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Lasso Selection in RadMap

Environment

Product Version Product Author
2019.1.219 RadMap for WinForms Hristo Merdjanov

Description

An example demonstrating how the objects shown on the map can be selected with lasso rectangle.

Solution

The mouse input in RadMap is handled by a special behavior class exposed by the InputBehavior property of the control. This example will demonstrate how a lasso rectangle can be painted on the map upon moving the mouse. The rectangle will be painted as a MapPolygon object added to a special layer in the map. The layer will be updated every time when the mouse is moved so that it will always contain a single object. After releasing the mouse, the elements which are located in the lasso rectangle will be selected using the SelectElement method of the input behavior class.

MapPin objects will also be added to the map in a separate layer upon double-click. These pins can be later selected with the lasso rectangle and are useful while testing.

In this example, the custom logic for creating the lasso rectangle and adding the pins will only work if the Ctrl key is pressed.

Figure 1: Lasso Selection

map-lasso-selection001

Custom Behavior Class

public class CustomMapInputBehavior : MapInputBehavior
{
    PointG mouseDownCoordinates = PointG.Empty;

    public override void OnMouseDown(MouseEventArgs e)
    {
        this.mouseDownCoordinates = this.GetLocation(e.Location);

        base.OnMouseDown(e);

        foreach (var item in this.MapElement.SelectedElements.ToList())
        {
            PointL pixelLocation = MapTileSystemHelper.LatLongToPixelXY(item.Location, this.MapElement.ZoomLevel);
            RectangleL drawRect = new RectangleL(pixelLocation.X - item.Size.Width / 2, pixelLocation.Y - item.Size.Height, item.Size.Width, item.Size.Height);
            PointL point = new PointL(e.X - this.MapElement.PanOffset.Width, e.Y - this.MapElement.PanOffset.Height);
            if (drawRect.Contains(point))
            {
                this.MapElement.SelectedElements.Remove(item);
                item.BackColor = Color.FromArgb(255, 17, 17, 17);
            }
        }
    }

    public override void OnMouseMove(MouseEventArgs e)
    {
        this.MapElement.Layers["Polygons"].Clear();
        if (e.Button == MouseButtons.Left && Control.ModifierKeys == Keys.Control)
        {
            PointG location = this.GetLocation(e.Location);

            if (this.mouseDownCoordinates != PointG.Empty)
            {
                List<PointG> points = new List<PointG>();
                points.Add(this.mouseDownCoordinates);
                points.Add(new PointG(location.Latitude, mouseDownCoordinates.Longitude));
                points.Add(location);
                points.Add(new PointG(mouseDownCoordinates.Latitude, location.Longitude));

                MapPolygon polygon = new MapPolygon(points);
                polygon.BackColor = Color.FromArgb(125, Color.LightGreen);
                this.MapElement.Layers["Polygons"].Add(polygon);
            }
        }
        else
        {
            base.OnMouseMove(e);
        }
    }

    public override void OnMouseUp(MouseEventArgs e)
    {
        base.OnMouseUp(e);

        MapPolygon polygon = this.MapElement.Layers["Polygons"].FirstOrDefault() as MapPolygon;
        if (polygon != null)
        {
            foreach (MapPin item in this.MapElement.Layers["Pins"])
            {
                if (polygon.GeographicBounds.Contains(item.Location))
                {
                    this.SelectElement(item, true);
                    item.BackColor = Color.LightCoral;
                }
            }
        }

        this.mouseDownCoordinates = PointG.Empty;
        this.MapElement.Layers["Polygons"].Clear();
    }

    public override void OnDoubleClick(EventArgs e)
    {
        MouseEventArgs args = e as MouseEventArgs;

        if (args.Button == MouseButtons.Left && Control.ModifierKeys == Keys.Control)
        {
            PointG location = this.GetLocation(args.Location);
            MapPin pin = new MapPin(location);
            this.MapElement.Layers["Pins"].Add(pin);
        }
        else
        {
            base.OnDoubleClick(e);
        }
    }

    private PointG GetLocation(Point mouseLocation)
    {
        PointL point = new PointL(mouseLocation.X - this.MapElement.PanOffset.Width, mouseLocation.Y - this.MapElement.PanOffset.Height);
        PointG location = MapTileSystemHelper.PixelXYToLatLong(point.X, point.Y, this.MapElement.ZoomLevel);

        while (location.Longitude > 180)
        {
            location.Longitude -= 360;
        }

        return location;
    }
}

Initial Setup

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        this.BackColor = Color.White;

        OpenStreetMapProvider osmProvider = new OpenStreetMapProvider();
        osmProvider.InitializationComplete += delegate(object sender, EventArgs e)
        {
            this.radMap1.BringIntoView(new PointG(40d, -99d), 4);
        };

        this.radMap1.MapElement.Providers.Add(osmProvider);
        MapLayer pinsLayer = new MapLayer("Polygons");
        this.radMap1.Layers.Add(pinsLayer);

        this.radMap1.MapElement.Providers.Add(osmProvider);
        pinsLayer = new MapLayer("Pins");
        this.radMap1.Layers.Add(pinsLayer);

        this.radMap1.InputBehavior = new CustomMapInputBehavior();
    }
}
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