This sample code provides a thumbnail for WMF-files, for which Windows 7 is missing a thumbnail provider.
procedure TMainForm.MyThumbnailProvider(const Path: Unicodestring; Width, Height: Integer; out Bitmap: TBitmap);
var APicture: TPicture;
begin
if LowerCase( ExtractFileExt( Path ) ) = '.wmf' then begin
APicture := TPicture.Create;
try
APicture.LoadFromFile( Path );
Bitmap := TBitmap.Create;
Bitmap.PixelFormat := pf24bit;
Bitmap.Width := Width;
Bitmap.Height := Height;
Bitmap.Canvas.Lock;///Important in multithreaded applications, see http://qc.embarcadero.com/wc/qcmain.aspx?d=55871
Bitmap.Canvas.StretchDraw(Rect(0,0,Width,Height), APicture.Graphic);
Bitmap.Canvas.Unlock;
finally
APicture.Free;
end;///try..finally
end;///if
end;
