summary>
/// Sets managed data to a clipboard DataObject.
/// </summary>
/// <param name="dataObject">The DataObject to set the data on.</param>
/// <param name="format">The clipboard format.</param>
/// <param name="data">The data object.</param>
/// <remarks>
/// Because the underlying data store is not storing managed objects, but
/// unmanaged ones, this function provides intelligent conversion, allowing
/// you to set unmanaged data into the COM implemented IDataObject.</remarks>
public static void SetDataEx(this IDataObject dataObject, string format, object data)
{
DataFormat dataFormat = DataFormats.GetDataFormat(format);
// Initialize the format structure
var formatETC = new FORMATETC();
formatETC.cfFormat = (short)dataFormat.Id;
formatETC.dwAspect = DVASPECT.DVASPECT_CONTENT;
formatETC.lindex = -1;
formatETC.ptd = IntPtr.Zero;
// Try to discover the TYMED from the format and data
TYMED tymed = GetCompatibleTymed(format, data);
// If a TYMED was found, we can use the system DataObject
// to convert our value for us.
if (tymed != TYMED.TYMED_NULL)
{
formatETC.tymed = tymed;
// Set data on an empty DataObject instance
var conv = new System.Windows.DataObject();
conv.SetData(format, data, true);
// Now retrieve the data, using the COM interface.
// This will perform a managed to unmanaged conversion for us.
STGMEDIUM medium;
((ComIDataObject)conv).GetData(ref formatETC, out medium);
try
{
// Now set the data on our data object
((ComIDataObject)dataObject).SetData(ref formatETC, ref medium, true);
}
catch
{
// On exceptions, release the medium
ReleaseStgMedium(ref medium);
throw;
}
}
else
{
// Since we couldn't determine a TYMED, this data
// is likely custom managed data, and won't be used
// by unmanaged code, so we'll use our custom marshaling
// implemented by our COM IDataObject extensions.
ComDataObjectExtensions.SetManagedData((ComIDataObject)dataObject, format, data);
}
}
/// <summary>
/// Gets managed data from a clipboard DataObject.
/// </summary>
/// <param name="dataObject">The DataObject to obtain the data from.</param>
/// <param name="format">The format for which to get the data in.</param>
/// <returns>The data object instance.</returns>
public static object GetDataEx(this IDataObject dataObject, string format)
{
// Get the data
object data = dataObject.GetData(format, true);
// If the data is a stream, we'll check to see if it
// is stamped by us for custom marshaling
if (data is Stream)
{
object data2 = ComDataObjectExtensions.GetManagedData((ComIDataObject)dataObject, format);
if (data2 != null)
{
return(data2);
}
}
return(data);
}
/// <summary>
/// Sets the drop description for the drag image manager.
/// </summary>
/// <param name="dataObject">The DataObject to set.</param>
/// <param name="type">The type of the drop image.</param>
/// <param name="format">The format string for the description.</param>
/// <param name="insert">The parameter for the drop description.</param>
/// <remarks>
/// When setting the drop description, the text can be set in two part,
/// which will be rendered slightly differently to distinguish the description
/// from the subject. For example, the format can be set as "Move to %1" and
/// the insert as "Temp". When rendered, the "%1" in format will be replaced
/// with "Temp", but "Temp" will be rendered slightly different from "Move to ".
/// </remarks>
public static void SetDropDescription(this IDataObject dataObject, DropImageType type, string format, string insert)
{
if (format != null && format.Length > 259)
{
throw new ArgumentException("Format string exceeds the maximum allowed length of 259.", "format");
}
if (insert != null && insert.Length > 259)
{
throw new ArgumentException("Insert string exceeds the maximum allowed length of 259.", "insert");
}
// Fill the structure
DropDescription dd;
dd.type = (int)type;
dd.szMessage = format;
dd.szInsert = insert;
ComDataObjectExtensions.SetDropDescription((ComIDataObject)dataObject, dd);
}
/// <summary>
/// Registers a Control as a drag source and provides default implementations of
/// GiveFeedback and QueryContinueDrag.
/// </summary>
/// <param name="control">The drag source Control instance.</param>
/// <param name="data">The DataObject associated to the drag source.</param>
/// <remarks>Callers must call UnregisterDefaultDragSource when the drag and drop
/// operation is complete to avoid memory leaks.</remarks>
public static void RegisterDefaultDragSource(Control control, IDataObject data)
{
// Cache the drag source and the associated data object
DragSourceEntry entry = new DragSourceEntry(data);
if (!s_dataContext.ContainsKey(control))
{
s_dataContext.Add(control, entry);
}
else
{
s_dataContext[control] = entry;
}
// We need to listen for drop description changes. If a drop target
// changes the drop description, we shouldn't provide a default one.
entry.adviseConnection = ComDataObjectExtensions.Advise(((Runtime.InteropServices.ComTypes.IDataObject)data), new AdviseSink(data), DropDescriptionFormat, 0);
// Hook up the default drag source event handlers
control.GiveFeedback += DefaultGiveFeedbackHandler;
control.QueryContinueDrag += DefaultQueryContinueDragHandler;
}
