protected internal override void GenerateBound()
{
const float shearEpsilon = 0.01f;
const float penMax = 2f;
Pen p = _pen.Content;
//画笔的宽度较大时，转角长度会很长，需要特别计算Bound
if (p != null && p.Width > penMax)
{
//存在倾斜，需要特别计算
Bound = (Math.Abs(_shear) > shearEpsilon) ?
Calculation.GetPenAndMatrixBounds(BasePath, p, Matrix) : Calculation.GetPenBounds(Path, p);
}
else
{
base.GenerateBound();
}
}
