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：

1 [C#]public void Transform ( 2  esriTransformDirection direction, 3     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：

1 [C#]public void Transform3D ( 2  esriTransformDirectiondirection, 3     ITransformation3Dtransformation);

 ITransformation3D是策略的抽象接口，如下：

 

 1   private void RotateAroundPoint()

 2         {

 3             //Point to be rotated

 4             IPoint rotatePoint = new ESRI.ArcGIS.Geometry.Point();

 5             rotatePoint.PutCoords(2, 2);

 6             //Point around which to rotate

 7             IPoint centerPoint = new ESRI.ArcGIS.Geometry.Point();

 8             centerPoint.PutCoords(1, 1);

 9             //Rotation Angle

10             double angle = 45 * Math.PI / 180.0;

11             //Rotate Around pCenter

12             IAffineTransformation2D3GEN affineTransformation = new AffineTransformation2D() as IAffineTransformation2D3GEN;

13             affineTransformation.Move(-centerPoint.X, -centerPoint.Y);//将参考点移动到原点

14             affineTransformation.Rotate(angle);//围绕原点旋转

15             affineTransformation.Move(centerPoint.X, centerPoint.Y);//再平移回原来的位置

16             ITransform2D transformator = rotatePoint as ITransform2D;

17             transformator.Transform(esriTransformDirection.esriTransformForward, affineTransformation as ITransformation);

18 

19 

20             IPoint rotatePoint2 = new ESRI.ArcGIS.Geometry.Point();

21             rotatePoint2.PutCoords(2, 2);

22             IAffineTransformation2D affineTransformation2D = new AffineTransformation2D() as IAffineTransformation2D;

23             // affineTransformation2D.Move(-centerPoint.X, -centerPoint.Y);//将参考点移动到原点

24             affineTransformation2D.Rotate(angle);//围绕原点旋转

25             //affineTransformation2D.Move(centerPoint.X, centerPoint.Y);//再平移回原来的位置

26             ITransform2D transformator2 = rotatePoint2 as ITransform2D;

27             transformator2.Transform(esriTransformDirection.esriTransformForward, affineTransformation2D);

28 

29             //Set up Comparison Point

30             //This is the point the transformation should result in

31             IPoint comparePoint = new ESRI.ArcGIS.Geometry.Point();

32             comparePoint.PutCoords(2, 2);

33             transformator = comparePoint as ITransform2D;

34             transformator.Rotate(centerPoint, angle);

35             System.Windows.Forms.MessageBox.Show(

36                 "Using IAffineTransformation2D3GEN.Rotate:  Point X:" + rotatePoint.X + ", Y:" + rotatePoint.Y + "\n" +

37                 "Using IAffineTransformation2D::Rotate,  Point X:" + rotatePoint2.X + ", Y:" + rotatePoint2.Y + "\n" +

38                 "Using ITransform2D::Rotate,  Point X: " + comparePoint.X + ", Y:" + comparePoint.Y + "\n" +

39                 "Did X coordinates match? " + (rotatePoint.X == comparePoint.X) + "\n" +

40                 "Did Y coordinates match? " + (rotatePoint.Y == comparePoint.Y)

41             );

42 

43         }

测试代码