Fix Capitalize First Letter fails with curved labels (fix #14875)

Instead of using QFont's inbuilt capitalization support, which
applies only on rendering and accordingly fails for curved
labels which are drawn one character at a time, we now manually
capitalize label text while registering features.

The capitalize first method from Qt was reimplemented in QgsStringUtils
(together with what I expect is better handling of unicode characters
over the Qt method).

This change also makes it possible to implement other capitalization
methods not directly supported by Qt

(cherry-picked from 15dd295)

python/core/qgsstringutils.sip

@@ -122,6 +122,25 @@ class QgsStringUtils
 #include <qgsstringutils.h>
 %End
   public:
+
+
+    //! Capitalization options
+    enum Capitalization
+    {
+      MixedCase, //!< Mixed case, ie no change
+      AllUppercase, //!< Convert all characters to uppercase
+      AllLowercase,  //!< Convert all characters to lowercase
+      ForceFirstLetterToCapital, //!< Convert just the first letter of each word to uppercase, leave the rest untouched
+    };
+
+    /** Converts a string by applying capitalization rules to the string.
+     * @param string input string
+     * @param capitalization capitalization type to apply
+     * @return capitalized string
+     * @note added in QGIS 3.0
+     */
+    static QString capitalize( const QString& string, Capitalization capitalization );
+
     /** Returns the Levenshtein edit distance between two strings. This equates to the minimum
      * number of character edits (insertions, deletions or substitutions) required to change
      * one string to another.

src/core/qgspallabeling.cpp

@@ -2306,6 +2306,7 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
 
   // calculate rest of font attributes and store any data defined values
   // this is done here for later use in making label backgrounds part of collision management (when implemented)
+  labelFont.setCapitalization( QFont::MixedCase ); // reset this - we don't use QFont's handling as it breaks with curved labels
   parseTextStyle( labelFont, fontunits, context );
   parseTextFormatting( context );
   parseTextBuffer( context );
@@ -2345,6 +2346,41 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
     labelText = substitutions.process( labelText );
   }
 
+  // apply capitalization
+  QgsStringUtils::Capitalization capitalization = QgsStringUtils::MixedCase;
+  // maintain API - capitalization may have been set in textFont
+  if ( textFont.capitalization() != QFont::MixedCase )
+  {
+    capitalization = static_cast< QgsStringUtils::Capitalization >( textFont.capitalization() );
+  }
+  // data defined font capitalization?
+  if ( dataDefinedEvaluate( QgsPalLayerSettings::FontCase, exprVal, &context.expressionContext() ) )
+  {
+    QString fcase = exprVal.toString().trimmed();
+    QgsDebugMsgLevel( QString( "exprVal FontCase:%1" ).arg( fcase ), 4 );
+
+    if ( !fcase.isEmpty() )
+    {
+      if ( fcase.compare( "NoChange", Qt::CaseInsensitive ) == 0 )
+      {
+        capitalization = QgsStringUtils::MixedCase;
+      }
+      else if ( fcase.compare( "Upper", Qt::CaseInsensitive ) == 0 )
+      {
+        capitalization = QgsStringUtils::AllUppercase;
+      }
+      else if ( fcase.compare( "Lower", Qt::CaseInsensitive ) == 0 )
+      {
+        capitalization = QgsStringUtils::AllLowercase;
+      }
+      else if ( fcase.compare( "Capitalize", Qt::CaseInsensitive ) == 0 )
+      {
+        capitalization = QgsStringUtils::ForceFirstLetterToCapital;
+      }
+    }
+  }
+  labelText = QgsStringUtils::capitalize( labelText, capitalization );
+
   // data defined format numbers?
   bool formatnum = formatNumbers;
   if ( dataDefinedEvaluate( QgsPalLayerSettings::NumFormat, exprVal, &context.expressionContext(), formatNumbers ) )
@@ -3396,7 +3432,6 @@ void QgsPalLayerSettings::parseTextStyle( QFont& labelFont,
     // copy over existing font settings
     //newFont = newFont.resolve( labelFont ); // should work, but let's be sure what's being copied
     newFont.setPixelSize( labelFont.pixelSize() );
-    newFont.setCapitalization( labelFont.capitalization() );
     newFont.setUnderline( labelFont.underline() );
     newFont.setStrikeOut( labelFont.strikeOut() );
     newFont.setWordSpacing( labelFont.wordSpacing() );
@@ -3433,39 +3468,6 @@ void QgsPalLayerSettings::parseTextStyle( QFont& labelFont,
   }
   labelFont.setLetterSpacing( QFont::AbsoluteSpacing, scaleToPixelContext( letterspace, context, fontunits, false, fontSizeMapUnitScale ) );
 
-  // data defined font capitalization?
-  QFont::Capitalization fontcaps = labelFont.capitalization();
-  if ( dataDefinedEvaluate( QgsPalLayerSettings::FontCase, exprVal, &context.expressionContext() ) )
-  {
-    QString fcase = exprVal.toString().trimmed();
-    QgsDebugMsgLevel( QString( "exprVal FontCase:%1" ).arg( fcase ), 4 );
-
-    if ( !fcase.isEmpty() )
-    {
-      if ( fcase.compare( "NoChange", Qt::CaseInsensitive ) == 0 )
-      {
-        fontcaps = QFont::MixedCase;
-      }
-      else if ( fcase.compare( "Upper", Qt::CaseInsensitive ) == 0 )
-      {
-        fontcaps = QFont::AllUppercase;
-      }
-      else if ( fcase.compare( "Lower", Qt::CaseInsensitive ) == 0 )
-      {
-        fontcaps = QFont::AllLowercase;
-      }
-      else if ( fcase.compare( "Capitalize", Qt::CaseInsensitive ) == 0 )
-      {
-        fontcaps = QFont::Capitalize;
-      }
-
-      if ( fontcaps != labelFont.capitalization() )
-      {
-        labelFont.setCapitalization( fontcaps );
-      }
-    }
-  }
-
   // data defined strikeout font style?
   if ( dataDefinedEvaluate( QgsPalLayerSettings::Strikeout, exprVal, &context.expressionContext(), labelFont.strikeOut() ) )
   {

src/core/qgsstringutils.cpp

@@ -17,6 +17,55 @@
 #include <QVector>
 #include <QRegExp>
 #include <QTextDocument> // for Qt::escape
+#include <QStringList>
+#include <QTextBoundaryFinder>
+
+QString QgsStringUtils::capitalize( const QString& string, QgsStringUtils::Capitalization capitalization )
+{
+  if ( string.isEmpty() )
+    return QString();
+
+  switch ( capitalization )
+  {
+    case MixedCase:
+      return string;
+
+    case AllUppercase:
+      return string.toUpper();
+
+    case AllLowercase:
+      return string.toLower();
+
+    case ForceFirstLetterToCapital:
+    {
+      QString temp = string;
+
+      QTextBoundaryFinder wordSplitter( QTextBoundaryFinder::Word, string.constData(), string.length(), 0, 0 );
+      QTextBoundaryFinder letterSplitter( QTextBoundaryFinder::Grapheme, string.constData(), string.length(), 0, 0 );
+
+      wordSplitter.setPosition( 0 );
+      bool first = true;
+#if QT_VERSION >= 0x050000
+      while (( first && wordSplitter.boundaryReasons() & QTextBoundaryFinder::StartOfItem )
+             || wordSplitter.toNextBoundary() >= 0 )
+#else
+      while (( first && wordSplitter.boundaryReasons() & QTextBoundaryFinder::StartWord )
+             || wordSplitter.toNextBoundary() >= 0 )
+#endif
+      {
+        first = false;
+        letterSplitter.setPosition( wordSplitter.position() );
+        letterSplitter.toNextBoundary();
+        QString substr = string.mid( wordSplitter.position(), letterSplitter.position() - wordSplitter.position() );
+        temp.replace( wordSplitter.position(), substr.length(), substr.toUpper() );
+      }
+      return temp;
+    }
+
+  }
+  // no warnings
+  return string;
+}
 
 int QgsStringUtils::levenshteinDistance( const QString& string1, const QString& string2, bool caseSensitive )
 {

src/core/qgsstringutils.h

@@ -17,6 +17,7 @@
 #include <QRegExp>
 #include <QList>
 #include <QDomDocument>
+#include <QFont> // for enum values
 #include "qgis.h"
 
 #ifndef QGSSTRINGUTILS_H
@@ -166,6 +167,23 @@ class CORE_EXPORT QgsStringUtils
 {
   public:
 
+    //! Capitalization options
+    enum Capitalization
+    {
+      MixedCase = QFont::MixedCase, //!< Mixed case, ie no change
+      AllUppercase = QFont::AllUppercase, //!< Convert all characters to uppercase
+      AllLowercase = QFont::AllLowercase,  //!< Convert all characters to lowercase
+      ForceFirstLetterToCapital = QFont::Capitalize, //!< Convert just the first letter of each word to uppercase, leave the rest untouched
+    };
+
+    /** Converts a string by applying capitalization rules to the string.
+     * @param string input string
+     * @param capitalization capitalization type to apply
+     * @return capitalized string
+     * @note added in QGIS 3.0
+     */
+    static QString capitalize( const QString& string, Capitalization capitalization );
+
     /** Returns the Levenshtein edit distance between two strings. This equates to the minimum
      * number of character edits (insertions, deletions or substitutions) required to change
      * one string to another.

tests/src/core/testqgslabelingenginev2.cpp

@@ -44,6 +44,7 @@ class TestQgsLabelingEngineV2 : public QObject
     void zOrder(); //test that labels are stacked correctly
     void testEncodeDecodePositionOrder();
     void testSubstitutions();
+    void testCapitalization();
 
   private:
     QgsVectorLayer* vl;
@@ -454,6 +455,66 @@ void TestQgsLabelingEngineV2::testSubstitutions()
   QCOMPARE( provider2->mLabels.at( 0 )->labelText(), QString( "bb label" ) );
 }
 
+void TestQgsLabelingEngineV2::testCapitalization()
+{
+  QgsFeature f( vl->fields(), 1 );
+  f.setGeometry( QgsGeometry::fromPoint( QgsPoint( 1, 2 ) ) );
+
+  // make a fake render context
+  QSize size( 640, 480 );
+  QgsMapSettings mapSettings;
+  mapSettings.setOutputSize( size );
+  mapSettings.setExtent( vl->extent() );
+  mapSettings.setLayers( QStringList() << vl->id() );
+  mapSettings.setOutputDpi( 96 );
+  QgsRenderContext context = QgsRenderContext::fromMapSettings( mapSettings );
+  QStringList attributes;
+  QgsLabelingEngineV2 engine;
+  engine.setMapSettings( mapSettings );
+
+  // no change
+  QgsPalLayerSettings settings;
+  QFont font = settings.textFont;
+  font.setCapitalization( QFont::MixedCase );
+  settings.textFont = font;
+  settings.fieldName = QString( "'a teSt LABEL'" );
+  settings.isExpression = true;
+
+  QgsVectorLayerLabelProvider* provider = new QgsVectorLayerLabelProvider( vl, "test", true, &settings );
+  engine.addProvider( provider );
+  provider->prepare( context, attributes );
+  provider->registerFeature( f, context );
+  QCOMPARE( provider->mLabels.at( 0 )->labelText(), QString( "a teSt LABEL" ) );
+
+  //uppercase
+  font.setCapitalization( QFont::AllUppercase );
+  settings.textFont = font;
+  QgsVectorLayerLabelProvider* provider2 = new QgsVectorLayerLabelProvider( vl, "test2", true, &settings );
+  engine.addProvider( provider2 );
+  provider2->prepare( context, attributes );
+  provider2->registerFeature( f, context );
+  QCOMPARE( provider2->mLabels.at( 0 )->labelText(), QString( "A TEST LABEL" ) );
+
+  //lowercase
+  font.setCapitalization( QFont::AllLowercase );
+  settings.textFont = font;
+  QgsVectorLayerLabelProvider* provider3 = new QgsVectorLayerLabelProvider( vl, "test3", true, &settings );
+  engine.addProvider( provider3 );
+  provider3->prepare( context, attributes );
+  provider3->registerFeature( f, context );
+  QCOMPARE( provider3->mLabels.at( 0 )->labelText(), QString( "a test label" ) );
+
+  //first letter uppercase
+  font.setCapitalization( QFont::Capitalize );
+  settings.textFont = font;
+  QgsVectorLayerLabelProvider* provider4 = new QgsVectorLayerLabelProvider( vl, "test4", true, &settings );
+  engine.addProvider( provider4 );
+  provider4->prepare( context, attributes );
+  provider4->registerFeature( f, context );
+  QCOMPARE( provider4->mLabels.at( 0 )->labelText(), QString( "A TeSt LABEL" ) );
+}
+
+
 bool TestQgsLabelingEngineV2::imageCheck( const QString& testName, QImage &image, int mismatchCount )
 {
   //draw background

tests/src/python/test_qgsstringutils.py

@@ -133,5 +133,49 @@ def testSaveRestore(self):
         self.assertEqual(c2.replacements(), c.replacements())
 
 
+class PyQgsStringUtils(unittest.TestCase):
+
+    def testMixed(self):
+        """ test mixed capitalization - ie, no change! """
+        self.assertFalse(QgsStringUtils.capitalize(None, QgsStringUtils.MixedCase))
+        self.assertEqual(QgsStringUtils.capitalize('', QgsStringUtils.MixedCase), '')
+        self.assertEqual(QgsStringUtils.capitalize('testing 123', QgsStringUtils.MixedCase), 'testing 123')
+        self.assertEqual(QgsStringUtils.capitalize('    tESTinG 123    ', QgsStringUtils.MixedCase), '    tESTinG 123    ')
+        self.assertEqual(QgsStringUtils.capitalize('    TESTING ABC', QgsStringUtils.MixedCase), '    TESTING ABC')
+
+    def testUpperCase(self):
+        """ test uppercase """
+        self.assertFalse(QgsStringUtils.capitalize(None, QgsStringUtils.AllUppercase))
+        self.assertEqual(QgsStringUtils.capitalize('', QgsStringUtils.AllUppercase), '')
+        self.assertEqual(QgsStringUtils.capitalize('testing 123', QgsStringUtils.AllUppercase), 'TESTING 123')
+        self.assertEqual(QgsStringUtils.capitalize('    tESTinG abc    ', QgsStringUtils.AllUppercase), '    TESTING ABC    ')
+        self.assertEqual(QgsStringUtils.capitalize('    TESTING ABC', QgsStringUtils.AllUppercase), '    TESTING ABC')
+
+    def testLowerCase(self):
+        """ test lowercase """
+        self.assertFalse(QgsStringUtils.capitalize(None, QgsStringUtils.AllLowercase))
+        self.assertEqual(QgsStringUtils.capitalize('', QgsStringUtils.AllLowercase), '')
+        self.assertEqual(QgsStringUtils.capitalize('testing 123', QgsStringUtils.AllLowercase), 'testing 123')
+        self.assertEqual(QgsStringUtils.capitalize('    tESTinG abc    ', QgsStringUtils.AllLowercase),
+                         '    testing abc    ')
+        self.assertEqual(QgsStringUtils.capitalize('    TESTING ABC', QgsStringUtils.AllLowercase), '    testing abc')
+
+    def testCapitalizeFirst(self):
+        """ test capitalize first """
+        self.assertFalse(QgsStringUtils.capitalize(None, QgsStringUtils.ForceFirstLetterToCapital))
+        self.assertEqual(QgsStringUtils.capitalize('', QgsStringUtils.ForceFirstLetterToCapital), '')
+        self.assertEqual(QgsStringUtils.capitalize('testing 123', QgsStringUtils.ForceFirstLetterToCapital), 'Testing 123')
+        self.assertEqual(QgsStringUtils.capitalize('testing', QgsStringUtils.ForceFirstLetterToCapital),
+                         'Testing')
+        self.assertEqual(QgsStringUtils.capitalize('Testing', QgsStringUtils.ForceFirstLetterToCapital),
+                         'Testing')
+        self.assertEqual(QgsStringUtils.capitalize('TESTING', QgsStringUtils.ForceFirstLetterToCapital),
+                         'TESTING')
+        self.assertEqual(QgsStringUtils.capitalize('    tESTinG abc    ', QgsStringUtils.ForceFirstLetterToCapital),
+                         '    TESTinG Abc    ')
+        self.assertEqual(QgsStringUtils.capitalize('    TESTING ABC', QgsStringUtils.ForceFirstLetterToCapital), '    TESTING ABC')
+        self.assertEqual(QgsStringUtils.capitalize('    testing abc', QgsStringUtils.ForceFirstLetterToCapital),
+                         '    Testing Abc')
+
 if __name__ == '__main__':
     unittest.main()