How to add circle to the mapview in python kivy

Question

i am trying to add circle to mapview. To a certain position on the map. I'm trying to make the radius in map canvas units. and I want it to be attached to that place even when I move or zoom with the map. I would like it in python if possible without a kv file. I would imagine the outcome like this: Map I will be glad for any help because I am quite stuck.

I just tried this:

class Circle(MapMarkerPopup):
    def __init__(self, **kwargs):
        super(Circle, self).__init__(**kwargs)
        with self.canvas:
            Color(0, 0, 0, .6)
            Line(circle=(self.x, self.y, 10), width=200)

Answer 1

You can imitate the MapMarker by creating a custom class, perhaps named MapCircle:

class MapCircle(ButtonBehavior, Widget):
    line_width = NumericProperty(2.0)
    """ Width of the circle line"""

    line_color = ListProperty([0, 0, 0, 1])
    """ Color of the circle line"""

    anchor_x = NumericProperty(0.5)
    """Anchor of the marker on the X axis. Defaults to 0.5, mean the anchor will
    be at the X center of the image.
    """

    anchor_y = NumericProperty(0)
    """Anchor of the marker on the Y axis. Defaults to 0, mean the anchor will
    be at the Y bottom of the image.
    """

    lat = NumericProperty(0)
    """Latitude of the marker
    """

    lon = NumericProperty(0)
    """Longitude of the marker
    """

    # (internal) reference to its layer
    _layer = None

    def detach(self):
        if self._layer:
            self._layer.remove_widget(self)
            self._layer = None

Then load this kv:

<MapCircle>:
    size_hint: None, None
    canvas:
        Color:
            rgba: root.line_color
        Line:
            width: root.line_width
            circle:
                (self.x, self.y, self.width)

which describes how the circle is drawn. Then, you just use this as you would a MapMarker:

class MapViewApp(App):
    def build(self):
        self.map = MapView(zoom=15, lat=49.566848, lon=-77.377053, double_tap_zoom=True)
        self.marker = MapCircle(lat=49.566848, lon=-77.377053, line_color=[1, 0, 0, 1], line_width=5, size=[20, 20])
        self.map.add_marker(self.marker)
        return self.map