[Qgis-developer] Saving map config, or the meaning of extent (again)

Nathan Woodrow madmanwoo at gmail.com
Sun Dec 7 22:26:44 PST 2014


> Keeping just center+scale+rotation in QgsMapSettings seems like a
cleaner solution.

Is it still possible to have the ability to set extents?  There are use
cases for setting it vs trying to work out the scale and center.

- Nathan

On Mon Dec 08 2014 at 2:51:21 PM Martin Dobias <wonder.sk at gmail.com> wrote:

> Hi Sandro
>
> On Tue, Dec 2, 2014 at 11:15 PM, Sandro Santilli <strk at keybit.net> wrote:
> >
> > I'm still thinking that the triplet center,scale,rotation would be the
> > simplest to retain. The problem with that is that keeping the scale
> > might result in a different area being exposed depending on the
> > output size. On the other hand keeping the extent would result in
> > a different scale being used depending on output size.
>
> Keeping just center+scale+rotation in QgsMapSettings seems like a
> cleaner solution. Having to worry about various kinds of extent with
> rotation in place will wear out our brains ("requested" extent,
> "visible" extent, rotated "visible" extent). With your proposed
> triplet we could at least get rid of the "requested" extent. (I still
> find it a bit difficult to explain why both requested / visible extent
> are needed - which is not a good sign!)
>
>
> > What's more worth saving: scale of visible area ?
>
> IMHO it does not really matter much.
>
> One issue I could see by saving center+scale instead of extent is that
> e.g. if you load a project with map extent to the whole project, in
> differently shaped QGIS window some bits of data may be slightly
> outside of the view. But even for this case the canvas could store its
> original
>
>
> Regards
> Martin
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