/// <summary>
/// Opens the specified file using the appropriate preview handler and displays the result in this PreviewHandlerHost.
/// </summary>
/// <param name="filename"></param>
/// <returns></returns>
public bool Open(string filename)
{
UnloadPreviewHandler();
if (String.IsNullOrEmpty(filename))
{
ErrorMessage = "No file loaded.";
return(false);
}
// try to get GUID for the preview handler
Guid guid = GetPreviewHandlerGUID(filename);
ErrorMessage = "";
if (guid != Guid.Empty)
{
try {
if (guid != mCurrentPreviewHandlerGUID)
{
mCurrentPreviewHandlerGUID = guid;
// need to instantiate a different COM type (file format has changed)
if (mCurrentPreviewHandler != null)
{
Marshal.FinalReleaseComObject(mCurrentPreviewHandler);
}
// use reflection to instantiate the preview handler type
Type comType = Type.GetTypeFromCLSID(mCurrentPreviewHandlerGUID);
mCurrentPreviewHandler = Activator.CreateInstance(comType);
}
if (mCurrentPreviewHandler is IInitializeWithFile)
{
// some handlers accept a filename
((IInitializeWithFile)mCurrentPreviewHandler).Initialize(filename, 0);
}
else if (mCurrentPreviewHandler is IInitializeWithStream)
{
if (File.Exists(filename))
{
// other handlers want an IStream (in this case, a file stream)
mCurrentPreviewHandlerStream = File.Open(filename, FileMode.Open);
StreamWrapper stream = new StreamWrapper(mCurrentPreviewHandlerStream);
((IInitializeWithStream)mCurrentPreviewHandler).Initialize(stream, 0);
}
else
{
ErrorMessage = "File not found.";
}
}
else if (mCurrentPreviewHandler 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)mCurrentPreviewHandler).Initialize(shellItem, 0);
}
if (mCurrentPreviewHandler is IPreviewHandler)
{
// bind the preview handler to the control's bounds and preview the content
Rectangle r = ClientRectangle;
((IPreviewHandler)mCurrentPreviewHandler).SetWindow(Handle, ref r);
((IPreviewHandler)mCurrentPreviewHandler).DoPreview();
return(true);
}
}
catch (Exception ex) {
ErrorMessage = "Preview could not be generated.\n" + ex.Message;
}
}
else
{
ErrorMessage = "No preview available.";
}
return(false);
}