Assembly assembly = GetType().Assembly;
                                                                   //这时候的路径是：命名空间+文件路径，以点相隔
            System.IO.Stream streamSmall = assembly.GetManifestResourceStream("mytest.leftbutton.png");

            //这个BitmapImage是wpf中的类
            BitmapImage bitmap = new BitmapImage();
            bitmap.BeginInit();//开始初始化
            bitmap.StreamSource = streamSmall;
            bitmap.EndInit();//结束初始化

            this.nininini.Source = bitmap;

new BitmapImage(new Uri("/MEFA.Controls;component/Resources/Images/leftbutton_紫色.png", UriKind.Relative));