Cleanup and refactor calculationg of label text metrics for curved

labels, and move methods for calculating curved text placement out of PAL so that they can be reused elsewhere
qgis · Apr 8, 2021 · 832d5e9 · 832d5e9
1 parent 19a3d8e
commit 832d5e9
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Showing 18 changed files with 687 additions and 388 deletions.
diff --git a/python/core/auto_generated/textrenderer/qgstextrenderer.sip.in b/python/core/auto_generated/textrenderer/qgstextrenderer.sip.in
@@ -224,7 +224,6 @@ Returns the height of a character when rendered with the specified text ``format
 
 };
 
-
 /************************************************************************
  * This file has been generated automatically from                      *
  *                                                                      *

diff --git a/python/core/auto_generated/textrenderer/qgstextrendererutils.sip.in b/python/core/auto_generated/textrenderer/qgstextrendererutils.sip.in
@@ -63,6 +63,8 @@ Attempts to decode a string representation of a text orientation.
 %End
 
 
+
+
 };
 
 

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
@@ -1551,6 +1551,7 @@ set(QGIS_CORE_HDRS
   textrenderer/qgstextformat.h
   textrenderer/qgstextfragment.h
   textrenderer/qgstextmasksettings.h
+  textrenderer/qgstextmetrics.h
   textrenderer/qgstextrenderer.h
   textrenderer/qgstextrendererutils.h
   textrenderer/qgstextshadowsettings.h

diff --git a/src/core/labeling/qgslabelfeature.cpp b/src/core/labeling/qgslabelfeature.cpp
@@ -31,8 +31,6 @@ QgsLabelFeature::~QgsLabelFeature()
     mPermissibleZoneGeosPrepared.reset();
     mPermissibleZoneGeos.reset();
   }
-
-  delete mInfo;
 }
 
 void QgsLabelFeature::setPermissibleZone( const QgsGeometry &geometry )

diff --git a/src/core/labeling/qgslabelfeature.h b/src/core/labeling/qgslabelfeature.h
@@ -27,7 +27,6 @@
 
 namespace pal
 {
-  class LabelInfo;
   class Layer;
 }
 
@@ -344,11 +343,6 @@ class CORE_EXPORT QgsLabelFeature
     //! Sets text of the label
     void setLabelText( const QString &text ) { mLabelText = text; }
 
-    //! Gets additional info required for curved label placement. Returns NULLPTR if not set
-    pal::LabelInfo *curvedLabelInfo() const { return mInfo; }
-    //! takes ownership of the instance
-    void setCurvedLabelInfo( pal::LabelInfo *info ) { mInfo = info; }
-
     //! Gets PAL layer of the label feature. Should be only used internally in PAL
     pal::Layer *layer() const { return mLayer; }
     //! Assign PAL layer to the label feature. Should be only used internally in PAL
@@ -596,8 +590,6 @@ class CORE_EXPORT QgsLabelFeature
     bool mAlwaysShow = false;
     //! text of the label
     QString mLabelText;
-    //! extra information for curved labels (may be NULLPTR)
-    pal::LabelInfo *mInfo = nullptr;
 
     //! Distance to allow label to overrun linear features
     double mOverrunDistance = 0;

diff --git a/src/core/labeling/qgspallabeling.cpp b/src/core/labeling/qgspallabeling.cpp
@@ -2524,13 +2524,28 @@ void QgsPalLayerSettings::registerFeature( const QgsFeature &f, QgsRenderContext
   // store the label's calculated font for later use during painting
   QgsDebugMsgLevel( QStringLiteral( "PAL font stored definedFont: %1, Style: %2" ).arg( labelFont.toString(), labelFont.styleName() ), 4 );
   lf->setDefinedFont( labelFont );
+  lf->setFontMetrics( *labelFontMetrics );
 
-  // TODO: only for placement which needs character info
-  // account for any data defined font metrics adjustments
   lf->setMaximumCharacterAngleInside( std::clamp( maxcharanglein, 20.0, 60.0 ) * M_PI / 180 );
   lf->setMaximumCharacterAngleOutside( std::clamp( maxcharangleout, -95.0, -20.0 ) * M_PI / 180 );
-  lf->calculateInfo( placement == QgsPalLayerSettings::Curved || placement == QgsPalLayerSettings::PerimeterCurved,
-                     labelFontMetrics.get(), xform, format().allowHtmlFormatting() ? &doc : nullptr );
+  switch ( placement )
+  {
+    case QgsPalLayerSettings::AroundPoint:
+    case QgsPalLayerSettings::OverPoint:
+    case QgsPalLayerSettings::Line:
+    case QgsPalLayerSettings::Horizontal:
+    case QgsPalLayerSettings::Free:
+    case QgsPalLayerSettings::OrderedPositionsAroundPoint:
+    case QgsPalLayerSettings::OutsidePolygons:
+      // these placements don't require text metrics
+      break;
+
+    case QgsPalLayerSettings::Curved:
+    case QgsPalLayerSettings::PerimeterCurved:
+      lf->setTextMetrics( QgsTextLabelFeature::calculateTextMetrics( xform, *labelFontMetrics, labelFont.letterSpacing(), labelFont.wordSpacing(), labelText, format().allowHtmlFormatting() ? &doc : nullptr ) );
+      break;
+  }
+
   // for labelFeature the LabelInfo is passed to feat when it is registered
 
   // TODO: allow layer-wide feature dist in PAL...?

diff --git a/src/core/labeling/qgstextlabelfeature.cpp b/src/core/labeling/qgstextlabelfeature.cpp
@@ -29,101 +29,89 @@ QgsTextLabelFeature::QgsTextLabelFeature( QgsFeatureId id, geos::unique_ptr geom
   mDefinedFont = QFont();
 }
 
-
-QgsTextLabelFeature::~QgsTextLabelFeature()
-{
-  delete mFontMetrics;
-}
-
+QgsTextLabelFeature::~QgsTextLabelFeature() = default;
 
 QString QgsTextLabelFeature::text( int partId ) const
 {
   if ( partId == -1 )
     return mLabelText;
   else
-    return mClusters.at( partId );
+    return mTextMetrics->grapheme( partId );
 }
 
 QgsTextCharacterFormat QgsTextLabelFeature::characterFormat( int partId ) const
 {
-  return mCharacterFormats.value( partId );
+  return mTextMetrics.has_value() ? mTextMetrics->graphemeFormat( partId ) : QgsTextCharacterFormat();
 }
 
 bool QgsTextLabelFeature::hasCharacterFormat( int partId ) const
 {
-  return partId < mCharacterFormats.size();
+  return mTextMetrics.has_value() && partId < mTextMetrics->graphemeFormatCount();
 }
 
-void QgsTextLabelFeature::calculateInfo( bool curvedLabeling, QFontMetricsF *fm, const QgsMapToPixel *xform, QgsTextDocument *document )
+void QgsTextLabelFeature::setFontMetrics( const QFontMetricsF &metrics )
 {
-  if ( mInfo )
-    return;
-
-  mFontMetrics = new QFontMetricsF( *fm ); // duplicate metrics for when drawing label
-
-  qreal letterSpacing = mDefinedFont.letterSpacing();
-  qreal wordSpacing = mDefinedFont.wordSpacing();
+  mFontMetrics = metrics; // duplicate metrics for when drawing label
+}
 
+QgsPrecalculatedTextMetrics QgsTextLabelFeature::calculateTextMetrics( const QgsMapToPixel *xform, const QFontMetricsF &fontMetrics, double letterSpacing, double wordSpacing, const QString &text, QgsTextDocument *document )
+{
   // create label info!
   const double mapScale = xform->mapUnitsPerPixel();
-  const double characterHeight = mapScale * fm->height();
-
-  // mLetterSpacing/mWordSpacing = 0.0 is default for non-curved labels
-  // (non-curved spacings handled by Qt in QgsPalLayerSettings/QgsPalLabeling)
-  qreal charWidth;
-  qreal wordSpaceFix;
+  const double characterHeight = mapScale * fontMetrics.height();
+  QStringList graphemes;
+  QVector< QgsTextCharacterFormat > graphemeFormats;
 
-  if ( document && curvedLabeling )
+  if ( document )
   {
     for ( const QgsTextBlock &block : std::as_const( *document ) )
     {
       for ( const QgsTextFragment &fragment : block )
       {
-        const QStringList graphemes = QgsPalLabeling::splitToGraphemes( fragment.text() );
-        for ( const QString &grapheme : graphemes )
+        const QStringList fragmentGraphemes = QgsPalLabeling::splitToGraphemes( fragment.text() );
+        for ( const QString &grapheme : fragmentGraphemes )
         {
-          mClusters.append( grapheme );
-          mCharacterFormats.append( fragment.characterFormat() );
+          graphemes.append( grapheme );
+          graphemeFormats.append( fragment.characterFormat() );
         }
       }
     }
   }
   else
   {
     //split string by valid grapheme boundaries - required for certain scripts (see #6883)
-    mClusters = QgsPalLabeling::splitToGraphemes( mLabelText );
+    graphemes = QgsPalLabeling::splitToGraphemes( text );
   }
 
-  std::vector< double > characterWidths( mClusters.count() );
-  for ( int i = 0; i < mClusters.count(); i++ )
+  QVector< double > characterWidths( graphemes.count() );
+  for ( int i = 0; i < graphemes.count(); i++ )
   {
     // 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->horizontalAdvance( mClusters[i] );
-    if ( curvedLabeling )
-    {
-      wordSpaceFix = qreal( 0.0 );
-      if ( mClusters[i] == QLatin1String( " " ) )
-      {
-        // word spacing only gets added once at end of consecutive run of spaces, see QTextEngine::shapeText()
-        int nxt = i + 1;
-        wordSpaceFix = ( nxt < mClusters.count() && mClusters[nxt] != QLatin1String( " " ) ) ? wordSpacing : qreal( 0.0 );
-      }
-      // this workaround only works for clusters with a single character. Not sure how it should be handled
-      // with multi-character clusters.
-      if ( mClusters[i].length() == 1 &&
-           !qgsDoubleNear( fm->horizontalAdvance( QString( mClusters[i].at( 0 ) ) ), fm->horizontalAdvance( mClusters[i].at( 0 ) ) + letterSpacing ) )
-      {
-        // word spacing applied when it shouldn't be
-        wordSpaceFix -= wordSpacing;
-      }
 
-      charWidth = fm->horizontalAdvance( QString( mClusters[i] ) ) + wordSpaceFix;
+    qreal wordSpaceFix = qreal( 0.0 );
+    if ( graphemes[i] == QLatin1String( " " ) )
+    {
+      // word spacing only gets added once at end of consecutive run of spaces, see QTextEngine::shapeText()
+      int nxt = i + 1;
+      wordSpaceFix = ( nxt < graphemes.count() && graphemes[nxt] != QLatin1String( " " ) ) ? wordSpacing : qreal( 0.0 );
+    }
+    // this workaround only works for clusters with a single character. Not sure how it should be handled
+    // with multi-character clusters.
+    if ( graphemes[i].length() == 1 &&
+         !qgsDoubleNear( fontMetrics.horizontalAdvance( QString( graphemes[i].at( 0 ) ) ), fontMetrics.horizontalAdvance( graphemes[i].at( 0 ) ) + letterSpacing ) )
+    {
+      // word spacing applied when it shouldn't be
+      wordSpaceFix -= wordSpacing;
     }
 
+    const double charWidth = fontMetrics.horizontalAdvance( QString( graphemes[i] ) ) + wordSpaceFix;
     characterWidths[i] = mapScale * charWidth;
   }
-  mInfo = new pal::LabelInfo( characterHeight, std::move( characterWidths ) );
+
+  QgsPrecalculatedTextMetrics res( graphemes, characterHeight, std::move( characterWidths ) );
+  res.setGraphemeFormats( graphemeFormats );
+  return res;
 }
 
 QgsTextDocument QgsTextLabelFeature::document() const

diff --git a/src/core/labeling/qgstextlabelfeature.h b/src/core/labeling/qgstextlabelfeature.h
@@ -19,6 +19,8 @@
 
 #include "qgslabelfeature.h"
 #include "qgstextdocument.h"
+#include "qgstextmetrics.h"
+#include <optional>
 
 class QgsTextCharacterFormat;
 
@@ -62,9 +64,6 @@ class QgsTextLabelFeature : public QgsLabelFeature
      */
     bool hasCharacterFormat( int partId ) const;
 
-    //! calculate data for info(). setDefinedFont() must have been called already.
-    void calculateInfo( bool curvedLabeling, QFontMetricsF *fm, const QgsMapToPixel *xform, QgsTextDocument *document = nullptr );
-
     //! Gets data-defined values
     const QMap< QgsPalLayerSettings::Property, QVariant > &dataDefinedValues() const { return mDataDefinedValues; }
     //! Sets data-defined values
@@ -75,8 +74,43 @@ class QgsTextLabelFeature : public QgsLabelFeature
     //! Font to be used for rendering
     QFont definedFont() { return mDefinedFont; }
 
-    //! Metrics of the font for rendering
-    QFontMetricsF *labelFontMetrics() { return mFontMetrics; }
+    /**
+     * Metrics of the font for rendering.
+     *
+     * May be NULLPTR.
+     */
+    QFontMetricsF *labelFontMetrics() { return mFontMetrics.has_value() ? &mFontMetrics.value() : nullptr; }
+
+    /**
+     * Sets the font \a metrics.
+     */
+    void setFontMetrics( const QFontMetricsF &metrics );
+
+    /**
+     * Returns additional info required for curved label placement.
+     *
+     * Returns NULLPTR if not set.
+     *
+     * \see setTextMetrics()
+     * \since QGIS 3.20
+     */
+    const QgsPrecalculatedTextMetrics *textMetrics() const { return mTextMetrics.has_value() ? &mTextMetrics.value() : nullptr; }
+
+    /**
+     * Sets additional text \a metrics required for curved label placement.
+     *
+     * \see textMetrics()
+     * \since QGIS 3.20
+     */
+    void setTextMetrics( const QgsPrecalculatedTextMetrics &metrics ) { mTextMetrics = metrics; }
+
+    /**
+     * Calculate text metrics for later retrieval via textMetrics().
+     *
+     * \since QGIS 3.20
+     */
+    static QgsPrecalculatedTextMetrics calculateTextMetrics( const QgsMapToPixel *xform, const QFontMetricsF &fontMetrics, double letterSpacing,
+        double wordSpacing, const QString &text = QString(), QgsTextDocument *document = nullptr );
 
     /**
      * Returns the document for the label.
@@ -125,15 +159,13 @@ class QgsTextLabelFeature : public QgsLabelFeature
     double maximumCharacterAngleOutside() const { return mMaximumCharacterAngleOutside; }
 
   protected:
-    //! List of graphemes (used for curved labels)
-    QStringList mClusters;
-
-    QList< QgsTextCharacterFormat > mCharacterFormats;
 
     //! Font for rendering
     QFont mDefinedFont;
+
     //! Metrics of the font for rendering
-    QFontMetricsF *mFontMetrics = nullptr;
+    std::optional< QFontMetricsF > mFontMetrics;
+
     //! Stores attribute values for data defined properties
     QMap< QgsPalLayerSettings::Property, QVariant > mDataDefinedValues;
 
@@ -142,6 +174,8 @@ class QgsTextLabelFeature : public QgsLabelFeature
     double mMaximumCharacterAngleInside = 0;
     double mMaximumCharacterAngleOutside = 0;
 
+    std::optional< QgsPrecalculatedTextMetrics > mTextMetrics;
+
 };
 
 #endif //QGSTEXTLABELFEATURE_H
diff --git a/src/core/labeling/qgsvectorlayerlabelprovider.cpp b/src/core/labeling/qgsvectorlayerlabelprovider.cpp
@@ -629,7 +629,6 @@ void QgsVectorLayerLabelProvider::drawLabelPrivate( pal::LabelPosition *label, Q
       }
     }
 
-
     QgsTextRenderer::HAlignment hAlign = QgsTextRenderer::AlignLeft;
     if ( tmpLyr.multilineAlign == QgsPalLayerSettings::MultiCenter )
       hAlign = QgsTextRenderer::AlignCenter;