[Qgis-developer] General questions & multiple map canvases

[Martin Dobias]

On 5/9/06, Radim Blazek <radim.blazek at gmail.com> wrote:
> Hi Martin,
>
> what about stable release? Don you want to skip 0.8?
> Could we leave this until 0.8 release? I know that debugging
> is boring but there is no other way.

As Tim has already explained, all this stuff is post 0.8 release.

>
> On 5/8/06, Martin Dobias <wonder.sk at gmail.com> wrote:
> > Two possibilities how to deal with using the same layer in more canvases:
> > - enable sharing of layers between layer sets with reference counting
> > - disable sharing of layers, allow cloning of layers
>
> I think that layers (as data sources) should be shared over application.
>

Right, layers should be considered as data sources and thus when
they're being edited it's better to share them to display them in the
same state for all map canvases. Also we will need a mechanism which
will try to detect if the same layer is being loaded another time and
not to create another copy of the data source but to use a copy
already being used.

> > Currently I'm in favour of cloning instead of sharing them, because
> > IMO it's more straightforward to use, moreover the shared layers would
> > need to have same properties in the map canvases (renderer, symbology,
> > transparency...)
>
> We should separate layer-data and its symbology maybe?

Separating layer data from its symbology seems to be the right
direction and think of QgsMapLayer as being a only data source,
providing symbology information to map renderer separately.

> But what about selection set and query?

Where do you see problems in these features? You mean that every map
canvas should allow select anouther set of features?


Martin

>
>
> Well I don't have capacity to think about this very complex problem
> as there are milions of things to do for 0.8, so if you want my
> reasonable oppinion wait until 0.8 is out.
>
> Radim
>