topic Error in definition of Drawable.Bounds in .NET Forum

Error in definition of Drawable.Bounds

Anonymous — Thu, 25 Jul 2013 16:00:47 GMT

I just ran into an odd problem with the Bounds method (inherited by all DBObjects). I was attempting to us it like:

Dim bounds As Extents3d = txt.Bounds

but VB stated:

Error 3 Option Strict On disallows implicit conversions from 'Autodesk.AutoCAD.DatabaseServices.Extents3d?' to 'Autodesk.AutoCAD.DatabaseServices.Extents3d'.

I looked to see where that question mark was coming from and if there was another class that I hadn't heard of. It turns out that in the type library, it is defined as:

Public Overridable ReadOnly Property Bounds As Autodesk.AutoCAD.DatabaseServices.Extents3d?
Member of Autodesk.AutoCAD.GraphicsInterface.Drawable

This really seems like an error in the type library, how do I ask Autodesk to fix it?

Dim bounds As Extents3d = DirectCast(txt.Bounds, Extents3d)

does not work since there is not a inheritance or implementation relationship to the typo.

Dim bounds As Extents3d = CType(txt.Bounds, Extents3d)

seems to work, but how do I get someone to fix the underlying problem? I think it effects every entity in the database since they all inherit from Drawable. Or did they do this on purpose for reasons that are beyond me?

Re: Error in definition of Drawable.Bounds

Norman_Yuan — Thu, 25 Jul 2013 16:25:43 GMT

@Anonymous wrote:
...

This really seems like an error in the type library, how do I ask Autodesk to fix it?
...

There is nothing to fix in AutoCAD API. DbObject.Bounds is a Nullable<T> type, where T is Extents3d, which is not the same as type Extents3d., that is why you get error when in VB.NET you set "Strict On" and when you cannot DirectCats(...) it. if you use C#, you get the same error.

You get a Extents3d value from Extents3d? (or any Nullable<T> types) by Nullable<T>.Value, only if the Nullable<T>.HasValue is true.

Re: Error in definition of Drawable.Bounds

Anonymous — Thu, 25 Jul 2013 19:16:17 GMT

Ah, thank you. I have not used nullable much myself and much of the sample code I read when it first came out used the "Nullable(Of" or Nullable<T> syntax, rather than the ? thus I did not recognise the operator. Not surprisingly "?" does not work well in search engines.

I can see why it would be useful to be nullable on a Text object since if the text string is empty, there would be no bounding box.

I am now using the following construction in my code:

If txt.Bounds.HasValue Then
bounds = txt.Bounds.Value

Else