[FEATURE] Label polygons using curved labels along perimeter

nyalldawson · nyalldawson · commit 5ab62a91d3a8 · 2016-08-10T08:09:02.000+10:00
This adds a new mode for labeling polygons, where the perimeter of the polygon is labeled using curved labeling. (cherry-picked from 5f33991)
diff --git a/src/app/qgslabelinggui.cpp b/src/app/qgslabelinggui.cpp
@@ -220,6 +220,7 @@ QgsLabelingGui::QgsLabelingGui( QgsVectorLayer* layer, QgsMapCanvas* mapCanvas,
   mPlacePolygonBtnGrp->addButton( radPolygonHorizontal, ( int )QgsPalLayerSettings::Horizontal );
   mPlacePolygonBtnGrp->addButton( radPolygonFree, ( int )QgsPalLayerSettings::Free );
   mPlacePolygonBtnGrp->addButton( radPolygonPerimeter, ( int )QgsPalLayerSettings::Line );
+  mPlacePolygonBtnGrp->addButton( radPolygonPerimeterCurved, ( int )QgsPalLayerSettings::PerimeterCurved );
   mPlacePolygonBtnGrp->setExclusive( true );
   connect( mPlacePolygonBtnGrp, SIGNAL( buttonClicked( int ) ), this, SLOT( updatePlacementWidgets() ) );
 
@@ -465,6 +466,7 @@ QgsLabelingGui::QgsLabelingGui( QgsVectorLayer* layer, QgsMapCanvas* mapCanvas,
   << radPolygonFree
   << radPolygonHorizontal
   << radPolygonPerimeter
+  << radPolygonPerimeterCurved
   << radPredefinedOrder
   << mFieldExpressionWidget;
   connectValueChanged( widgets, SLOT( updatePreview() ) );
@@ -672,6 +674,9 @@ void QgsLabelingGui::init()
     case QgsPalLayerSettings::Free:
       radPolygonFree->setChecked( true );
       break;
+    case QgsPalLayerSettings::PerimeterCurved:
+      radPolygonPerimeterCurved->setChecked( true );
+      break;
   }
 
   // Label repeat distance
@@ -962,11 +967,17 @@ QgsPalLayerSettings QgsLabelingGui::layerSettings()
     lyr.placement = QgsPalLayerSettings::OrderedPositionsAroundPoint;
   }
   else if (( curPlacementWdgt == pageLine && radLineParallel->isChecked() )
-           || ( curPlacementWdgt == pagePolygon && radPolygonPerimeter->isChecked() )
-           || ( curPlacementWdgt == pageLine && radLineCurved->isChecked() ) )
+           || ( curPlacementWdgt == pagePolygon && radPolygonPerimeter->isChecked() ) )
+  {
+    lyr.placement = QgsPalLayerSettings::Line;
+  }
+  else if ( curPlacementWdgt == pageLine && radLineCurved->isChecked() )
+  {
+    lyr.placement = QgsPalLayerSettings::Curved;
+  }
+  else if ( curPlacementWdgt == pagePolygon && radPolygonPerimeterCurved->isChecked() )
   {
-    bool curved = ( curPlacementWdgt == pageLine && radLineCurved->isChecked() );
-    lyr.placement = ( curved ? QgsPalLayerSettings::Curved : QgsPalLayerSettings::Line );
+    lyr.placement = QgsPalLayerSettings::PerimeterCurved;
   }
   else if (( curPlacementWdgt == pageLine && radLineHorizontal->isChecked() )
            || ( curPlacementWdgt == pagePolygon && radPolygonHorizontal->isChecked() ) )
@@ -1707,7 +1718,8 @@ void QgsLabelingGui::updatePlacementWidgets()
   }
   else if (( curWdgt == pageLine && radLineParallel->isChecked() )
            || ( curWdgt == pagePolygon && radPolygonPerimeter->isChecked() )
-           || ( curWdgt == pageLine && radLineCurved->isChecked() ) )
+           || ( curWdgt == pageLine && radLineCurved->isChecked() )
+           || ( curWdgt == pagePolygon && radPolygonPerimeterCurved->isChecked() ) )
   {
     showLineFrame = true;
     showDistanceFrame = true;
@@ -1717,9 +1729,11 @@ void QgsLabelingGui::updatePlacementWidgets()
     chkLineOrientationDependent->setEnabled( offline );
     mPlacementDistanceFrame->setEnabled( offline );
 
-    showMaxCharAngleFrame = ( curWdgt == pageLine && radLineCurved->isChecked() );
+    bool isCurved = ( curWdgt == pageLine && radLineCurved->isChecked() )
+                    || ( curWdgt == pagePolygon && radPolygonPerimeterCurved->isChecked() );
+    showMaxCharAngleFrame = isCurved;
     // TODO: enable mMultiLinesFrame when supported for curved labels
-    enableMultiLinesFrame = !( curWdgt == pageLine && radLineCurved->isChecked() );
+    enableMultiLinesFrame = !isCurved;
   }
 
   mPlacementLineFrame->setVisible( showLineFrame );
@@ -1731,7 +1745,8 @@ void QgsLabelingGui::updatePlacementWidgets()
   mPlacementDistanceFrame->setVisible( showDistanceFrame );
   mPlacementOffsetTypeFrame->setVisible( showOffsetTypeFrame );
   mPlacementRotationFrame->setVisible( showRotationFrame );
-  mPlacementRepeatDistanceFrame->setVisible( curWdgt == pageLine || ( curWdgt == pagePolygon && radPolygonPerimeter->isChecked() ) );
+  mPlacementRepeatDistanceFrame->setVisible( curWdgt == pageLine || ( curWdgt == pagePolygon &&
+      ( radPolygonPerimeter->isChecked() || radPolygonPerimeterCurved->isChecked() ) ) );
   mPlacementMaxCharAngleFrame->setVisible( showMaxCharAngleFrame );
 
   mMultiLinesFrame->setEnabled( enableMultiLinesFrame );
diff --git a/src/core/pal/feature.cpp b/src/core/pal/feature.cpp
@@ -1008,10 +1008,21 @@ int FeaturePart::createCurvedCandidatesAlongLine( QList< LabelPosition* >& lPos,
   // and the line has right-to-left direction
   bool reversed = ( !( flags & FLAG_MAP_ORIENTATION ) ? isRightToLeft : false );
 
+  // an orientation of 0 means try both orientations and choose the best
+  int orientation = 0;
+  if ( !( flags & FLAG_MAP_ORIENTATION )
+       && mLF->layer()->arrangement() == QgsPalLayerSettings::PerimeterCurved )
+  {
+    //... but if we are labeling the perimeter of a polygon and using line orientation flags,
+    // then we can only accept a single orientation, as we need to ensure that the labels fall
+    // inside or outside the polygon (and not mixed)
+    orientation = reversed ? -1 : 1;
+  }
+
   // generate curved labels
   for ( int i = 0; i*delta < total_distance; i++ )
   {
-    LabelPosition* slp = curvedPlacementAtOffset( mapShape, path_distances, 0, 1, i * delta );
+    LabelPosition* slp = curvedPlacementAtOffset( mapShape, path_distances, orientation, 1, i * delta );
 
     if ( slp )
     {
@@ -1325,6 +1336,8 @@ int FeaturePart::createCandidates( QList< LabelPosition*>& lPos,
       case GEOS_LINESTRING:
         if ( mLF->layer()->arrangement() == QgsPalLayerSettings::Curved )
           createCurvedCandidatesAlongLine( lPos, mapShape );
+        else if ( mLF->layer()->arrangement() == QgsPalLayerSettings::PerimeterCurved )
+          createCurvedCandidatesAlongLine( lPos, mapShape );
         else
           createCandidatesAlongLine( lPos, mapShape );
         break;
@@ -1344,6 +1357,9 @@ int FeaturePart::createCandidates( QList< LabelPosition*>& lPos,
           case QgsPalLayerSettings::Line:
             createCandidatesAlongLine( lPos, mapShape );
             break;
+          case QgsPalLayerSettings::PerimeterCurved:
+            createCurvedCandidatesAlongLine( lPos, mapShape );
+            break;
           default:
             createCandidatesForPolygon( lPos, mapShape );
             break;
diff --git a/src/core/pal/labelposition.cpp b/src/core/pal/labelposition.cpp
@@ -99,6 +99,7 @@ LabelPosition::LabelPosition( int id, double x1, double y1, double w, double h,
 
   // upside down ? (curved labels are always correct)
   if ( feature->layer()->arrangement() != QgsPalLayerSettings::Curved &&
+       feature->layer()->arrangement() != QgsPalLayerSettings::PerimeterCurved &&
        this->alpha > M_PI / 2 && this->alpha <= 3*M_PI / 2 )
   {
     bool uprightLabel = false;
diff --git a/src/core/qgspallabeling.cpp b/src/core/qgspallabeling.cpp
@@ -2374,7 +2374,7 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
   double maxcharanglein = 20.0; // range 20.0-60.0
   double maxcharangleout = -20.0; // range 20.0-95.0
 
-  if ( placement == QgsPalLayerSettings::Curved )
+  if ( placement == QgsPalLayerSettings::Curved || placement == QgsPalLayerSettings::PerimeterCurved )
   {
     maxcharanglein = maxCurvedCharAngleIn;
     maxcharangleout = maxCurvedCharAngleOut;
@@ -2518,7 +2518,7 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
 
   GEOSGeometry* geos_geom_clone;
   GEOSGeomTypes geomType = ( GEOSGeomTypes ) GEOSGeomTypeId_r( QgsGeometry::getGEOSHandler(), geos_geom );
-  if (( geomType == GEOS_POLYGON || geomType == GEOS_MULTIPOLYGON ) && repeatDistance > 0 && placement == Line )
+  if (( geomType == GEOS_POLYGON || geomType == GEOS_MULTIPOLYGON ) && repeatDistance > 0 && ( placement == Line || placement == PerimeterCurved ) )
   {
     geos_geom_clone = GEOSBoundary_r( QgsGeometry::getGEOSHandler(), geos_geom );
   }
@@ -2879,7 +2879,8 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, QgsRenderContext &cont
 
   // TODO: only for placement which needs character info
   // account for any data defined font metrics adjustments
-  lf->calculateInfo( placement == QgsPalLayerSettings::Curved, labelFontMetrics.data(), xform, rasterCompressFactor, maxcharanglein, maxcharangleout );
+  lf->calculateInfo( placement == QgsPalLayerSettings::Curved || placement == QgsPalLayerSettings::PerimeterCurved,
+                     labelFontMetrics.data(), xform, rasterCompressFactor, maxcharanglein, maxcharangleout );
   // 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/qgspallabeling.h b/src/core/qgspallabeling.h
@@ -89,6 +89,7 @@ class CORE_EXPORT QgsPalLayerSettings
       Horizontal, /**< Arranges horizontal candidates scattered throughout a polygon feature. Applies to polygon layers only.*/
       Free, /**< Arranges candidates scattered throughout a polygon feature. Candidates are rotated to respect the polygon's orientation. Applies to polygon layers only.*/
       OrderedPositionsAroundPoint, /**< Candidates are placed in predefined positions around a point. Peference is given to positions with greatest cartographic appeal, eg top right, bottom right, etc. Applies to point layers only.*/
+      PerimeterCurved, /** Arranges candidates following the curvature of a polygon's boundary. Applies to polygon layers only.*/
     };
 
     //! Positions for labels when using the QgsPalLabeling::OrderedPositionsAroundPoint placement mode
diff --git a/src/ui/qgslabelingguibase.ui b/src/ui/qgslabelingguibase.ui

Original file line number	Diff line number	Diff line change
`@@ -99,6 +99,7 @@ LabelPosition::LabelPosition( int id, double x1, double y1, double w, double h,`
`99`	`99`
`100`	`100`	`// upside down ? (curved labels are always correct)`
`101`	`101`	`if ( feature->layer()->arrangement() != QgsPalLayerSettings::Curved &&`
	`102`	`+ feature->layer()->arrangement() != QgsPalLayerSettings::PerimeterCurved &&`
`102`	`103`	`this->alpha > M_PI / 2 && this->alpha <= 3*M_PI / 2 )`
`103`	`104`	`{`
`104`	`105`	`bool uprightLabel = false;`