In debug builds, throw a warning when transforming coordinates

and no coordinate transform context has been set.

Author: nyalldawson

src/core/qgscoordinatetransform.cpp

@@ -54,11 +54,17 @@ QgsCoordinateTransform::QgsCoordinateTransform( const QgsCoordinateReferenceSyst
 QgsCoordinateTransform::QgsCoordinateTransform( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &destination, const QgsCoordinateTransformContext &context )
 {
   d = new QgsCoordinateTransformPrivate( source, destination, context );
+#ifdef QGISDEBUG
+  d->mHasContext = true;
+#endif
 }
 
 QgsCoordinateTransform::QgsCoordinateTransform( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &destination, const QgsProject *project )
 {
   d = new QgsCoordinateTransformPrivate( source, destination, project ? project->transformContext() : QgsCoordinateTransformContext() );
+#ifdef QGISDEBUG
+  d->mHasContext = true;
+#endif
 }
 
 QgsCoordinateTransform::QgsCoordinateTransform( const QgsCoordinateTransform &o )
@@ -93,6 +99,9 @@ void QgsCoordinateTransform::setContext( const QgsCoordinateTransformContext &co
 {
   d.detach();
   d->mContext = context;
+#ifdef QGISDEBUG
+  d->mHasContext = true;
+#endif
   d->calculateTransforms();
   d->initialize();
 }

src/core/qgscoordinatetransform_p.cpp

@@ -69,6 +69,9 @@ QgsCoordinateTransformPrivate::QgsCoordinateTransformPrivate( const QgsCoordinat
   , mSourceCRS( other.mSourceCRS )
   , mDestCRS( other.mDestCRS )
   , mContext( other.mContext )
+#ifdef QGISDEBUG
+  , mHasContext( other.mHasContext )
+#endif
   , mSourceDatumTransform( other.mSourceDatumTransform )
   , mDestinationDatumTransform( other.mDestinationDatumTransform )
 {
@@ -106,6 +109,11 @@ bool QgsCoordinateTransformPrivate::initialize()
 
   mIsValid = true;
 
+#ifdef QGISDEBUG
+  if ( !mHasContext )
+    qWarning( "No QgsCoordinateTransformContext context set for transform" );
+#endif
+
   int sourceDatumTransform = mSourceDatumTransform;
   int destDatumTransform = mDestinationDatumTransform;
   bool useDefaultDatumTransform = ( sourceDatumTransform == - 1 && destDatumTransform == -1 );

src/core/qgscoordinatetransform_p.h

@@ -103,6 +103,10 @@ class QgsCoordinateTransformPrivate : public QSharedData
     //! Transform context
     QgsCoordinateTransformContext mContext;
 
+#ifdef QGISDEBUG
+    bool mHasContext = false;
+#endif
+
     QString mSourceProjString;
     QString mDestProjString;