解决方案 | 获取所有的打印输出的图纸尺寸的名称GetCanonicalMediaNames返回为空的原因竟然是官方帮助文件给我带来了误导-CAD VBA

巨大的坑，该代码来自于acadauto_2014--AutoCAD2014 ActiveX Reference Guide.chm 但是存在一个巨大的bug。

'获取所有的打印输出的图纸尺寸的名称 ，但是事前必须设置【打印机对象】也就是 Layouts("Model").ConfigName = "DWF Classic.pc3" 这样的代码，否则返回为空。
也就是说，必须先设置打印机，才能知道可打印图纸的尺寸。这个逻辑才是对的。这里是采用的vba ，其他的语言比如Python也是一样的

Sub Example_GetCanonicalMediaNames() '获取所有的打印输出的图纸尺寸的名称 ，但是事前必须设置【打印机对象】也就是 Layouts("Model").ConfigName = "DWF Classic.pc3" 这样的代码，否则返回为空
    ' This example gets the current plot device information
    ' and then displays the list of plot device names,
    ' media names, localized media names, and plot style
    ' table entries.
    Dim Layout As ACADLayout
    Set Layout = ThisDrawing.ModelSpace.Layout
 
    ' Refresh the current plot information for
    ' this session.
    Layout.RefreshPlotDeviceInfo
 
    ' List all the valid device names for the system
    Dim plotDevices As Variant
    plotDevices = Layout.GetPlotDeviceNames()
 
    Dim x As Integer
    For x = LBound(plotDevices) To UBound(plotDevices)
        MsgBox plotDevices(x)
    Next
 
    ' List all the media names, and their localized version
    Dim mediaNames As Variant
    mediaNames = Layout.GetCanonicalMediaNames()
 
    For x = LBound(mediaNames) To UBound(mediaNames)
        MsgBox mediaNames(x)
        MsgBox Layout.GetLocaleMediaName(mediaNames(x))
    Next
 
    ' List all the entries in the plot style table
    Dim styleNames As Variant
    styleNames = Layout.GetPlotStyleTableNames()
 
    For x = LBound(styleNames) To UBound(styleNames)
        MsgBox styleNames(x)
    Next
 
End Sub