Add transform context to QgsMapSettings and QgsRenderContext

And also throw warnings when the context isn't set for these objects

Author: nyalldawson

python/core/qgsmapsettings.sip

@@ -310,6 +310,27 @@ Return the distance in geographical coordinates that equals to one pixel in the
  :rtype: QgsDatumTransformStore
 %End
 
+    QgsCoordinateTransformContext transformContext() const;
+%Docstring
+ Returns the coordinate transform context, which stores various
+ information regarding which datum transforms should be used when transforming points
+ from a source to destination coordinate reference system.
+
+.. versionadded:: 3.0
+.. seealso:: setTransformContext()
+ :rtype: QgsCoordinateTransformContext
+%End
+
+    void setTransformContext( const QgsCoordinateTransformContext &context );
+%Docstring
+ Sets the coordinate transform ``context``, which stores various
+ information regarding which datum transforms should be used when transforming points
+ from a source to destination coordinate reference system.
+
+.. versionadded:: 3.0
+.. seealso:: transformContext()
+%End
+
     const QgsMapToPixel &mapToPixel() const;
 %Docstring
  :rtype: QgsMapToPixel
@@ -442,6 +463,7 @@ Gets segmentation tolerance type (maximum angle or maximum difference between cu
 
 
 
+
     void updateDerived();
 };
 

python/core/qgsrendercontext.sip

@@ -110,6 +110,27 @@ class QgsRenderContext
  :rtype: QgsDistanceArea
 %End
 
+    QgsCoordinateTransformContext transformContext() const;
+%Docstring
+ Returns the context's coordinate transform context, which stores various
+ information regarding which datum transforms should be used when transforming points
+ from a source to destination coordinate reference system.
+
+.. versionadded:: 3.0
+.. seealso:: setTransformContext()
+ :rtype: QgsCoordinateTransformContext
+%End
+
+    void setTransformContext( const QgsCoordinateTransformContext &context );
+%Docstring
+ Sets the context's coordinate transform ``context``, which stores various
+ information regarding which datum transforms should be used when transforming points
+ from a source to destination coordinate reference system.
+
+.. versionadded:: 3.0
+.. seealso:: transformContext()
+%End
+
     const QgsRectangle &extent() const;
 %Docstring
  :rtype: QgsRectangle

src/app/qgsmapsavedialog.cpp

@@ -295,6 +295,7 @@ void QgsMapSaveDialog::applyMapSettings( QgsMapSettings &mapSettings )
   mapSettings.setBackgroundColor( mMapCanvas->canvasColor() );
   mapSettings.setRotation( mMapCanvas->rotation() );
   mapSettings.setLayers( mMapCanvas->layers() );
+  mapSettings.setTransformContext( QgsProject::instance()->transformContext() );
 
   //build the expression context
   QgsExpressionContext expressionContext;

src/core/composer/qgscomposermap.cpp

@@ -165,6 +165,7 @@ QgsMapSettings QgsComposerMap::mapSettings( const QgsRectangle &extent, QSizeF s
   jobMapSettings.setBackgroundColor( Qt::transparent );
   jobMapSettings.setRotation( mEvaluatedMapRotation );
   jobMapSettings.setEllipsoid( mComposition->project()->ellipsoid() );
+  jobMapSettings.setTransformContext( mComposition->project()->transformContext() );
 
   //set layers to render
   QList<QgsMapLayer *> layers = layersToRender( &expressionContext );

src/core/qgsmapsettings.cpp

@@ -362,6 +362,23 @@ double QgsMapSettings::scale() const
   return mScale;
 }
 
+QgsCoordinateTransformContext QgsMapSettings::transformContext() const
+{
+#ifdef QGISDEBUG
+  if ( !mHasTransformContext )
+    qWarning( "No QgsCoordinateTransformContext context set for transform" );
+#endif
+
+  return mTransformContext;
+}
+
+void QgsMapSettings::setTransformContext( const QgsCoordinateTransformContext &context )
+{
+  mTransformContext = context;
+#ifdef QGISDEBUG
+  mHasTransformContext = true;
+#endif
+}
 
 QgsCoordinateTransform QgsMapSettings::layerTransform( const QgsMapLayer *layer ) const
 {

src/core/qgsmapsettings.h

@@ -274,6 +274,26 @@ class CORE_EXPORT QgsMapSettings
     const QgsDatumTransformStore &datumTransformStore() const { return mDatumTransformStore; } SIP_SKIP
     QgsDatumTransformStore &datumTransformStore() { return mDatumTransformStore; }
 
+    /**
+     * Returns the coordinate transform context, which stores various
+     * information regarding which datum transforms should be used when transforming points
+     * from a source to destination coordinate reference system.
+     *
+     * \since QGIS 3.0
+     * \see setTransformContext()
+     */
+    QgsCoordinateTransformContext transformContext() const;
+
+    /**
+     * Sets the coordinate transform \a context, which stores various
+     * information regarding which datum transforms should be used when transforming points
+     * from a source to destination coordinate reference system.
+     *
+     * \since QGIS 3.0
+     * \see transformContext()
+     */
+    void setTransformContext( const QgsCoordinateTransformContext &context );
+
     const QgsMapToPixel &mapToPixel() const { return mMapToPixel; }
 
     /**
@@ -410,6 +430,11 @@ class CORE_EXPORT QgsMapSettings
     QgsScaleCalculator mScaleCalculator;
     QgsMapToPixel mMapToPixel;
 
+    QgsCoordinateTransformContext mTransformContext;
+#ifdef QGISDEBUG
+    bool mHasTransformContext = false;
+#endif
+
     void updateDerived();
 };
 

src/core/qgsrendercontext.cpp

@@ -95,6 +95,23 @@ QgsRenderContext QgsRenderContext::fromQPainter( QPainter *painter )
   return context;
 }
 
+QgsCoordinateTransformContext QgsRenderContext::transformContext() const
+{
+#ifdef QGISDEBUG
+  if ( !mHasTransformContext )
+    qWarning( "No QgsCoordinateTransformContext context set for transform" );
+#endif
+  return mTransformContext;
+}
+
+void QgsRenderContext::setTransformContext( const QgsCoordinateTransformContext &context )
+{
+  mTransformContext = context;
+#ifdef QGISDEBUG
+  mHasTransformContext = true;
+#endif
+}
+
 void QgsRenderContext::setFlags( QgsRenderContext::Flags flags )
 {
   mFlags = flags;
@@ -142,6 +159,7 @@ QgsRenderContext QgsRenderContext::fromMapSettings( const QgsMapSettings &mapSet
   ctx.setSegmentationToleranceType( mapSettings.segmentationToleranceType() );
   ctx.mDistanceArea.setSourceCrs( mapSettings.destinationCrs() );
   ctx.mDistanceArea.setEllipsoid( mapSettings.ellipsoid() );
+  ctx.setTransformContext( mapSettings.transformContext() );
   //this flag is only for stopping during the current rendering progress,
   //so must be false at every new render operation
   ctx.setRenderingStopped( false );

src/core/qgsrendercontext.h

@@ -32,6 +32,7 @@
 #include "qgsrectangle.h"
 #include "qgsvectorsimplifymethod.h"
 #include "qgsdistancearea.h"
+#include "qgscoordinatetransformcontext.h"
 
 class QPainter;
 class QgsAbstractGeometry;
@@ -131,6 +132,26 @@ class CORE_EXPORT QgsRenderContext
      */
     const QgsDistanceArea &distanceArea() const { return mDistanceArea; }
 
+    /**
+     * Returns the context's coordinate transform context, which stores various
+     * information regarding which datum transforms should be used when transforming points
+     * from a source to destination coordinate reference system.
+     *
+     * \since QGIS 3.0
+     * \see setTransformContext()
+     */
+    QgsCoordinateTransformContext transformContext() const;
+
+    /**
+     * Sets the context's coordinate transform \a context, which stores various
+     * information regarding which datum transforms should be used when transforming points
+     * from a source to destination coordinate reference system.
+     *
+     * \since QGIS 3.0
+     * \see transformContext()
+     */
+    void setTransformContext( const QgsCoordinateTransformContext &context );
+
     const QgsRectangle &extent() const {return mExtent;}
 
     const QgsMapToPixel &mapToPixel() const {return mMapToPixel;}
@@ -397,6 +418,11 @@ class CORE_EXPORT QgsRenderContext
     double mSegmentationTolerance = M_PI_2 / 90;
 
     QgsAbstractGeometry::SegmentationToleranceType mSegmentationToleranceType = QgsAbstractGeometry::MaximumAngle;
+
+    QgsCoordinateTransformContext mTransformContext;
+#ifdef QGISDEBUG
+    bool mHasTransformContext = false;
+#endif
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS( QgsRenderContext::Flags )

src/gui/qgsmapcanvas.cpp

@@ -137,6 +137,12 @@ QgsMapCanvas::QgsMapCanvas( QWidget *parent )
   {
     mSettings.setEllipsoid( QgsProject::instance()->ellipsoid() );
   } );
+  mSettings.setTransformContext( QgsProject::instance()->transformContext() );
+  connect( QgsProject::instance(), &QgsProject::transformContextChanged,
+           this, [ = ]
+  {
+    mSettings.setTransformContext( QgsProject::instance()->transformContext() );
+  } );
 
   //segmentation parameters
   QgsSettings settings;