scaling issue question

[Didrik Pinte]

Hi,

Does anyone know why the max_scale computation in Thuban/UI/view.py was
restricted this way ? 

        # The window coordinates used when drawing the shapes must fit
        # into 16bit signed integers.
        max_len = max(pwidth, pheight)
        if max_len:
            max_scale = 32767.0 / max_len
        else:
            # FIXME: What to do in this case? The bbox is effectively
            # empty so any scale should work.
            max_scale = scale

Where comes the limitation on 16 bit from ?

The following bugs/tickets are due to this limitation :
- https://www.intevation.de/rt/webrt?serial_num=2559
-
http://wald.intevation.org/tracker/index.php?func=detail&aid=435&group_id=6&atid=105

You can test it easily by loading the iceland sample session and zooming
in. You are stuck at a 3km scale. Setting the max_scale to a value of
32767 allow you to zoom in nearly indefinetily without errors. 

What is the rationale around that ?

Didrik
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