Add a signal to QgsLayoutContext when flags change

python/core/layout/qgslayoutcontext.sip

@@ -8,7 +8,7 @@
 
 
 
-class QgsLayoutContext
+class QgsLayoutContext : QObject
 {
 %Docstring
  Stores information relating to the current context and rendering settings for a layout.
@@ -168,11 +168,20 @@ class QgsLayoutContext
  :rtype: bool
 %End
 
+  signals:
+
+    void flagsChanged( QgsLayoutContext::Flags flags );
+%Docstring
+ Emitted whenever the context's ``flags`` change.
+.. seealso:: setFlags()
+%End
+
 };
 
 
 
 
+
 /************************************************************************
  * This file has been generated automatically from                      *
  *                                                                      *

src/core/CMakeLists.txt

@@ -972,7 +972,6 @@ SET(QGIS_CORE_HDRS
   composer/qgspaperitem.h
 
   layout/qgslayoutaligner.h
-  layout/qgslayoutcontext.h
   layout/qgslayoutgridsettings.h
   layout/qgslayoutitemundocommand.h
   layout/qgslayoutmeasurement.h

src/core/layout/qgslayoutcontext.cpp

@@ -24,15 +24,26 @@ QgsLayoutContext::QgsLayoutContext()
 
 void QgsLayoutContext::setFlags( const QgsLayoutContext::Flags flags )
 {
+  if ( flags == mFlags )
+    return;
+
   mFlags = flags;
+  emit flagsChanged( mFlags );
 }
 
 void QgsLayoutContext::setFlag( const QgsLayoutContext::Flag flag, const bool on )
 {
+  Flags newFlags = mFlags;
   if ( on )
-    mFlags |= flag;
+    newFlags |= flag;
   else
-    mFlags &= ~flag;
+    newFlags &= ~flag;
+
+  if ( newFlags == mFlags )
+    return;
+
+  mFlags = newFlags;
+  emit flagsChanged( mFlags );
 }
 
 QgsLayoutContext::Flags QgsLayoutContext::flags() const

src/core/layout/qgslayoutcontext.h

@@ -31,9 +31,11 @@ class QgsVectorLayer;
  * \brief Stores information relating to the current context and rendering settings for a layout.
  * \since QGIS 3.0
  */
-class CORE_EXPORT QgsLayoutContext
+class CORE_EXPORT QgsLayoutContext : public QObject
 {
 
+    Q_OBJECT
+
   public:
 
     //! Flags for controlling how a layout is rendered
@@ -179,6 +181,14 @@ class CORE_EXPORT QgsLayoutContext
      */
     bool pagesVisible() const { return mPagesVisible; }
 
+  signals:
+
+    /**
+     * Emitted whenever the context's \a flags change.
+     * \see setFlags()
+     */
+    void flagsChanged( QgsLayoutContext::Flags flags );
+
   private:
 
     Flags mFlags = 0;
@@ -195,6 +205,8 @@ class CORE_EXPORT QgsLayoutContext
 
 };
 
+Q_DECLARE_METATYPE( QgsLayoutContext::Flags )
+
 #endif //QGSLAYOUTCONTEXT_H
 
 

src/core/qgsapplication.cpp

@@ -43,6 +43,7 @@
 #include "qgsuserprofilemanager.h"
 #include "qgsreferencedgeometry.h"
 #include "qgs3drendererregistry.h"
+#include "qgslayoutcontext.h"
 
 #include "gps/qgsgpsconnectionregistry.h"
 #include "processing/qgsprocessingregistry.h"
@@ -152,6 +153,7 @@ void QgsApplication::init( QString profileFolder )
   qRegisterMetaType<QgsMessageLog::MessageLevel>( "QgsMessageLog::MessageLevel" );
   qRegisterMetaType<QgsReferencedRectangle>( "QgsReferencedRectangle" );
   qRegisterMetaType<QgsReferencedPointXY>( "QgsReferencedPointXY" );
+  qRegisterMetaType<QgsLayoutContext::Flags>( "QgsLayoutContext::Flags" );
 
   QString prefixPath( getenv( "QGIS_PREFIX_PATH" ) ? getenv( "QGIS_PREFIX_PATH" ) : applicationDirPath() );
   // QgsDebugMsg( QString( "prefixPath(): %1" ).arg( prefixPath ) );

tests/src/core/testqgslayoutcontext.cpp

@@ -21,6 +21,7 @@
 #include "qgsvectorlayer.h"
 #include <QObject>
 #include "qgstest.h"
+#include <QtTest/QSignalSpy>
 
 class TestQgsLayoutContext: public QObject
 {
@@ -81,16 +82,27 @@ void TestQgsLayoutContext::creation()
 void TestQgsLayoutContext::flags()
 {
   QgsLayoutContext context;
+  QSignalSpy spyFlagsChanged( &context, &QgsLayoutContext::flagsChanged );
+
   //test getting and setting flags
   context.setFlags( QgsLayoutContext::Flags( QgsLayoutContext::FlagAntialiasing | QgsLayoutContext::FlagUseAdvancedEffects ) );
+  // default flags, so should be no signal
+  QCOMPARE( spyFlagsChanged.count(), 0 );
+
   QVERIFY( context.flags() == ( QgsLayoutContext::FlagAntialiasing | QgsLayoutContext::FlagUseAdvancedEffects ) );
   QVERIFY( context.testFlag( QgsLayoutContext::FlagAntialiasing ) );
   QVERIFY( context.testFlag( QgsLayoutContext::FlagUseAdvancedEffects ) );
   QVERIFY( ! context.testFlag( QgsLayoutContext::FlagDebug ) );
   context.setFlag( QgsLayoutContext::FlagDebug );
+  QCOMPARE( spyFlagsChanged.count(), 1 );
   QVERIFY( context.testFlag( QgsLayoutContext::FlagDebug ) );
   context.setFlag( QgsLayoutContext::FlagDebug, false );
+  QCOMPARE( spyFlagsChanged.count(), 2 );
   QVERIFY( ! context.testFlag( QgsLayoutContext::FlagDebug ) );
+  context.setFlag( QgsLayoutContext::FlagDebug, false ); //no change
+  QCOMPARE( spyFlagsChanged.count(), 2 );
+  context.setFlags( QgsLayoutContext::FlagDebug );
+  QCOMPARE( spyFlagsChanged.count(), 3 );
 }
 
 void TestQgsLayoutContext::feature()