基于 com 接口编程基础（ i）

Copyright © 2001, 2002 ESRI. All rights reserved. Introduction to Programming ArcObjects with VBA

基于 COM 接口编程基础（ I ）

6-2Introduction to Programming ArcObjects with VBACopyright © 2001, 2002 ESRI. All rights reserved.

Lesson overview

COM: 组件对象模型 Component Object Model

使用 COM 类 Working with COM classes 接口 Interfaces

多态 Polymorphism

接口查询 QueryInterface

测试一个对象的引用 Testing an object reference Is it nothing?

What type of object is it?


Introducing COM

COM is a standard for creating classes

Classes can be reused between applications Independent of programming language

All ArcObjects are COM classes

Technologies based on COM Object Linking and Embedding (OLE)

OLE DB

ActiveX is any technology built on COM

DCOM and COM+


COM classes have interfaces

对象拥有一个或多个接口

接口是定义了一组方法和属性的逻辑关系与对象的通信是通过接口来进行的

RaceCar

AccelerateBrake

Fuel

停靠站圈速度IRace

IDrive

垃圾车

加速刹车

燃料

拾起倾倒IGarbage

IDrive


Instantiate COM classes with an interface Dim <variable> As <some interface>

Interfaces group properties and methods

Dim pGarbage As IDriveSet pGarbage = New GarbageTruck

pGarbage.Fuel = "Full"pGarbage.Accelerate

Working with ArcObjects COM classes

GarbageTruck

AccelerateBrake

Fuel

PickUp

DumpIGarbage

IDrive


More on interfaces …

一个组合音响的例子一个对象可以播放收音机、磁带、 CD

必须使用适当的接口如果选择了播放磁带的接口，则不能收听收音机

IRadio

ITape

ICD

Dim pBBox As ITapeSet pBBox = New BoomBoxpBBox.FM = True


IDrive

燃料

加速

刹车

多态许多不同的类可以支持相同的接口

拥有相同的所有的方法和属性可以有不同的执行方式和拥有不同的属性值


ArcObjects 多态许多 ArcGIS 的类都表现出多态的特性 General interfaces for all subtypes

ILayer: All layer types (raster, tin, feature, etc.)

IGxFile: All ArcCatalog file types (shapefile, map, table, etc.)

IActiveView: Map (data view) and PageLayout (layout view)

Several others …


Using methods and properties

Dim the variable pointing to an interface

Instantiate the object (Set)

Call methods, set properties

Only use methods and properties for the declared interface

'Create a new RaceCar with IDriveDim pCar As IDriveSet pCar = New RaceCarpCar.AcceleratepCar.Fuel = "Full"

pCar.PitStop

RaceCar

AccelerateBrake

Fuel

PitStop

LapTimeIRace

IDrive

6-10

Introduction to Programming ArcObjects with VBACopyright © 2001, 2002 ESRI. All rights reserved.

Getting other interfaces

QueryInterface (QI)

Access other methods and properties

Q I

RaceCar

AccelerateBrake

Fuel

PitStop

LapTimeIRace

IDrive

'Create a new RaceCar with the IDrive interfaceDim pCar As IDriveSet pCar = New RaceCarpCar.Accelerate

'Switch interfacesDim pRace As IRaceSet pRace = pCarpRace.PitStoppCar.Accelerate'**pCar and pRace point to the same object**Dim pArea As IArea

Dim pPt As IPoint

Set pArea = pPolygon ' QI for IArea on pPolygon

Set pPt = pArea.Center

6-12


Testing an object reference

Is an object Nothing?

If pLayer Is Nothing Then MsgBox "You must select a layer." Exit SubEnd If

If TypeOf pLayer Is IFeatureLayer Then MsgBox "You selected a Feature Layer. "Else MsgBox "This layer is not a Feature Layer."End If

What TypeOf object is it?

6-14


COM class code

Interface module 定义方法和属性

Class module 实现方法和属性

Client module 实例化类使用方法和属性 Client

Server

InterfaceInterface

6-16


Using library names

Many libraries may share interface or class names 可以明白地引用对象库

'Create a new point and line from the esriCore library

Dim pPoint As esriCore.IPoint

Dim pLine As esriCore.ILine

Set pPoint = New Point

Set pLine = New Line

6-17


Using the ESRI Object Browser

Lists classes, interfaces, properties, and methods

C:\ArcGIS\arcexe83\ArcObjects Developer Kit\Utilities

所在位置： C:\ArcGIS\arcexe83\ArcObjects Developer Kit\Utilities

6-18


Exercise 6 overview

Design an interface

Create a COM class Implement an interface

Write client code that uses your COM class

Use QueryInterface


理解对象模型图（ OMD ）(II)

6-20


Lesson overview

ArcObject 的对象模型图阅读一个对象的模型图

类的类型类的相互关系

接口、属性、方法的图标

根据 OMD 图表编写程序

6-21


OMDs help you write code Show interfaces, methods, and properties for each class

Show relationships between classes

在几个图表中拥有超过 1,500 个类超过 1,600 个接口

ArcObject object model diagrams

6-22


在哪里可以找到 ArcGIS OMD 图表 Start > Programs > ArcGIS > ArcObjects Developer Help

简单的、详细的类图 PDF files

电子书籍光盘中软件安装的目录中

6-23


Relationship symbols

继承组成用来创建对应关系 1 ： N

联合

*_____

蛋

鸟

翅膀

羽毛

2

Abstract

Class

Class

Class

小鸡CoClass

巢CoClass

*

6-24


类和他们相应的对象

ArcMap objects

MxDocument

Map

Layer

*

*

FeatureLayer

Application

6-25


Not creatable or instantiable Can never have instances of an abstract class

Define general interfaces for subclasses Subclasses inherit interfaces

OMD symbol: 2D shaded rectangle

抽象类（没有阴影）

6-26


实例化类 (Class) Noncreatable class

Cannot create with the New keyword

Obtain instances from other objects

OMD Symbol: 3D Rectangle with no shade

Dim pNewRow As IRowSet pNewRow = pTable.CreateRow

生成

6-27


Creatable: Use the New keyword

Dim pMap As IMap

Set pMap = New Map

Instantiable: Obtain from other objects

Dim pMap As IMap

Set pMap = pMxDocument.FocusMap

OMD symbol: Shaded 3D rectangle

可创建的类 (CoClass)

6-28


Where to begin? Getting into the OMD

特殊的全局变量 Application: IApplication interface of the Application object

ThisDocument: IDocument interface of the MxDocument object

阅读 ArcMap 或 ArcCatalog OMD 图表的入口

Application

ThisDocument

6-29


Property and method symbols

Property 哑铃形状的图标

Method

Property Get(read)

Property Get(read)

Property Set(write)

Property Set(write)

6-30


Property Put: Most ArcObjects properties Property holds a value or a copy of an object

Do not use Set keyword

Property Put by Reference: Some ArcObjects properties Property holds a reference to an object

Must use the Set keyword

如果引用对象发生了变化，对象的属性将同步受到影像

Setting properties

pLayer.Name = "Port Moresby" 'No Set keyword

Set pLayer.FeatureClass = pMoresbyData 'Must use Set!

6-31


Return a value Name: String

Return an object reference Document: IDocument

StatusBar: IStatusBar

Getting properties

返回一个值Dim strName As String Dim pDoc As IDocumentDim pBar As IStatusBarstrName = Application.NameMsgBox strName

返回一个引用Set pDoc = Application.DocumentSet pBar = Application.StatusBar pBar.Message(0) pDoc.Title

6-32


棒棒糖类型的图标 ( )

Finding interfaces

这些接口也是有效的。但是详细的属性和方法必须在其它地方浏览。(e.g., Object Browser).

这些接口也是有效的。但是详细的属性和方法必须在其它地方浏览。(e.g., Object Browser).

该接口被本类使用 .所有的属性和放都列表在类图中 .

该接口被本类使用 .所有的属性和放都列表在类图中 .

继承接口是有效的继承接口是有效的

6-34


FeatureLayer on Map Layer OMD

FeatureLayer on Map Layer OMD

概念上 , 这是一个对象模型事实上 , 被分别在几张图表里存放

虫洞表现了图表与图表间的连接关系

Wormholes

Element on ArcMap OMD

Element on ArcMap OMD

虫洞

6-35


Example: MxDocument > Map > layer Get the FocusMap (active data frame) from MxDocument

MxDocument may have several Maps ( * )

Get a layer from the the Map Many types of layers ( )

Dim pMxDoc As IMxDocumentSet pMxDoc = ThisDocumentDim pMap As IMapSet pMap = pMxDoc.FocusMapDim pLayer As ILayerSet pLayer = pMap.Layer(1)

'Is pLayer a FeatureLayer?If TypeOf pLayer Is IFeatureLayer Then

MsgBox "Yes!, it’s a feature layer"End If

MxDocument

Map

FeatureLayer

Layer*

*

Others

A

6-36


Exercise 7 overview

Interpret the ArcObject object model diagrams Write code to change the ArcMap caption

Work with the MxDocument and its Maps

Use the TypeOf keyword to test an object reference


Maps and layers(III)

6-38


Lesson overview

访问 maps and layers

遍历 maps 和 layers Collections

Enumerations

创建一个新的图层使用图层对象的属性

设置一个图层的数据源

6-39


Object model overview

FeatureLayer

Map

MxDocument

Application

ArcMap

*

*Layer

FeatureDataset*

Geodatabase

FeatureClass

Table

DataSet

0 .. 1

Map Layer

6-40


Accessing maps

Access maps from MxDocument

Get the active map

Get all maps (IMaps) A collection of Maps

Dim pMxDoc As IMxDocumentSet pMxDoc = ThisDocumentDim pMap As IMapSet pMap = pMxDoc.FocusMap

Dim pAllMaps As IMapsSet pAllMaps = pMxDoc.Maps

一个地图文档可以包含有多个数据框，每个数据框都可以拥有不同的图层和表现。 FocusMap 是指向当前活动的数据框

6-41


Accessing layers Access layers from Map or MxDocument

Get the selected layer (IMxDocument)

Get a specific layer (IMap)

Get all layers (IMap) An enumeration of layers

Dim pLayer As ILayerSet pLayer = pMxDoc.SelectedLayer

Dim pAllLayers As IEnumLayerSet pAllLayers = pMap.Layers

Dim pLayer As ILayerSet pMap = pMxDoc.FocusMapSet pLayer = pMap.Layer(3)

6-42


遍历 Maps 集合 Collections are ordered

Reference items by position (index)

First item is at position 0

' Map collection example … Dim intIndex As Integer Dim pMaps As IMaps Set pMaps = pMxDoc.Maps

For intIndex = 0 To pMaps.Count - 1 MsgBox pMaps.Item(intIndex).Name Next intIndex

00

11

22

' Syntax Example For <index = start> To <end> ' process each item … Next <index>

' Syntax Example For <index = start> To <end> ' process each item … Next <index>

6-43


遍历一个 Map 对象中的图层对象 IMap’s Layers property returns IEnumLayers

Like a collection with fewer methods and properties

Next returns ILayer

Reset moves to top of Enum

Set pLayer = pLayers.Next

Nothing

pLayers.Reset

IEnumLayerTop




Dim pLayer As ILayerDim pLayers As IEnumLayerSet pLayers = pMap.Layers

6-44


遍历一个 Map 对象中的图层对象 Do While or Do Until

Loop based on a Condition (Boolean)

' Layer enum example Dim pLayer As ILayer Dim pMapLayers As IEnumLayer Set pMapLayers = pMap.Layers

Set pLayer = pMapLayers.Next Do Until pLayer Is Nothing MsgBox pLayer.Name Set pLayer = pMapLayers.Next Loop

Nothing

' Syntax ExampleDo Until/While <a condition is true> 'Run this codeLoop

' Syntax ExampleDo Until/While <a condition is true> 'Run this codeLoop

!

6-45


Managing flow in a loop

Exit a loop prematurely when a condition is true For Next loops: Exit For

Do While and Do Until loops: Exit Do

Dim pCityMap As IMapDim X As IntegerFor X = 0 To pMaps.Count - 1 If pMaps.Item(X).Name = "Cities" Then Set pCityMap = pMaps.Item(X) Exit For End IfNext X MsgBox "All Done", vbInformation

6-46


Loop review

Loop a specified number of times For Next

Loop based on condition Do While

Do Until

小心无限循环'Here is an Endless LoopDo While Not MsgBox("Add a Record?") = vbYes 'Code here to add a record to a table MsgBox "Record Added"Loop

6-47


Adding a new layer to a map

Layer is an abstract class: Not creatable Creatable subclasses: TinLayer, FeatureLayer, RasterLayer, etc.

'Make a New FeatureLayerDim pFLayer As ILayerSet pFLayer = New FeatureLayer

'Add a layer to MxDocument or Map Dim pMxDoc As IMxDocument Dim pMap As IMap Set pMxDoc = ThisDocument Set pMap = pMxDoc.FocusMap

pMap.AddLayer pFLayer

没有设置数据源，所以图标为失去数据连接的状态。

6-48


使用图层对象的属性 Ilayer 接口的属性

Name, Visible, ShowTips, MaximumScale, MinimumScale, etc.

IGeoDataset 接口属性 Extent, SpatialReference

'This code will work for ANY type of layer'Access the document’s selected layer Dim pLayer As ILayer Set pLayer = pMxDoc.SelectedLayer'Set basic layer properties pLayer.Name = "Streets" pLayer.Visible = True pLayer.ShowTips = False

6-49


Setting a FeatureLayer’s data source

FeatureClass property (IFeatureLayer) 指定显示的数据源以传引用的方式 (must use the Set keyword)

更多的数据访问例子在以后的课程中'Make a new FeatureLayerDim pFLayer As IFeatureLayerSet pFLayer = New FeatureLayer

'Get another layer’s FeatureClassDim pFClass As IFeatureClassSet pFClass = pSomeOtherLayer.FeatureClass

'Set the new layer’s FeatureClass propertySet pFLayer.FeatureClass = pFClass

6-50


Exercise 8 overview

Loop Maps in a document

Layers in a map

Fields in a layer table

Add a layer to a map Set basic properties

Set the data source


Data access and creation(IIII)

6-52


Lesson overview

Data creation objects Workspace

FeatureDataset

FeatureClass

Working with fields and field collections

Creating Tables and FeatureClasses

Adding rows

Editing table values

FeatureClassesFeatureClasses

WorkspaceWorkspaceFeatureDatasetFeatureDataset

6-53


Data creation objects

Table

FieldsField1 ..

DatasetWorkspaceWorkspaceFactory

AccessWorkspaceFactory

Row

*

FeatureClassArcInfoWorkspaceFactory

ShapefileWorkspaceFactory

Others

Which ones can be created new?Which ones can be created new?

*

6-55


Opening an existing Workspace

Use IWorkspaceFactory to return a Workspace object Generic interface for all sub-types of WorkspaceFactory

OpenFromFile: Access an existing folder on disk

Open: Connect to an existing database (e.g., ArcSDE)

Dim pWFactory As IWorkspaceFactorySet pWFactory = New ArcInfoWorkspaceFactory

Dim pWFactory As IWorkspaceFactorySet pWFactory = New ArcInfoWorkspaceFactory

Dim pWorkspace As IWorkspaceSet pWorkspace = pWFactory.OpenFromFile("D:\Covers", 0)

Dim pWorkspace As IWorkspaceSet pWorkspace = pWFactory.OpenFromFile("D:\Covers", 0)

6-57


Getting a FeatureDataset

IFeatureWorkspace interface on Workspace OpenFeatureDataset method

Dim pFWorkspace As IFeatureWorkspaceSet pFWorkspace = pWorkspace 'QI for IFeatureWorkspace

Dim pCover As IFeatureDatasetSet pCover = pFWorkspace.OpenFeatureDataset("streets")


WorkspaceWorkspaceFeatureDatasetFeatureDataset

6-58


Getting FeatureClasses

Use IFeatureClassContainer to get existing FeatureClasses from a FeatureDataset

Dim pFCC As IFeatureClassContainerDim pStreetArcs As IFeatureClassSet pFCC = pCover 'QI for IFeatureClassContainerSet pStreetArcs = pFCC.ClassByName("arc")

Dim pFCC As IFeatureClassContainerDim pStreetArcs As IFeatureClassSet pFCC = pCover 'QI for IFeatureClassContainerSet pStreetArcs = pFCC.ClassByName("arc")


6-59


Exercise 9A overview Add a ShapeFile layer to a map

Private Sub AddShapeFile_Click()

Dim pWF As IWorkspaceFactory

Set pWF = New ShapefileWorkspaceFactory

Dim pFWS As IFeatureWorkspace

Set pFWS = pWF.OpenFromFile("C:\USA", 0)

Dim pFClass As IFeatureClass

Set pFClass = pFWS.OpenFeatureClass("STATES")

Dim pFLayer As IFeatureLayer

Set pFLayer = New FeatureLayer

Set pFLayer.FeatureClass = pFClass

Dim pDataset As IDataset

Set pDataset = pFClass

pFLayer.Name = pDataset.Name

Dim pDoc As IMxDocument

Set pDoc = ThisDocument

pDoc.AddLayer pFLayer

End Sub

6-60


Working with Name objects

A lightweight version of the object it represents Use Open on IName to return the object

Several creatable subtypes

6-61


Creating a new Workspace

Use IWorkspaceFactory to get a WorkspaceName Create method

Use IName to get a Workspace Open method

6-63


Creating a new Table or FeatureClass

Use IFeatureWorkspace interface on Workspace CreateTable and CreateFeatureClass methods

Requires a Fields collection

6-64


Field and Fields classes

Tables and FeatureClasses have an associated Fields A Fields is a Collection

A Fields object has Field objects One or several (1..*)

Creatable

6-65


IField and IFieldEdit

Get field properties with IField Read-only

Set field properties with IFieldEdit Write-only

Dim pNameField As IFieldEdit

Set pNameField = New Field

With pNameField

.Name = "StreetName"

.Type = esriFieldTypeString

.Length = 16

End With

6-66


Creating a Fields collection

Use the IFieldsEdit interface AddField method: Puts a field in the collection

Dim pFieldsEdit As IFieldsEdit

Set pFieldsEdit = New Fields

pFieldsEdit.AddField pOIDField

pFieldsEdit.AddField pNameField

pFieldsEdit.AddField pSalesField

'Field = Fields !

6-67


Creating a Table or FeatureClass

Use IFeatureWorkspace interface on Workspace CreateTable and CreateFeatureClass methods

Dim pTable As ITable

Set pTable = pFeatureWorkspace.CreateTable _

("Store55", pFieldsEdit, Nothing, Nothing, "")

Table NameTable Name

Fields CollectionFields Collection ArcSDE Configuration Keyword

ArcSDE Configuration Keyword

如果是创建 FeatrueClass 则需要指定 FeatureType 和 ShapeFieldName 参数

如果是创建 FeatrueClass 则需要指定 FeatureType 和 ShapeFieldName 参数

6-69


Work with fields in a table

IFields interface FieldCount 返回所有字段的数目 FindField 返回查找的字段的索引号 Field 返回指定索引号的字段

For intLoop = 1 To pFClass.Fields.FieldCount – 1

MsgBox pFClass.Fields.Field(intLoop).Name

Next intLoop

intFieldNum = pTable.Fields.FindField("Area")

If intFieldNum > -1 Then '-1 means the field was not found

Set pAreaField = pTable.Fields.Field(intFieldNum)

End If

6-70


Adding rows and values to a table

调用 Itable 对象的 CreateRow 方法，返回一个 Row 对象调用 IFeatureClass 的 CreateFeature 方法则返回一个 Feature 对象

Value property 使用 Get 或 set 方法了进行赋值

指定字段的索引号

Dim pRow As IRow

Set pRow = pTable.CreateRow

pRow.Value(1) = "Jesse White" 'Name

pRow.Value(pTable.FindField("Age")) = 35 'Age

pRow.Store 保存提交新的行保存提交新的行

TableRow

FeatureClassFeature

Feature 有一个 Shape 属性来保几何对象Feature 有一个 Shape 属性来保几何对象

6-71


Exercise 9B overview

Make a new ShapeFile

Create a new table Add records

Edit values


Geometry and geoprocessing(V)

Thad Tilton:Thad Tilton:

6-73


Lesson overview

Geometry

Operators: Working with feature geometry

Drawing geometry

Geoprocessing

6-74


线段：在曲线的起点和终点之间线段集合成 paths/rings

Paths/rings 集合成 lines/polygons

可以在任何层次上编辑

Feature geometry

Segments

Bezier curve

Line Circular arc

3 Rings (closed paths)

2 Paths

1 Poly1 Line

Points Multipoints PolygonsPolylines

6-75


Geometry objects

Point MultiPoint

Ring

PathSegment

Geometry

EnvelopeCurve

Polyline

Line BezierCurveCircularArc

Polycurve

**

*

Polygon

*

Geometrycollection

*

6-76


Points and multipoints

点是零维的通过 X 、 Y坐标来定义可以拥有 Z 和 M 属性值

Multipoints 是 points 的集合

Point

Multipoint with

six points

Dim pPoint As IPoint

Set pPoint = New Point

pPoint.X = 300

pPoint.Y = 450

Dim pMultiPts As IPointCollection

Set pMultiPts = New MultiPoint

pMultiPts.AddPoint pPoint

6-77


由起点、终点和方程定义三个方面组成

子类 : Line, BezierCurve, CircularArc

线段用来创建其它的几个对象 Paths, polylines, rings, and polygons

Dim pSegment As ILine

Set pSegment = New Line

pSegment.FromPoint = pPointA

pSegment.ToPoint = pPointB

Segments

From

To

FromTo

6-78


Paths and polygons

Polylines由一组闭合或不闭合的 Paths 组成

Polygons由一个或多个 rings 组成

Path with four segments

Polygon with seven rings

6-79


Envelopes

定义了 feature 的空间范围最小外接矩形

所有的几何对象都有 Envelop 属性 Get or set with IGeometry :: Envelope

Dim pEnvelope As IEnvelope

Set pEnvelope = pLine.Envelope

6-80


Zooming in to a Feature

Get the extent using a shape’s Envelope property On the IGeometry interface

Set the ActiveView Extent property with an Envelope

Feature Geometry

Envelope

1 Polygon Feature

pMxDoc.ActiveView.Extent = pFeature.Shape.EnvelopepMxDoc.ActiveView.Refresh

pMxDoc.ActiveView.Extent = pFeature.Shape.EnvelopepMxDoc.ActiveView.Refresh

6-81


Displaying features

调用 IScreenDisplay 接口的几个 Draw 方法 StartDrawing: 为绘制准备显示环境 DrawPoint, DrawMultipoint, DrawPolyline, DrawPolygon

FinishDrawing: 把缓存中的内容绘制到屏幕上

Quick draw of geometry and symbol

Dim pDisplay As IScreenDisplay

Set pDisplay = pMxApplication.Display

pDisplay.StartDrawing pDisplay.HDC, esriNoScreenCache

pDisplay.SetSymbol pSym

pDisplay.DrawPolygon pPolygon

pDisplay.FinishDrawing

6-82


Geometry spatial operator interfaces

Interfaces supported by subtypes of Geometry ITopologicalOperator （空间操作） IProximityOperator （测量） IRelationalOperator （检查）

用于 …完成例如 buffer, cut, clip等空间操作测量 shapes之间的距离检查空间关系通过空间标准来进行查询

6-83


ITopologicalOperator

提供方法去操作几何对象由 Point, Multipoint, Polyline, and Polygon提供

Dim pTopoOp As ITopologicalOperator

Dim pBuffPoly As IPolygon

Set pTopoOp = pFeature.Shape

Set pBuffPoly = pTopoOp.Buffer (intBufferDistance)

Buffer

IntersectUnion

Cut Clip

6-84


IRelationalOperator

提供检查空间关系的功能 (return Boolean) Equals: 几何对象在空间上是否相同 ?

Touches: 边界是否接触 ?

Contains: 是否是包容关系 ?

其它操作

Dim pRelationOp As IRelationalOperator

Dim booTouches As Boolean

Set pRelationOp = pPoly

booTouches = pRelationOp.Touches (pAnotherPoly)

6-85


IProximityOperator

提供检查两个空间对象的相邻关系功能 ReturnDistance: Returns the minimum distance between

features (double)

ReturnNearestPoint: Finds and returns the nearest point on the specified feature (point)

Dim pProxOp As IProximityOperator

Dim dblDistance As Double

Set pProxOp = pLine

dblDistance = pProxOp.ReturnDistance (pSomeOtherLine)

?

6-86


Geoprocessing

IBasicGeoprocessor provides access to methods found in the Geoprocessing Wizard

Use for an entire Feature class

Most methods require an input table Clip

Dissolve

Intersect

Merge

Union

BasicGeoprocessor

IBasicGeoprocessor : IUnknown

SpatialReference: ISpatialReference

Clip (in InputTable: ITable, inuseSelectedInput: Boolean, in clipTable:ITable, in useSelectedClip: Boolean, inTolerance: Double, in OutputName:IFeatureClassName): IFeatureClass

Merge (in Tables: IArray, in fieldsTable:ITable, in OutputName:IFeatureClassName): IFeatureClass

Dissolve (in InputTable: ITable, inuseSelected: Boolean, in dissolveField:String, in summaryFields: String, inOutputName: IDatasetName): ITable

Intersect (in InputTable: ITable, inuseSelectedInput: boolean, inoverlayTable: ITable, inuseSelectedOverlay: Boolean, inTolerance: Double, in OutputName:IFeatureClassName): IFeatureClass

Union (in InputTable: ITable, inuseSelectedInput: Boolean, inoveralyTable: ITable, in overlayTable:ITable, in useSelectedOverlay: Boolean, inTolerance: Double, in OutputName:IFeatureClassName): IFeatureClass

IBasicGeoprocessor

6-87


Area and length

Each feature is a type of Geometry

QueryInterface to Curve (Line features) or Polygon

Dim pArea As IArea

Set pArea = pPoly ‘QI

Msgbox pArea.Area

Dim pCurve As ICurve

Set pCurve = pLine ‘QI

Msgbox pCurve.Length

Polygon

IPolygon: IPolycurve

ExteriorRingCount: Long

QueryExteriorRings(ExteriorRings: IRing)

CloseFindExteriorRing(interiorRing: IRing): IRing

QueryInteriorRings(exteriorRings: IRing,interiorRings: IRing)

IPolygon

IAreaInteriorRingCount(exteriorRing: IRong): Long

SimplifyPreserveFromTo

CurveICurve: IGeometry

FromPoint: IPoint

ICurve

IsClosed: Boolean

Length: Double

ToPont: IPoint

6-88


Exercise 10 overview

Create point features from coordinates

Store point features

Assign feature attributes

Create a polygon from a Point collection

Challenge: Calculate the area from the polygon you created


Working with subsets and selections(VI)

6-90


Lesson overview

从 Table 或 Layer 对象中取得当前的选择集 SelectionSet

从 records 对象中取得一个 subset游标 Cursor

特征游标 FeatureCursor

查询过滤器和空间过滤器 QueryFilters and SpatialFilters

Three types of cursors: Search, Update, and Insert

遍历一个 cursor 的记录 Displaying a subset of layer features

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Object Model overview

TableCursor

FeatureClassFeatureCursor

QueryFilter

Row

Feature

= ‘in conjunction with’ = ‘in conjunction with’

SelectionSet

SpatialFilter

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SelectionSet

Get the currently selected records (Rows or Features) IFeatureSelection :: SelectionSet (FeatureLayer)

ITableWindow :: SelectionSet (TableWindow)

Public Sub GetLayerSelection() Dim pMxDoc As IMxDocument Dim pFSel As IFeatureSelection Dim pSelSet As ISelectionSet Set pMxDoc = ThisDocument

Set pFSel = pMxDoc.SelectedLayer 'QueryInterface Set pSelSet = pFSel.SelectionSet MsgBox pSelSet.Count & " selected features"End Sub

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Creating a QueryFilter

Create a QueryFilter with the New keyword

Set the WhereClause property (string)

QueryFilterQueryFilter

WhereClauseWhereClause

Dim pQFilter As IQueryFilter

Set pQFilter = New QueryFilter

pQFilter.WhereClause = "LENGTH > 100000"

Dim pQFilter As IQueryFilter

Set pQFilter = New QueryFilter

pQFilter.WhereClause = "LENGTH > 100000"

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Returning a Search cursor

Apply to a Table or FeatureClass Search method

Returns a Cursor or FeatureCursor

Dim pFCursor As IFeatureCursor

Set pFCursor = pFClass.Search(pQFilter, True)

Dim pFCursor As IFeatureCursor

Set pFCursor = pFClass.Search(pQFilter, True)

'What do you think this code does?

Set pFCursor = pFClass.Search(Nothing, True)

'What do you think this code does?

Set pFCursor = pFClass.Search(Nothing, True)

FeatureClass

Search

QueryFilter

FeatureCursor

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SpatialFilter

Type of QueryFilter

Select features based on a spatial relationship

Geometry Property• Point• Line• Polygon

Geometry Property• Point• Line• Polygon

SpatialRel Property• Inside• Contains• Intersects• Etc …

SpatialRel Property• Inside• Contains• Intersects• Etc …

Dim pSFilter As ISpatialFilterSet pSFilter = New SpatialFilterSet pSFilter.Geometry = pBufferPolygonpSFilter.SpatialRel = esriSpatialRelContainsSet pFCursor = pCityFClass.Search (pSFilter, True)

Dim pSFilter As ISpatialFilterSet pSFilter = New SpatialFilterSet pSFilter.Geometry = pBufferPolygonpSFilter.SpatialRel = esriSpatialRelContainsSet pFCursor = pCityFClass.Search (pSFilter, True)

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三种类型的 cursors

由调用的方法来决定返回的游标 Search cursor

Search method

Use for read-only analysis of a record subset

Update cursor Update method

Use to update or delete records in the database

Insert cursor Insert method

Use to insert new records into the database

Dim myCursor As IFeatureCursor

Set myCursor = pFClass.Search(pQFilter, False)


Set myCursor = pFClass.Search(pQFilter, False)


Set myCursor = pFClass.Update(pQFilter, False)


Set myCursor = pFClass.Update(pQFilter, False)


Set myCursor = pFClass.Insert(True)


Set myCursor = pFClass.Insert(True)

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访问游标中的记录当游标初始化完成，游标指针指向第一个位置的上面使用 NextRow/NextFeature 方法来返回一个 Row/Feature

Set myRow = myCursor.NextRowSet myRow = myCursor.NextRowSet myRow = myCursor.NextRow

Set myRow = myCursor.NextRow

myCursor initializes heremyCursor initializes here

Dim myCursor As ICursorSet myCursor = pTable.Search(pQFilter, False)

Nothing is returned when all records have been accessedNothing is returned when all records have been accessed

CursorCursor

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Dim pFeature As IFeatureDim intLength As Long

Set pFeature = pFCursor.NextFeatureDo Until pFeature Is Nothing intLength = intLength + pFeature.Value(9) Set pFeature = pFCursor.NextFeatureLoopMsgBox pFClass.FeatureCount(pQFilter) & _

" roads longer than 100 km." & _ " The total length is " & intLength

例子 : 统计游标中的属性 Use a Do Until loop

Loop until no more features (Nothing)

Use IFeatureClass::FeatureCount to count features

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回顾 : Features and geometry

Every feature has geometry (shape)

All geometry has an envelope A bounding rectangle

Use an Envelope to set the ArcMap extent

'Zoom to Qatar …pQFilter.WhereClause = "Name = ‘Qatar’"Set pFCursor = pFClass.Search (pQFilter, True)Set pFeature = pFCursor.NextFeatureIf Not pFeature Is Nothing Then Dim pEnv As IEnvelope Set pEnv = pFeature.Shape.Envelope pMxDoc.ActiveView.Extent = pEnvEnd If

'Zoom to Qatar …pQFilter.WhereClause = "Name = ‘Qatar’"Set pFCursor = pFClass.Search (pQFilter, True)Set pFeature = pFCursor.NextFeatureIf Not pFeature Is Nothing Then Dim pEnv As IEnvelope Set pEnv = pFeature.Shape.Envelope pMxDoc.ActiveView.Extent = pEnvEnd If

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显示图层中的部分要素使用 IFeatureLayerDefinition :: DefinitionExpression

创建一个临时的要素子集用于显示和分析

Public Sub MakeLayerDefinition() Dim pMxDoc As IMxDocument Dim pFDefine As IFeatureLayerDefinition Set pMxDoc = ThisDocument Set pFDefine = pMxDoc.SelectedLayer 'QueryInterface pFDefine.DefinitionExpression = "Pop > 3000000" pMxDoc.ActiveView.Refresh 'Refresh the display End Sub

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Exercise 11 overview

显示图层的一个子集 IFeatureLayerDefinition :: DefinitionExpression

对一个要素子集进行统计 IQueryFilter :: WhereClause

FeatureCursors

根据属性或空间关系形成一个游标 SpatialFilter

SelectionSet

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例子：遍历 GeoDatabase 数据集、要素类

Sub BrowsFeatureClassInFeatureDatasset()

' 定义一个 WorkSpaceFactory 类工厂

Dim pSdeWorkspaceFactory As IWorkspaceFactory

' 定义一个 WorkSpace 对象

Dim pSdeWorkspace As IWorkspace

' 定义一个 PropertySet 对象 , 用来设置 SDE连接信息 .

Dim pConnectionProperties As IPropertySet

' 创建一个新的 PropertySet 对象

Set pConnectionProperties = New PropertySet

With pConnectionProperties

.SetProperty "SERVER", "afei"

.SetProperty "INSTANCE", "5151/tcp"

.SetProperty "DATABASE", "sde"

.SetProperty "USER", "sde"

.SetProperty "PASSWORD", "sde"

.SetProperty "VERSION", "SDE.DEFAULT"

End With

' 定义一个 SDE 类型的 WorkSpace 类工厂

Set pSdeWorkspaceFactory = New SdeWorkspaceFactory

' 通过类工厂的 Create 方法返回一个 Sde 类型的 WorkSpace 对象 .

Set pSdeWorkspace = pSdeWorkspaceFactory.Open(pConnectionProperties, 0)

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遍历要素集（ FeatureDataset ）If Not pSdeWorkspace Is Nothing Then

'---------------------------------------------------

' 定义一个数据集集合对象

Dim pDatasets As IEnumDataset

' 通过接口查询返回所有 FeatureDataset类型的数据集集合

Set pDatasets = pSdeWorkspace.Datasets(esriDTFeatureDataset)

' 定义一个数据集对象

Dim pDataset As IFeatureDataset

'取得第一个数据集

Set pDataset = pDatasets.Next

' 如果该数据集不是空的

If Not pDataset Is Nothing Then

' 定义一个 FeatureClassContainer 对象

Dim pFeatureCC As IFeatureClassContainer

' 通过接口查询返回FeatureClassContainer 对象 .

Set pFeatureCC = pDataset

' 定义一个特征类集合对象

Dim pEFC As IEnumFeatureClass

' 通过接口查询返回集合对象

Set pEFC = pFeatureCC.Classes

' 定义特征类对象

Dim pFC As IFeatureClass

'取得第一个特征类

Set pFC = pEFC.Next

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遍历要素类（ FeatureClass ）

Do While Not pFC Is Nothing

' 显示特征类得别名

MsgBox pFC.AliasName

' 循环到下一个特征类

Set pFC = pEFC.Next

Loop

End If

'--------------------------------------------------

Else

MsgBox " 连接错误 "

End If

End Sub

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遍历一个 FeatureClass 中的 Feature 对象 If Not InFeatureClass Is Nothing Then Dim i As Long For i = 0 To InFeatureClass.FeatureCount(Nothing) - 1 Dim Ft As IFeature Dim Geo As IGeometry Set Ft = InFeatureClass.GetFeature(i) Set Geo = Ft.ShapeCopy Set Geo = Nothing Set Ft = Nothing Next iEnd If

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上机操作练习课程内容

基于 com 接口编程基础（ i）

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