/// <summary>
/// This method uses the GetUIObjectOf method of IShellFolder to obtain the IDropTarget of a
/// CShItem.
/// </summary>
/// <param name="item">The item for which to obtain the IDropTarget</param>
/// <param name="dropTarget">The IDropTarget interface of the input Folder</param>
/// <returns>true if successful in obtaining the IDropTarget Interface.</returns>
/// <remarks>The original FileBrowser version of this returned the IntPtr which points to
/// the interface. This is not needed since GetTypedObjectForIUnknown manages that IntPtr.
/// For all purposes, the CShItem.GetDropTargetOf routine is more efficient and provides
/// the same interface.</remarks>
public static bool GetIDropTarget(ShellItem item, ref FlShell.Interop.IDropTarget dropTarget)
{
IntPtr dropTargetPtr = IntPtr.Zero;
ShellItem parent = item.Parent;
if (parent == null)
{
parent = item;
}
IShellFolder folder;
if (item == ShellItem.Desktop)
{
folder = item.GetIShellFolder();
}
else
{
folder = item.Parent.GetIShellFolder();
}
IntPtr relpidl = Shell32.ILFindLastID(item.Pidl);
if (parent.GetIShellFolder().GetUIObjectOf(IntPtr.Zero, 1, new IntPtr[] { relpidl }, Ole32.IID_IDropTarget, 0, out dropTargetPtr) == 0)
{
dropTarget = (FlShell.Interop.IDropTarget)Marshal.GetTypedObjectForIUnknown(dropTargetPtr, typeof(FlShell.Interop.IDropTarget));
return(true);
}
else
{
dropTarget = null;
dropTargetPtr = IntPtr.Zero;
return(false);
}
}
/// <summary>
/// It obtains a DragDropEffects flag variable indicating the input ShellItem's ability to accept a Paste from the Clipboard.
/// </summary>
/// <param name="item">The item whose ability to accept a Paste is to be queried.</param>
/// <returns>A DragDropEffect indicating what actions the input ShellItem is willing to do.</returns>
/// <remarks>Used to determine if Paste is a valid menu item.</remarks>
public static DragDropEffects CanDropClipboard(ShellItem item)
{
System.Runtime.InteropServices.ComTypes.IDataObject dataObject;
Ole32.OleGetClipboard(out dataObject);
FlShell.Interop.IDropTarget target = null;
DragDropEffects retVal = DragDropEffects.None;
if (GetIDropTarget(item, ref target))
{
DragDropEffects effects = DragDropEffects.Copy;
target.DragEnter(dataObject, MK.MK_CONTROL, new Point(), ref effects);
//if (target.DragEnter(dataObject, MK.MK_CONTROL, new Point(), ref effects) == (int)HResult.S_OK)
//{
if (effects == DragDropEffects.Copy)
{
retVal = retVal | DragDropEffects.Copy;
}
target.DragLeave();
//}
effects = DragDropEffects.Move;
target.DragEnter(dataObject, MK.MK_SHIFT, new Point(), effects);
//if (target.DragEnter(dataObject, MK.MK_SHIFT, new Point(), effects) == (int)HResult.S_OK)
//{
if (effects == DragDropEffects.Move)
{
retVal = retVal | DragDropEffects.Move;
}
target.DragLeave();
//}
effects = DragDropEffects.Link;
target.DragEnter(dataObject, MK.MK_ALT, new Point(), effects);
//if (target.DragEnter(dataObject, MK.MK_ALT, new Point(), effects) == (int)HResult.S_OK)
//{
if (effects == DragDropEffects.Link)
{
retVal = retVal | DragDropEffects.Link;
}
target.DragLeave();
//}
Marshal.ReleaseComObject(target);
}
return(retVal);
}
