关于启用对象级别事件 （VBA/ActiveX）

每当折线更新时，显示闭合折线的面积

此示例创建包含事件的轻量级折线。然后，每当折线发生更改时，折线的事件处理程序都会显示新区域。要触发事件，只需在AutoCAD中更改折线的大小即可。请记住，在激活事件处理程序之前，必须运行子例程。CreatePLineWithEvents

Public WithEvents PLine As AcadLWPolyline

Sub CreatePLineWithEvents()
 ' This example creates a light weight polyline
 Dim points(0 To 9) As Double
 points(0) = 1: points(1) = 1
 points(2) = 1: points(3) = 2
 points(4) = 2: points(5) = 2
 points(6) = 3: points(7) = 3
 points(8) = 3: points(9) = 2
 Set PLine = ThisDrawing.ModelSpace. _
 AddLightWeightPolyline(points)
 PLine.Closed = True
 ThisDrawing.Application.ZoomAll
End Sub

Private Sub PLine_Modified _
 (ByVal pObject As AutoCAD.IAcadObject)
 ' This event is triggered when the polyline is resized.
 ' If the polyline is deleted the modified event is still
 ' triggered, so we use the error handler to avoid
 ' reading data from a deleted object.
 On Error GoTo ERRORHANDLER
 MsgBox "The area of " & pObject.ObjectName & " is: " _
 & pObject.Area
 Exit Sub

ERRORHANDLER:
 MsgBox Err.Description
End Sub