二维图形的矩阵变换（二）——WPF中的矩阵变换基础

    public class GeometryTransForm
    {
        Matrix _matrix;
        public Matrix Matrix
        {
            get { return _matrix; }
            private set { _matrix = value; }
        }

        /// <summary>
        ///  获取一个恒等变换
        /// </summary>
        public static GeometryTransForm Identity
        {
            get { return new GeometryTransForm(); }
        }

        /// <summary>
        /// 以指定点为中心旋转指定的角度。
        /// </summary>
        /// <param name="angle">要旋转的角度（单位为度）。</param>
        /// <param name="centerX">要围绕其旋转的点的 x 坐标。</param>
        /// <param name="centerY">要围绕其旋转的点的 y 坐标。</param>
        public GeometryTransForm Rotate(double angle, double centerX = 0, double centerY = 0)
        {
            _matrix.RotateAt(angle, centerX, centerY);
            return this;
        }


        /// <summary>
        /// 围绕指定的点按指定的量缩放
        /// </summary>
        /// <param name="scaleX">沿 x 轴的缩放量</param>
        /// <param name="scaleY">沿 y 轴的缩放量</param>
        /// <param name="centerX">缩放操作中心点的 x 坐标</param>
        /// <param name="centerY">缩放操作中心点的 y 坐标</param>
        public GeometryTransForm Scale(double scaleX, double scaleY, double centerX = 0, double centerY = 0)
        {
            _matrix.ScaleAt(scaleX, scaleY, centerX, centerY);

            return this;
        }

        /// <summary>
        /// 在 x 和 y 维中指定角度的扭曲。
        /// </summary>
        /// <param name="skewX">用于扭曲此的 x 维角度</param>
        /// <param name="skewY">用于扭曲此的 y 维角度</param>
        public GeometryTransForm Skew(double skewX, double skewY)
        {
            _matrix.Skew(skewX, skewY);
            return this;
        }


        /// <summary>
        /// 按指定偏移量的平移
        /// </summary>
        /// <param name="offsetX">沿 x 轴的偏移量</param>
        /// <param name="offsetY">沿 y 轴的偏移量</param>
        public GeometryTransForm Translate(double offsetX, double offsetY)
        {
            _matrix.Translate(offsetX, offsetY);
            return this;
        }


        public GeometryTransForm Transfrom(GeometryTransForm transform)
        {
            return Transfrom(transform.Matrix);
        }

        public GeometryTransForm Transfrom(Matrix transform)
        {
            _matrix = _matrix * transform;
            return this;
        }


        /// <summary>
        /// 反转变换
        /// </summary>
        public GeometryTransForm Invert()
        {
            _matrix.Invert();
            return this;
        }

        public static Point operator *(Point point, GeometryTransForm transform)
        {
            return point * transform.Matrix;
        }


        //如果是struct就用不着这个了，每一次 = 都是Clone
        public GeometryTransForm Clone()
        {
            return new GeometryTransForm() { Matrix = this.Matrix };
        }
    }