[Scilab-users] xpoly()

[Stefan Du Rietz]

On 2014-11-20 23:58, Samuel Gougeon wrote:
> Hello,
>
> Le 19/11/2014 18:39, Stefan Du Rietz a écrit :
>> Hello,
>>
>> I have made quite an effort to write commands in numerous sci-files
>> with the low level function xpoly() to avoid changes to the axes.
>>
>> But (surprise, surprise!),
>
> The fix of the bug 8956  has been announced in the Release Notes of
> Scilab 5.5.0 :
> #8956 - xpoly, xfpoly, xrect, xsegs and xarc did not update
> data_bounds property.
> http://bugzilla.scilab.org/8956
> See also http://bugzilla.scilab.org/13365, fixed in 5.5.1

But if you consider it a new bug, you will not read about fixes ...

> The new behavior has been reported as a buggy one at
> http://bugzilla.scilab.org/show_bug.cgi?id=13643
> But as written in comment of that report, I fully agree with the #8656
> reporter (and duplicates ones):
> The former behavior was very bad, while from the new one, it is
> trivial to get the former behavior.
>
> As Antoine has written it, if you want to keep the data bounds
> unchanged, from Scilab  5.5.1 you just have to save the initial bounds
> (no need to copy and save the full axes!) and finally restore them:
> ax = gca();
> DBold = ax.data_bounds;
> // Then here plot tens, hundred or thousands xpoly(), xfpolys(),
> xarcs(), xsegs(), etc...
> // Finally, restore the entering bounds;
> ax.data_bounds = DBold;
> // and that's it!
>
> Whereas with the former behavior, updating data bounds with an
> external script was impossible.
> Reasons are somewhat detailled here:
> http://bugzilla.scilab.org/show_bug.cgi?id=13643#c2
>
> This is why this fix and the new behavior should rather be considered
> as a big improvement, since there is no specific  Scilab function
> dedicated to bounds recalculation.
> Unfortunately, replot() does not do that :
> http://help.scilab.org/docs/5.5.1/en_US/replot.html
>
> By the way, when one plots something, it looks quite expected to be
> able to see the plotted object. It was often not the case for
> geometrical shapes with the former behavior of xpoly() and of other
> comparable plotting functions, with no way to compute relevant data
> bounds.
>
> Regards
> Samuel
>
Hello Samuel,
thank you for your comprehensive reply, which I have now investigated.

Yet, I cannot agree with you.

Do you really consider it logical that a built-in low level line 
function (xpoly) should change a superior entity (axes) when there 
already is a built-in plot function (plot2d) for that?

And that you can prevent (with a.auto_scale = "off") the plot function 
but not the line function to change the axes???

Furthermore, if you want to draw "thousands" of lines with xpoly(), it 
must take some time to recalculate the data_bounds every time!

"when one plots something" and wants "to be able to see the plotted 
object" one can use plot2d ...

If I use a low level line function, it is because I know what I am 
doing and don't want anything to interfere with it!

So I will add my comments to the bug report 13643. This behaviour is 
absurd.

Regards
Stefan