Avoid more needless project dirtying

python/core/auto_generated/qgscoordinatetransformcontext.sip.in

@@ -63,6 +63,7 @@ Copy constructor
 %End
 
 
+    bool operator==( const QgsCoordinateTransformContext &rhs ) const;
 
     void clear();
 %Docstring

src/core/qgscoordinatetransformcontext.cpp

@@ -36,6 +36,19 @@ QgsCoordinateTransformContext &QgsCoordinateTransformContext::operator=( const Q
   return *this;
 }
 
+bool QgsCoordinateTransformContext::operator==( const QgsCoordinateTransformContext &rhs ) const
+{
+  if ( d == rhs.d )
+    return true;
+
+  d->mLock.lockForRead();
+  rhs.d->mLock.lockForRead();
+  bool equal = d->mSourceDestDatumTransforms == rhs.d->mSourceDestDatumTransforms;
+  d->mLock.unlock();
+  rhs.d->mLock.unlock();
+  return equal;
+}
+
 void QgsCoordinateTransformContext::clear()
 {
   d.detach();

src/core/qgscoordinatetransformcontext.h

@@ -80,6 +80,7 @@ class CORE_EXPORT QgsCoordinateTransformContext
      */
     QgsCoordinateTransformContext &operator=( const QgsCoordinateTransformContext &rhs ) SIP_SKIP;
 
+    bool operator==( const QgsCoordinateTransformContext &rhs ) const ;
 
     /**
      * Clears all stored transform information from the context.

src/core/qgsproject.cpp

@@ -278,6 +278,13 @@ QgsProjectProperty *addKey_( const QString &scope,
   return nullptr;
 }
 
+/**
+ * Remove a given key
+
+\param scope scope of key
+\param key key name
+\param rootProperty is the property from which to start adding
+*/
 
 void removeKey_( const QString &scope,
                  const QString &key,
@@ -614,6 +621,9 @@ QgsCoordinateReferenceSystem QgsProject::crs() const
 
 void QgsProject::setCrs( const QgsCoordinateReferenceSystem &crs )
 {
+  if ( crs == mCrs )
+    return;
+
   mCrs = crs;
   writeEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectionsEnabled" ), crs.isValid() ? 1 : 0 );
   setDirty( true );
@@ -631,7 +641,6 @@ QString QgsProject::ellipsoid() const
 void QgsProject::setEllipsoid( const QString &ellipsoid )
 {
   writeEntry( QStringLiteral( "Measure" ), QStringLiteral( "/Ellipsoid" ), ellipsoid );
-  setDirty( true );
   emit ellipsoidChanged( ellipsoid );
 }
 
@@ -642,6 +651,9 @@ QgsCoordinateTransformContext QgsProject::transformContext() const
 
 void QgsProject::setTransformContext( const QgsCoordinateTransformContext &context )
 {
+  if ( context == mTransformContext )
+    return;
+
   mTransformContext = context;
   emit transformContextChanged();
 }
@@ -834,7 +846,7 @@ void QgsProject::setSnappingConfig( const QgsSnappingConfig &snappingConfig )
     return;
 
   mSnappingConfig = snappingConfig;
-  setDirty();
+  setDirty( true );
   emit snappingConfigChanged( mSnappingConfig );
 }
 
@@ -2084,9 +2096,11 @@ bool QgsProject::readBoolEntry( const QString &scope, const QString &key, bool d
 
 bool QgsProject::removeEntry( const QString &scope, const QString &key )
 {
-  removeKey_( scope, key, mProperties );
-
-  setDirty( true );
+  if ( findKey_( scope, key, mProperties ) )
+  {
+    removeKey_( scope, key, mProperties );
+    setDirty( true );
+  }
 
   return !findKey_( scope, key, mProperties );
 }
@@ -2357,6 +2371,9 @@ bool QgsProject::evaluateDefaultValues() const
 
 void QgsProject::setEvaluateDefaultValues( bool evaluateDefaultValues )
 {
+  if ( evaluateDefaultValues == mEvaluateDefaultValues )
+    return;
+
   const QMap<QString, QgsMapLayer *> layers = mapLayers();
   QMap<QString, QgsMapLayer *>::const_iterator layerIt = layers.constBegin();
   for ( ; layerIt != layers.constEnd(); ++layerIt )
@@ -2848,6 +2865,9 @@ const QgsProjectMetadata &QgsProject::metadata() const
 
 void QgsProject::setMetadata( const QgsProjectMetadata &metadata )
 {
+  if ( metadata == mMetadata )
+    return;
+
   mMetadata = metadata;
   emit metadataChanged();
 

tests/src/python/test_qgscoordinatetransformcontext.py

@@ -408,6 +408,19 @@ def testReadWriteSettings(self):
                          {('EPSG:4204', 'EPSG:4326'): QgsDatumTransform.TransformPair(source_id_1, dest_id_1),
                           ('EPSG:4205', 'EPSG:4326'): QgsDatumTransform.TransformPair(source_id_2, dest_id_2)})
 
+    def testEqualOperator(self):
+        context1 = QgsCoordinateTransformContext()
+        context2 = QgsCoordinateTransformContext()
+        self.assertTrue(context1 == context2)
+
+        context1.addSourceDestinationDatumTransform(QgsCoordinateReferenceSystem('EPSG:3111'),
+                                                    QgsCoordinateReferenceSystem('EPSG:4283'), 1, 2)
+        self.assertFalse(context1 == context2)
+
+        context2.addSourceDestinationDatumTransform(QgsCoordinateReferenceSystem('EPSG:3111'),
+                                                    QgsCoordinateReferenceSystem('EPSG:4283'), 1, 2)
+        self.assertTrue(context1 == context2)
+
 
 if __name__ == '__main__':
     unittest.main()

tests/src/python/test_qgsproject.py

@@ -1121,7 +1121,7 @@ def testWriteEntry(self):
         self.assertTrue(ok)
         self.assertEqual(q, query)
 
-    def testWriteEntryDirtying(self):
+    def testDirtying(self):
 
         project = QgsProject()
 
@@ -1140,6 +1140,27 @@ def testWriteEntryDirtying(self):
         self.assertTrue(project.writeEntry('myscope', 'myentry', False))
         self.assertTrue(project.isDirty())
 
+        # removing an existing entry should dirty the project
+        project.setDirty(False)
+        self.assertTrue(project.removeEntry('myscope', 'myentry'))
+        self.assertTrue(project.isDirty())
+
+        # removing a non-existing entry should _not_ dirty the project
+        project.setDirty(False)
+        self.assertTrue(project.removeEntry('myscope', 'myentry'))
+        self.assertFalse(project.isDirty())
+
+        # setting a project CRS with a new value should dirty the project
+        project.setCrs(QgsCoordinateReferenceSystem('EPSG:4326'))
+        project.setDirty(False)
+        project.setCrs(QgsCoordinateReferenceSystem('EPSG:3148'))
+        self.assertTrue(project.isDirty())
+
+        # setting a project CRS with the same project CRS should not dirty the project
+        project.setDirty(False)
+        project.setCrs(QgsCoordinateReferenceSystem('EPSG:3148'))
+        self.assertFalse(project.isDirty())
+
 
 if __name__ == '__main__':
     unittest.main()