In [6]:
from IPython.html import widgets
from IPython.utils import traitlets
Define the Python component of the Google Maps widget.
In [7]:
class GoogleMapsWidget(widgets.DOMWidget):
_view_name = traitlets.Unicode('GoogleMapsView', sync=True)
value = traitlets.Unicode(sync=True)
description = traitlets.Unicode(sync=True)
lat = traitlets.CFloat(0, help="Center latitude, -90 to 90", sync=True)
lng = traitlets.CFloat(0, help="Center longitude, -180 to 180", sync=True)
zoom = traitlets.CInt(0, help="Zoom level, 0 to ~25", sync=True)
bounds = traitlets.List([], help="Visible bounds, [W, S, E, N]", sync=True)
def __init__(self, lng=0.0, lat=0.0, zoom=2):
self.lng = lng
self.lat = lat
self.zoom = zoom
def addLayer(self, image, vis_params, name=None, visible=True):
mapid = image.getMapId(vis_params)
self.send({'command':'addLayer', 'mapid': mapid['mapid'], 'token': mapid['token'], 'name': name, 'visible': visible})
def center(self, lng, lat, zoom=None):
self.send({'command': 'center', 'lng': lng, 'lat': lat, 'zoom': zoom})
Define the Javascript code for the widget.
In [8]:
%%javascript
require(["widgets/js/widget"], function(WidgetManager){
var maps = [];
// Define the GoogleMapsView
var GoogleMapsView = IPython.DOMWidgetView.extend({
render: function() {
// Resize widget element to be 100% wide
this.$el.css('width', '100%');
// iframe source; just enough to load Google Maps and let us poll whether initialization is complete
var src='<html style="height:100%"><head>' +
'<scr'+'ipt src="http://maps.googleapis.com/maps/api/js?sensor=false"></scr'+'ipt>' +
'<scr'+'ipt>google.maps.event.addDomListener(window,"load",function(){ready=true});</scr'+'ipt>' +
'</head>' +
'<body style="height:100%; margin:0px; padding:0px"></body></html>';
// Create the Google Maps container element.
this.$iframe = $('<iframe />')
.css('width', '100%')
.css('height', '300px')
.attr('srcdoc', src)
.appendTo(this.$el);
var self = this; // hold onto this for initMapWhenReady
// Wait until maps library has finished loading in iframe, then create map
function initMapWhenReady() {
// Iframe document and window
var doc = self.$iframe[0].contentDocument;
var win = self.$iframe[0].contentWindow;
if (!win || !win.ready) {
// Maps library not yet loaded; try again soon
setTimeout(initMapWhenReady, 20);
return;
}
// Maps library finished loading. Build map now.
var mapOptions = {
center: new win.google.maps.LatLng(self.model.get('lat'), self.model.get('lng')),
zoom: self.model.get('zoom')
};
var mapDiv = $('<div />')
.css('width', '100%')
.css('height', '100%')
.appendTo($(doc.body));
self.map = new win.google.maps.Map(mapDiv[0], mapOptions);
// Add an event listeners for user panning, zooming, and resizing map
// TODO(rsargent): Bind self across all methods, and save some plumbing here
win.google.maps.event.addListener(self.map, 'bounds_changed', function () {
self.handleBoundsChanged();
});
self.initializeLayersControl();
}
initMapWhenReady();
},
LayersControl: function(widget, controlDiv, map) {
var win = widget.$iframe[0].contentWindow;
var chicago = new win.google.maps.LatLng(41.850033, -87.6500523);
// Set CSS styles for the DIV containing the control
// Setting padding to 5 px will offset the control
// from the edge of the map.
controlDiv.style.padding = '5px';
// Set CSS for the control border.
var $controlUI = $('<div />')
.css('backgroundColor', 'white')
.css('borderStyle', 'solid')
.css('borderWidth', '1px')
.css('cursor', 'pointer')
.css('textAlign', 'center')
.appendTo($(controlDiv));
// Set CSS for the control interior.
var $controlContents = $('<div />')
.css('fontFamily', 'Arial,sans-serif')
.css('fontSize', '12px')
.css('paddingLeft', '4px')
.css('paddingRight', '4px')
.css('paddingTop', '0px')
.css('paddingBottom', '0px')
.appendTo($controlUI);
this.$controlTable = $('<table />')
.append($('<tr><td colspan=2>Layers</td></tr>'))
.appendTo($controlContents);
},
initializeLayersControl: function() {
var doc = this.$iframe[0].contentDocument;
var win = this.$iframe[0].contentWindow;
// Create the DIV to hold the control and call the LayersControl() constructor
// passing in this DIV.
var layersControlDiv = document.createElement('div');
this.layersControl = new this.LayersControl(this, layersControlDiv, this.map);
layersControlDiv.index = 1;
this.map.controls[win.google.maps.ControlPosition.TOP_RIGHT].push(layersControlDiv);
},
// Map geometry changed (pan, zoom, resize)
handleBoundsChanged: function() {
this.model.set('lng', this.map.getCenter().lng());
this.model.set('lat', this.map.getCenter().lat());
this.model.set('zoom', this.map.getZoom());
var bounds = this.map.getBounds();
var playgroundCompatible = [bounds.getSouthWest().lng(), bounds.getSouthWest().lat(),
bounds.getNorthEast().lng(), bounds.getNorthEast().lat()];
this.model.set('bounds', playgroundCompatible);
this.touch();
},
// Receive custom messages from Python backend
on_msg: function(msg) {
var win = this.$iframe[0].contentWindow;
if (msg.command == 'addLayer') {
this.addLayer(msg.mapid, msg.token, msg.name, msg.visible);
} else if (msg.command == 'center') {
this.map.setCenter(new win.google.maps.LatLng(msg.lat, msg.lng));
if (msg.zoom !== null) {
this.map.setZoom(msg.zoom);
}
}
},
// Add an Earth Engine layer
addLayer: function(mapid, token, name, visible) {
var win = this.$iframe[0].contentWindow;
var eeMapOptions = {
getTileUrl: function(tile, zoom) {
var url = ['https://earthengine.googleapis.com/map',
mapid, zoom, tile.x, tile.y].join("/");
url += '?token=' + token
return url;
},
tileSize: new win.google.maps.Size(256, 256),
opacity: visible ? 1.0 : 0.0,
};
// Create the overlay map type
var mapType = new win.google.maps.ImageMapType(eeMapOptions);
// Overlay the Earth Engine generated layer
this.map.overlayMapTypes.push(mapType);
// Update layer visibility control
var maxSlider = 100;
function updateOpacity() {
mapType.setOpacity($checkbox[0].checked ? $slider[0].value / 100.0 : 0);
}
var $checkbox = $('<input type="checkbox">')
.prop('checked', visible)
.change(updateOpacity);
var $slider = $('<input type="range" />')
.prop('min', 0)
.prop('max', maxSlider)
.prop('value', maxSlider)
.css('width', '60px')
.on('input', updateOpacity);
// If user doesn't specify a layer name, create a default
if (name === null) {
name = 'Layer ' + this.map.overlayMapTypes.length;
}
var $row = $('<tr />');
$('<td align="left" />').append($checkbox).append(name).appendTo($row);
$('<td />').append($slider).appendTo($row);
this.layersControl.$controlTable.append($row);
}
});
// Register the GoogleMapsView with the widget manager.
WidgetManager.register_widget_view('GoogleMapsView', GoogleMapsView);
});
In [ ]: