ArcGIS Engine Developer Guide

.NET APPLICATION PROGRAMMING INTERFACE
Events
The type library importer creates several types that enable managed applications
to sink to events fired by COM classes. The first type is a delegate that is named
after the event interface plus an underscore followed by the event name, then the
word EventHandler. For example, the SelectionChanged event defined on the
IActiveViewEvents interface has the following delegate defined:
IActiveViewEvents_SelectionChangedEventHandler. The importer also creates an
event interface with an ‘_Event’ suffix added to the end of the original interface
name. For example, IActiveViewEvents generates IActiveViewEvents_Event. Use the
event interfaces to set up event sinks.
Non-OLE automation-compliant types
COM types that are not OLE automation compliant generally do not work in
.NET. ArcGIS contains a few noncompliant methods, and these cannot be used
in .NET. However, in most cases, supplemental interfaces have been added that
have the offending members rewritten compliantly. For example, when defining
an envelope via a point array, you can’t use IEnvelope::DefineFromPoints; instead,
you must use IEnvelopeGEN::DefineFromPoints.
[VB.NET]
Dim pointArray(1) As IPoint
pointArray(0) = New PointClass
pointArray(1) = New PointClass
pointArray(0).PutCoords(0, 0)
pointArray(1).PutCoords(100, 100)
Dim env As IEnvelope
Dim envGEN As IEnvelopeGEN
env = New EnvelopeClass
envGEN = New EnvelopeClass
' Won't compile
env.DefineFromPoints(2, pointArray)
' Doesn't work
env.DefineFromPoints(2, pointArray(0))
' Works
envGEN.DefineFromPoints(pointArray)
[C#]
IPoint[] pointArray = new IPoint[2];
pointArray[0] = new PointClass();
pointArray[1] = new PointClass();
pointArray[0].PutCoords(0,0);
pointArray[1].PutCoords(100,100);
IEnvelope env = new EnvelopeClass();
IEnvelopeGEN envGEN = new EnvelopeClass();
// Won't compile
148 • ArcGIS Engine Developer Guide