ArcEngine几何变换中的策略模式

使用策略模式可以减少分支语句，switch...Case，同时便于策略的扩展。

1. ITransform2D接口的Transform方法：

 [C#]public void Transform (
     esriTransformDirection  direction,
     ITransformation  transformation);

大部分的Geometry对象都实现了ITransform接口，比如：IPoint，IPolygon的基类

ITransformation是策略的抽象接口，如下：

2. ITransform3D接口的Transform3D方法：

 [C#]public void Transform3D (
     esriTransformDirectiondirection,
     ITransformation3Dtransformation);

ITransformation3D是策略的抽象接口，如下：

   private void RotateAroundPoint()
         {
             //Point to be rotated
             IPoint rotatePoint = new ESRI.ArcGIS.Geometry.Point();
             rotatePoint.PutCoords(, );
             //Point around which to rotate
             IPoint centerPoint = new ESRI.ArcGIS.Geometry.Point();
             centerPoint.PutCoords(, );
             //Rotation Angle
             double angle =  * Math.PI / 180.0;
             //Rotate Around pCenter
             IAffineTransformation2D3GEN affineTransformation = new AffineTransformation2D() as IAffineTransformation2D3GEN;
             affineTransformation.Move(-centerPoint.X, -centerPoint.Y);//将参考点移动到原点
             affineTransformation.Rotate(angle);//围绕原点旋转
             affineTransformation.Move(centerPoint.X, centerPoint.Y);//再平移回原来的位置
             ITransform2D transformator = rotatePoint as ITransform2D;
             transformator.Transform(esriTransformDirection.esriTransformForward, affineTransformation as ITransformation);

             IPoint rotatePoint2 = new ESRI.ArcGIS.Geometry.Point();
             rotatePoint2.PutCoords(, );
             IAffineTransformation2D affineTransformation2D = new AffineTransformation2D() as IAffineTransformation2D;
             // affineTransformation2D.Move(-centerPoint.X, -centerPoint.Y);//将参考点移动到原点
             affineTransformation2D.Rotate(angle);//围绕原点旋转
             //affineTransformation2D.Move(centerPoint.X, centerPoint.Y);//再平移回原来的位置
             ITransform2D transformator2 = rotatePoint2 as ITransform2D;
             transformator2.Transform(esriTransformDirection.esriTransformForward, affineTransformation2D);

             //Set up Comparison Point
             //This is the point the transformation should result in
             IPoint comparePoint = new ESRI.ArcGIS.Geometry.Point();
             comparePoint.PutCoords(, );
             transformator = comparePoint as ITransform2D;
             transformator.Rotate(centerPoint, angle);
             System.Windows.Forms.MessageBox.Show(
                 "Using IAffineTransformation2D3GEN.Rotate:  Point X:" + rotatePoint.X + ", Y:" + rotatePoint.Y + "\n" +
                 "Using IAffineTransformation2D::Rotate,  Point X:" + rotatePoint2.X + ", Y:" + rotatePoint2.Y + "\n" +
                 "Using ITransform2D::Rotate,  Point X: " + comparePoint.X + ", Y:" + comparePoint.Y + "\n" +
                 "Did X coordinates match? " + (rotatePoint.X == comparePoint.X) + "\n" +
                 "Did Y coordinates match? " + (rotatePoint.Y == comparePoint.Y)
             );

         }

测试代码