public void DeleteFile(string str)
{
files.Remove(str);
string path1 = DataUtility.GetScreenShotPath() + str;
string path2 = DataUtility.GetScreenThumbnailPath() + str;
File.Delete(path1);
File.Delete(path2);
DeleteVideo(str);
UIImage im = imageGallery.GetImage(str);
if (im != null)
{
im.Delete(false);
}
}