Graphics: Title and label properties

[Shai Ayal]

On Sun, Jul 20, 2008 at 6:29 PM, Michael Goffioul <
michael.goffioul at gmail.com> wrote:

> On Sun, Jul 20, 2008 at 10:35 AM, Maciek Gajewski
> <maciej.gajewski0 at gmail.com> wrote:
> > Hello
> >
> > I've noticed that current axes code doesn't takes special care for title
> and
> > x/y/(z) label items. They are created when appropriate, but I think (and
> > compatibility suggest) that axes should initialize they properties, and
> then
> > update them when needed.
> >
> > Especially:
> >
> > - positions of all these labels should be updated whenever xlim/ylim/zlim
> > changes, so labels and title are painted in proper positions,
> > - clipping should be set off, so labels can be displayed outside axes
> plot
> > box,
> > - y-label should be rotated 90 degrees
> > etc.
> >
> > This could be done in backend, but IMO octave should take care of this.
> Are
> > there any plans to do it? If no, I'd like to do it .
>
> Help is always welcome. These kind of things (let's call it label/title
> auto-location) are currently handled in the OpenGL renderer, when the
> axes is rendered. This is probably not the best place, but this seemed
> convenient (as a first draft), because placing correctly the labels
> involves knowledge of rendering information like the font metrics.
>
> Placing correctly the labels and title means determining the position,
> the rotation and the Horz./Vert. alignment. This must take into account
> the current axes transformation (2D/3D, azimuth and elevation angles...),
> but also the tick marks length and text (both font metric and actual text.
> For instance, taking your remark above that the y-label should be
> rotated 90 degrees, this is only true for plain-2D (azimuth=0,
> elevation=90).
>
> AFAIK Shai is working on the text engine, including an interface to
> get font metrics. This should help in placing the labels correctly. But
> definitely, this auto-location should be taken out of the OpenGL
> renderer. So, again, help is always welcome.


Sadly "Working  on it" is highly exaggerated :( . I'm afraid I have been
unable to contribute for the last two-three months. So, please proceed w/o
me if you want. I'll try to join in later if I can commit the time ...

Shai
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