matplotlib-devel

[matplotlib-devel] question about the figure class

[Jochen V. <vo...@se...>]

Hello,

why is figure derived from the Artist class?
This causes some special casing (figure is the
only artist where artist.figure does not point to
the figure).

The the figure actually used as an Artist somewhere?
What would break if it would not be derived from
Artist?

I tried the patch
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
diff -u -r1.5 figure.py
--- figure.py   21 Oct 2004 19:57:50 -0000      1.5
+++ figure.py   2 Nov 2004 19:35:03 -0000
@@ -13,7 +13,7 @@
=20
=20
=20
-class Figure(Artist):
+class Figure:
    =20
     def __init__(self,
                  figsize   =3D None,  # defaults to rc figure.figsize
@@ -27,7 +27,7 @@
         paper size is a w,h tuple in inches
         DPI is dots per inch=20
         """
-        Artist.__init__(self)
+        #Artist.__init__(self)
         #self.set_figure(self)
=20
         if figsize is None  : figsize   =3D rcParams['figure.figsize']
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
and everything still seems to work.  Maybe a figure
should be just something which uses artists to do its
work instead of being one itself.

What do you think?
Jochen
--=20
http://seehuhn.de/

Re: [matplotlib-devel] question about the figure class

[John H. <jdh...@ac...>]

>>>>> "Jochen" == Jochen Voss <vo...@se...> writes:

    Jochen> Hello, why is figure derived from the Artist class?  This
    Jochen> causes some special casing (figure is the only artist
    Jochen> where artist.figure does not point to the figure).

    Jochen> The the figure actually used as an Artist somewhere?  What
    Jochen> would break if it would not be derived from Artist?

In a couple of places - in the call to set_transform in
Figure._set_artist_props and when FigureCanvas calls
figure.draw(renderer).  One could write a figure class that was not
derived form Artist, but I don't really see the benefit of changing
it.  The Artist hierarchy are basically all the things that implement
draw(renderer).  Of course in a dynamically typed language one doesn't
need to derive from Artist to implement draw(renderer), but it seems
conceptually cleaner to do so in this case -- plus I have already done
the Artist hierarchy in graphviz and included it in the users guide
:-)

It might also break some code which is relying on the Artist methods,
eg fig.get_transform (for people who want to add lines, text, etc in
fig coords).  I doubt there are many such people, but it is a
possibility.

    Jochen> I tried the patch

I didn't test this - did it pass backend_driver?

JDH

Re: [matplotlib-devel] question about the figure class

[Jochen V. <vo...@se...>]

Hello John,

On Wed, Nov 03, 2004 at 04:14:55PM -0600, John Hunter wrote:
> >>>>> "Jochen" =3D=3D Jochen Voss <vo...@se...> writes:
>     Jochen> The the figure actually used as an Artist somewhere?  What
>     Jochen> would break if it would not be derived from Artist?
>=20
> In a couple of places - in the call to set_transform in
> Figure._set_artist_props ...
I see.

> ... and when FigureCanvas calls figure.draw(renderer).
This is different, isn't it?  FigureCanvas calls figure.draw(renderer)
only calls this with proper figures and never with other Artists.
So inheritance is not used here.

> ... The Artist hierarchy are basically all the things that implement
> draw(renderer). ...
Ok!  This makes it look ok to me.
I am just in the process of understanding how the internals
of matplotlib work.

>     Jochen> I tried the patch
>=20
> I didn't test this - did it pass backend_driver?
It seemed to work fine, but maybe I just didn't spot the
problems.  Now I can't really understand how the set_transform calls
in Figure._set_artist_props could possible have worked.

Thank you very much,
Jochen
--=20
http://seehuhn.de/

Re: [matplotlib-devel] question about the figure class

[John H. <jdh...@ac...>]

>>>>> "Jochen" == Jochen Voss <vo...@se...> writes:
    Jochen> It seemed to work fine, but maybe I just didn't spot the
    Jochen> problems.  Now I can't really understand how the
    Jochen> set_transform calls in Figure._set_artist_props could
    Jochen> possible have worked.

Basically, noone ever uses the figure transform.  One could, if you
want to draw in figure coords (0,0 is lower left of figure, 1,1 is
upper right, it's just that this doesn't happen in real life very
often.  I doubt any of the backend_driver scripts utilize this.

JDH