Merge pull request #41241 from 3nids/longer-preview

QgsExpressionPreviewWidget: display longer preview in tooltip if needed
qgis · Jan 28, 2021 · c4a69f6 · c4a69f6
2 parents f073292 + 2f54585
commit c4a69f6
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Showing 4 changed files with 18 additions and 13 deletions.
diff --git a/python/core/auto_generated/expression/qgsexpression.sip.in b/python/core/auto_generated/expression/qgsexpression.sip.in
@@ -590,13 +590,14 @@ Returns the translated name for a function group.
 :param group: untranslated group name
 %End
 
-    static QString formatPreviewString( const QVariant &value, bool htmlOutput = true );
+    static QString formatPreviewString( const QVariant &value, bool htmlOutput = true, int maximumPreviewLength = 60 );
 %Docstring
 Formats an expression result for friendly display to the user. Truncates the result to a sensible
 length, and presents text representations of non numeric/text types (e.g., geometries and features).
 
 :param value: expression result to format
 :param htmlOutput: set to ``True`` to allow HTML formatting, or ``False`` for plain text output
+:param maximumPreviewLength: define the maximum character length of the preview
 
 :return: formatted string, may contain HTML formatting characters if ``htmlOutput`` is ``True``
 

diff --git a/src/core/expression/qgsexpression.cpp b/src/core/expression/qgsexpression.cpp
@@ -942,10 +942,8 @@ QString QgsExpression::group( const QString &name )
   return sGroups()->value( name, name );
 }
 
-QString QgsExpression::formatPreviewString( const QVariant &value, const bool htmlOutput )
+QString QgsExpression::formatPreviewString( const QVariant &value, const bool htmlOutput, int maximumPreviewLength )
 {
-  static const int MAX_PREVIEW = 60;
-
   const QString startToken = htmlOutput ? QStringLiteral( "<i>&lt;" ) : QStringLiteral( "<" );
   const QString endToken = htmlOutput ? QStringLiteral( "&gt;</i>" ) : QStringLiteral( ">" );
 
@@ -1015,9 +1013,9 @@ QString QgsExpression::formatPreviewString( const QVariant &value, const bool ht
   else if ( value.type() == QVariant::String )
   {
     const QString previewString = value.toString();
-    if ( previewString.length() > MAX_PREVIEW + 3 )
+    if ( previewString.length() > maximumPreviewLength + 3 )
     {
-      return tr( "'%1…'" ).arg( previewString.left( MAX_PREVIEW ) );
+      return tr( "'%1…'" ).arg( previewString.left( maximumPreviewLength ) );
     }
     else
     {
@@ -1036,9 +1034,9 @@ QString QgsExpression::formatPreviewString( const QVariant &value, const bool ht
         separator = QStringLiteral( "," );
 
       mapStr.append( QStringLiteral( " '%1': %2" ).arg( it.key(), formatPreviewString( it.value(), htmlOutput ) ) );
-      if ( mapStr.length() > MAX_PREVIEW - 3 )
+      if ( mapStr.length() > maximumPreviewLength - 3 )
       {
-        mapStr = tr( "%1…" ).arg( mapStr.left( MAX_PREVIEW - 2 ) );
+        mapStr = tr( "%1…" ).arg( mapStr.left( maximumPreviewLength - 2 ) );
         break;
       }
     }
@@ -1060,9 +1058,9 @@ QString QgsExpression::formatPreviewString( const QVariant &value, const bool ht
 
       listStr.append( " " );
       listStr.append( formatPreviewString( arrayValue, htmlOutput ) );
-      if ( listStr.length() > MAX_PREVIEW - 3 )
+      if ( listStr.length() > maximumPreviewLength - 3 )
       {
-        listStr = QString( tr( "%1…" ) ).arg( listStr.left( MAX_PREVIEW - 2 ) );
+        listStr = QString( tr( "%1…" ) ).arg( listStr.left( maximumPreviewLength - 2 ) );
         break;
       }
     }

diff --git a/src/core/expression/qgsexpression.h b/src/core/expression/qgsexpression.h
@@ -595,10 +595,11 @@ class CORE_EXPORT QgsExpression
      * length, and presents text representations of non numeric/text types (e.g., geometries and features).
      * \param value expression result to format
      * \param htmlOutput set to TRUE to allow HTML formatting, or FALSE for plain text output
+     * \param maximumPreviewLength define the maximum character length of the preview
      * \returns formatted string, may contain HTML formatting characters if \a htmlOutput is TRUE
      * \since QGIS 2.14
      */
-    static QString formatPreviewString( const QVariant &value, bool htmlOutput = true );
+    static QString formatPreviewString( const QVariant &value, bool htmlOutput = true, int maximumPreviewLength = 60 );
 
     /**
      * Create an expression allowing to evaluate if a field is equal to a

diff --git a/src/gui/qgsexpressionpreviewwidget.cpp b/src/gui/qgsexpressionpreviewwidget.cpp
@@ -98,9 +98,10 @@ void QgsExpressionPreviewWidget::refreshPreview()
     }
 
     QVariant value = mExpression.evaluate( &mExpressionContext );
+    QString preview = QgsExpression::formatPreviewString( value );
     if ( !mExpression.hasEvalError() )
     {
-      mPreviewLabel->setText( QgsExpression::formatPreviewString( value ) );
+      mPreviewLabel->setText( preview );
     }
 
     if ( mExpression.hasParserError() || mExpression.hasEvalError() )
@@ -124,7 +125,11 @@ void QgsExpressionPreviewWidget::refreshPreview()
     else
     {
       mPreviewLabel->setStyleSheet( QString() );
-      setExpressionToolTip( QString() );
+      QString longerPreview = QgsExpression::formatPreviewString( value, true, 255 );
+      if ( longerPreview != preview )
+        setExpressionToolTip( longerPreview );
+      else
+        setExpressionToolTip( QString() );
       emit expressionParsed( true );
       setParserError( false );
       setEvalError( false );