Fix incorrect warning dialog appearing when creating new ramp

Previously a "not available" warning dialog would appear when
attempting to create a new color ramp using the categorised renderer.

Author: nyalldawson

python/gui/symbology-ng/qgscolorrampcombobox.sip

@@ -17,6 +17,12 @@ class QgsColorRampComboBox : QComboBox
     //! return new instance of the current color ramp or NULL if there is no active color ramp
     QgsVectorColorRampV2* currentColorRamp();
 
+    /**Returns true if the current selection in the combo box is the option for creating
+     * a new color ramp
+     * @note added in QGIS 2.7
+     */
+    bool createNewColorRampSelected() const;
+
     //! @note not available in python bindings
     // static QSize rampIconSize;
 

src/gui/symbology-ng/qgscategorizedsymbolrendererv2widget.cpp

@@ -630,7 +630,7 @@ QgsVectorColorRampV2* QgsCategorizedSymbolRendererV2Widget::getColorRamp()
   {
     if ( cboCategorizedColorRamp->count() == 0 )
       QMessageBox::critical( this, tr( "Error" ), tr( "There are no available color ramps. You can add them in Style Manager." ) );
-    else
+    else if ( !cboCategorizedColorRamp->createNewColorRampSelected() )
       QMessageBox::critical( this, tr( "Error" ), tr( "The selected color ramp is not available." ) );
   }
   return ramp;

src/gui/symbology-ng/qgscolorrampcombobox.cpp

@@ -74,6 +74,12 @@ QgsVectorColorRampV2* QgsColorRampComboBox::currentColorRamp()
     return mStyle->colorRamp( rampName );
 }
 
+bool QgsColorRampComboBox::createNewColorRampSelected() const
+{
+  int index = currentIndex();
+  return index == count() - 1; //create new ramp is last item in combobox
+}
+
 void QgsColorRampComboBox::setSourceColorRamp( QgsVectorColorRampV2* sourceRamp )
 {
   mSourceColorRamp = sourceRamp->clone();

src/gui/symbology-ng/qgscolorrampcombobox.h

@@ -37,6 +37,12 @@ class GUI_EXPORT QgsColorRampComboBox : public QComboBox
     //! return new instance of the current color ramp or NULL if there is no active color ramp
     QgsVectorColorRampV2* currentColorRamp();
 
+    /**Returns true if the current selection in the combo box is the option for creating
+     * a new color ramp
+     * @note added in QGIS 2.7
+     */
+    bool createNewColorRampSelected() const;
+
     //! @note not available in python bindings
     static QSize rampIconSize;