[GRASS-dev] future after d.frame?

[Markus Neteler]

(picking up an old topic)

On Wed, Oct 8, 2008 at 3:05 PM, Glynn Clements <glynn at gclements.plus.com> wrote:
>
> Yann Chemin wrote:
>
>> attached is a composition that should be dumped as
>> image file at each new temporal increment,
>> in order to become an animation eventually.
>> As d.frame is gone in GRASS 7,
>> I'd like to know if anyone has an idea on how to make
>> this happen within the new environmental conditions?
>
> For d.rast.leg (scripts/d.rast.leg/d.rast.leg.py in 7.0), I used the
> following function as a drop-in replacement for the d.frame command:
>
> def make_frame(f, b, t, l, r):
>     (ft, fb, fl, fr) = f
>
>     t /= 100.0
>     b /= 100.0
>     l /= 100.0
>     r /= 100.0
>
>     rt = fb + t * (ft - fb)
>     rb = fb + b * (ft - fb)
>     rl = fl + l * (fr - fl)
>     rr = fl + r * (fr - fl)
>     s = '%f,%f,%f,%f' % (rt, rb, rl, rr)
>     os.environ['GRASS_FRAME'] = s
>
> This converts the coordinates used by d.frame (percentages, with the
> origin at the lower left) to the coordinates used by the GRASS_FRAME
> variable (display units, typically pixels (raster) or points
> (PostScript etc), with the origin at the upper left).
>
> The first argument, "f", is the parent frame, which was obtained with:
>
>     s = grass.read_command('d.info', flags = 'f')
>     f = tuple([float(x) for x in s.split()[1:5]])
>
> This allows the output to nest inside an existing frame rather than
> forcibly resetting to "full screen" (the notion of "resetting" doesn't
> fit well with EPS or SVG).
>
> Also, to compose multiple d.* commands into a single image when using
> immediate rendering, you need to set GRASS_PNG_READ=TRUE. Otherwise,
> each d.* command will erase the image (raster formats, e.g. PNG) or
> truncate the file (vector formats, e.g. PS/PDF/SVG).
>
> One feature which the display architecture currently lacks is the
> ability to create multiple frames (in the sense of animation) from a
> single command. Actually, you can almost do this with the PostScript
> driver; call R_erase() between each frame, and manually change the
> ERASE function in the output to use showpage instead of erasepage.

It would be great to have something corresponding to d.frame also in GRASS 7.
And,or, have not only GRASS_FRAME but also GRASS_FRAME_PERCENT
in order to easier split the wx monitor from command line.

Any thoughts? Or is there anything more recent I am not aware of?

Markus