[Qgis-developer] destinationSrsChanged, custom srs

[Matthias Kuhn]

Hi Martin,

QgsMapSettings is a data only object, meaning that new map settings
objects are created from a map canvas "snapshot" for every rendering job
and therefore they don't change and don't need to (and cannot) emit signals.

That also means: map canvas is the one who manages CRS information [1].
In short:
mapCanvas.destinationCrsChanged.connect(onCrsChanged)

For the QgsCoordinateTransform question, how are you generating the
transform object? I assume with createFromWkt or createFromProj4 it
should work, but I'm sure there are people more experienced with this
part of the API out there.

Matthias

http://qgis.org/api/classQgsMapCanvas.html#ac6fdcc726339b6ff65abc7150a22b2d5

On 11/29/2016 09:37 AM, Martin Landa wrote:
> Hi all,
> 
> when working with students on new QGIS plugin some questions raised.
> 
> First we use destinationSrsChanged signal from QgsMapRender (which is
> DEPRECATED). We couldn't find similar signal in QgsMapSettings class.
> 
> In the code we also transform coordinates using QgsCoordinateTransform
> class. It works except of user defined srs, eg. USER:100000. In this
> case isValid() return False and transformation do not work.
> 
> Any ideas? Thanks, Martin
>