ArcGis+VBA开发.ppt

Programming ArcInfo? with Visual Basic for Applications Intro-* Geometry spatial operator interfaces There are several interfaces provided by ArcMap that you may want to use for working with feature geometry. These interfaces will allow you to do things like: Measure distance between features Evaluate spatial relationships Produce new geometry based on the spatial relationships of existing features Query features based on spatial criteria Programming ArcInfo? with Visual Basic for Applications Intro-* ITopologicalOperator interface Coming from an ArcInfo background, you may think of operations such as buffer, clip, and intersect as functions that you would call in your Visual Basic code. Perhaps the features on which you are operating would be the arguments passed to the function, much like command line ArcInfo. This is not the case. Instead, the programmer working with ArcInfo geometry objects will ask the geometry object to perform operations on itself. The ITopologicalOperator interface is supported by the Point, Multipoint, Polyline, and Polygon geometry classes. When you are working with one of these objects, you can queryinterface to the ITopologicalOperator interface, then call the appropriate method. Be aware that these operators are working on individual geometries, and not entire datasets. Also realize that most methods will require additional geometry as parameters, and that most methods return geometry (Buffer, for example, returns a polygon object). Listed above are some of the most common topological operations, check your object model diagram for all properties and methods supported by ITopologicalOperator. Programming ArcInfo? with Visual Basic for Applications Intro-* IRelationalOperator interface Like the ITopologicalOperator interface, IRelationalOperator is supported by the Point, Multipoint, Polyline, and Polygon classes. Additionally, it is supported by the Envelope class. Working with the IRelationalOperator interface allows the programme