public class WindStyle: TextStyle
    {

        private Dictionary<string, GeoImage> m_WindImages;
        private ZoomLevelSet m_ZoomLevels;
        private List<GriddedZoomLevelDef> m_ZoomLevelDef;
        public WindStyle(Dictionary<string, GeoImage> windImages, ZoomLevelSet zoomLevels, List<GriddedZoomLevelDef> zoomLevelDef )
            : base()
        {
            m_WindImages = windImages;
            m_ZoomLevels = zoomLevels;
            m_ZoomLevelDef = zoomLevelDef;

            if (m_WindImages == null || m_WindImages.Count == 0)
                m_WindImages = CreateWindGeoImages();

        }



        internal static Dictionary<string, GeoImage> CreateWindGeoImages()
        {
            string windDirectory = Path.Combine(Singleton.Variables.ApplicationSettings.WeatherShpSplitPath, "img");
            Dictionary<string, GeoImage> dicImages = new Dictionary<string, GeoImage>();

            foreach (string file in Directory.GetFiles(windDirectory, "wind*.png"))
            {
                Bitmap b = new Bitmap(file);
                Bitmap scaled = new Bitmap(b, new Size((int)(b.Width * 0.6), (int)(b.Height * 0.6)));
                MemoryStream stream = new MemoryStream();
                scaled.Save(stream, ImageFormat.Png);
                dicImages.AddIfNotExists(Path.GetFileNameWithoutExtension(file).ToLower(), new GeoImage(stream));

            }
            return dicImages;
        }
        
        protected override Collection<string> GetRequiredColumnNamesCore()
        {
          
            var results = new Collection<string>(){"val", "spd"};
            return results;
        }

       
        protected override Collection<Feature> FilterFeaturesCore(IEnumerable<Feature> features, GeoCanvas canvas)
        {
            if (m_ZoomLevelDef == null || m_ZoomLevelDef.Count < 2)
            {
                return new Collection<Feature>(features.ToList());
            }
            int currentZoomLevel = StyleUtils.GetCurrentZoomLevel(m_ZoomLevels, canvas.CurrentWorldExtent, (double)canvas.Width, canvas.MapUnit);
            GriddedZoomLevelDef startFromZoomLevel = null;

            for (int i = 0; i <= m_ZoomLevelDef.Count - 2; i++)
            {
                if (currentZoomLevel >= m_ZoomLevelDef[i].ZoomLevel && currentZoomLevel < m_ZoomLevelDef[i + 1].ZoomLevel)
                {
                    startFromZoomLevel = m_ZoomLevelDef[i];
                    break;
                }
            }

            if (startFromZoomLevel == null)
                return new Collection<Feature>(features.ToList());
            else
                return new Collection<Feature>(features.AsParallel().Where(f => IsMatch(f, currentZoomLevel, startFromZoomLevel.DisplayInterval)).ToList());

        }

        private bool IsMatch(Feature feature,  int currentZoomLevel, double displayInterval)
        {
            PointShape pointDegrees = (PointShape)Singleton.DefaultProjection.ConvertToInternalProjection(feature.GetBoundingBox().GetCenterPoint());
            if (pointDegrees.Y < 0)
                feature.Tag = "S";
            else
                feature.Tag = "N";
            if (Math.Round(pointDegrees.X, 2) % displayInterval == 0 && Math.Round(pointDegrees.Y, 2) % displayInterval == 0)
                return true;
            else
                return false;
              
        }
       
        protected override void DrawCore(IEnumerable<Feature> features, GeoCanvas canvas, Collection<SimpleCandidate> labelsInThisLayer, System.Collections.ObjectModel.Collection<SimpleCandidate> labelsInAllLayers)
        {
            Collection<Feature> filteredFeatures = FilterFeatures(features, canvas);

            
            foreach (Feature feature in filteredFeatures)
            {
                float angle = float.Parse(feature.ColumnValues["val"]);
                float spd = float.Parse(feature.ColumnValues["spd"]);

                int speed = (int)(Math.Round(spd / 5.0) * 5.0);


                if (speed > 100) speed = 100;
                if (speed > 0)
                {

                    PointShape centerPoint = feature.GetBoundingBox().GetCenterPoint();
                    string key = ("wind_" + feature.Tag.ToString() + "_" + speed).ToLower();

                    if (m_WindImages.ContainsKey(key))
                    {
                            canvas.DrawWorldImageWithoutScaling(m_WindImages[key], centerPoint.X, centerPoint.Y, DrawingLevel.LabelLevel, 0, 0, -angle);
                    }
                    else
                    {
                        Logger.Log.Error("wind key " + key + " not found");
                    }

                }

            }


        }
        
    }