Fix broken rendering of curved labels for scripts which use >1 char

nyalldawson · nyalldawson · commit 71b5a99388f3 · 2015-06-24T21:45:59.000+10:00
graphemes (fix #6883) Cherry-picked from 2dc5d95
diff --git a/src/core/dxf/qgsdxfpallabeling.cpp b/src/core/dxf/qgsdxfpallabeling.cpp
@@ -79,8 +79,7 @@ void QgsDxfPalLabeling::drawLabel( pal::LabelPosition* label, QgsRenderContext&
       return;
 
     //label text
-    QString text = g->text();
-    QString txt = label->getPartId() == -1 ? text : QString( text[ label->getPartId()] );
+    QString txt = g->text( label->getPartId() );
 
     //angle
     double angle = label->getAlpha() * 180 / M_PI;
diff --git a/src/core/qgspalgeometry.h b/src/core/qgspalgeometry.h
@@ -4,6 +4,7 @@
 #include "qgsgeometry.h"
 #include <pal/feature.h>
 #include <pal/palgeometry.h>
+#include <QTextBoundaryFinder>
 
 using namespace pal;
 
@@ -49,6 +50,19 @@ class QgsPalGeometry : public PalGeometry
     const char* strId() { return mStrId.data(); }
     QString text() { return mText; }
 
+    /** Returns the text component corresponding to a specified label part
+     * @param partId. Set to -1 for labels which are not broken into parts (eg, non-curved labels), or the required
+     * part index for labels which are broken into parts (curved labels)
+     * @note added in QGIS 2.10
+     */
+    QString text( int partId ) const
+    {
+      if ( partId == -1 )
+        return mText;
+      else
+        return mClusters.at( partId );
+    }
+
     pal::LabelInfo* info( QFontMetricsF* fm, const QgsMapToPixel* xform, double fontScale, double maxinangle, double maxoutangle )
     {
       if ( mInfo )
@@ -74,29 +88,41 @@ class QgsPalGeometry : public PalGeometry
       // (non-curved spacings handled by Qt in QgsPalLayerSettings/QgsPalLabeling)
       qreal charWidth;
       qreal wordSpaceFix;
-      mInfo = new pal::LabelInfo( mText.count(), labelHeight, maxinangle, maxoutangle );
-      for ( int i = 0; i < mText.count(); i++ )
+
+      //split string by valid grapheme boundaries - required for certain scripts (see #6883)
+      QTextBoundaryFinder boundaryFinder( QTextBoundaryFinder::Grapheme, mText );
+      int currentBoundary = -1;
+      int previousBoundary = 0;
+      while (( currentBoundary = boundaryFinder.toNextBoundary() ) > 0 )
+      {
+        mClusters << mText.mid( previousBoundary, currentBoundary - previousBoundary );
+        previousBoundary = currentBoundary;
+      }
+
+      mInfo = new pal::LabelInfo( mClusters.count(), labelHeight, maxinangle, maxoutangle );
+      for ( int i = 0; i < mClusters.count(); i++ )
       {
-        mInfo->char_info[i].chr = mText[i].unicode();
+        //doesn't appear to be used anywhere:
+        //mInfo->char_info[i].chr = textClusters[i].unicode();
 
         // reconstruct how Qt creates word spacing, then adjust per individual stored character
         // this will allow PAL to create each candidate width = character width + correct spacing
-        charWidth = fm->width( mText[i] );
+        charWidth = fm->width( mClusters[i] );
         if ( mCurvedLabeling )
         {
           wordSpaceFix = qreal( 0.0 );
-          if ( mText[i] == QString( " " )[0] )
+          if ( mClusters[i] == QString( " " ) )
           {
             // word spacing only gets added once at end of consecutive run of spaces, see QTextEngine::shapeText()
             int nxt = i + 1;
-            wordSpaceFix = ( nxt < mText.count() && mText[nxt] != QString( " " )[0] ) ? mWordSpacing : qreal( 0.0 );
+            wordSpaceFix = ( nxt < mClusters.count() && mClusters[nxt] != QString( " " ) ) ? mWordSpacing : qreal( 0.0 );
           }
-          if ( fm->width( QString( mText[i] ) ) - fm->width( mText[i] ) - mLetterSpacing != qreal( 0.0 ) )
+          if ( fm->width( QString( mClusters[i] ) ) - fm->width( mClusters[i] ) - mLetterSpacing != qreal( 0.0 ) )
           {
             // word spacing applied when it shouldn't be
             wordSpaceFix -= mWordSpacing;
           }
-          charWidth = fm->width( QString( mText[i] ) ) + wordSpaceFix;
+          charWidth = fm->width( QString( mClusters[i] ) ) + wordSpaceFix;
         }
 
         double labelWidth = mapScale * charWidth / fontScale;
@@ -135,6 +161,7 @@ class QgsPalGeometry : public PalGeometry
   protected:
     GEOSGeometry* mG;
     QString mText;
+    QStringList mClusters;
     QByteArray mStrId;
     QgsFeatureId mId;
     LabelInfo* mInfo;
diff --git a/src/core/qgspallabeling.cpp b/src/core/qgspallabeling.cpp
@@ -4324,8 +4324,7 @@ void QgsPalLabeling::drawLabel( pal::LabelPosition* label, QgsRenderContext& con
   {
 
     // TODO: optimize access :)
-    QString text = (( QgsPalGeometry* )label->getFeaturePart()->getUserGeometry() )->text();
-    QString txt = ( label->getPartId() == -1 ? text : QString( text[label->getPartId()] ) );
+    QString txt = (( QgsPalGeometry* )label->getFeaturePart()->getUserGeometry() )->text( label->getPartId() );
     QFontMetricsF* labelfm = (( QgsPalGeometry* )label->getFeaturePart()->getUserGeometry() )->getLabelFontMetrics();
 
     //add the direction symbol if needed

Original file line number	Diff line number	Diff line change
`@@ -4324,8 +4324,7 @@ void QgsPalLabeling::drawLabel( pal::LabelPosition* label, QgsRenderContext& con`
`4324`	`4324`	`{`
`4325`	`4325`
`4326`	`4326`	`// TODO: optimize access :)`
`4327`		`- QString text = (( QgsPalGeometry* )label->getFeaturePart()->getUserGeometry() )->text();`
`4328`		`- QString txt = ( label->getPartId() == -1 ? text : QString( text[label->getPartId()] ) );`
	`4327`	`+ QString txt = (( QgsPalGeometry* )label->getFeaturePart()->getUserGeometry() )->text( label->getPartId() );`
`4329`	`4328`	`QFontMetricsF* labelfm = (( QgsPalGeometry* )label->getFeaturePart()->getUserGeometry() )->getLabelFontMetrics();`
`4330`	`4329`
`4331`	`4330`	`//add the direction symbol if needed`