anchor.diff:    protected
       // tile generation
       function GenerateTileCalc(const aExtent: TExtent; aBitmap: FMX.Graphics.TBitmap; aPixelWidth, aPixelHeight: Double): TGenerateTileStatus; override;
  +    function ComputeDistanceBetweenPoints(aXDiff, aYDiff: Double): Double;
       procedure DrawDefaultPath(path: TPathData; aBitmap: FMX.Graphics.TBitmap);
       function CalculateWidth(aActiveValue, aRefValue: Double; var aValidFlag: Boolean): Double; Virtual;
       function GetPaletteColor(aActiveTexture, aRefTexture: Double; var aValidFlag: Boolean): TGeoColors;
  
positive.code:   end;
  end;
  
  { TSliceDiffGeometryClassChangePolygonStripeLR }
  
  constructor TSliceDiffGeometryPolygonStripeLR.Create(aLayer: TLayer; aPalette: TWDPalette; aTimeStamp: TDateTime; aCurrentSlice, aRefSlice: TSliceGeometryPolygonLR);
  begin
  
negative.code:                   begin
                      xn := yCurr-yPrev;
                      yn := xPrev-xCurr;
                      pointDist := ComputeDistanceBetweenPoints(xn, yn);
  
                      if validL then
                      begin
  