ArcEngine - 开发接口集(9)

3. Dim pConnectionProperties As IPropertySet 4.

5. Set pConnectionProperties = New PropertySet 6. With pConnectionProperties

7. .SetProperty \8. .SetProperty \9. .SetProperty \10. .SetProperty \11. .SetProperty \12. End With 13.

14. Set pSdeWorkspaceFactory = New SdeWorkspaceFactory

15. Set pSdeWorkspace = pSdeWorkspaceFactory.Open(pConnectionProperties, 0) IWorkspaceFactory接口的第二个方法OpenFromFile (fileName, hWnd ) （方法，从一个路径打开一个工作空间，并返回IWorkspace类型的变量） 例子代码：

1. Dim pSdeWorkspaceFactory As IWorkspaceFactory 2. Dim pSdeWorkspace As IWorkspace 3.

4. Set pSdeWorkspaceFactory = New SdeWorkspaceFactory 5. Set

pSdeWorkspace

=

pSdeWorkspaceFactory.OpenFromFile(\

23. 关于ITopologicalOperator接口（esriGeometry） 例子代码：

1. Share a line segment

2. This sample uses ITopologicalOperator::Intersect to do the equivalent of a

select by location with the share a line segment operator. 3. Public Sub ShareLineSegment() 4.

5. Dim pMxDoc As IMxDocument 6. Set pMxDoc = ThisDocument 7. Dim pMap As IMap

8. Set pMap = pMxDoc.FocusMap

9. Dim pFL1 As IFeatureLayer, pFL2 As IFeatureLayer 10. Set pFL1 = pMap.Layer(0) ' first layer of map 11. Set pFL2 = pMap.Layer(1) ' second layer 12. Dim pF1 As IFeature, pF2 As IFeature

13. Set pF1 = pFL1.FeatureClass.GetFeature(1) ' get feature with ID=1 in first

layer's feature class 14.

15. Dim pfs As IFeatureSelection 16. Set pfs = pFL2 17. Dim id As Long

18. id = pfs.SelectionSet.IDs.Next ' get first id in selection set an

actual function would probably loop over the selection 19.

20. Set pF2 = pFL2.FeatureClass.GetFeature(id) ' this is line 2 21.

22. 'is there an intersection bw the two features 23. Dim pTopo As ITopologicalOperator

24. Set pTopo = pF1.Shape ' store the line 1 shape in the topo op 25. If Not pTopo.IsSimple Then pTopo.Simplify 26. Dim pGeom As IGeometry

27. Set pGeom = pTopo.Intersect(pF2.Shape, esriGeometry1Dimension) ' get

intersection with line 2 28. If pGeom.IsEmpty Then

29. MsgBox \

points\30. Exit Sub 31. End If

32. ' pGeom now contains the intersection of pf1 and pf2

33. ' because dimension = esriGeometry1Dimension 34. ' it is a geometry of type polyline

35. ' if the intersection of the two features consisted of a point or points pgeom

would be empty

36. ' we could use ITopologicalOperator::Intersect with 0 dimension to find about

those points 37.

38. 'if pGeom contains only two vertices then the intersection is a simple line

segment

39. '3 vertices means it's a polyline with two successive segments

40. '>3 means we have several segments or a polyline or a combination of these 41. Dim ppc1 As IPointCollection 42. Set ppc1 = pGeom 43. Dim l As Long, g As Long 44. l = ppc1.PointCount 45. If l = 2 Then

46. MsgBox \47. ElseIf l = 3 Then

48. MsgBox \

of 2 segments\49. ElseIf l > 3 Then

50. Dim pGeomColl As IGeometryCollection 51. Set pGeomColl = pGeom 52. g = pGeomColl.GeometryCount

53. MsgBox \

polyline(s)and/or segment(s)\54. End If 55. End Sub

可以讲一个Polygon类型的数据或者Polyline的数据赋值给该接口的变量，如： 1. Set pUnionedPolylines = New Polyline 2. Set pTopOp = pUnionedPolylines

ITopologicalOperator接口的第一个方法ConstructUnion(geometries ) （方法，合并图形的工具，输入的参数是一个IEnumGeometry类型的参数，此方法效率甚高）

ITopologicalOperator接口的第二个方法Cut(cutter, leftGeom, rightGeom) （方法，剪切图形，第一个参数为剪切的线要素，为IPloyline类型，第二个第三个参数均为剪切后的图形，为输出参数）

ITopologicalOperator接口的第三个方法Boundary（方法，获取一个图形的边框，一个Polygon的boundary是一个Polyline类型的要素，一个Polyline的boundary是一个nultipoint类型的要素，一个Point的boundary是为空的）

ITopologicalOperator接口的第四个方法Buffer(distance) （方法，创造一个Polygon的要素来显示缓冲区域，参数为缓冲距离） 例子代码：

1. 'This example demonstrates how to use ITopologicalOperator::Buffer 2. Sub exampleITopologicalOperator_Buffer()

3. Dim ptc As IPointCollection, i As Long, pa As IArea, ptopo As

ITopologicalOperator

4. Dim pt(4) As IPoint, poutPoly As IPolygon 5. Set ptc = New Polygon

6. 'The spatial reference should be set here using IGeometry::SpatialReference

(Code skipped here) 7. For i = 0 To 4

8. Set pt(i) = New Point 9. Next

10. pt(0).PutCoords 0, 0 11. pt(1).PutCoords 0, 10 12. pt(2).PutCoords 10, 10 13. pt(3).PutCoords 10, 0 14. pt(4).PutCoords 0, 0 15. ptc.AddPoints 5, pt(0) 16. Set pa = ptc

17. Debug.Print \18. Set ptopo = ptc

19. Set poutPoly = ptopo.Buffer(1) 'Outside buffer

20. Set pa = poutPoly

21. Debug.Print \22. Set poutPoly = ptopo.Buffer(-1) 'Inside buffer 23. Set pa = poutPoly

24. Debug.Print \25. End Sub

ITopologicalOperator接口的第五个方法Clip (clipperEnvelope ) （方法，输入一个IEnvelope类型的变量，来获取被这个边框剪切的要素，并将切割后的变量返回给调用方法的变量）

ITopologicalOperator

接口的第六个方法

QueryClipped (clipperEnvelope,

clippedGeometry ) （方法，与Clip类似，但是第二个参数为剪切后返回输出的参数，本身不会改变）

ITopologicalOperator接口的第七个方法ConvexHull（方法，构造一个Geometry，大部分为Polygon类型的几何要素，该要素为调用此方法的ITopologicalOperator类型的变量最小的外边框）

ITopologicalOperator接口的第八个方法SymmetricDifference (other ) （方法，并集减去交集的部分，调用次方法的变量为第一个参数，other为第二个参数，最后返回变量到一个Geometry类型的变量，该变量的范围均在两个参数范围内，但不在两个参数相交的部分）

24. 创建Buffer并选择里面的要素

======================================================== 怎样创建buffer：（来源于管网线处理删除冗余节点）

======================================================== 1. Dim pTopOper As ITopologicalOperator 2. Set pTopOper = pfeature.Shape 3. Dim pGeometry As IGeometry 4. Set pGeometry = pTopOper.Buffer(1)

(注意，这个pfeature是在前面定义的pfeature=pFeatureCursor.NextFeature,不用重新定义一个)

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