[GLLUG] Cross Platform Graphics Library

[Jeremy Bowers]

Frank Louis Tuma wrote:
> 
> I am looking for a cross platform c++ graphics library. I am aware of 
> GTK+, but not all that familiar with what it has to offer. Is is 
> relatively easy to make  Visio-style functionality from GTK+ or do I 
> have to do a bunch of work to get an interface like that up and running? 
> I am already familiar with the windows SDK and plan on coding my 
> application in C++. If anybody knows of other graphic libraries or has 
> any more info please let me know.
> Thanks!
> /:Frank

GTK+ is better referred to as a "widget library". A "graphics library" 
is something like OpenGL (for 3D graphics) or the graphics part of the 
SDL (comparable to screen handling in DirectX). In Windows terms, GTK+ 
is more like the Windows widget set.

Visio-like functionality, at least in the general case, is intrinsically 
hard. It is easy to plop a few shapes down, it gets harder if you are 
responsible for manipulating them, it gets downright tough if you start 
wanting to zoom, automatically re-organize, or do anything else 
complicated. It is certainly possible, but no fun.

What are you trying to do, exactly? If all you want is a Visio-like 
program that draws things, but you want custom symbols, I'd recommend 
looking into Dia and seeing how hard it is to add you custom symbols to 
a functional drawing program.

http://www.gnome.org/projects/dia/

Depending on your needs, you may even be able to implement whatever 
other advanced features you want as either hacks in Dia, or as filters 
on the files Dia outputs.

Failing that, the best toolkit support I've heard of for this sort of 
thing is Tk's Canvas widget. However, I don't think you can use that 
from C++; Tcl, Python, or Perl seem to be the choices for that. The 
Canvas supports dropping objects on it and remembering what they are, so 
you can create event handlers for them and such, where most current 
Canvas objects only support drawing. From what I gather, both of the 
major next versions of GTK+ and QT are going to have much better support 
for that, but in the meantime my understanding is they don't.

It is impossible to stay on top of all the major widget sets 
capabilities so I welcome correction on any of these points :-)... but 
make sure you understand what the Tk Canvas widget can do before 
claiming that GTK or QT can match it; it's a rather nice widget to work 
with. At least as of about 6 months ago they can not.