Re: [graphviz-interest] CGraph C API and dot rendering: how to render the graph left-to-right?

On 1/3/14 6:00 PM, Jeremy Friesner wrote:
> Hi all,
>
> I have a C++ program that uses the CGraph API (in conjunction with the "dot" rendering engine to render a directed graph.   Here is an example of a rendered graph in my program:
>
> http://www.lcscanada.com/jaf/avb_graph.png
>
> That works fine, but it would be preferable if the graph's nodes were placed such that the edges flowed from left to right, rather than top to bottom.  Here's a mockup showing roughly the layout I would prefer:
>
> http://www.lcscanada.com/jaf/lr_graph.png
>
> Does anyone know what I can do to achieve this?
>
> I tried the following (directly after my call to agopen(NULL, Agdirected, NULL))):
>
>          SET_RANKDIR(mygraph, RANKDIR_LR);
>
> as well as
>
>          SET_RANKDIR(mygraph, (RANKDIR_LR<<2)|RANKDIR_LR);
>
>
I believe you've got the right attribute but the wrong API. Try using 
the string-valued approach:

     agsafeset(mygraph,"rankdir","LR","");

(The macros in types.h are intended to be read-only after you've done 
the graph layout.)

     Emden

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