Re: Bond Graph modeling with Dia

[Dave <spamless4 iasun2 epfl ch>]

I'm submitting line.c code that implements line gaps (with gap > 0), or 
allows lines to extend beyond their anchors (with gap < 0).  This code 
is copyrighted 2002 by me (David Hoover) and can be used and copied 
under the terms of the GNU General Public License (like the rest of the 
Dia project code).

I believe this code to be 100% backward compatible with the previous 
line.c since the default properties all result in no gap and the same 
line bounding box and distance measures as before.  Please correct me if 
I am wrong :-).

Usage is documented slightly in the code.  I am including an example 
that uses standard objects and demonstrates the usefulness (and 
coolness, I think) of 'the gap'.  This example is necessary for you to 
try out the gap because I have not written any GTK code that allows one 
to configure gaps with the GUI.  If you want to make your own gaps for 
now, you need to add dia attributes to the XML.  See the example.  Can't 
properties generate GTK dialog boxes automatically?  How do you do that? 
 Is it easy?  Somebody want to do that?

I have gotten the gap to work with version 0.9, and I am able to export 
.eps and .fig files.  With the current CVS, I am unable to do either of 
the above.  I also had problems compiling the current CVS. In addition, 
Dia from CVS generates XML without line separators.  So the included 
example was made with version 0.9, but is editable with the current CVS 
version.

I would like to congratulate the Dia team for writing a tool that is so 
easy to extend.  I am amazed that I was able to get this gap code 
written so quickly and with so little effort.  Thanks!

In order to make this gap code more useful, it would be nice if future 
shapes be designed with a connection point in the center.  It would also 
be nice if the basic shapes had connection points in the center as well. 
 For the moment, there are hardly any shapes with center connection points.

For bond graph creation, the next major step is making some changes in 
the arrow code, and creating the basic bond graph elements.  This will 
require some input from the mtt team.

Dave.





Alan Horkan wrote:

>On Tue, 19 Nov 2002, Dave wrote:
>
>  
>
>>What do I need to do to contribute my code?  I am the author of other
>>GPL'ed programs.  Do I need to sign anything to submit code?  Should I
>>use CVS, or send a diff to somebody?
>>    
>>
>
>http://mail.gnome.org/archives/dia-list/2002-February/msg00126.html
>
>as far as i know there is no single person/entity that holds the copyright
>of Dia (any future change of licensing would be a nightmare).
>
>Make it clear that you are making the code available under the terms of
>the GPL, make a patch against CVS.  If it patches cleanly against CVS you
>will make Cyrille happier, if it does not patch cleanly you will probably
>be asked to do it again.
>
>you could attach the patch to a bugzilla report if it is big.
>
>read the link, save me typing
>
>Later
>Alan
>
>
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>  
>

gap_example2.dia.gz

gap.patch.gz

gap_example2.eps