Updated Wiki: Shapefile symbology

// opening shapefilestring filename = @"d:\my_data.shp";
var sf = new Shapefile();
if (!sf.Open(filename))
{
    MessageBox.Show("Failed to open file: " + filename);
    return;
}

// 1. let's assume that we want to set a unique color to a 10-th shape// in a shapefile; let's create a category to do itint shapeIndex = 10;
string categoryName = "red_shapes";   // any name can be usedvar ct = sf.Categories.Add(categoryName);

// set red color for fillvar utils = new Utils();
ct.DrawingOptions.FillColor = utils.ColorByName(tkMapColor.Red);

// to apply the category to the shape any of 3 overloads of Shapefile.ShapeCategoryint categoryIndex = sf.Categories.CategoryIndex[ct];
sf.set_ShapeCategory(shapeIndex, categoryIndex);     // either (the fastest)
sf.set_ShapeCategory2(shapeIndex, categoryName);   // or
sf.set_ShapeCategory3(shapeIndex, ct);             // or// 2. Now let's assume that shapes from 5th to 14th should be red as well:for (int i = 5; i < 14; i++)
{
    sf.set_ShapeCategory(i, categoryIndex);
}

// 3. Perhaps we want to do it based on attributes from DBF table;// shapes with Type field having value "hot" should be redint fieldIndex = sf.get_FieldIndexByName("Type");
if (fieldIndex != -1)
{
    for (int i = 0; i < sf.NumShapes; i++)
    {
        var value = sf.get_CellValue(fieldIndex, i).ToString();
        if (value == "hot")
            sf.set_ShapeCategory(i, categoryIndex);
    }
}

// 4. The same using expressions (under the hood this calls sf.set_ShapeCategory,// just like the previous one
ct.Expression = "[Type] = \"hot\"";
sf.Categories.ApplyExpression(categoryIndex);
            
// 5. Probably user doesn't like red; simply change category definition// no need to loop through shapes once again
ct.DrawingOptions.FillColor = utils.ColorByName(tkMapColor.Orange);

// 6. finally add it the mapint layerHandle = axMap1.AddLayer(sf, true);