[Qgis-developer] General questions & multiple map canvases

[Radim Blazek]

Hi.
I think that in any casee, it should allow effective rectification
(georeferencing)
of rasters. That means 4 views, all with different zoom and each pair
with different
layers displayed.

On 5/7/06, humarco <marco.hugentobler at karto.baug.ethz.ch> wrote:
> I can see two different possible directions of how multiple canvas could work:
>
> 1. Different views to the same project. The canvases use exaclty the same
> layer set, symbology, legend (not necessarily the same CRS). Only the view
> extent is different.
>
> 2. Different views to different projects. Each canvas has a different layer
> set, symbology, CRS, legend.
>
> I can imagine uses for both.

Yes, It think that both should be possible.

> Personally i would prefer the first one. The user
> could have 2. by opening multiple qgis windows.

Yes, but impossible to do georeferencing using standard views
and sources cannot be shared.

> In case the general consensus is 2., wouldn't it be simpler to have
> independent instances of legend, maplayers and even layer registries for each
> canvas? As the data providers read from disk, there wouldn't be much storage
> overhead compared to sharing maplayers.

There are certainly layers which dont read from disk. I believe that layer
should be shared over application. It is also important to have only one
shared source to get updates (editing) immediately visible in all views.

Radim