Make sure variable editor widgets always show current variables

On behalf of Faunalia, sponsored by ENEL

python/core/composer/qgscomposition.sip

@@ -900,4 +900,9 @@ class QgsComposition : QGraphicsScene
 
     /** Is emitted when the composition has an updated status bar message for the composer window*/
     void statusMsgChanged( QString message );
+
+    /** Emitted whenever the expression variables stored in the composition have been changed.
+     * @note added in QGIS 3.0
+     */
+    void variablesChanged();
 };

python/core/qgsapplication.sip

@@ -379,7 +379,23 @@ static void qtgui_UpdatePyArgv(PyObject *argvlist, int argc, char **argv)
     bool x11EventFilter ( XEvent * event );
 %End
 
+  public slots:
+
+    /** Causes the application instance to emit the settingsChanged() signal. This should
+     * be called whenever global, application-wide settings are altered to advise listeners
+     * that they may need to update their state.
+     * @see settingsChanged()
+     * @note added in QGIS 3.0
+     */
+    void emitSettingsChanged();
+
   signals:
     //! @note not available in python bindings
     // void preNotify( QObject * receiver, QEvent * event, bool * done );
+
+    /** Emitted whenever any global, application-wide settings are changed.
+     * @note added in QGIS 3.0
+     * @see emitSettingsChanged()
+     */
+    void settingsChanged();
 };

python/core/qgsproject.sip

@@ -397,6 +397,11 @@ class QgsProject : QObject
     //! Emitted when the home path of the project changes
     void homePathChanged();
 
+    /** Emitted whenever the expression variables stored in the project have been changed.
+     * @note added in QGIS 3.0
+     */
+    void variablesChanged();
+
   public slots:
 
     /**
@@ -408,6 +413,13 @@ class QgsProject : QObject
      */
     void setDirty( bool b = true );
 
+    /** Causes the project to emit the variablesChanged() signal. This should
+     * be called whenever expression variables related to the project are changed.
+     * @see variablesChanged()
+     * @note added in QGIS 3.0
+     */
+    void emitVariablesChanged();
+
   private:
 
     QgsProject(); // private 'cause it's a singleton

src/app/composer/qgscomposeritemwidget.cpp

@@ -23,6 +23,7 @@
 #include "qgspoint.h"
 #include "qgsdatadefinedbutton.h"
 #include "qgsexpressioncontext.h"
+#include "qgsproject.h"
 #include <QColorDialog>
 #include <QPen>
 
@@ -109,6 +110,14 @@ QgsVectorLayer* QgsComposerItemBaseWidget::atlasCoverageLayer() const
 
 //QgsComposerItemWidget
 
+void QgsComposerItemWidget::updateVariables()
+{
+  QgsExpressionContext* context = mItem->createExpressionContext();
+  mVariableEditor->setContext( context );
+  mVariableEditor->setEditableScopeIndex( context->scopeCount() - 1 );
+  delete context;
+}
+
 QgsComposerItemWidget::QgsComposerItemWidget( QWidget* parent, QgsComposerItem* item )
     : QgsComposerItemBaseWidget( parent, item )
     , mItem( item )
@@ -141,12 +150,17 @@ QgsComposerItemWidget::QgsComposerItemWidget( QWidget* parent, QgsComposerItem*
 
   connect( mTransparencySlider, SIGNAL( valueChanged( int ) ), mTransparencySpnBx, SLOT( setValue( int ) ) );
 
-  QgsExpressionContext* context = mItem->createExpressionContext();
+  updateVariables();
-  mVariableEditor->setContext( context );
-  mVariableEditor->setEditableScopeIndex( context->scopeCount() - 1 );
-  delete context;
-
   connect( mVariableEditor, SIGNAL( scopeChanged() ), this, SLOT( variablesChanged() ) );
+  // listen out for variable edits
+  QgsApplication* app = qobject_cast<QgsApplication*>( QgsApplication::instance() );
+  if ( app )
+  {
+    connect( app, SIGNAL( settingsChanged() ), this, SLOT( updateVariables() ) );
+  }
+  connect( QgsProject::instance(), SIGNAL( variablesChanged() ), this, SLOT( updateVariables() ) );
+  if ( mItem->composition() )
+    connect( mItem->composition(), SIGNAL( variablesChanged() ), this, SLOT( updateVariables() ) );
 
   //connect atlas signals to data defined buttons
   QgsAtlasComposition* atlas = atlasComposition();

src/app/composer/qgscomposeritemwidget.h

@@ -142,8 +142,7 @@ class QgsComposerItemWidget: public QgsComposerItemBaseWidget, private Ui::QgsCo
   private slots:
 
     void variablesChanged();
-
+    void updateVariables();
-
 };
 
 #endif //QGSCOMPOSERITEMWIDGET_H

src/app/composer/qgscompositionwidget.cpp

@@ -23,6 +23,7 @@
 #include "qgssymbolv2selectordialog.h"
 #include "qgssymbollayerv2utils.h"
 #include "qgsexpressioncontext.h"
+#include "qgsproject.h"
 #include <QColorDialog>
 #include <QWidget>
 #include <QPrinter> //for screen resolution
@@ -45,13 +46,15 @@ QgsCompositionWidget::QgsCompositionWidget( QWidget* parent, QgsComposition* c )
   //read with/height from composition and find suitable entries to display
   displayCompositionWidthHeight();
 
-  mVariableEditor->context()->appendScope( QgsExpressionContextUtils::globalScope() );
+  updateVariables();
-  mVariableEditor->context()->appendScope( QgsExpressionContextUtils::projectScope() );
-  mVariableEditor->context()->appendScope( QgsExpressionContextUtils::compositionScope( mComposition ) );
-  mVariableEditor->reloadContext();
-  mVariableEditor->setEditableScopeIndex( 2 );
-
   connect( mVariableEditor, SIGNAL( scopeChanged() ), this, SLOT( variablesChanged() ) );
+  // listen out for variable edits
+  QgsApplication* app = qobject_cast<QgsApplication*>( QgsApplication::instance() );
+  if ( app )
+  {
+    connect( app, SIGNAL( settingsChanged() ), this, SLOT( updateVariables() ) );
+  }
+  connect( QgsProject::instance(), SIGNAL( variablesChanged() ), this, SLOT( updateVariables() ) );
 
   if ( mComposition )
   {
@@ -209,6 +212,16 @@ void QgsCompositionWidget::resizeMarginsChanged()
       mLeftMarginSpinBox->value() );
 }
 
+void QgsCompositionWidget::updateVariables()
+{
+  QgsExpressionContext context;
+  context << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope()
+  << QgsExpressionContextUtils::compositionScope( mComposition );
+  mVariableEditor->setContext( &context );
+  mVariableEditor->setEditableScopeIndex( 2 );
+}
+
 void QgsCompositionWidget::setDataDefinedProperty( const QgsDataDefinedButton* ddBtn, QgsComposerObject::DataDefinedProperty property )
 {
   if ( !mComposition )

src/app/composer/qgscompositionwidget.h

@@ -83,6 +83,8 @@ class QgsCompositionWidget: public QWidget, private Ui::QgsCompositionWidgetBase
 
     void resizeMarginsChanged();
 
+    void updateVariables();
+
   private:
     QgsComposition* mComposition;
     QMap<QString, QgsCompositionPaper> mPaperMap;

src/app/qgsoptions.cpp

@@ -1481,6 +1481,12 @@ void QgsOptions::saveOptions()
   }
 
   saveDefaultDatumTransformations();
+
+  QgsApplication* app = qobject_cast<QgsApplication*>( QgsApplication::instance() );
+  if ( app )
+  {
+    app->emitSettingsChanged();
+  }
 }
 
 void QgsOptions::rejectOptions()

src/app/qgsprojectproperties.cpp

@@ -1187,6 +1187,7 @@ void QgsProjectProperties::apply()
 
   //save variables
   QgsExpressionContextUtils::setProjectVariables( mVariableEditor->variablesInActiveScope() );
+  QgsProject::instance()->emitVariablesChanged();
 
   emit refresh();
 }

src/core/composer/qgscomposition.cpp

@@ -1069,6 +1069,8 @@ bool QgsComposition::readXML( const QDomElement& compositionElem, const QDomDocu
 
   updateBounds();
 
+  emit variablesChanged();
+
   return true;
 }
 
@@ -3506,6 +3508,9 @@ void QgsComposition::setDataDefinedProperty( const QgsComposerObject::DataDefine
 void QgsComposition::setCustomProperty( const QString& key, const QVariant& value )
 {
   mCustomProperties.setValue( key, value );
+
+  if ( key.startsWith( "variable" ) )
+    emit variablesChanged();
 }
 
 QVariant QgsComposition::customProperty( const QString& key, const QVariant& defaultValue ) const

src/core/composer/qgscomposition.h

@@ -1146,6 +1146,11 @@ class CORE_EXPORT QgsComposition : public QGraphicsScene
     /** Is emitted when the composition has an updated status bar message for the composer window*/
     void statusMsgChanged( const QString& message );
 
+    /** Emitted whenever the expression variables stored in the composition have been changed.
+     * @note added in QGIS 3.0
+     */
+    void variablesChanged();
+
     friend class QgsComposerObject; //for accessing dataDefinedEvaluate, readDataDefinedPropertyMap and writeDataDefinedPropertyMap
     friend class QgsComposerModel; //for accessing updateZValues (should not be public)
     friend class TestQgsComposition;

src/core/qgsapplication.cpp

@@ -1371,3 +1371,8 @@ void QgsApplication::setMaxThreads( int maxThreads )
   QgsDebugMsg( QString( "set QThreadPool max thread count to %1" ).arg( QThreadPool::globalInstance()->maxThreadCount() ) );
 }
 
+void QgsApplication::emitSettingsChanged()
+{
+  emit settingsChanged();
+}
+

src/core/qgsapplication.h

@@ -364,10 +364,26 @@ class CORE_EXPORT QgsApplication : public QApplication
     }
 #endif
 
+  public slots:
+
+    /** Causes the application instance to emit the settingsChanged() signal. This should
+     * be called whenever global, application-wide settings are altered to advise listeners
+     * that they may need to update their state.
+     * @see settingsChanged()
+     * @note added in QGIS 3.0
+     */
+    void emitSettingsChanged();
+
   signals:
     //! @note not available in python bindings
     void preNotify( QObject * receiver, QEvent * event, bool * done );
 
+    /** Emitted whenever any global, application-wide settings are changed.
+     * @note added in QGIS 3.0
+     * @see emitSettingsChanged()
+     */
+    void settingsChanged();
+
   private:
     static void copyPath( const QString& src, const QString& dst );
     static QObject* ABISYM( mFileOpenEventReceiver );

src/core/qgsproject.cpp

@@ -412,6 +412,11 @@ void QgsProject::setDirty( bool b )
   imp_->dirty = b;
 }
 
+void QgsProject::emitVariablesChanged()
+{
+  emit variablesChanged();
+}
+
 void QgsProject::setFileName( const QString& name )
 {
   if ( name == imp_->file.fileName() )

src/core/qgsproject.h

@@ -462,6 +462,11 @@ class CORE_EXPORT QgsProject : public QObject
     //! Emitted when the home path of the project changes
     void homePathChanged();
 
+    /** Emitted whenever the expression variables stored in the project have been changed.
+     * @note added in QGIS 3.0
+     */
+    void variablesChanged();
+
   public slots:
 
     /**
@@ -473,6 +478,13 @@ class CORE_EXPORT QgsProject : public QObject
      */
     void setDirty( bool b = true );
 
+    /** Causes the project to emit the variablesChanged() signal. This should
+     * be called whenever expression variables related to the project are changed.
+     * @see variablesChanged()
+     * @note added in QGIS 3.0
+     */
+    void emitVariablesChanged();
+
   private slots:
     void onMapLayersAdded( const QList<QgsMapLayer*>& layers );
     void cleanTransactionGroups( bool force = false );

src/gui/qgsvariableeditorwidget.h

@@ -65,12 +65,6 @@ class GUI_EXPORT QgsVariableEditorWidget : public QWidget
      */
     QgsExpressionContext* context() const { return mContext.data(); }
 
-    /** Reloads all scopes from the editor's current context. This method should be called
-     * after adding or removing scopes from the attached context.
-     * @see context()
-     */
-    void reloadContext();
-
     /** Sets the editable scope for the widget. Only variables from the editable scope can
      * be modified by users.
      * @param scopeIndex index of current editable scope. Set to -1 to disable
@@ -107,6 +101,14 @@ class GUI_EXPORT QgsVariableEditorWidget : public QWidget
      */
     QgsStringMap variablesInActiveScope() const;
 
+  public slots:
+
+    /** Reloads all scopes from the editor's current context. This method should be called
+     * after adding or removing scopes from the attached context.
+     * @see context()
+     */
+    void reloadContext();
+
   signals:
 
     /** Emitted when the user has modified a scope using the widget.

tests/src/core/testqgsapplication.cpp

@@ -83,6 +83,7 @@ void TestQgsApplication::platformName()
   QCOMPARE( QgsApplication::platform(), QString( "desktop" ) );
 }
 
+
 void TestQgsApplication::checkPaths()
 {
   QString myPath = QgsApplication::authorsFilePath();

tests/src/core/testqgscomposition.cpp

@@ -53,6 +53,7 @@ class TestQgsComposition : public QObject
     void resizeToContentsMargin();
     void resizeToContentsMultiPage();
     void georeference();
+    void variablesEdited();
 
   private:
     QgsComposition *mComposition;
@@ -583,5 +584,19 @@ void TestQgsComposition::georeference()
   delete composition;
 }
 
+void TestQgsComposition::variablesEdited()
+{
+  QgsMapSettings ms;
+  QgsComposition c( ms );
+  QSignalSpy spyVariablesChanged( &c, SIGNAL( variablesChanged() ) );
+
+  c.setCustomProperty( "not a variable", "1" );
+  QVERIFY( spyVariablesChanged.count() == 0 );
+  c.setCustomProperty( "variableNames", "1" );
+  QVERIFY( spyVariablesChanged.count() == 1 );
+  c.setCustomProperty( "variableValues", "1" );
+  QVERIFY( spyVariablesChanged.count() == 2 );
+}
+
 QTEST_MAIN( TestQgsComposition )
 #include "testqgscomposition.moc"

tests/src/core/testqgsproject.cpp

@@ -31,6 +31,7 @@ class TestQgsProject : public QObject
 
     void testReadPath();
     void testProjectUnits();
+    void variablesChanged();
 };
 
 void TestQgsProject::init()
@@ -124,6 +125,13 @@ void TestQgsProject::testProjectUnits()
   QCOMPARE( prj->areaUnits(), QgsUnitTypes::Acres );
 }
 
+void TestQgsProject::variablesChanged()
+{
+  QSignalSpy spyVariablesChanged( QgsProject::instance(), SIGNAL( variablesChanged() ) );
+  QgsProject::instance()->emitVariablesChanged();
+  QVERIFY( spyVariablesChanged.count() == 1 );
+}
+
 
 QTEST_MAIN( TestQgsProject )
 #include "testqgsproject.moc"