问如何利用点空间与半径相交边界盒和点

EN

    /// <summary>
    /// This method creates a rectangular geographic envelope that is expanded by the 
    /// specified geographic amount in the original geographic units.  Envelopes 
    /// are useful in that they are simpler than geographic shapes,
    /// and so are much quicker to do intersection testing with.
    /// </summary>
    /// <param name="center">The center point in X and Y.</param>
    /// <returns>A rectangular Envelope that contains the center point.</returns>
    public static Envelope Extend(Coordinate center, double distance)
    {
        Envelope result = new Envelope(center);
        result.ExpandBy(distance);
        return result;
    }

    /// <summary>
    /// Intersection testing with an envelope works the same as with the slower 
    /// and heavier geometries, but should be considerably faster.
    /// </summary>
    /// <param name="testPoint">The test point.</param>
    /// <param name="box">The Envelope that has the box.</param>
    /// <returns>Boolean, true if the box intersects with (contains, or touches) the 
    /// test point.</returns>
    public static bool ContainsTest(Coordinate testPoint, Envelope box)
    {
        return box.Intersects(testPoint);
    }

    /// <summary>
    /// To get a geographic envelope 10 pixels around an X, Y position of a pixel 
    /// coordinate on the map, in terms of the actual visible map component (and not 
    /// the possibly extended buffer of the map frame).
    /// </summary>
    /// <param name="center">The pixel position of the center on the map control</param>
    /// <param name="map">The map control</param>
    /// <returns>A Geographic envelope</returns>
    public static Envelope Expand(Point center, Map map)
    {
        Rectangle rect = new Rectangle(center.X - 10, center.Y - 10, 20, 20);
        // Get the geographic points
        return map.PixelToProj(rect);
    }

    /// <summary>
    /// To get a pixel coordinate bounding rectangle around a geographic point for 
    /// hit testing is similar.
    /// </summary>
    /// <param name="test">The geographic coordinate</param>
    /// <param name="map">The map control</param>
    /// <returns>A pixel coordinate rectangle for the specified coordinate</returns>
    public static Rectangle Bounds(Coordinate test, Map map)
    {
        Envelope result = new Envelope(center);
        result.ExpandBy(distance);
        return map.ProjToPixel(result);
    }