[pal] Scale coordinates stored in pal rtrees to full float ranges

Avoids crashes caused by super-heavy labeling jobs, where a huge
number of candidates causes the rtree to branch out to a level
where the leaf size becomes comparable to float epsilon values

src/core/pal/pal.cpp

@@ -91,11 +91,16 @@ Layer *Pal::addLayer( QgsAbstractLabelProvider *provider, const QString &layerNa
 
 std::unique_ptr<Problem> Pal::extract( const QgsRectangle &extent, const QgsGeometry &mapBoundary )
 {
+  // expand out the incoming buffer by 1000x -- that's the visible map extent, yet we may be getting features which exceed this extent
+  // (while 1000x may seem excessive here, this value is only used for scaling coordinates in the spatial indexes
+  // and the consequence of inserting coordinates outside this extent is worse than the consequence of setting this value too large.)
+  const QgsRectangle maxCoordinateExtentForSpatialIndices = extent.buffered( std::max( extent.width(), extent.height() ) * 1000 );
+
   // to store obstacles
-  PalRtree< FeaturePart > obstacles;
-  PalRtree< LabelPosition > allCandidatesFirstRound;
+  PalRtree< FeaturePart > obstacles( maxCoordinateExtentForSpatialIndices );
+  PalRtree< LabelPosition > allCandidatesFirstRound( maxCoordinateExtentForSpatialIndices );
   std::vector< FeaturePart * > allObstacleParts;
-  std::unique_ptr< Problem > prob = qgis::make_unique< Problem >();
+  std::unique_ptr< Problem > prob = qgis::make_unique< Problem >( maxCoordinateExtentForSpatialIndices );
 
   double bbx[4];
   double bby[4];

src/core/pal/palrtree.h

@@ -35,6 +35,20 @@ class PalRtree : public RTree<T *, float, 2, float>
 {
   public:
 
+    /**
+     * Constructor for PalRtree. The \a maxBounds argument specifies the maximum bounding box
+     * for all coordinates which will be stored in the index.
+     */
+    PalRtree( const QgsRectangle &maxBounds )
+      : mXMin( maxBounds.xMinimum() )
+      , mYMin( maxBounds.yMinimum() )
+      , mXRes( ( std::numeric_limits< float >::max() - 1 ) / ( maxBounds.xMaximum() - maxBounds.xMinimum() ) )
+      , mYRes( ( std::numeric_limits< float >::max() - 1 ) / ( maxBounds.yMaximum() - maxBounds.yMinimum() ) )
+      , mMaxBounds( maxBounds )
+    {
+
+    }
+
     /**
      * Inserts new \a data into the spatial index, with the specified \a bounds.
      *
@@ -43,14 +57,13 @@ class PalRtree : public RTree<T *, float, 2, float>
      */
     void insert( T *data, const QgsRectangle &bounds )
     {
+      std::array< float, 4 > scaledBounds = scaleBounds( bounds );
       this->Insert(
       {
-        static_cast< float >( bounds.xMinimum() ),
-        static_cast< float >( bounds.yMinimum() )
+        scaledBounds[0], scaledBounds[ 1]
       },
       {
-        static_cast< float>( bounds.xMaximum() ),
-        static_cast< float >( bounds.yMaximum() )
+        scaledBounds[2], scaledBounds[3]
       },
       data );
     }
@@ -63,14 +76,13 @@ class PalRtree : public RTree<T *, float, 2, float>
      */
     void remove( T *data, const QgsRectangle &bounds )
     {
+      std::array< float, 4 > scaledBounds = scaleBounds( bounds );
       this->Remove(
       {
-        static_cast< float >( bounds.xMinimum() ),
-        static_cast< float >( bounds.yMinimum() )
+        scaledBounds[0], scaledBounds[ 1]
       },
       {
-        static_cast< float>( bounds.xMaximum() ),
-        static_cast< float >( bounds.yMaximum() )
+        scaledBounds[2], scaledBounds[3]
       },
       data );
     }
@@ -82,18 +94,36 @@ class PalRtree : public RTree<T *, float, 2, float>
      */
     bool intersects( const QgsRectangle &bounds, const std::function< bool( T *data )> &callback ) const
     {
+      std::array< float, 4 > scaledBounds = scaleBounds( bounds );
       this->Search(
       {
-        static_cast< float >( bounds.xMinimum() ),
-        static_cast< float >( bounds.yMinimum() )
+        scaledBounds[0], scaledBounds[ 1]
       },
       {
-        static_cast< float>( bounds.xMaximum() ),
-        static_cast< float >( bounds.yMaximum() )
+        scaledBounds[2], scaledBounds[3]
       },
       callback );
       return true;
     }
+
+  private:
+
+    // Coordinates are scaled inside the index so that they cover the maximum range for float values
+    double mXMin = 0;
+    double mYMin = 0;
+    double mXRes = 1;
+    double mYRes = 1;
+    const QgsRectangle mMaxBounds;
+    std::array<float, 4> scaleBounds( const QgsRectangle &bounds ) const
+    {
+      return
+      {
+        static_cast< float >( ( std::max( bounds.xMinimum(), mMaxBounds.xMinimum() ) - mXMin ) / mXRes ),
+        static_cast< float >( ( std::max( bounds.yMinimum(), mMaxBounds.yMinimum() ) - mYMin ) / mYRes ),
+        static_cast< float >( ( std::min( bounds.xMaximum(), mMaxBounds.xMaximum() ) - mXMin ) / mXRes ),
+        static_cast< float >( ( std::min( bounds.yMaximum(), mMaxBounds.yMaximum() ) - mYMin ) / mYRes )
+      };
+    }
 };
 
 #endif

src/core/pal/problem.cpp

@@ -54,7 +54,12 @@ inline void delete_chain( Chain *chain )
   }
 }
 
-Problem::Problem() = default;
+Problem::Problem( const QgsRectangle &extent )
+  : mAllCandidatesIndex( extent )
+  , mActiveCandidatesIndex( extent )
+{
+
+}
 
 Problem::~Problem() = default;
 

src/core/pal/problem.h

@@ -71,7 +71,13 @@ namespace pal
       friend class Pal;
 
     public:
-      Problem();
+
+      /**
+       * Constructor for Problem.
+       *
+       * The \a extent argument specifies the bounds of the incoming coordinates.
+       */
+      Problem( const QgsRectangle &extent );
 
       //Problem(char *lorena_file, bool displayAll);