Point In Polygon Testing

This example uses selection, but is not the easiest way to select in response to mouse clicks, which is already provided as a MapFunction. Instead, this give an idea of a practical application of selecting a polygon based on the fact that it intersects with a coordinate that is clicked. This relies on a very new fix to the code base to work correctly, but if you have the latest version it should work fine.

{{ using System; using System.Windows.Forms; using MapWindow.Data; using MapWindow.Geometries; using MapWindow.Map; namespace WindowsFormsApplication19 { public partial class Form1 : Form { public Form1() { InitializeComponent(); map1.MouseUp += map1_MouseUp; map1.FunctionMode = FunctionModes.Pan; }

    // Handle the mouse up event
    void map1_MouseUp(object sender, MouseEventArgs e)
    {
        // only select polygons with the right button
        if(e.Button != MouseButtons.Right) return;

        // Get the geographic location of the mouse click
        Coordinate c = map1.PixelToProj(e.Location);

        // Return if no data layers exist
        if(map1.Layers.Count < 1) return;

        
        // Also, mpl can be used to change the selection color.
        IMapPolygonLayer mpl = map1.Layers[0](0) as IMapPolygonLayer;

        // If the first layer is not a polygon layer, exit.
        if(mpl == null) return;

        // Get the featureset that contains the actual polygon data for the layer
        IFeatureSet fs = map1.Layers[0](0).DataSet as IFeatureSet;

        // If this is null or not a featureset, exit
        if(fs == null) return;

        // Set up an index 
        int iShape = 0;
        
        // Cycle through the shapes
        foreach (ShapeRange shape in fs.ShapeIndices)
        {
            // Test if the coordinate is in the polygon
            if(shape.Intersects(c))
            {
                // Select the polygon if the the coordinate intersects.
                mpl.Select(iShape);
            }
            iShape++;
        }
    }
    // Allow the addition of background layers
    private void btnAdd_Click(object sender, EventArgs e)
    {
        map1.AddLayer();
    }
}

} }}