[labeling] Fix curved labeling fails when line feature geometry

begins with small segments Fixes #28699
qgis · May 30, 2019 · 328b0af · 328b0af
1 parent fcacd00
commit 328b0af
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Showing 3 changed files with 57 additions and 1 deletion.
diff --git a/src/core/pal/feature.cpp b/src/core/pal/feature.cpp
@@ -1000,7 +1000,7 @@ LabelPosition *FeaturePart::curvedPlacementAtOffset( PointSet *path_positions, d
     {
       LabelInfo::CharacterInfo &ci = li->char_info[i];
       double start_x, start_y, end_x, end_y;
-      if ( !nextCharPosition( ci.width, path_distances[index], path_positions, endindex, _distance, start_x, start_y, end_x, end_y ) )
+      if ( !nextCharPosition( ci.width, path_distances[endindex], path_positions, endindex, _distance, start_x, start_y, end_x, end_y ) )
       {
         return nullptr;
       }

diff --git a/tests/src/core/testqgslabelingengine.cpp b/tests/src/core/testqgslabelingengine.cpp
@@ -55,6 +55,7 @@ class TestQgsLabelingEngine : public QObject
     void testAdjacentParts();
     void testTouchingParts();
     void testMergingLinesWithForks();
+    void testCurvedLabelsWithTinySegments();
     void testLabelBoundary();
     void testLabelBlockingRegion();
     void testLabelRotationWithReprojection();
@@ -981,6 +982,61 @@ void TestQgsLabelingEngine::testMergingLinesWithForks()
   QVERIFY( imageCheck( QStringLiteral( "label_multipart_touching_branches" ), img, 20 ) );
 }
 
+void TestQgsLabelingEngine::testCurvedLabelsWithTinySegments()
+{
+  // test drawing curved labels when input linestring has many small segments
+  QgsPalLayerSettings settings;
+  setDefaultLabelParams( settings );
+
+  QgsTextFormat format = settings.format();
+  format.setSize( 20 );
+  format.setColor( QColor( 0, 0, 0 ) );
+  settings.setFormat( format );
+
+  settings.fieldName = QStringLiteral( "'XXXXXXXXXXXXXXXXXXXXXXXXXX'" );
+  settings.isExpression = true;
+  settings.placement = QgsPalLayerSettings::Curved;
+
+  std::unique_ptr< QgsVectorLayer> vl2( new QgsVectorLayer( QStringLiteral( "LineString?crs=epsg:3946&field=id:integer" ), QStringLiteral( "vl" ), QStringLiteral( "memory" ) ) );
+  vl2->setRenderer( new QgsNullSymbolRenderer() );
+
+  QgsFeature f;
+  f.setAttributes( QgsAttributes() << 1 );
+  // our geometry starts with many small segments, followed by long ones
+  QgsGeometry g( QgsGeometry::fromWkt( QStringLiteral( "LineString (190000 5000010, 190100 5000000)" ) ) );
+  g = g.densifyByCount( 100 );
+  qgsgeometry_cast< QgsLineString * >( g.get() )->addVertex( QgsPoint( 190200, 5000000 ) );
+  f.setGeometry( g );
+  QVERIFY( vl2->dataProvider()->addFeature( f ) );
+
+  vl2->setLabeling( new QgsVectorLayerSimpleLabeling( settings ) );  // TODO: this should not be necessary!
+  vl2->setLabelsEnabled( true );
+
+  // make a fake render context
+  QSize size( 640, 480 );
+  QgsMapSettings mapSettings;
+  mapSettings.setDestinationCrs( vl2->crs() );
+
+  mapSettings.setOutputSize( size );
+  mapSettings.setExtent( g.boundingBox() );
+  mapSettings.setLayers( QList<QgsMapLayer *>() << vl2.get() );
+  mapSettings.setOutputDpi( 96 );
+  mapSettings.setFlag( QgsMapSettings::UseRenderingOptimization, false );
+
+  QgsLabelingEngineSettings engineSettings = mapSettings.labelingEngineSettings();
+  engineSettings.setFlag( QgsLabelingEngineSettings::UsePartialCandidates, false );
+  engineSettings.setFlag( QgsLabelingEngineSettings::DrawLabelRectOnly, true );
+  //engineSettings.setFlag( QgsLabelingEngineSettings::DrawCandidates, true );
+  mapSettings.setLabelingEngineSettings( engineSettings );
+
+  QgsMapRendererSequentialJob job( mapSettings );
+  job.start();
+  job.waitForFinished();
+
+  QImage img = job.renderedImage();
+  QVERIFY( imageCheck( QStringLiteral( "label_curved_label_small_segments" ), img, 20 ) );
+}
+
 void TestQgsLabelingEngine::testLabelBoundary()
 {
   // test that no labels are drawn outside of the specified label boundary

diff --git a/...abel_curved_label_small_segments/expected_label_curved_label_small_segments.png b/...abel_curved_label_small_segments/expected_label_curved_label_small_segments.png