expression button and expression capability added to the field model

python/gui/gui.sip

@@ -29,6 +29,7 @@
 %Include qgsexpressionbuilderwidget.sip
 %Include qgsexpressionhighlighter.sip
 %Include qgsfieldcombobox.sip
+%Include qgsfieldexpressionwidget.sip
 %Include qgsfieldmodel.sip
 %Include qgsfieldvalidator.sip
 %Include qgsfiledropedit.sip

python/gui/qgsfieldcombobox.sip

@@ -1,5 +1,9 @@
 /**
  * @brief The QgsFieldComboBox is a combo box which displays the list of fields of a given layer.
+ * If allowed, expression may also be added at the bottom of the list of fields.
+ * It can be combined with a QgsExpressioButton to set the expression using the dedicated expression builder dialog.
+ * It might also be combined with a QgsMapLayerComboBox and the fields will be automatically updated according to the chosen layer.
+ * @see QgsExpressioButton, QgsMapLayerComboBox
  * @note added in 2.3
  */
 class QgsFieldComboBox : QComboBox
@@ -17,13 +21,25 @@ class QgsFieldComboBox : QComboBox
     explicit QgsFieldComboBox( QWidget *parent /TransferThis/ = 0 );
 
     /**
-     * @brief currentField returns the currently selected field
+     * @brief currentField returns the currently selected field or expression if allowed
+     * @param isExpression determines if the string returned is the name of a field or an expression
      */
-    QString currentField();
+    QString currentField( bool *isExpression = 0 );
+
+    //!! setAllowExpression sets if expression can be added the combo box
+    void setAllowExpression( bool allowExpression );
+    //! returns if the widget allows expressions to be added or not
+    bool allowExpression();
+
+    //! Returns the currently used layer
+    QgsVectorLayer* layer();
 
   signals:
     /**
-     * @brief fieldChanged the signal is emitted when the currently selected field changes
+     * @brief setField sets the currently selected field
+     * if expressions are allowed in the widget,
+     * then it will either set it as selected
+     * if it already exists, or it will add it otherwise
      */
     void fieldChanged( QString fieldName );
 

python/gui/qgsfieldexpressionwidget.sip

@@ -0,0 +1,44 @@
+
+class QgsFieldExpressionWidget : QWidget
+{
+%TypeHeaderCode
+#include "qgsfieldexpressionwidget.h"
+%End
+
+  public:
+    /**
+     * @brief QgsFieldExpressionWidget creates a widget with a combo box to display the fields and expression and a button to open the expression dialog
+     */
+    explicit QgsFieldExpressionWidget( QWidget *parent /TransferThis/ = 0 );
+
+    //! define the title used in the expression dialog
+    void setExpressionDialogTitle( QString title );
+
+    //! set the geometry calculator used in the expression dialog
+    void setGeomCalculator( const QgsDistanceArea &da );
+
+    //! return a pointer to the combo box in the widget
+    QgsFieldComboBox* fieldComboBox();
+
+    //! return a pointer to the tool button used in the widget
+    QToolButton* toolButton();
+
+    /**
+     * @brief currentField returns the currently selected field or expression if allowed
+     * @param isExpression determines if the string returned is the name of a field or an expression
+     */
+    QString currentField( bool *isExpression = 0 );
+
+    //! Returns the currently used layer
+    QgsVectorLayer* layer();
+
+  public slots:
+    //! set the layer used to display the fields and expression
+    void setLayer( QgsMapLayer* layer );
+
+    //! sets the current field or expression in the widget
+    void setField( QString fieldName );
+
+    //! open the expression dialog to edit the current or add a new expression
+    void editExpression();
+};

python/gui/qgsfieldmodel.sip

@@ -1,19 +1,22 @@
 
 /**
  * @brief The QgsFieldModel class is a model to display the list of fields of a layer in widgets.
+ * If allowed, expressions might be added to the end of the model.
  * It can be associated with a QgsMapLayerModel to dynamically display a layer and its fields.
  * @note added in 2.3
  */
-
 class QgsFieldModel : QAbstractItemModel
 {
 %TypeHeaderCode
 #include "qgsfieldmodel.h"
 %End
 
   public:
-    static const int FieldNameRole;
-    static const int FieldIndexRole;
+    enum FieldRoles {
+      FieldNameRole = 33, /* Qt::UserRole + 1, SIP does not accept any arithmetic" */
+      FieldIndexRole = 34,
+      ExpressionRole = 35
+    };
 
     /**
      * @brief QgsFieldModel creates a model to display the fields of a given layer
@@ -24,12 +27,30 @@ class QgsFieldModel : QAbstractItemModel
      * @brief indexFromName returns the index corresponding to a given fieldName
      */
     QModelIndex indexFromName( QString fieldName );
+
+    /**
+     * @brief setAllowExpression determines if expressions are allowed to be added to the model
+     */
+    void setAllowExpression( bool allowExpression );
+    bool allowExpression();
+
+    /**
+     * @brief setExpression sets a single expression to be added after the fields at the end of the model
+     * @return the model index of the newly added expression
+     */
+    QModelIndex setExpression( QString expression );
+
+    /**
+     * @brief layer returns the currently used layer
+     */
+    QgsMapLayer* layer();
 
   public slots:
     /**
      * @brief setLayer sets the layer of whch fields are displayed
      */
     void setLayer( QgsMapLayer *layer );
+
 
     // QAbstractItemModel interface
   public:

src/app/qgslabelinggui.cpp

@@ -58,8 +58,7 @@ QgsLabelingGui::QgsLabelingGui( QgsVectorLayer* layer, QgsMapCanvas* mapCanvas,
   mPreviewSize = 24;
 
   // main layer label-enabling connections
-  connect( chkEnableLabeling, SIGNAL( toggled( bool ) ), cboFieldName, SLOT( setEnabled( bool ) ) );
-  connect( chkEnableLabeling, SIGNAL( toggled( bool ) ), btnExpression, SLOT( setEnabled( bool ) ) );
+  connect( chkEnableLabeling, SIGNAL( toggled( bool ) ), mFieldExpressionWidget, SLOT( setEnabled( bool ) ) );
   connect( chkEnableLabeling, SIGNAL( toggled( bool ) ), mLabelingFrame, SLOT( setEnabled( bool ) ) );
 
   // connections for groupboxes with separate activation checkboxes (that need to honor data defined setting)
@@ -96,7 +95,6 @@ QgsLabelingGui::QgsLabelingGui( QgsVectorLayer* layer, QgsMapCanvas* mapCanvas,
   connect( mLimitLabelChkBox, SIGNAL( toggled( bool ) ), mLimitLabelSpinBox, SLOT( setEnabled( bool ) ) );
 
   connect( btnEngineSettings, SIGNAL( clicked() ), this, SLOT( showEngineConfigDialog() ) );
-  connect( btnExpression, SIGNAL( clicked() ), this, SLOT( showExpressionDialog() ) );
 
   // set placement methods page based on geometry type
   switch ( layer->geometryType() )
@@ -121,7 +119,14 @@ QgsLabelingGui::QgsLabelingGui( QgsVectorLayer* layer, QgsMapCanvas* mapCanvas,
   mDirectSymbolsFrame->setVisible( layer->geometryType() == QGis::Line );
   mMinSizeFrame->setVisible( layer->geometryType() != QGis::Point );
 
-  populateFieldNames(); // this is just for label text combo box
+  // field combo and expression button
+  mFieldExpressionWidget->setLayer( mLayer );
+  QgsDistanceArea myDa;
+  myDa.setSourceCrs( mLayer->crs().srsid() );
+  myDa.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoid( QgsProject::instance()->readEntry( "Measure", "/Ellipsoid", GEO_NONE ) );
+  mFieldExpressionWidget->setGeomCalculator( myDa );
+
   populateFontCapitalsComboBox();
 
   // set up quadrant offset button group
@@ -234,15 +239,11 @@ void QgsLabelingGui::init()
 
   // enable/disable main options based upon whether layer is being labeled
   chkEnableLabeling->setChecked( lyr.enabled );
-  cboFieldName->setEnabled( chkEnableLabeling->isChecked() );
-  btnExpression->setEnabled( chkEnableLabeling->isChecked() );
+  mFieldExpressionWidget->setEnabled( chkEnableLabeling->isChecked() );
   mLabelingFrame->setEnabled( chkEnableLabeling->isChecked() );
 
-  // add the current expression to the bottom of the list
-  if ( lyr.isExpression && !lyr.fieldName.isEmpty() )
-    cboFieldName->addItem( lyr.fieldName );
-
-  cboFieldName->setCurrentIndex( cboFieldName->findText( lyr.fieldName ) );
+  // set the current field or add the current expression to the bottom of the list
+  mFieldExpressionWidget->setField( lyr.fieldName );
 
   // populate placement options
   int distUnitIndex = lyr.distInMapUnits ? 1 : 0;
@@ -509,10 +510,9 @@ QgsPalLayerSettings QgsLabelingGui::layerSettings()
 
   lyr.enabled = chkEnableLabeling->isChecked();
 
-  lyr.fieldName = cboFieldName->currentText();
-  // Check if we are an expression. Also treats expressions with just a column name as non expressions,
-  // this saves time later so we don't have to parse the expression tree.
-  lyr.isExpression = mLayer->fieldNameIndex( lyr.fieldName ) == -1 && !lyr.fieldName.isEmpty();
+  bool isExpression;
+  lyr.fieldName = mFieldExpressionWidget->currentField( &isExpression );
+  lyr.isExpression = isExpression;
 
   lyr.dist = 0;
   lyr.placementFlags = 0;
@@ -775,15 +775,6 @@ void QgsLabelingGui::setDataDefinedProperty( const QgsDataDefinedButton* ddBtn,
   lyr.setDataDefinedProperty( p, map.value( "active" ).toInt(), map.value( "useexpr" ).toInt(), map.value( "expression" ), map.value( "field" ) );
 }
 
-void QgsLabelingGui::populateFieldNames()
-{
-  const QgsFields& fields = mLayer->pendingFields();
-  for ( int idx = 0; idx < fields.count(); ++idx )
-  {
-    cboFieldName->addItem( fields[idx].name() );
-  }
-}
-
 void QgsLabelingGui::populateDataDefinedButtons( QgsPalLayerSettings& s )
 {
   // don't register enable/disable siblings, since visual feedback from data defined buttons should be enough,
@@ -1175,30 +1166,6 @@ void QgsLabelingGui::showEngineConfigDialog()
   dlg.exec();
 }
 
-void QgsLabelingGui::showExpressionDialog()
-{
-  QgsExpressionBuilderDialog dlg( mLayer, cboFieldName->currentText() , this );
-  dlg.setWindowTitle( tr( "Expression based label" ) );
-
-  QgsDistanceArea myDa;
-  myDa.setSourceCrs( mLayer->crs().srsid() );
-  myDa.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
-  myDa.setEllipsoid( QgsProject::instance()->readEntry( "Measure", "/Ellipsoid", GEO_NONE ) );
-  dlg.setGeomCalculator( myDa );
-
-  if ( dlg.exec() == QDialog::Accepted )
-  {
-    QString expression =  dlg.expressionText();
-    //Only add the expression if the user has entered some text.
-    if ( !expression.isEmpty() )
-    {
-      cboFieldName->addItem( expression );
-      cboFieldName->setCurrentIndex( cboFieldName->count() - 1 );
-    }
-  }
-  activateWindow(); // set focus back parent
-}
-
 void QgsLabelingGui::syncDefinedCheckboxFrame( QgsDataDefinedButton* ddBtn, QCheckBox* chkBx, QFrame* f )
 {
   if ( ddBtn->isActive() && !chkBx->isChecked() )

src/app/qgslabelinggui.h

@@ -45,7 +45,6 @@ class APP_EXPORT QgsLabelingGui : public QWidget, private Ui::QgsLabelingGuiBase
     void apply();
     void changeTextColor( const QColor &color );
     void showEngineConfigDialog();
-    void showExpressionDialog();
     void changeBufferColor( const QColor &color );
 
     void updateUi();

src/gui/CMakeLists.txt

@@ -89,6 +89,7 @@ qgsexpressionselectiondialog.cpp
 qgsextentgroupbox.cpp
 qgsfeatureselectiondlg.cpp
 qgsfieldcombobox.cpp
+qgsfieldexpressionwidget.cpp
 qgsfieldmodel.cpp
 qgsfieldvalidator.cpp
 qgsfiledropedit.cpp
@@ -233,6 +234,7 @@ qgsexpressionselectiondialog.h
 qgsextentgroupbox.h
 qgsfeatureselectiondlg.h
 qgsfieldcombobox.h
+qgsfieldexpressionwidget.h
 qgsfieldmodel.h
 qgsfieldvalidator.h
 qgsfilterlineedit.h
@@ -303,6 +305,7 @@ qgsexpressionhighlighter.h
 qgsexpressionselectiondialog.h
 qgsfeatureselectiondlg.h
 qgsfieldcombobox.h
+qgsfieldexpressionwidget.h
 qgsfieldmodel.h
 qgsfieldvalidator.h
 qgsfiledropedit.h

src/gui/qgsfieldcombobox.cpp

@@ -31,21 +31,41 @@ void QgsFieldComboBox::setLayer( QgsMapLayer *layer )
   mFieldModel->setLayer( layer );
 }
 
+QgsVectorLayer *QgsFieldComboBox::layer()
+{
+  QgsMapLayer* layer = mFieldModel->layer();
+  QgsVectorLayer* vl = dynamic_cast<QgsVectorLayer*>( layer );
+  if ( vl )
+    return vl;
+  else
+    return 0;
+}
+
 void QgsFieldComboBox::setField( QString fieldName )
 {
   QModelIndex idx = mFieldModel->indexFromName( fieldName );
   if ( idx.isValid() )
   {
     setCurrentIndex( idx.row() );
+    return;
   }
-  else
+
+  if ( mAllowExpression )
   {
-    setCurrentIndex( -1 );
+    mFieldModel->setExpression( fieldName );
+    setCurrentIndex( findText( fieldName ) );
+    return;
   }
+  setCurrentIndex( -1 );
 }
 
-QString QgsFieldComboBox::currentField()
+QString QgsFieldComboBox::currentField( bool *isExpression )
 {
+  if ( isExpression )
+  {
+    *isExpression = false;
+  }
+
   int i = currentIndex();
 
   const QModelIndex index = mFieldModel->index( i, 0 );
@@ -54,8 +74,31 @@ QString QgsFieldComboBox::currentField()
     return "";
   }
 
-  QString name = mFieldModel->data( index, QgsFieldModel::FieldNameRole ).toString();
-  return name;
+  QString fieldName = mFieldModel->data( index, QgsFieldModel::FieldNameRole ).toString();
+  if ( !fieldName.isEmpty() )
+  {
+    return fieldName;
+  }
+
+  if ( mAllowExpression )
+  {
+    QString expression = mFieldModel->data( index, QgsFieldModel::ExpressionRole ).toString();
+    if ( !expression.isEmpty() )
+    {
+      if ( isExpression )
+      {
+        *isExpression = true;
+      }
+      return expression;
+    }
+  }
+
+  return "";
+}
+
+void QgsFieldComboBox::setAllowExpression( bool allowExpression )
+{
+  mFieldModel->setAllowExpression( allowExpression );
 }
 
 void QgsFieldComboBox::indexChanged( int i )