void ArrangeHeader() { // 面板在滚动栏下侧时正常布局,超出上侧时始终布局在滚动栏顶部位置 double top = _deltaY < 0 ? -_deltaY : 0; _colHeader.Arrange(new Rect(_topLeftWidth, top, _owner.Cols.TotalWidth, _colHeader.DesiredSize.Height)); // 测量时DesiredSize(0,0) _topLeft.Arrange(new Rect(-_deltaX, top, _topLeftWidth, _colHeader.DesiredSize.Height)); }