[labeling] Fix line anchor placements are reversed for labels which

sit below lines
qgis · Feb 3, 2022 · 75a5bb3 · 75a5bb3
1 parent 3ae5e9a
commit 75a5bb3
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Showing 39 changed files with 93 additions and 5 deletions.
diff --git a/src/core/pal/feature.cpp b/src/core/pal/feature.cpp
@@ -1325,6 +1325,7 @@ std::size_t FeaturePart::createCurvedCandidatesAlongLine( std::vector< std::uniq
     expanded = mapShape->clone();
     expanded->extendLineByDistance( overrun, overrun, mLF->overrunSmoothDistance() );
     mapShape = expanded.get();
+    shapeLength += 2 * overrun;
   }
 
   QgsLabeling::LinePlacementFlags flags = mLF->arrangementFlags();
@@ -1370,6 +1371,9 @@ std::size_t FeaturePart::createCurvedCandidatesAlongLine( std::vector< std::uniq
     }
   }
 
+  // calculate the anchor point for the original line shape as a GEOS point
+  const geos::unique_ptr originalPoint = mapShape->interpolatePoint( shapeLength * mLF->lineAnchorPercent() );
+
   std::vector< std::unique_ptr< LabelPosition >> positions;
   for ( PathOffset offset : { PositiveOffset, NoOffset, NegativeOffset } )
   {
@@ -1394,7 +1398,20 @@ std::size_t FeaturePart::createCurvedCandidatesAlongLine( std::vector< std::uniq
     if ( qgsDoubleNear( totalDistance, 0.0 ) )
       continue;
 
-    const double lineAnchorPoint = totalDistance * mLF->lineAnchorPercent();
+    double lineAnchorPoint = 0;
+    if ( originalPoint && offset != NoOffset )
+    {
+      // the actual anchor point for the offset curves is the closest point on those offset curves
+      // to the anchor point on the original line. This avoids anchor points which differ greatly
+      // on the positive/negative offset lines due to line curvature.
+      lineAnchorPoint = currentMapShape->lineLocatePoint( originalPoint.get() );
+    }
+    else
+    {
+      lineAnchorPoint = totalDistance * mLF->lineAnchorPercent();
+      if ( offset == NegativeOffset )
+        lineAnchorPoint = totalDistance - lineAnchorPoint;
+    }
 
     if ( pal->isCanceled() )
       return 0;
@@ -1411,16 +1428,21 @@ std::size_t FeaturePart::createCurvedCandidatesAlongLine( std::vector< std::uniq
         break;
 
       case QgsLabelLineSettings::AnchorType::Strict:
-        distanceAlongLineToStartCandidate = std::min( lineAnchorPoint, totalDistance * 0.99 - getLabelWidth() );
+        distanceAlongLineToStartCandidate = std::clamp( lineAnchorPoint - getLabelWidth() / 2, 0.0, totalDistance * 0.99 - getLabelWidth() );
         singleCandidateOnly = true;
         break;
     }
 
+    bool hasTestedFirstPlacement = false;
     for ( ; distanceAlongLineToStartCandidate <= totalDistance; distanceAlongLineToStartCandidate += delta )
     {
+      if ( singleCandidateOnly && hasTestedFirstPlacement )
+        break;
+
       if ( pal->isCanceled() )
         return 0;
 
+      hasTestedFirstPlacement = true;
       // placements may need to be reversed if using map orientation and the line has right-to-left direction
       bool labeledLineSegmentIsRightToLeft = false;
       const QgsTextRendererUtils::LabelLineDirection direction = ( flags & QgsLabeling::LinePlacementFlag::MapOrientation ) ? QgsTextRendererUtils::RespectPainterOrientation : QgsTextRendererUtils::FollowLineDirection;
@@ -1484,9 +1506,6 @@ std::size_t FeaturePart::createCurvedCandidatesAlongLine( std::vector< std::uniq
 
       if ( p )
         positions.emplace_back( std::move( p ) );
-
-      if ( singleCandidateOnly )
-        break;
     }
   }
 

diff --git a/src/core/pal/pointset.cpp b/src/core/pal/pointset.cpp
@@ -1036,6 +1036,44 @@ void PointSet::getPointByDistance( double *d, double *ad, double dl, double *px,
   }
 }
 
+geos::unique_ptr PointSet::interpolatePoint( double distance ) const
+{
+  const GEOSGeometry *thisGeos = geos();
+  if ( !thisGeos )
+    return nullptr;
+
+  try
+  {
+    geos::unique_ptr res( GEOSInterpolate_r( QgsGeos::getGEOSHandler(), thisGeos, distance ) );
+    return res;
+  }
+  catch ( GEOSException &e )
+  {
+    qWarning( "GEOS exception: %s", e.what() );
+    return nullptr;
+  }
+}
+
+double PointSet::lineLocatePoint( const GEOSGeometry *point ) const
+{
+  const GEOSGeometry *thisGeos = geos();
+  if ( !thisGeos )
+    return -1;
+
+  double distance = -1;
+  try
+  {
+    distance = GEOSProject_r( QgsGeos::getGEOSHandler(), thisGeos, point );
+  }
+  catch ( GEOSException &e )
+  {
+    qWarning( "GEOS exception: %s", e.what() );
+    return -1;
+  }
+
+  return distance;
+}
+
 const GEOSGeometry *PointSet::geos() const
 {
   if ( !mGeos )

diff --git a/src/core/pal/pointset.h b/src/core/pal/pointset.h
@@ -42,6 +42,7 @@
 
 #include "qgis_core.h"
 #include "qgsrectangle.h"
+#include "qgsgeos.h"
 
 namespace pal
 {
@@ -185,6 +186,16 @@ namespace pal
       */
       void getPointByDistance( double *d, double *ad, double dl, double *px, double *py );
 
+      /**
+       * Returns a GEOS geometry representing the point interpolated on the shape by distance.
+       */
+      geos::unique_ptr interpolatePoint( double distance ) const;
+
+      /**
+       * Returns the distance along the geometry closest to the specified GEOS \a point.
+       */
+      double lineLocatePoint( const GEOSGeometry *point ) const;
+
       /**
        * Returns the point set's GEOS geometry.
       */

diff --git a/tests/src/core/testqgslabelingengine.cpp b/tests/src/core/testqgslabelingengine.cpp
@@ -3631,6 +3631,26 @@ void TestQgsLabelingEngine::testLineAnchorCurved()
 
   img = job2.renderedImage();
   QVERIFY( imageCheck( QStringLiteral( "curved_anchor_end" ), img, 20 ) );
+
+  settings.lineSettings().setLineAnchorPercent( 0.3 );
+  settings.lineSettings().setAnchorType( QgsLabelLineSettings::AnchorType::Strict );
+  vl2->setLabeling( new QgsVectorLayerSimpleLabeling( settings ) );
+  QgsMapRendererSequentialJob job3( mapSettings );
+  job3.start();
+  job3.waitForFinished();
+
+  img = job3.renderedImage();
+  QVERIFY( imageCheck( QStringLiteral( "curved_anchor_30_above" ), img, 20 ) );
+
+  settings.lineSettings().setPlacementFlags( QgsLabeling::LinePlacementFlag::BelowLine );
+  vl2->setLabeling( new QgsVectorLayerSimpleLabeling( settings ) );
+  QgsMapRendererSequentialJob job4( mapSettings );
+  job4.start();
+  job4.waitForFinished();
+
+  img = job4.renderedImage();
+  QVERIFY( imageCheck( QStringLiteral( "curved_anchor_30_below" ), img, 20 ) );
+
 }
 
 void TestQgsLabelingEngine::testLineAnchorCurvedConstraints()

diff --git a/...xpected_pal_canvas_line/sp_curved_placement_above/sp_curved_placement_above.png b/...xpected_pal_canvas_line/sp_curved_placement_above/sp_curved_placement_above.png
diff --git a/...cted_pal_canvas_line/sp_curved_placement_above/v1/sp_curved_placement_above.png b/...cted_pal_canvas_line/sp_curved_placement_above/v1/sp_curved_placement_above.png
diff --git a/...cted_pal_canvas_line/sp_curved_placement_above/v2/sp_curved_placement_above.png b/...cted_pal_canvas_line/sp_curved_placement_above/v2/sp_curved_placement_above.png
diff --git a/...l_images/expected_pal_canvas_line/sp_length_expression/sp_length_expression.png b/...l_images/expected_pal_canvas_line/sp_length_expression/sp_length_expression.png
diff --git a/...mages/expected_pal_canvas_line/sp_length_expression/v1/sp_length_expression.png b/...mages/expected_pal_canvas_line/sp_length_expression/v1/sp_length_expression.png
diff --git a/...mages/expected_pal_canvas_line/sp_length_expression/v2/sp_length_expression.png b/...mages/expected_pal_canvas_line/sp_length_expression/v2/sp_length_expression.png
diff --git a/...l_composer_line/sp_img_curved_placement_above/sp_img_curved_placement_above.png b/...l_composer_line/sp_img_curved_placement_above/sp_img_curved_placement_above.png
diff --git a/...omposer_line/sp_img_curved_placement_above/v1/sp_img_curved_placement_above.png b/...omposer_line/sp_img_curved_placement_above/v1/sp_img_curved_placement_above.png
diff --git a/...omposer_line/sp_img_curved_placement_above/v2/sp_img_curved_placement_above.png b/...omposer_line/sp_img_curved_placement_above/v2/sp_img_curved_placement_above.png
diff --git a/...xpected_pal_composer_line/sp_img_length_expression/sp_img_length_expression.png b/...xpected_pal_composer_line/sp_img_length_expression/sp_img_length_expression.png
diff --git a/...cted_pal_composer_line/sp_img_length_expression/v1/sp_img_length_expression.png b/...cted_pal_composer_line/sp_img_length_expression/v1/sp_img_length_expression.png
diff --git a/...cted_pal_composer_line/sp_img_length_expression/v2/sp_img_length_expression.png b/...cted_pal_composer_line/sp_img_length_expression/v2/sp_img_length_expression.png
diff --git a/...l_composer_line/sp_pdf_curved_placement_above/sp_pdf_curved_placement_above.png b/...l_composer_line/sp_pdf_curved_placement_above/sp_pdf_curved_placement_above.png
diff --git a/...omposer_line/sp_pdf_curved_placement_above/v1/sp_pdf_curved_placement_above.png b/...omposer_line/sp_pdf_curved_placement_above/v1/sp_pdf_curved_placement_above.png
diff --git a/...omposer_line/sp_pdf_curved_placement_above/v2/sp_pdf_curved_placement_above.png b/...omposer_line/sp_pdf_curved_placement_above/v2/sp_pdf_curved_placement_above.png
diff --git a/...xpected_pal_composer_line/sp_pdf_length_expression/sp_pdf_length_expression.png b/...xpected_pal_composer_line/sp_pdf_length_expression/sp_pdf_length_expression.png
diff --git a/...cted_pal_composer_line/sp_pdf_length_expression/v1/sp_pdf_length_expression.png b/...cted_pal_composer_line/sp_pdf_length_expression/v1/sp_pdf_length_expression.png
diff --git a/...cted_pal_composer_line/sp_pdf_length_expression/v2/sp_pdf_length_expression.png b/...cted_pal_composer_line/sp_pdf_length_expression/v2/sp_pdf_length_expression.png
diff --git a/...l_composer_line/sp_svg_curved_placement_above/sp_svg_curved_placement_above.png b/...l_composer_line/sp_svg_curved_placement_above/sp_svg_curved_placement_above.png
diff --git a/...omposer_line/sp_svg_curved_placement_above/v1/sp_svg_curved_placement_above.png b/...omposer_line/sp_svg_curved_placement_above/v1/sp_svg_curved_placement_above.png
diff --git a/...omposer_line/sp_svg_curved_placement_above/v2/sp_svg_curved_placement_above.png b/...omposer_line/sp_svg_curved_placement_above/v2/sp_svg_curved_placement_above.png
diff --git a/...xpected_pal_composer_line/sp_svg_length_expression/sp_svg_length_expression.png b/...xpected_pal_composer_line/sp_svg_length_expression/sp_svg_length_expression.png
diff --git a/...cted_pal_composer_line/sp_svg_length_expression/v1/sp_svg_length_expression.png b/...cted_pal_composer_line/sp_svg_length_expression/v1/sp_svg_length_expression.png
diff --git a/...cted_pal_composer_line/sp_svg_length_expression/v2/sp_svg_length_expression.png b/...cted_pal_composer_line/sp_svg_length_expression/v2/sp_svg_length_expression.png
diff --git a/..._curved_above_instead_of_below/sp_prefer_line_curved_above_instead_of_below.png b/..._curved_above_instead_of_below/sp_prefer_line_curved_above_instead_of_below.png
diff --git a/...urved_above_instead_of_online/sp_prefer_line_curved_above_instead_of_online.png b/...urved_above_instead_of_online/sp_prefer_line_curved_above_instead_of_online.png
diff --git a/...elingengine/expected_curved_anchor_30_above/expected_curved_anchor_30_above.png b/...elingengine/expected_curved_anchor_30_above/expected_curved_anchor_30_above.png
diff --git a/...elingengine/expected_curved_anchor_30_below/expected_curved_anchor_30_below.png b/...elingengine/expected_curved_anchor_30_below/expected_curved_anchor_30_below.png
diff --git a/...ine/expected_label_curved_label_above_1/expected_label_curved_label_above_1.png b/...ine/expected_label_curved_label_above_1/expected_label_curved_label_above_1.png
diff --git a/.../expected_label_curved_label_above_1/v1/expected_label_curved_label_above_1.png b/.../expected_label_curved_label_above_1/v1/expected_label_curved_label_above_1.png
diff --git a/.../expected_label_curved_label_above_1/v2/expected_label_curved_label_above_1.png b/.../expected_label_curved_label_above_1/v2/expected_label_curved_label_above_1.png
diff --git a/...ine/expected_label_curved_label_below_1/expected_label_curved_label_below_1.png b/...ine/expected_label_curved_label_below_1/expected_label_curved_label_below_1.png
diff --git a/.../expected_label_curved_label_below_1/v1/expected_label_curved_label_below_1.png b/.../expected_label_curved_label_below_1/v1/expected_label_curved_label_below_1.png
diff --git a/.../expected_label_curved_label_below_1/v2/expected_label_curved_label_below_1.png b/.../expected_label_curved_label_below_1/v2/expected_label_curved_label_below_1.png
diff --git a/...cted_label_multipart_touching_lines/expected_label_multipart_touching_lines.png b/...cted_label_multipart_touching_lines/expected_label_multipart_touching_lines.png