Modernise diagram properties UI:

Switch to stacked widget, QgsScaleRangeWidget, QgsFieldExpression
widget, QgsDoubleSpinBoxes.

Rearrange and reword controls to clarify their behaviour.

python/core/qgsdiagramrendererv2.sip

@@ -87,6 +87,7 @@ class QgsDiagramSettings
     bool scaleByArea;
     int angleOffset;
 
+    bool scaleBasedVisibility;
     //scale range (-1 if no lower / upper bound )
     double minScaleDenominator;
     double maxScaleDenominator;

src/app/qgsdiagramproperties.h

@@ -38,15 +38,13 @@ class APP_EXPORT QgsDiagramProperties : public QWidget, private Ui::QgsDiagramPr
   public slots:
     void apply();
     void on_mDiagramTypeComboBox_currentIndexChanged( int index );
-    void on_mTransparencySlider_valueChanged( int value );
     void on_mAddCategoryPushButton_clicked();
     void on_mAttributesTreeWidget_itemDoubleClicked( QTreeWidgetItem * item, int column );
     void on_mFindMaximumValueButton_clicked();
     void on_mRemoveCategoryPushButton_clicked();
     void on_mDiagramFontButton_clicked();
     void on_mDiagramAttributesTreeWidget_itemDoubleClicked( QTreeWidgetItem * item, int column );
     void on_mEngineSettingsButton_clicked();
-    void showSizeAttributeExpressionDialog();
     void showAddAttributeExpressionDialog();
     void on_mDiagramStackedWidget_currentChanged( int index );
     void on_mPlacementComboBox_currentIndexChanged( int index );
@@ -56,9 +54,6 @@ class APP_EXPORT QgsDiagramProperties : public QWidget, private Ui::QgsDiagramPr
 
     QgsVectorLayer* mLayer;
 
-  private:
-    int mAvailableAttributes;
-
 };
 
 #endif // QGSDIAGRAMPROPERTIES_H

src/core/qgsdiagramrendererv2.cpp

@@ -91,6 +91,14 @@ void QgsDiagramSettings::readXML( const QDomElement& elem, const QgsVectorLayer*
 
   minScaleDenominator = elem.attribute( "minScaleDenominator", "-1" ).toDouble();
   maxScaleDenominator = elem.attribute( "maxScaleDenominator", "-1" ).toDouble();
+  if ( elem.hasAttribute( "scaleBasedVisibility" ) )
+  {
+    scaleBasedVisibility = ( elem.attribute( "scaleBasedVisibility", "1" ) != "0" );
+  }
+  else
+  {
+    scaleBasedVisibility = minScaleDenominator >= 0 && maxScaleDenominator >= 0;
+  }
 
   //mm vs map units
   if ( elem.attribute( "sizeType" ) == "MM" )
@@ -199,6 +207,7 @@ void QgsDiagramSettings::writeXML( QDomElement& rendererElem, QDomDocument& doc,
   categoryElem.setAttribute( "penColor", penColor.name() );
   categoryElem.setAttribute( "penAlpha", penColor.alpha() );
   categoryElem.setAttribute( "penWidth", QString::number( penWidth ) );
+  categoryElem.setAttribute( "scaleBasedVisibility", scaleBasedVisibility );
   categoryElem.setAttribute( "minScaleDenominator", QString::number( minScaleDenominator ) );
   categoryElem.setAttribute( "maxScaleDenominator", QString::number( maxScaleDenominator ) );
   categoryElem.setAttribute( "transparency", QString::number( transparency ) );

src/core/qgsdiagramrendererv2.h

@@ -120,6 +120,7 @@ class CORE_EXPORT QgsDiagramSettings
         , transparency( 0 )
         , scaleByArea( true )
         , angleOffset( 90 * 16 ) //top
+        , scaleBasedVisibility( false )
         , minScaleDenominator( -1 )
         , maxScaleDenominator( -1 )
         , minimumSize( 0.0 )
@@ -140,6 +141,7 @@ class CORE_EXPORT QgsDiagramSettings
     bool scaleByArea;
     int angleOffset;
 
+    bool scaleBasedVisibility;
     //scale range (-1 if no lower / upper bound )
     double minScaleDenominator;
     double maxScaleDenominator;