[FEATURE] Evaluate expressions entered in QgsDoubleSpinBox

Allows entry of QGIS expressions into the spin box. The expression
is evaluated on enter or loss of focus and then discarded.

(refs #10544)

Author: nyalldawson

python/core/qgsexpression.sip

@@ -110,6 +110,15 @@ class QgsExpression
                                           const QgsDistanceArea* distanceArea = 0
                                         );
 
+    /**Attempts to evaluate a text string as an expression to a resultant double
+     * value.
+     * @param text text to evaluate as expression
+     * @param fallbackValue value to return if text can not be evaluated as a double
+     * @returns evaluated double value, or fallback value
+     * @note added in QGIS 2.7
+    */
+    static double evaluateToDouble( const QString& text, const double fallbackValue );
+
     enum UnaryOperator
     {
       uoNot,

python/gui/editorwidgets/qgsdoublespinbox.sip

@@ -19,24 +19,41 @@ class QgsDoubleSpinBox : QDoubleSpinBox
     void setShowClearButton( const bool showClearButton );
     bool showClearButton() const;
 
+    /**Sets if the widget will allow entry of simple expressions, which are
+     * evaluated and then discarded.
+     * @param enabled set to true to allow expression entry
+     * @note added in QGIS 2.7
+     */
+    void setExpressionsEnabled( const bool enabled );
+    /**Returns whether the widget will allow entry of simple expressions, which are
+     * evaluated and then discarded.
+     * @returns true if spin box allows expression entry
+     * @note added in QGIS 2.7
+     */
+    bool expressionsEnabled() const;
+
     //! Set the current value to the value defined by the clear value.
     virtual void clear();
 
     /**
      * @brief setClearValue defines the clear value as a custom value and will automatically set the clear value mode to CustomValue
-     * @param defines the numerical value used as the clear value
+     * @param customValue defines the numerical value used as the clear value
      * @param clearValueText is the text displayed when the spin box is at the clear value. If not specified, no special value text is used.
      */
     void setClearValue( double customValue, QString clearValueText = QString() );
     /**
      * @brief setClearValueMode defines if the clear value should be the minimum or maximum values of the widget or a custom value
+     * @param mode mode to user for clear value
      * @param clearValueText is the text displayed when the spin box is at the clear value. If not specified, no special value text is used.
      */
     void setClearValueMode( ClearValueMode mode, QString clearValueText = QString() );
 
     //! returns the value used when clear() is called.
     double clearValue() const;
 
+    virtual double valueFromText( const QString & text ) const;
+    virtual QValidator::State validate( QString & input, int & pos ) const;
+
   protected:
     virtual void resizeEvent( QResizeEvent* event );
     virtual void changeEvent( QEvent* event );

python/gui/editorwidgets/qgsspinbox.sip

@@ -23,13 +23,14 @@ class QgsSpinBox : QSpinBox
     virtual void clear();
 
     /**
-     * @brief setClearValue defines the clear value as a custom value and will automatically set the clear value mode to CustomValue
-     * @param defines the numerical value used as the clear value
+     * @brief setClearValue defines the clear value for the widget and will automatically set the clear value mode to CustomValue
+     * @param customValue defines the numerical value used as the clear value
      * @param clearValueText is the text displayed when the spin box is at the clear value. If not specified, no special value text is used.
      */
     void setClearValue( int customValue, QString clearValueText = QString() );
     /**
      * @brief setClearValueMode defines if the clear value should be the minimum or maximum values of the widget or a custom value
+     * @param mode mode to user for clear value
      * @param clearValueText is the text displayed when the spin box is at the clear value. If not specified, no special value text is used.
      */
     void setClearValueMode( ClearValueMode mode, QString clearValueText = QString() );

src/core/qgsexpression.cpp

@@ -2074,6 +2074,27 @@ QString QgsExpression::replaceExpressionText( const QString &action, const QgsFe
   return expr_action;
 }
 
+double QgsExpression::evaluateToDouble( const QString &text, const double fallbackValue )
+{
+  bool ok;
+  //first test if text is directly convertible to double
+  double convertedValue = text.toDouble( &ok );
+  if ( ok )
+  {
+    return convertedValue;
+  }
+
+  //otherwise try to evalute as expression
+  QgsExpression expr( text );
+  QVariant result = expr.evaluate();
+  convertedValue = result.toDouble( &ok );
+  if ( expr.hasEvalError() || !ok )
+  {
+    return fallbackValue;
+  }
+  return convertedValue;
+}
+
 
 ///////////////////////////////////////////////
 // nodes

src/core/qgsexpression.h

@@ -200,6 +200,16 @@ class CORE_EXPORT QgsExpression
                                           const QMap<QString, QVariant> *substitutionMap = 0,
                                           const QgsDistanceArea* distanceArea = 0
                                         );
+
+    /**Attempts to evaluate a text string as an expression to a resultant double
+     * value.
+     * @param text text to evaluate as expression
+     * @param fallbackValue value to return if text can not be evaluated as a double
+     * @returns evaluated double value, or fallback value
+     * @note added in QGIS 2.7
+    */
+    static double evaluateToDouble( const QString& text, const double fallbackValue );
+
     enum UnaryOperator
     {
       uoNot,

src/gui/editorwidgets/qgsdoublespinbox.cpp

@@ -20,7 +20,7 @@
 #include <QToolButton>
 
 #include "qgsdoublespinbox.h"
-
+#include "qgsexpression.h"
 #include "qgsapplication.h"
 #include "qgslogger.h"
 
@@ -29,6 +29,7 @@ QgsDoubleSpinBox::QgsDoubleSpinBox( QWidget *parent )
     , mShowClearButton( true )
     , mClearValueMode( MinimumValue )
     , mCustomClearValue( 0.0 )
+    , mExpressionsEnabled( true )
 {
   mClearButton = new QToolButton( this );
   mClearButton->setIcon( QgsApplication::getThemeIcon( "/mIconClear.svg" ) );
@@ -51,6 +52,11 @@ void QgsDoubleSpinBox::setShowClearButton( const bool showClearButton )
   mClearButton->setVisible( shouldShowClearForValue( value() ) );
 }
 
+void QgsDoubleSpinBox::setExpressionsEnabled( const bool enabled )
+{
+  mExpressionsEnabled = enabled;
+}
+
 void QgsDoubleSpinBox::changeEvent( QEvent *event )
 {
   QDoubleSpinBox::changeEvent( event );
@@ -105,6 +111,63 @@ double QgsDoubleSpinBox::clearValue() const
     return mCustomClearValue;
 }
 
+QString QgsDoubleSpinBox::stripped( const QString &originalText ) const
+{
+  //adapted from QAbstractSpinBoxPrivate::stripped
+  //trims whitespace, prefix and suffix from spin box text
+  QString text = originalText;
+  if ( specialValueText().size() == 0 || text != specialValueText() )
+  {
+    int from = 0;
+    int size = text.size();
+    bool changed = false;
+    if ( prefix().size() && text.startsWith( prefix() ) )
+    {
+      from += prefix().size();
+      size -= from;
+      changed = true;
+    }
+    if ( suffix().size() && text.endsWith( suffix() ) )
+    {
+      size -= suffix().size();
+      changed = true;
+    }
+    if ( changed )
+      text = text.mid( from, size );
+  }
+
+  text = text.trimmed();
+
+  return text;
+}
+
+double QgsDoubleSpinBox::valueFromText( const QString &text ) const
+{
+  if ( !mExpressionsEnabled )
+  {
+    return QDoubleSpinBox::valueFromText( text );
+  }
+
+  QString trimmedText = stripped( text );
+  if ( trimmedText.isEmpty() )
+  {
+    return clearValue();
+  }
+
+  return QgsExpression::evaluateToDouble( trimmedText, value() );
+}
+
+QValidator::State QgsDoubleSpinBox::validate( QString &input, int &pos ) const
+{
+  if ( !mExpressionsEnabled )
+  {
+    QValidator::State r = QDoubleSpinBox::validate( input, pos );
+    return r;
+  }
+
+  return QValidator::Acceptable;
+}
+
 int QgsDoubleSpinBox::frameWidth() const
 {
   return style()->pixelMetric( QStyle::PM_DefaultFrameWidth );

src/gui/editorwidgets/qgsdoublespinbox.h

@@ -28,6 +28,7 @@ class GUI_EXPORT QgsDoubleSpinBox : public QDoubleSpinBox
 {
     Q_OBJECT
     Q_PROPERTY( bool showClearButton READ showClearButton WRITE setShowClearButton )
+    Q_PROPERTY( bool expressionsEnabled READ expressionsEnabled WRITE setExpressionsEnabled )
 
   public:
     enum ClearValueMode
@@ -43,24 +44,41 @@ class GUI_EXPORT QgsDoubleSpinBox : public QDoubleSpinBox
     void setShowClearButton( const bool showClearButton );
     bool showClearButton() const {return mShowClearButton;}
 
+    /**Sets if the widget will allow entry of simple expressions, which are
+     * evaluated and then discarded.
+     * @param enabled set to true to allow expression entry
+     * @note added in QGIS 2.7
+     */
+    void setExpressionsEnabled( const bool enabled );
+    /**Returns whether the widget will allow entry of simple expressions, which are
+     * evaluated and then discarded.
+     * @returns true if spin box allows expression entry
+     * @note added in QGIS 2.7
+     */
+    bool expressionsEnabled() const {return mExpressionsEnabled;}
+
     //! Set the current value to the value defined by the clear value.
     virtual void clear();
 
     /**
      * @brief setClearValue defines the clear value as a custom value and will automatically set the clear value mode to CustomValue
-     * @param defines the numerical value used as the clear value
+     * @param customValue defines the numerical value used as the clear value
      * @param clearValueText is the text displayed when the spin box is at the clear value. If not specified, no special value text is used.
      */
     void setClearValue( double customValue, QString clearValueText = QString() );
     /**
      * @brief setClearValueMode defines if the clear value should be the minimum or maximum values of the widget or a custom value
+     * @param mode mode to user for clear value
      * @param clearValueText is the text displayed when the spin box is at the clear value. If not specified, no special value text is used.
      */
     void setClearValueMode( ClearValueMode mode, QString clearValueText = QString() );
 
     //! returns the value used when clear() is called.
     double clearValue() const;
 
+    virtual double valueFromText( const QString & text ) const;
+    virtual QValidator::State validate( QString & input, int & pos ) const;
+
   protected:
     virtual void resizeEvent( QResizeEvent* event );
     virtual void changeEvent( QEvent* event );
@@ -76,7 +94,10 @@ class GUI_EXPORT QgsDoubleSpinBox : public QDoubleSpinBox
     ClearValueMode mClearValueMode;
     double mCustomClearValue;
 
+    bool mExpressionsEnabled;
+
     QToolButton* mClearButton;
+    QString stripped( const QString &originalText ) const;
 };
 
 #endif // QGSDOUBLESPPINBOX_H

src/gui/editorwidgets/qgsspinbox.h

@@ -48,12 +48,13 @@ class GUI_EXPORT QgsSpinBox : public QSpinBox
 
     /**
      * @brief setClearValue defines the clear value for the widget and will automatically set the clear value mode to CustomValue
-     * @param defines the numerical value used as the clear value
+     * @param customValue defines the numerical value used as the clear value
      * @param clearValueText is the text displayed when the spin box is at the clear value. If not specified, no special value text is used.
      */
     void setClearValue( int customValue, QString clearValueText = QString() );
     /**
      * @brief setClearValueMode defines if the clear value should be the minimum or maximum values of the widget or a custom value
+     * @param mode mode to user for clear value
      * @param clearValueText is the text displayed when the spin box is at the clear value. If not specified, no special value text is used.
      */
     void setClearValueMode( ClearValueMode mode, QString clearValueText = QString() );

tests/src/core/testqgsexpression.cpp

@@ -285,6 +285,7 @@ class TestQgsExpression: public QObject
       QTest::newRow( "max(1,3.5,-2.1)" ) << "max(1,3.5,-2.1)" << false << QVariant( 3.5 );
       QTest::newRow( "min(-1.5)" ) << "min(-1.5)" << false << QVariant( -1.5 );
       QTest::newRow( "min(-16.6,3.5,-2.1)" ) << "min(-16.6,3.5,-2.1)" << false << QVariant( -16.6 );
+      QTest::newRow( "min(5,3.5,-2.1)" ) << "min(5,3.5,-2.1)" << false << QVariant( -2.1 );
       QTest::newRow( "clamp(-2,1,5)" ) << "clamp(-2,1,5)" << false << QVariant( 1.0 );
       QTest::newRow( "clamp(-2,-10,5)" ) << "clamp(-2,-10,5)" << false << QVariant( -2.0 );
       QTest::newRow( "clamp(-2,100,5)" ) << "clamp(-2,100,5)" << false << QVariant( 5.0 );
@@ -327,6 +328,7 @@ class TestQgsExpression: public QObject
       QTest::newRow( "substr" ) << "substr('HeLLo', 3,2)" << false << QVariant( "LL" );
       QTest::newRow( "substr outside" ) << "substr('HeLLo', -5,2)" << false << QVariant( "" );
       QTest::newRow( "regexp_substr" ) << "regexp_substr('abc123','(\\\\d+)')" << false << QVariant( "123" );
+      QTest::newRow( "regexp_substr no hit" ) << "regexp_substr('abcdef','(\\\\d+)')" << false << QVariant( "" );
       QTest::newRow( "regexp_substr invalid" ) << "regexp_substr('abc123','([[[')" << true << QVariant();
       QTest::newRow( "strpos" ) << "strpos('Hello World','World')" << false << QVariant( 6 );
       QTest::newRow( "strpos outside" ) << "strpos('Hello World','blah')" << false << QVariant( -1 );
@@ -345,6 +347,8 @@ class TestQgsExpression: public QObject
       QTest::newRow( "wordwrap" ) << "wordwrap('university of qgis',-3,' ')" << false << QVariant( "university\nof qgis" );
       QTest::newRow( "wordwrap" ) << "wordwrap('university of qgis\nsupports many multiline',-5,' ')" << false << QVariant( "university\nof qgis\nsupports\nmany multiline" );
       QTest::newRow( "format" ) << "format('%1 %2 %3 %1', 'One', 'Two', 'Three')" << false << QVariant( "One Two Three One" );
+      QTest::newRow( "concat" ) << "concat('a', 'b', 'c', 'd')" << false << QVariant( "abcd" );
+      QTest::newRow( "concat single" ) << "concat('a')" << false << QVariant( "a" );
 
       // implicit conversions
       QTest::newRow( "implicit int->text" ) << "length(123)" << false << QVariant( 3 );
@@ -977,6 +981,15 @@ class TestQgsExpression: public QObject
         lst << i;
       QtConcurrent::blockingMap( lst, _parseAndEvalExpr );
     }
+
+    void evaluateToDouble()
+    {
+      QCOMPARE( QgsExpression::evaluateToDouble( QString( "5" ), 0.0 ), 5.0 );
+      QCOMPARE( QgsExpression::evaluateToDouble( QString( "5+6" ), 0.0 ), 11.0 );
+      QCOMPARE( QgsExpression::evaluateToDouble( QString( "5*" ), 7.0 ), 7.0 );
+      QCOMPARE( QgsExpression::evaluateToDouble( QString( "a" ), 9.0 ), 9.0 );
+      QCOMPARE( QgsExpression::evaluateToDouble( QString(), 9.0 ), 9.0 );
+    }
 };
 
 QTEST_MAIN( TestQgsExpression )

tests/src/gui/CMakeLists.txt

@@ -119,6 +119,7 @@ ADD_QGIS_TEST(zoomtest testqgsmaptoolzoom.cpp)
 ADD_QGIS_TEST(projectionissues testprojectionissues.cpp)
 ADD_QGIS_TEST(scalecombobox testqgsscalecombobox.cpp)
 ADD_QGIS_TEST(dualviewtest testqgsdualview.cpp )
+ADD_QGIS_TEST(doublespinbox testqgsdoublespinbox.cpp)
 ADD_QGIS_TEST(rubberbandtest testqgsrubberband.cpp )
 ADD_QGIS_TEST(mapcanvastest testqgsmapcanvas.cpp )