理解对象模型图(OMD).ppt

AO/AE编程基础(1),1.2 理解对象模型图（OMD）,6-2,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,6-3,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,6-4,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,6-5,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,*,6-6,类和他们相应的对象,ArcMap objects,MxDocument,Map,Layer,*,*,FeatureLayer,Application,6-7,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）,6-8,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 IRow Set pNewRow = pTable.CreateRow,生 成,6-9,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),6-10,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,6-11,Property and method symbols,Property 哑铃形状的图标 Method,6-12,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!,6-13,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 IDocument Dim pBar As IStatusBar strName = Application.Name MsgBox strName 返回一个引用 Set pDoc = Application.Document Set pBar = Application.StatusBar pBar.Message(0) pDoc.Title,6-14,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).,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,6-15,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,虫洞,6-16,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 IMxDocument Set pMxDoc = ThisDocument Dim pMap As IMap Set pMap = pMxDoc.FocusMap Dim pLayer As ILayer Set pLayer = pMap.Layer(1) Is pLayer a FeatureLayer? If TypeOf pLayer Is IFeatureLayer Then MsgBox “Yes!, its a feature layer“ End If,MxDocument,Map,FeatureLayer,Layer,*,*,Others,A,6-17,Exercise 2 overview,Interpret the ArcOb