Show user-facing warnings when coordinate transform between two

dynamic CRSes at different coordinate epochs is attempted This is not currently supported by PROJ, so the results will be misleading.
qgis · May 13, 2021 · c0743d6 · c0743d6
1 parent a703e87
commit c0743d6
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Showing 7 changed files with 143 additions and 1 deletion.
diff --git a/src/app/qgsappcoordinateoperationhandlers.cpp b/src/app/qgsappcoordinateoperationhandlers.cpp
@@ -63,11 +63,18 @@ QgsAppMissingGridHandler::QgsAppMissingGridHandler( QObject *parent )
     emit fallbackOperationOccurred( sourceCrs, destinationCrs, desired );
   } );
 
+  QgsCoordinateTransform::setDynamicCrsToDynamicCrsWarningHandler( [ = ]( const QgsCoordinateReferenceSystem & sourceCrs,
+      const QgsCoordinateReferenceSystem & destinationCrs )
+  {
+    emit dynamicToDynamicWarning( sourceCrs, destinationCrs );
+  } );
+
   connect( this, &QgsAppMissingGridHandler::missingRequiredGrid, this, &QgsAppMissingGridHandler::onMissingRequiredGrid, Qt::QueuedConnection );
   connect( this, &QgsAppMissingGridHandler::missingPreferredGrid, this, &QgsAppMissingGridHandler::onMissingPreferredGrid, Qt::QueuedConnection );
   connect( this, &QgsAppMissingGridHandler::coordinateOperationCreationError, this, &QgsAppMissingGridHandler::onCoordinateOperationCreationError, Qt::QueuedConnection );
   connect( this, &QgsAppMissingGridHandler::missingGridUsedByContextHandler, this, &QgsAppMissingGridHandler::onMissingGridUsedByContextHandler, Qt::QueuedConnection );
   connect( this, &QgsAppMissingGridHandler::fallbackOperationOccurred, this, &QgsAppMissingGridHandler::onFallbackOperationOccurred, Qt::QueuedConnection );
+  connect( this, &QgsAppMissingGridHandler::dynamicToDynamicWarning, this, &QgsAppMissingGridHandler::onDynamicToDynamicWarning, Qt::QueuedConnection );
 
   connect( QgsProject::instance(), &QgsProject::cleared, this, [ = ]
   {
@@ -301,6 +308,30 @@ void QgsAppMissingGridHandler::onFallbackOperationOccurred( const QgsCoordinateR
   bar->pushWidget( widget, Qgis::Warning, 0 );
 }
 
+void QgsAppMissingGridHandler::onDynamicToDynamicWarning( const QgsCoordinateReferenceSystem &sourceCrs, const QgsCoordinateReferenceSystem &destinationCrs )
+{
+  if ( !shouldWarnAboutDynamicCrsForCurrentProject( sourceCrs, destinationCrs ) )
+    return;
+
+  const QString shortMessage = tr( "Cannot transform between dynamic CRS at difference coordinate epochs" );
+  const QString longMessage = tr( "<p>Transformation between %1 and %3 is not currently supported.</p><p><b>The results will be unpredictable and should not be used for high accuracy work.</b>" ).arg( sourceCrs.userFriendlyIdentifier(), destinationCrs.userFriendlyIdentifier() );
+
+  QgsMessageBar *bar = QgisApp::instance()->messageBar();
+  QgsMessageBarItem *widget = bar->createMessage( QString(), shortMessage );
+  QPushButton *detailsButton = new QPushButton( tr( "Details" ) );
+  connect( detailsButton, &QPushButton::clicked, this, [longMessage]
+  {
+    // dlg has deleted on close
+    QgsMessageOutput * dlg( QgsMessageOutput::createMessageOutput() );
+    dlg->setTitle( tr( "Unsupported Transformation" ) );
+    dlg->setMessage( longMessage, QgsMessageOutput::MessageHtml );
+    dlg->showMessage();
+  } );
+
+  widget->layout()->addWidget( detailsButton );
+  bar->pushWidget( widget, Qgis::Critical, 0 );
+}
+
 bool QgsAppMissingGridHandler::shouldWarnAboutPair( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &dest )
 {
   if ( mAlreadyWarnedPairs.contains( qMakePair( source, dest ) ) || mAlreadyWarnedPairs.contains( qMakePair( dest, source ) ) )
@@ -333,3 +364,14 @@ bool QgsAppMissingGridHandler::shouldWarnAboutBallparkPairForCurrentProject( con
   mAlreadyWarnedBallparkPairsForProject.append( qMakePair( source, dest ) );
   return true;
 }
+
+bool QgsAppMissingGridHandler::shouldWarnAboutDynamicCrsForCurrentProject( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &dest )
+{
+  if ( mAlreadyWarnedDynamicCrsForProject.contains( qMakePair( source, dest ) ) || mAlreadyWarnedDynamicCrsForProject.contains( qMakePair( dest, source ) ) )
+  {
+    return false;
+  }
+
+  mAlreadyWarnedDynamicCrsForProject.append( qMakePair( source, dest ) );
+  return true;
+}
diff --git a/src/app/qgsappcoordinateoperationhandlers.h b/src/app/qgsappcoordinateoperationhandlers.h
@@ -53,6 +53,9 @@ class QgsAppMissingGridHandler : public QObject
                                     const QgsCoordinateReferenceSystem &destinationCrs,
                                     const QString &desired );
 
+    void dynamicToDynamicWarning( const QgsCoordinateReferenceSystem &sourceCrs,
+                                  const QgsCoordinateReferenceSystem &destinationCrs );
+
   private slots:
 
     void onMissingRequiredGrid( const QgsCoordinateReferenceSystem &sourceCrs,
@@ -76,15 +79,20 @@ class QgsAppMissingGridHandler : public QObject
                                       const QgsCoordinateReferenceSystem &destinationCrs,
                                       const QString &desired );
 
+    void onDynamicToDynamicWarning( const QgsCoordinateReferenceSystem &sourceCrs,
+                                    const QgsCoordinateReferenceSystem &destinationCrs );
+
   private:
 
     bool shouldWarnAboutPair( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &dest );
     bool shouldWarnAboutPairForCurrentProject( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &dest );
     bool shouldWarnAboutBallparkPairForCurrentProject( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &dest );
+    bool shouldWarnAboutDynamicCrsForCurrentProject( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &dest );
 
     QList< QPair< QgsCoordinateReferenceSystem, QgsCoordinateReferenceSystem > > mAlreadyWarnedPairs;
     QList< QPair< QgsCoordinateReferenceSystem, QgsCoordinateReferenceSystem > > mAlreadyWarnedPairsForProject;
     QList< QPair< QgsCoordinateReferenceSystem, QgsCoordinateReferenceSystem > > mAlreadyWarnedBallparkPairsForProject;
+    QList< QPair< QgsCoordinateReferenceSystem, QgsCoordinateReferenceSystem > > mAlreadyWarnedDynamicCrsForProject;
 };
 
 #endif // QGSAPPCOORDINATEOPERATIONHANDLERS_H
diff --git a/src/core/proj/qgscoordinatetransform.cpp b/src/core/proj/qgscoordinatetransform.cpp
@@ -1052,3 +1052,8 @@ void QgsCoordinateTransform::setFallbackOperationOccurredHandler( const std::fun
 {
   sFallbackOperationOccurredHandler = handler;
 }
+
+void QgsCoordinateTransform::setDynamicCrsToDynamicCrsWarningHandler( const std::function<void ( const QgsCoordinateReferenceSystem &, const QgsCoordinateReferenceSystem & )> &handler )
+{
+  QgsCoordinateTransformPrivate::setDynamicCrsToDynamicCrsWarningHandler( handler );
+}
diff --git a/src/core/proj/qgscoordinatetransform.h b/src/core/proj/qgscoordinatetransform.h
@@ -679,6 +679,15 @@ class CORE_EXPORT QgsCoordinateTransform
         const QgsCoordinateReferenceSystem &destinationCrs,
         const QString &desiredOperation )> &handler );
 
+    /**
+     * Sets a custom \a handler to use when the desired coordinate operation for use between \a sourceCrs and
+     * \a destinationCrs is a dynamic CRS to dynamic CRS transform, not currently supported by PROJ.
+     *
+     * \since QGIS 3.20
+     */
+    static void setDynamicCrsToDynamicCrsWarningHandler( const std::function< void( const QgsCoordinateReferenceSystem &sourceCrs,
+        const QgsCoordinateReferenceSystem &destinationCrs )> &handler );
+
 #endif
 
   private:

diff --git a/src/core/proj/qgscoordinatetransform_p.cpp b/src/core/proj/qgscoordinatetransform_p.cpp
@@ -48,6 +48,9 @@ std::function< void( const QgsCoordinateReferenceSystem &sourceCrs,
                      const QgsCoordinateReferenceSystem &destinationCrs,
                      const QgsDatumTransform::TransformDetails &desiredOperation )> QgsCoordinateTransformPrivate::sMissingGridUsedByContextHandler = nullptr;
 
+std::function< void( const QgsCoordinateReferenceSystem &sourceCrs,
+                     const QgsCoordinateReferenceSystem &destinationCrs )> QgsCoordinateTransformPrivate::sDynamicCrsToDynamicCrsWarningHandler = nullptr;
+
 Q_NOWARN_DEPRECATED_PUSH // because of deprecated members
 QgsCoordinateTransformPrivate::QgsCoordinateTransformPrivate()
 {
@@ -174,7 +177,10 @@ bool QgsCoordinateTransformPrivate::initialize()
        && !std::isnan( mSourceCoordinateEpoch ) && mSourceCoordinateEpoch != mDestCoordinateEpoch )
   {
     // transforms from dynamic crs to dynamic crs with different coordinate epochs are not yet supported by PROJ
-
+    if ( sDynamicCrsToDynamicCrsWarningHandler )
+    {
+      sDynamicCrsToDynamicCrsWarningHandler( mSourceCRS, mDestCRS );
+    }
   }
 
   // init the projections (destination and source)
@@ -560,6 +566,11 @@ void QgsCoordinateTransformPrivate::setCustomMissingGridUsedByContextHandler( co
   sMissingGridUsedByContextHandler = handler;
 }
 
+void QgsCoordinateTransformPrivate::setDynamicCrsToDynamicCrsWarningHandler( const std::function<void ( const QgsCoordinateReferenceSystem &, const QgsCoordinateReferenceSystem & )> &handler )
+{
+  sDynamicCrsToDynamicCrsWarningHandler = handler;
+}
+
 void QgsCoordinateTransformPrivate::freeProj()
 {
   QgsReadWriteLocker locker( mProjLock, QgsReadWriteLocker::Write );

diff --git a/src/core/proj/qgscoordinatetransform_p.h b/src/core/proj/qgscoordinatetransform_p.h
@@ -165,6 +165,15 @@ class QgsCoordinateTransformPrivate : public QSharedData
         const QgsCoordinateReferenceSystem &destinationCrs,
         const QgsDatumTransform::TransformDetails &desiredOperation )> &handler );
 
+    /**
+     * Sets a custom \a handler to use when the desired coordinate operation for use between \a sourceCrs and
+     * \a destinationCrs is a dynamic CRS to dynamic CRS transform, not currently supported by PROJ.
+     *
+     * \since QGIS 3.20
+     */
+    static void setDynamicCrsToDynamicCrsWarningHandler( const std::function< void( const QgsCoordinateReferenceSystem &sourceCrs,
+        const QgsCoordinateReferenceSystem &destinationCrs )> &handler );
+
   private:
 
     void freeProj();
@@ -186,6 +195,9 @@ class QgsCoordinateTransformPrivate : public QSharedData
                                 const QgsCoordinateReferenceSystem &destinationCrs,
                                 const QgsDatumTransform::TransformDetails &desiredOperation )> sMissingGridUsedByContextHandler;
 
+    static std::function< void( const QgsCoordinateReferenceSystem &sourceCrs,
+                                const QgsCoordinateReferenceSystem &destinationCrs )> sDynamicCrsToDynamicCrsWarningHandler;
+
     QgsCoordinateTransformPrivate &operator= ( const QgsCoordinateTransformPrivate & ) = delete;
 };
 

diff --git a/tests/src/core/testqgscoordinatetransform.cpp b/tests/src/core/testqgscoordinatetransform.cpp
@@ -44,6 +44,7 @@ class TestQgsCoordinateTransform: public QObject
 #if PROJ_VERSION_MAJOR>7 || (PROJ_VERSION_MAJOR == 7 && PROJ_VERSION_MINOR >= 2)
     void transformEpoch_data();
     void transformEpoch();
+    void dynamicToDynamicErrorHandler();
 #endif
     void transformLKS();
     void transformContextNormalize();
@@ -463,6 +464,60 @@ void TestQgsCoordinateTransform::transformEpoch()
   QGSCOMPARENEAR( x, outX, precision );
   QGSCOMPARENEAR( y, outY, precision );
 }
+
+void TestQgsCoordinateTransform::dynamicToDynamicErrorHandler()
+{
+  // test that warnings are raised when attempting a dynamic crs to dynamic crs transformation (not supported by PROJ)
+  int counter = 0;
+  QgsCoordinateTransform::setDynamicCrsToDynamicCrsWarningHandler( [&counter]( const QgsCoordinateReferenceSystem &, const QgsCoordinateReferenceSystem & )
+  {
+    counter++;
+  } );
+
+  // no warnings -- no coordinate epoch set (although we should consider a different warning in this situation!!)
+  QgsCoordinateReferenceSystem src( QStringLiteral( "EPSG:9000" ) );
+  QgsCoordinateReferenceSystem dest( QStringLiteral( "EPSG:9000" ) );
+  QgsCoordinateTransform t( src, dest, QgsCoordinateTransformContext() );
+  QCOMPARE( counter, 0 );
+
+  // no warnings, static to static
+  src = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:7844" ) );
+  dest = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:3111" ) );
+  t = QgsCoordinateTransform( src, dest, QgsCoordinateTransformContext() );
+  QCOMPARE( counter, 0 );
+
+  // no warnings, static to dynamic
+  src = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:7844" ) );
+  dest = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:9000" ) );
+  dest.setCoordinateEpoch( 2030 );
+  t = QgsCoordinateTransform( src, dest, QgsCoordinateTransformContext() );
+  QCOMPARE( counter, 0 );
+
+  // no warnings, dynamic to static
+  src = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:9000" ) );
+  src.setCoordinateEpoch( 2030 );
+  dest = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:7844" ) );
+  t = QgsCoordinateTransform( src, dest, QgsCoordinateTransformContext() );
+  QCOMPARE( counter, 0 );
+
+  // no warnings, same dynamic CRS to same dynamic CRS with same epoch
+  src = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:9000" ) );
+  src.setCoordinateEpoch( 2030 );
+  dest = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:9000" ) );
+  dest.setCoordinateEpoch( 2030 );
+  t = QgsCoordinateTransform( src, dest, QgsCoordinateTransformContext() );
+  QCOMPARE( counter, 0 );
+
+  // yes warnings, dynamic CRS to dynamic CRS with different epoch
+  src = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:9000" ) );
+  src.setCoordinateEpoch( 2030 );
+  dest = QgsCoordinateReferenceSystem( QStringLiteral( "EPSG:9000" ) );
+  dest.setCoordinateEpoch( 2025 );
+  t = QgsCoordinateTransform( src, dest, QgsCoordinateTransformContext() );
+  QCOMPARE( counter, 1 );
+
+  QgsCoordinateTransform::setDynamicCrsToDynamicCrsWarningHandler( nullptr );
+}
 #endif
 
 void TestQgsCoordinateTransform::transformBoundingBox()