main_custom_markers.py

import dash
import dash_leaflet as dl
from dash import Dash, html, Output, Input
import dash_bootstrap_components as dbc
from dash.exceptions import PreventUpdate

purple_dot = {"iconUrl": 'https://storage.googleapis.com/terrakio_webapps/purple_dot.png', "iconSize": [40, 40]}
red_triangle = {"iconUrl": 'https://storage.googleapis.com/terrakio_webapps/red_triangle.png', "iconSize": [40, 40]}

hires_url = "https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}"


app = dash.Dash(external_stylesheets=[dbc.themes.BOOTSTRAP])

app.layout = dbc.Container(
    [
        dbc.Row([
            dbc.Col([
                dl.Map(center=[-28.34, 148.42], zoom=13, children=[
                    dl.TileLayer(url=hires_url),
                    dl.FeatureGroup([
                        dl.EditControl(id="edit_control", draw=dict(circle=False, circlemarker=False, rectangle=False, polyline=False, polygon=False)),
                        dl.Marker(position=[-28.34, 148.42], icon=purple_dot),
                        dl.Marker(position=[-28.33, 148.411], icon=red_triangle),
                        ]),
                ],  style={'width': '1000px', 'height': '500px'}),
            ] , md=8),
            dbc.Col([
                dbc.RadioItems(
                id="radios",
                className="btn-group",
                inputClassName="btn-check",
                labelClassName="btn btn-outline-primary",
                labelCheckedClassName="active",
                options=[
                    {"label": "Dot", "value": 1},
                    {"label": "Triangle", "value": 2},
                ],
                value=1),
            ] , md=4),
        ]),
        dbc.Row([
            dbc.Col(html.Div(id="json"), md=4),
        ], align="center",),
    ],
    fluid=True,
)

@app.callback(
        Output("json", "children"),
        Input("edit_control", "geojson"))
def mirror(x):
    if not x:
        raise PreventUpdate
    return str(x)

if __name__ == "__main__":
    app.run_server(port=8081, debug=True)