/// <summary>
/// Opens the specified stream using the preview handler COM type with the provided GUID and displays the result in this PreviewHandlerHost.
/// </summary>
/// <param name="stream"></param>
/// <param name="previewHandler"></param>
/// <param name="clientRectangle"> </param>
/// <param name="handle"> </param>
/// <returns></returns>
public string Open(Stream stream, Guid previewHandler, Rectangle clientRectangle, IntPtr handle)
{
UnloadPreviewHandler();
if (stream == null)
{
return "The file could not be previewed.";
}
if (previewHandler != Guid.Empty)
{
try
{
if (previewHandler != _currentPreviewHandlerGUID)
{
_currentPreviewHandlerGUID = previewHandler;
// need to instantiate a different COM type (file format has changed)
if (_currentPreviewHandler != null)
{
Marshal.FinalReleaseComObject(_currentPreviewHandler);
GC.Collect();
}
// use reflection to instantiate the preview handler type
Type comType = Type.GetTypeFromCLSID(_currentPreviewHandlerGUID);
_currentPreviewHandler = Activator.CreateInstance(comType);
}
var currentPreviewHandler = _currentPreviewHandler as IInitializeWithStream;
if (currentPreviewHandler != null)
{
// must wrap the stream to provide compatibility with IStream
_currentPreviewHandlerStream = stream;
var wrapped = new StreamWrapper(_currentPreviewHandlerStream);
(currentPreviewHandler).Initialize(wrapped, 0);
}
var handler = _currentPreviewHandler as IPreviewHandler;
if (handler != null)
{
// bind the preview handler to the control's bounds and preview the content
Rectangle r = clientRectangle;
(handler).SetWindow(handle, ref r);
(handler).DoPreview();
return "success";
}
}
catch (Exception ex)
{
return "The file could not be previewed.\n" + ex.Message;
}
}
else
{
return "No preview is registered for this type of file.";
}
return "failure";
}
/// <summary>
/// Opens the specified file using the appropriate preview handler and displays the result in this PreviewHandlerHost.
/// </summary>
/// <param name="filename"></param>
/// <param name="clientRectangle"> </param>
/// <param name="handle"> </param>
/// <returns></returns>
public string Open(string filename,Rectangle clientRectangle, IntPtr handle)
{
_status = HandlerStatus.None;
UnloadPreviewHandler();
if (String.IsNullOrEmpty(filename))
{
return "No file loaded";
}
if (!File.Exists(filename))
{
return "The file was not found";
}
// try to get GUID for the preview handler
Guid guid = GetPreviewHandlerGUID(filename);
if (guid != Guid.Empty)
{
_status = HandlerStatus.FoundGuid;
try
{
if (guid != _currentPreviewHandlerGUID)
{
_currentPreviewHandlerGUID = guid;
// need to instantiate a different COM type (file format has changed)
if (_currentPreviewHandler != null)
{
Marshal.FinalReleaseComObject(_currentPreviewHandler);
GC.Collect();
}
// use reflection to instantiate the preview handler type
Type comType = Type.GetTypeFromCLSID(_currentPreviewHandlerGUID);
_currentPreviewHandler = Activator.CreateInstance(comType);
}
_status = HandlerStatus.Instantiated;
//try stream first
if (_currentPreviewHandler is IInitializeWithStream)
{
// some handlers want an IStream (in this case, a file stream)
_currentPreviewHandlerStream = new MemoryStream();
using (var fs = File.Open(filename, FileMode.Open, FileAccess.Read))
{
fs.CopyTo(_currentPreviewHandlerStream);
}
var stream = new StreamWrapper(_currentPreviewHandlerStream);
((IInitializeWithStream)_currentPreviewHandler).Initialize(stream, 0);
}
else if (_currentPreviewHandler is IInitializeWithFile)
{
// some handlers accept a filename
((IInitializeWithFile)_currentPreviewHandler).Initialize(filename, 0);
}
else if (_currentPreviewHandler is IInitializeWithItem)
{
// a third category exists, must be initialised with a shell item
IShellItem shellItem;
SHCreateItemFromParsingName(filename, IntPtr.Zero, new Guid(GUID_ISHELLITEM), out shellItem);
((IInitializeWithItem)_currentPreviewHandler).Initialize(shellItem, 0);
}
_status = HandlerStatus.Initialized;
var currentPreviewHandler = _currentPreviewHandler as IPreviewHandler;
if (currentPreviewHandler != null)
{
// bind the preview handler to the control's bounds and preview the content
Rectangle r = clientRectangle;
(currentPreviewHandler).SetWindow(handle, ref r);
Application.DoEvents();
(currentPreviewHandler).DoPreview();
return "success";
}
}
catch (Exception ex)
{
_status = HandlerStatus.Failed;
return "The file could not be previewed\n" + ex.Message;
}
}
else
{
return "No previewer is registered for this type of file";
}
return "Unable to preview file";
}
