[Qgis-developer] Simplify tool dialog

Martin Dobias wonder.sk at gmail.com
Tue Dec 15 06:03:48 EST 2009

On Tue, Dec 15, 2009 at 11:46 AM, strk <strk at keybit.net> wrote:
> Hi all,
> I've had problems using the simplify tool due to inadeguate range
> of the slider being used. I've seen qgis tries to compute this range
> automatically ( QgsMapToolSimplify::calculateSliderBoudaries() ).

the idea behind the slider was that it is more intuitive to use than
requiring a numeric tolerance parameter (that might be complicated for
users to figure out empirically). So we will calculate the boundaries
of slider for each simplified shape. On the left side the shape should
stay untouched, on the right side the shape should be reduced to
minimal number of vertices (two for lines, three for polygons).

> Now, I've no idea what that calculator does but for me any position
> not touching the left side was too much. If you accept a suggestion
> I think having a numeric field, in addition to the slider, would
> help in these cases (ie: allowing me to enter a precise number).
> Hopefully qt has neat widgets for this kind of things.

The slider range should be probably logarithmic instead of linear to
avoid the kind of problem you have.

I also understand that power users might want to specify the tolerance
precisely, so adding a spin box with tolerance (connected to slider)
makes sense. Please file an enhancement ticket for this.


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