.NET

[#1]

First off, I have working code for opening a cad drawing from an external program.  That is perfect.

What I'm at a loss for is how can I force a drawing that is NOT readonly to open as readonly from outside cad.    I know it's possible within cad, but that doesn't help me.

Can anyone help me out here?

[#2 · Accepted solution]

How does your external program open a drawing? Without seeing your perfectly working code, I assume it automates AutoCAD via COM API AcadDocuments.Open() method (that is the drawing is still opened in AUTOCAD!)

This method has 2 optional argument to specify if the drawing to be opened as READONLY, and specify a PASSWORD if the drawing is password-protected:

AcadDocuments.Open "C:\....\mydrawing.dwg", True

opens a drawing as read-only.

[#3]

Actually, no.  I'm using this to open drawings in cad..

System.Diagnostics.Process.Start(dwgpath)

Sounds like i should be doing the other way..   Is there some place I can get a look at working examples?

[#4]

I have not tried it , but without rewriting all of your existing code, I believe you could just set the ReadOnly Attribute on the file.

[#5]

Not really an option (mainly because I still want the file to be editable at other times).

[#6]

So Toggle the Attribute before opening, and toggle it back after closing.  I assumed that went without saying.

[#7]

I didn't mean my last comment to be condescending, and I agree with Norman, that if you use the built-in COM mechanisms to open a drawing, there is a built-in way to open them read-only, but I just thought I would try to provide an alternative way, that did not require a significant change in your existing code.

I will admit, my suggestion requires that the users of your program have (probably a network based) permission to alter the read/write access to the file in question.  At my company, that problem could come into question under certain circumstances, but not usually when dealing with drawings.

[#8]

It's alright, everyone should let there inner Tony T out a few times.  

I had briefly thought of doing it that way, but wasn't able to find a way of doing it.   I've since gone the COM route.  Works great (after several google searches and code corrections).

[#9]

Would be interesting to show a result of your code,

Regards,

Oleg

[#10]

Not much to it, but here you go.  (though for some reason cad crashes if it's used to many times in one session... (5+ i've found))

Used with vanilla 2011

Public Sub Open_DWG ()
        Dim ACAD As Object
        Dim MyAcadPath As String = "dwgpath"
        Dim bReadOnly As Boolean = True

        On Error Resume Next
        ACAD = GetObject(, "autocad.Application")
        If Err.Number <> 0 Then
            Err.Clear()
            ACAD = CreateObject("autocad.Application")
            If Err.Number <> 0 Then
                MessageBox.Show("Failed to start", MessageBoxButtons.OK, MessageBoxIcon.Information)
                GoTo EndOpen
            End If
        End If
        'ACAD.Visible = True
        Err.Clear()
        Dim NewFile As Object = ACAD.Documents.Open(MyAcadPath, bReadOnly)
        If Err.Number <> 0 Then
            MessageBox.Show("Failed to open", MessageBoxButtons.OK, MessageBoxIcon.Information)
        End If
EndOpen:
        ACAD = Nothing
        NewFile = Nothing
    End Sub