[GRASS5] Window Extents and region settings in X...

Eric G. Miller egm2 at jps.net
Tue Feb 27 23:57:14 EST 2001

I noticed after the bit of work I've done on d.area, that I still have a
small inconsistency with much of the rest of the display code.  Here's
the scenario:

1) User open's monitor
2) Monitor's dimensions aren't proportional to the current region
3) Display program set's up region setting translation after opening
4) Display program draws to monitor, but large portions in the Y or
   X extents are unused.

This is especially disconcerting looking when a portion of a vector map
abruptly cuts off, even though there's more vector data and window real
estate available.  It's less disturbing with raster data, given its
rectangularity already...

I noticed I wasn't catching this with d.area and portions of the vector
will be drawn outside the "clipping area" because portions of the
polygons lie within the "drawing area" and hence the whole polygon is
returned, despite Vect_constraint_window() (which behaves correctly).

I wonder if it is desirable to keep this behavior, or to see if we can't
have region settings (for display purposes) extended in whichever
direction has the unused window real estate? I'm not sure that such a
thing could be done in the driver/raster lib area in such a way that
the display modules would all automatically utilize that adjusted

P.S. For those of you following my d.area ramblings:  Other than the
clipping thing, it seems to work well (albeit slow in extreme
circumstances).  I did try to compare it to d.vect.cats and noticed that
d.vect.cats seems to have a *HUGE MEMORY LEAK*.  So, d.vect.cats was
unusable as a comparison (I had to end up killing it if I tried to draw
all the possible categories for a certain large vector map).
Eric G. Miller <egm2 at jps.net>

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