WPF 动态布局Grid

//开启线程加载
            Action a = () =>
            {
                var row = 7;
                var column = 9;

                var path = "../../face_img/";
                var files = Directory.GetFiles(path);
                for (var i = 0; i < row; i++)
                {
                    faceGrid.RowDefinitions.Add(new RowDefinition());
                }
                for (var i = 0; i < column; i++)
                {
                    faceGrid.ColumnDefinitions.Add(new ColumnDefinition());
                }
                var index = 0;
                for (var i = 0; i < row; i++)
                {
                    for (var j = 0; j < column; j++, index++)
                    {
                        if (index < files.Length)
                        {
                            var btn = new Button { Width = 25, Height = 25 };
                            var image = new GifImage { Source = System.IO.Path.GetFullPath(files[index]), Stretch = Stretch.Fill };
                            btn.Click += btn_Click;
                            image.ToolTip = "["+ System.IO.Path.GetFileName(files[index]) + "]";
                            btn.Tag = "[" + System.IO.Path.GetFileName(files[index]) + "]";
                            image.OpacityMask = this.Background;
                            image.Width = btn.Width-1;
                            image.Height = btn.Height-1;
                            btn.BorderBrush = Brushes.WhiteSmoke;
                            btn.Background = Brushes.White;
                            btn.Content = image;
                            Grid.SetRow(btn, i);
                            Grid.SetColumn(btn, j);
                         
                            faceGrid.Children.Add(btn);
                        }
                    }
                }
            };
            this.faceGrid.Dispatcher.Invoke(a);