Opening WMS changes QGIS Project/Main canvas CRS to EPSG:3857

[Fabian Thiel]

How to reproduce:

• Go to Tools → Open WMS Layer
• Select e.g. Google Satellite
• In Data Sources select this layer and open in new Map View

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[Benjamin Jakimow]

This might be a QGIS issue. I know a similar problem from the EO Time Series Viewer.

[Benjamin Jakimow]

Data Source URL:

type=xyz&url=https://mt1.google.com/vt/lyrs%3Ds%26x%3D{x}%26y%3D{y}%26z%3D{z}&zmax=19&zmin=0

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[Benjamin Jakimow]

This behavior is cause by the QgsLayerTreeMapCanvasBrigde (qgsmaplayertree.cpp line 112 ff):

  if ( mFirstCRS.isValid() && firstLayers )
  {
    const QgsGui::ProjectCrsBehavior projectCrsBehavior = QgsSettings().enumValue( QStringLiteral( "/projections/newProjectCrsBehavior" ),  QgsGui::UseCrsOfFirstLayerAdded, QgsSettings::App );
    switch ( projectCrsBehavior )
    {
      case QgsGui::UseCrsOfFirstLayerAdded:
      {
        const bool planimetric = QgsSettings().value( QStringLiteral( "measure/planimetric" ), true, QgsSettings::Core ).toBool();
        // Only adjust ellipsoid to CRS if it's not set to planimetric
        QgsProject::instance()->setCrs( mFirstCRS, !planimetric );
        break;
      }

      case QgsGui::UsePresetCrs:
        break;
    }
  }

In a new EnMAP-Box MapView, the QgsLayerTreeMapCanvasBrigde connected the QgsMapCanvas with its LayerTree. Added a new layer to the QgsMapCanvas will set mFirstCRS to the new layers’s CRS and trigger:

QgsProject::instance()->setCrs( mFirstCRS, !planimetric )

which changes the QGIS MapCanvas CRS. By commit history, this has been added to

[Benjamin Jakimow]

refactoring mapcanvas.py: added mFirstCrs

added snippet for qgsmaplayertreebridge_problem.py (addresses #656)

→ <<cset a95f033e6c93>>

[Benjamin Jakimow]

@Fabian Thiel the problem should not exist anymore if there is at least one layers visible in the main QGIS layer tree. Please check and close this issue if appropriate.