AddCategoryRange.cs

This example demonstrates how to calculate area of polygons and to set 3 ranges of categories with different symbology. This example demonstrates quite elaborate specification of categories. In most cases much easier approaches can be used (see ShapefileCategories.Generate). Here is a screenshot with the results of the code execution.

// ReSharper disable ArrangeAccessorOwnerBody
// ReSharper disable DelegateSubtraction
// ReSharper disable PossibleInvalidCastExceptionInForeachLoop
// ReSharper disable CheckNamespace
 
using System.IO;
using System.Windows.Forms;
using AxMapWinGIS;
using MapWinGIS;
// ReSharper disable SuggestVarOrType_BuiltInTypes
// ReSharper disable SuggestVarOrType_SimpleTypes
 
namespace Examples
{
    public partial class MapExamples
    {
        // <summary>
        // Calculates area of polygons and sets 3 range of categories with different symbology
        // </summary>
        public void AddCategoryRange(AxMap axMap, string dataPath)
        {
            axMap.Projection = tkMapProjection.PROJECTION_GOOGLE_MERCATOR;
 
            string filename = dataPath + "landuse.shp";
            if (File.Exists(filename) == false)
            {
                MessageBox.Show(@"Failed to open file: " + filename);
                return;
            }
 
            Shapefile sf = new Shapefile();
            if (!sf.Open(filename)) return;
            
            if (!sf.StartEditingTable())
            {
                MessageBox.Show(@"Failed to open editing mode.");
                return;
            }
            
            int fieldIndex = sf.Table.FieldIndexByName["Area"];
            
            if (fieldIndex == -1)
                fieldIndex = sf.EditAddField("Area", FieldType.DOUBLE_FIELD, 15, 18);
 
            for (int i = 0; i < sf.NumShapes; i++)
            {
                double area = sf.Shape[i].Area * 100000.0;
                sf.EditCellValue(fieldIndex, i, area);
            }
 
            // adding to map
            int handle = axMap.AddLayer(sf, true);
            sf = axMap.get_Shapefile(handle);     // in case a copy of shapefile was created by GlobalSettings.ReprojectLayersOnAdding
 
            double mean = sf.Table.MeanValue[fieldIndex];
            double stDev = sf.Table.StandardDeviation[fieldIndex];
            double min = (double)sf.Table.MinValue[fieldIndex];
            double max = (double)sf.Table.MaxValue[fieldIndex];
 
            var scheme = new ColorScheme();
 
            // 1. the first range [min; mean - stDev]
            Utils utils = new Utils();
            sf.DefaultDrawingOptions.FillType = tkFillType.ftHatch;
            sf.DefaultDrawingOptions.FillHatchStyle = tkGDIPlusHatchStyle.hsDiagonalBrick;
            
            sf.Categories.AddRange(fieldIndex, tkClassificationType.ctNaturalBreaks, 5, min, mean);
            scheme.SetColors2(tkMapColor.Red, tkMapColor.Yellow);
            
            // apply colors 0 and 4 are indices of categories, since 5 categories were added - from 0 to 4
            sf.Categories.ApplyColorScheme3(tkColorSchemeType.ctSchemeRandom, scheme, tkShapeElements.shElementFill, 0, 4);
 
            // 2. the second range [mean - stDev; mean + stDev]
            // the default drawing options will be copied to the new categories
            sf.DefaultDrawingOptions.FillType = tkFillType.ftHatch;
            sf.DefaultDrawingOptions.FillHatchStyle = tkGDIPlusHatchStyle.hsCross;
            sf.Categories.AddRange(fieldIndex, tkClassificationType.ctEqualIntervals, 5, mean, mean + stDev);
            scheme.SetColors2(tkMapColor.Green, tkMapColor.Blue);
            sf.Categories.ApplyColorScheme3(tkColorSchemeType.ctSchemeGraduated, scheme, tkShapeElements.shElementFill, 5, 9);
 
            // 3. the third range [mean + stDev; max]
            // the default drawing options will be copied to the new categories
            sf.DefaultDrawingOptions.FillType = tkFillType.ftGradient;
            sf.DefaultDrawingOptions.FillColor2 = utils.ColorByName(tkMapColor.Gray);
            sf.Categories.AddRange(fieldIndex, tkClassificationType.ctEqualIntervals, 5, mean + stDev, max);
            scheme.SetColors2(tkMapColor.Pink, tkMapColor.Violet);
            sf.Categories.ApplyColorScheme3(tkColorSchemeType.ctSchemeGraduated, scheme, tkShapeElements.shElementFill, 10, 14);
 
            // apply expresions should be called exlicitly
            sf.Categories.ApplyExpressions();
            axMap.Redraw();
 
            // saving options to see categories desription in XML
            axMap.SaveLayerOptions(handle, "categories_sample", true, "");
        }
 
        // <summary>
        // To apply the same options on the next loading
        // </summary>
        private void RestoreCategories(AxMap axMap, string dataPath)
        {
            string filename = dataPath + "landuse.shp";
            Shapefile sf = new Shapefile();
            if (!sf.Open(filename)) return;
            
            int handle = axMap.AddLayer(sf, true);
            string description = "";
            axMap.LoadLayerOptions(handle, "categories_sample", ref description);
        }
    }
}