private IntPtr GetHBitmap(string fileName, int width, int height, Win32Helper.ThumbnailOptions options)
{
Win32Helper.IShellItem nativeShellItem;
Guid shellItem2Guid = new Guid(Win32Helper.IShellItem2Guid);
int retCode = Win32Helper.SHCreateItemFromParsingName(fileName, IntPtr.Zero, ref shellItem2Guid, out nativeShellItem);
if (retCode != 0)
{
throw Marshal.GetExceptionForHR(retCode);
}
Win32Helper.NativeSize nativeSize = new Win32Helper.NativeSize();
nativeSize.Width = width;
nativeSize.Height = height;
IntPtr hBitmap;
Win32Helper.HResult hr = ((Win32Helper.IShellItemImageFactory)nativeShellItem).GetImage(nativeSize, options, out hBitmap);
Marshal.ReleaseComObject(nativeShellItem);
if (hr == Win32Helper.HResult.Ok)
{
return(hBitmap);
}
throw Marshal.GetExceptionForHR((int)hr);
}
private Bitmap GetBitmapThumbnail(string fileName, int width = 80, int height = 80, Win32Helper.ThumbnailOptions options = Win32Helper.ThumbnailOptions.None)
{
IntPtr hBitmap = GetHBitmap(System.IO.Path.GetFullPath(fileName), width, height, options);
try
{
Bitmap bmp = Bitmap.FromHbitmap(hBitmap);
if (Bitmap.GetPixelFormatSize(bmp.PixelFormat) < 32)
{
return(bmp);
}
return(CreateAlphaBitmap(bmp, System.Drawing.Imaging.PixelFormat.Format32bppArgb));
}
finally
{
// delete HBitmap to avoid memory leaks
Win32Helper.DeleteObject(hBitmap);
}
}
public string GetJPGThumbnail(string filename, int width = 80, int height = 80, Win32Helper.ThumbnailOptions options = Win32Helper.ThumbnailOptions.None)
{
if (!File.Exists(filename))
{
return(string.Empty);
}
Bitmap bit = GetBitmapThumbnail(filename, width, height, options);
if (bit == null)
{
return(string.Empty);
}
return(GetThumbnailFilePath(bit));
}
