[gui] Remove deprecated labeling properties tab for new projects or older ones that don't use them

- Deprecated tab remains active for older projects, if any layer uses them
- Deprecated tab an be disabled/enabled via console commands for project entry, e.g.:
  QgsProject.instance().writeEntry('DeprecatedLabels', '/Enabled', bool) or
  QgsProject.instance().removeEntry('DeprecatedLabels', '/')

Author: dakcarto

src/app/qgisapp.cpp

@@ -1899,6 +1899,12 @@ void QgisApp::setupConnections()
   connect( this, SIGNAL( projectRead() ),
            this, SLOT( fileOpenedOKAfterLaunch() ) );
 
+  // handle deprecated labels in project for QGIS 2.0
+  connect( this, SIGNAL( newProject() ),
+           this, SLOT( checkForDeprecatedLabelsInProject() ) );
+  connect( this, SIGNAL( projectRead() ),
+           this, SLOT( checkForDeprecatedLabelsInProject() ) );
+
   //
   // Do we really need this ??? - its already connected to the esc key...TS
   //
@@ -4602,6 +4608,39 @@ void QgisApp::saveAsVectorFileGeneral( bool saveOnlySelection )
   delete dialog;
 }
 
+void QgisApp::checkForDeprecatedLabelsInProject()
+{
+  bool ok;
+  QgsProject::instance()->readBoolEntry( "DeprecatedLabels", "/Enabled", false, &ok );
+  if ( ok ) // project already flagged (regardless of project property value)
+  {
+    return;
+  }
+
+  if ( QgsMapLayerRegistry::instance()->count() > 0 )
+  {
+    bool depLabelsUsed = false;
+    QMap<QString, QgsMapLayer*> layers = QgsMapLayerRegistry::instance()->mapLayers();
+    for ( QMap<QString, QgsMapLayer*>::iterator it = layers.begin(); it != layers.end(); it++ )
+    {
+      QgsVectorLayer *vl = qobject_cast<QgsVectorLayer *>( it.value() );
+      if ( !vl )
+      {
+        continue;
+      }
+
+      depLabelsUsed = vl->hasLabelsEnabled();
+      if ( depLabelsUsed )
+      {
+        break;
+      }
+    }
+    if ( depLabelsUsed )
+    {
+      QgsProject::instance()->writeEntry( "DeprecatedLabels", "/Enabled", true );
+    }
+  }
+}
 
 void QgisApp::layerProperties()
 {

src/app/qgisapp.h

@@ -1038,6 +1038,10 @@ class QgisApp : public QMainWindow, private Ui::MainWindow
     //! shows label settings dialog (for labeling-ng)
     void labeling();
 
+    /** Check if deprecated labels are used in project, and flag projects that use them (QGIS 2.0)
+     */
+    void checkForDeprecatedLabelsInProject();
+
     //! save current vector layer
     void saveAsFile();
     void saveSelectionAsVectorFile();

src/app/qgsvectorlayerproperties.cpp

@@ -267,7 +267,7 @@ QgsVectorLayerProperties::QgsVectorLayerProperties(
 
 QgsVectorLayerProperties::~QgsVectorLayerProperties()
 {
-  if ( layer->hasGeometryType() )
+  if ( mOptsPage_LabelsOld && layer->hasGeometryType() )
   {
     disconnect( labelDialog, SIGNAL( labelSourceSet() ), this, SLOT( setLabelCheckBox() ) );
   }
@@ -412,6 +412,20 @@ void QgsVectorLayerProperties::syncToLayer( void )
   mFieldsPropertiesDialog->init();
 
   QObject::connect( labelCheckBox, SIGNAL( clicked( bool ) ), this, SLOT( enableLabelOptions( bool ) ) );
+
+  // delete deprecated labels tab if not already used by project
+  // NOTE: this is not ideal, but a quick fix for QGIS 2.0 release
+  bool ok;
+  bool dl = QgsProject::instance()->readBoolEntry( "DeprecatedLabels", "/Enabled", false, &ok );
+  if ( !ok || ( ok && !dl ) ) // project not flagged or set to use deprecated labels
+  {
+    if ( mOptsPage_LabelsOld )
+    {
+      disconnect( labelDialog, SIGNAL( labelSourceSet() ), this, SLOT( setLabelCheckBox() ) );
+      delete mOptsPage_LabelsOld;
+      mOptsPage_LabelsOld = 0;
+    }
+  }
 } // reset()
 
 
@@ -462,10 +476,13 @@ void QgsVectorLayerProperties::apply()
 
   actionDialog->apply();
 
-  if ( labelDialog )
-    labelDialog->apply();
-  layer->enableLabels( labelCheckBox->isChecked() );
-  layer->setLayerName( mLayerOrigNameLineEdit->text() );
+  if ( mOptsPage_LabelsOld )
+  {
+    if ( labelDialog )
+      labelDialog->apply();
+    layer->enableLabels( labelCheckBox->isChecked() );
+    layer->setLayerName( mLayerOrigNameLineEdit->text() );
+  }
 
   // Apply fields settings
   mFieldsPropertiesDialog->apply();