SelectBox.cs

This example demonstrates how to manually select shapes and to show information about the their relative area. The shapes area selected by mouse dragging. Chart is update automatically. Here is a screenshot with the results of the code.

using System;
using System.Windows.Forms;
using AxMapWinGIS;
using MapWinGIS;
using System.IO;

public partial class MapExamples
{
    // <summary>
    // Adds the layers and register event handler.
    // </summary>
    public void SelectBox(AxMap axMap1, string dataPath)
    {
        string filename = dataPath + "landuse.shp";

        if (!File.Exists(filename))
        {
            MessageBox.Show("Couldn't file the file: " + filename);
            return;
        }

        Shapefile sf = new Shapefile();
        sf.Open(filename, null);
        if (!sf.StartEditingShapes(true, null))
        {
            MessageBox.Show("Failed to start edit mode: " + sf.Table.get_ErrorMsg(sf.LastErrorCode));
        }
        else
        {
            sf.UseQTree = true;
            sf.Labels.Generate("[Name]", tkLabelPositioning.lpCentroid, false);

            axMap1.AddLayer(sf, true);
            axMap1.SendSelectBoxFinal = true;
            MapEvents.SelectBoxFinal += new AxMapWinGIS._DMapEvents_SelectBoxFinalEventHandler(axMap1_SelectBoxFinal); // change MapEvents to axMap1
            axMap1.MapUnits = tkUnitsOfMeasure.umMeters;
            axMap1.CurrentScale = 50000;
            axMap1.CursorMode = tkCursorMode.cmSelection;
         }
    }

    // <summary>
    // Performs selection, updates charts
    // </summary>
    void axMap1_SelectBoxFinal(object sender, _DMapEvents_SelectBoxFinalEvent e)
    {
        // it's assumed here that the layer we want to edit is the first 1 (with 0 index)
        int layerHandle = axMap1.get_LayerHandle(0);  
        Shapefile sf = axMap1.get_Shapefile(layerHandle);
        if (sf != null)
        {
            double left = 0.0;
            double top = 0.0;
            double bottom = 0.0;
            double right = 0.0;
            axMap1.PixelToProj(e.left, e.top, ref left, ref top);
            axMap1.PixelToProj(e.right, e.bottom, ref right, ref bottom);

            object result = null;
            Extents ext = new Extents();
            ext.SetBounds(left, bottom, 0.0, right, top, 0.0);
            
            sf.SelectNone();
            if (sf.SelectShapes(ext, 0.0, SelectMode.INTERSECTION, ref result))
            {
                int[] shapes = result as int[];
                for (int i = 0; i < shapes.Length; i++)
                {
                    sf.set_ShapeSelected(shapes[i], true);
                }
            }
            axMap1.Redraw();
        }
    }
}