From graphics-request at octave dot org Tue Nov 30 03:30:32 2004
Subject: Re: Oplot
From: Ole Jacob Hagen <waterthrill at yahoo dot no>
To: graphics at octave dot org
Date: Tue, 30 Nov 2004 10:26:42 +0100

Hi, Shai.


Yes, thanks to Shai, we have contour-plot in Oplot. ;-)


Have you looked at Props-source? And it's usage in the following classes :
OpFigureManager (Props::Root), OpFigureWindow (Props::Figure), 
OpAxesObject (Props::Axes), OpLineObject (Props::Line)? These four 
classes represents each a graphics object. And the virtual method 
property_changed is run, when a property has changed. This is due to a 
callback setup.

Actually, Prop-package is the heart in Oplot.

Root::instance().setRootCallbackInterface(this) inside ctor of 
OpFigureManager says that every callbacks regarding a property change in 
root-object is controlled to OpFigureManager.

In Octave: f = figure; will make this code run.
% snip of code %

> int OpFigureManager::new_figure( Figure* fig) {
>     OpFigureWindow* fw = new OpFigureWindow(fig, this);
>     fig->setCallbackInterface(fw);
>     this->addFigureWindow(fw, (int) fig->getHandle());
>     return 0;
> }

% end snip of code %
We create a new OpFigureWindows, and connects the Figure-callbacks to 
our newly created OpFigureWindow instance.  And we adds this figure 
window into a QPtrList.

When we create a line-object, by using h = plot(x,y) will run this code, 
since Line is a child of Axes
% snip of code %

> int OpAxesObject::new_child( Object* p,  Object* child) {
>      if((*child->get_string("Type") == "Line")) {
>         Line* line = static_cast<Line*>(child);
>         OpLineObject *lineobject = new OpLineObject(line, this);
>         line->setCallbackInterface(lineobject);
>             }
>  return 0;
> }
>
% end snip of code %
We create a OpLineObject and connects the callbacks of line-object into 
our OpLineObject.
So every change in a line-object in octave, e.g set(h, 'color',[0 1 0]) 
will make property_change inside OpLineObject be executed.


Could this be used by visualisation applications, if we convience Paul 
Kienzle to merge it into octave-forge?
This means that Octave has a common library for handling graphics 
objects, which can be used by many visualisation applications. The 
visualisation application will be responsible of communication interface 
to and from Octave. And Props will be a layer that handles graphics 
objects, and properties within the visualisation application. Octave 
doesn't need duplicate copies of datas.

Can I test the possibility to use Props inside OctPlot? Or will you Shai?
It would be interesting if it's feasible. ;-) It should be.

The code needs some refactoring, I guess. But refactoring is good, not 
evil.

If more people are interested in Props-package and how it really works, 
then send me an email, and I will send you some more documentation about 
it.

Cheers,

Ole J.