Drag (move) a polygon using Google Maps v3 - javascript

The Google Maps API for a Polygon does not offer a drag method.
What would be an efficient way of implementing such a feature (i.e., sufficiently optimised so that it would not kill a four year old laptop)?
Thank you!

I found the Google Maps V2 Polygon Implementation to be very limiting for the needs I have had and solved it by creating a custom overlay. My group is currently stuck on IE6 so I have yet to migrate over to Google Maps V3 - but taking a quick look at the API shows that you could probably do a similar thing that I did in V2 with V3.
Essentially the idea is:
Create a Custom Overlay
Populate it with your own SVG/VML Polygons and attach a drag event to this custom polygon object
Custom Overlays:
Here is some information to get you started on making your own custom overlay:
http://code.google.com/apis/maps/documentation/javascript/overlays.html#CustomOverlays
Creating your own "Dragable" Polygon Object:
Once you get that down you'll want to add your own polygons to the custom overlay instead of using GPolygons. I went through the painful process of learning SVG/VML and writing a library to bridge SVG/VML together - you could do that, but I would recommend starting by trying to use another library such as Raphaël.
http://raphaeljs.com/
Using Raphaël will save you a whole lot of time trying to figure out how to get cross-browser Vector Graphic (Polygon) functionality - and best of all it supports drag events already, here is an example from their library:
http://raphaeljs.com/graffle.html
Once you have a custom overlay and you are able to throw some Raphaël objects onto it the last step is to translate the coordinates you want from a Lat/Lng value to a Pixel value. This is available in the MapCanvasProjection of V3:
http://code.google.com/apis/maps/documentation/javascript/reference.html#MapCanvasProjection
You can use fromLatLngToDivPixel to figure out what the actual pixel values are for the points on your Raphael polygon, draw it, then add it to the overlay with a drag event.

Since version 3.11 (dated Jan 22, 2013) it's possible to just set the draggable property onto the google.maps.Polygon instance; see this example.
If you want to programmatically move a polygon, you'll need a custom Google Maps Extension which I wrote, as the API does not provide such a method.

Here's how I do it. Find the approximate center of the polygon, and add a marker, then add a drag listener to the marker. On lat/lng change, subtract the difference from the original marker lat/lng, subtract the difference to each of the paths, then, set the original position to the new position. Make sure that in your javascript api call that you have library=geometry,drawing
google.maps.event.addListener(draw, 'overlaycomplete', function(shape) {
// POLYGON
if (shape.type == 'polygon') {
var bounds = new google.maps.LatLngBounds(); var i;
var path = shape.overlay.getPath();
for (i = 0; i < path.length; i++) { bounds.extend(path.getAt(i)); }
shape.latLng = bounds.getCenter();
marker = getMarker(map,shape);
shape.overlay.marker = marker;
markers.push(marker);
}
google.maps.event.addListener(marker, 'drag', function(event) {
shape.overlay.move(event.latLng, shape, path);
});
google.maps.event.addListener(shape.overlay, 'rightclick', function() {
this.setMap(null);
this.marker.setMap(null);
draw.setDrawingMode('polygon');
});
});
}
google.maps.Polygon.prototype.move = function(latLng, shape, p) {
var lat = latLng.lat();
var lng = latLng.lng();
latDiff = shape.latLng.lat()-lat;
lngDiff = shape.latLng.lng()-lng;
for (i = 0; i < p.length; i++) {
pLat = p.getAt(i).lat();
pLng = p.getAt(i).lng();
p.setAt(i,new google.maps.LatLng(pLat-latDiff,pLng-lngDiff));
}
shape.latLng = latLng;
}
function getMarker(map,shape){
var infowindow = new google.maps.InfoWindow();
if(shape.type=='polygon'){ latLng = shape.latLng; }
marker = new google.maps.Marker({
position: latLng,
map:map,
draggable:true,
clickable: true,
animation: google.maps.Animation.DROP
});
shape.overlay.marker = marker;
shape.overlay.bindTo('center',marker,'position');
google.maps.event.addListener(marker, 'click', (function(marker) {
return function() {
infowindow.setContent('polygon');
infowindow.open(map, marker);
toggleBounce(marker);
}
})(marker));
google.maps.event.addListener(infowindow,'closeclick', (function(marker) {
return function() {
marker.setAnimation(null);
}
})(marker));
return marker;
}
If you have any questions, feel free to contact me.

You could have markers for each point on the polygon, these markers could have drag and at the end of each drag, the polygon could be redrawn.
You could also have a marker in the center of the polygon representing the polygon as a whole, when you move that marker, every marker could be moved by the same amount to maintain the shape.

Okay - so after seeing the website you are trying to implement I started to feel like Raphael may not be necessary because it is a pretty heavy JS Library - and if you are only trying to draw a rectangle polygon I thought, why not just do it with a single lightweight DIV instead?
However I think the Raphael solution would still hold water for many other cases - so I think I'll just post another possible answer.
Here is a working example I threw together:
http://www.johnmick.net/drag-div-v3/
Feel free to take a look at the source:
http://www.johnmick.net/drag-div-v3/js/main.js
Essentially we do the following
Create the Custom Overlay
Create the draggable div polygon and, using jQuery UI, make it draggable
Tie an event that listens to when the dragging has stopped that updates the LatLng position of the rectangle
Add the object to the Custom Overlay
Implement the draw function to redraw the rectangle during zooms and pans
Currently I am only storing one LatLng value for the Rectangle (being the top left corner) - you could easily extend this example to store all 4 points of the rectangle and have the shape dynamically resize itself on zooms. You may want to do that, otherwise as users zoom out they will get a climate report for a larger and larger area.

Related

Google Maps API v3, Remove Marker icon or changing to "null"?

I'm writing a Python Flask application in which I'm using Google Maps. I want to be able to add labels to a polyline that I've drawn which symbolizes a ship route.
The route is drawn using a set of coordinates and the polyline feature of the Maps API. I want to add time labels to the polyline and the easiest way seems to be to use Map Markers. However I don't want the large standard pins to show up, but would prefer a small icon/marker together with my text or even none at all. As far as I have gathered you can create "Circles" (which are modifiable) or "Markers" (which you only can change the icon of). I would prefer to go with "Circles", but those you apparently can't add text to..
How can I add text to my map and avoid the Google Maps Pins showing up?
Currently I have an list of objects that contains latitude, longitude and date + time. I'm iterating through it adding markers, but as I do I would like to keep out the marker icon or instead draw the circles if someone knows how to draw circles with added text?
for(i = 0; i < markerList.length; i++){
var position = new google.maps.LatLng(markerList[i].lat, markerList[i].lng);
var date = markerList[i].date;
var marker = new google.maps.Marker({
position: position,
label: date,
map: map,
icon: "None" //Produces error: 404 (NOT FOUND)
});
}
Being able to change the label size also is a very much appreciated function, but I have been unable to find any information about whether that is available. Being able to change the color of the text would also be nice.
As no answers have been given yet and I've sort of found a solution to my problem I guess I will share for others out there with the same problem. At least until someone comes up with a better solution:
I ended up using a predefined symbol and scaling it down to 0 in size as follows:
for(i = 0; i < markerList.length; i++){
var position = new google.maps.LatLng(markerList[i].lat, markerList[i].lng);
var date = markerList[i].date;
var marker = new google.maps.Marker({
position: position,
label: date,
map: map,
icon: {
path: google.maps.SymbolPath.CIRCLE,
scale: 0
}
});
}
Sadly I haven't found a way to mess with the label yet.
try markerWithlabel and you can change the icon of the marker whit a svg or png plus the label too
like this jsfiddel
.
#Zeliax You can add visible: false to not have marker icon show on your google map. icon prop looks for a path that you want specify for your marker to look as. It is basically a url for your display image.

d3.js Shape scaling/google map controls and showing markers inside a shape area

Working on this application which I have broken down here.
http://jsfiddle.net/pPMqQ/81/
In this example I want to
show markers only inside the shape area
allow for zoom of the map and scaling of the shape area
here is my pseudo code
identifyMarkersInShape: function(){
//__ function is invoked every time a shape is drawn/editted
// hides all the markers
//finds the markers inside the given shape
},
bindEvents: function(){
//handle zoom of the map and scale of the path shape
}
Fully working example: http://jsfiddle.net/PDf9G/5/
Edit: Now simplifies polygon before adding it to the map. Editing the polygon works as well.
First, the css and html: I moved the div called #canvas1 after the map and gave it absolute positioning and z-index = 0. I also gave the map the same absolute positioning to ensure that they always line up with each other, and gave it a z-index of 10.
When the draw button is clicked the canvas is moved to the front. The user can use it to draw free form using d3. When they are done the shape they drew is converted to a google maps polygon.
addShapeToBaseMap: function(divCoords) {
var geoCoords = []
for (var i = 0; i < divCoords.length; i++)
geoCoords.push(overlay.getProjection().fromContainerPixelToLatLng(new google.maps.Point(Number(divCoords[i][0]), Number(divCoords[i][1]))));
poly = new google.maps.Polygon({
paths: geoCoords,
strokeColor: '#FF0000',
strokeOpacity: 0.8,
strokeWeight: 2,
fillColor: '#FF0000',
fillOpacity: 0.35
});
poly.setMap(map);
Then we do do the hiding/showing of the markers. Using d3 this way is really silly and defeats the purpose. You need to add the google geometry library to your url to use this (&libraries=geometry). I'm sure there are faster ways and if you're dealing with large datasets you'll want to make this better.
for (var i = 0; i < data.length; i++) {
if (!google.maps.geometry.poly.containsLocation(new google.maps.LatLng(data[i]['lat'], data[i]['lng']), poly)) {
d3.select("#" + data[i]['name']).classed({'hide': true});
} else {
d3.select("#" + data[i]['name']).classed({'hide': false});
}
}
This works because when we appended the markers we added their name as the id on the marker element. The only reason I can see to do this is because the svg gives you better control over styling. Last:
svg.select(".selection").remove()
d3.select("#canvas1").classed({'front': false});
$('.draw').removeClass('highlight');
},
We remove the shape we drew from the drawing layer. If we don't do this, if the user moves the map and then turns the drawing layer back on, the shape will be in the wrong place. Then we move the canvas to the back and turn off the highlighting on the drawing button.
The edit function was taken from your most recent code. If the edit button or polygon is clicked the editing function is turned on on the polygon.
I would also recommend taking a look at Leaflet. The integration with d3 is a bit easier and you can have multiple svg layers, which would allow you to put the drawing layer as a map overlay instead of a separate div.
geojson-utils is a node/browser javascript package that has a bunch of utilities for dealing with geojson paths.
One of the many things that it has is a very solid point in polygon algorithm designed for dealing with geojson paths.
You also might want to consider using Leaflet.js instead of Google Maps, it has a few more tools for going to and from geojson based data. It also has a lot of really useful tools already written like Leaflet.draw which has the code already needed to "draw" these paths on top of the maps.

How to find lat/lon location that is closest to mouse cursor on the google map

I have many markers.
On the left I have list of marker-abstractions of actual markers on the google map.
I decided to use polylines
var flightPlanCoordinates = [
new google.maps.LatLng(near_cursor_lat, near_cursor_lon),
new google.maps.LatLng(marker_lat, marker_lon)
];
var flightPath = new google.maps.Polyline({
path: flightPlanCoordinates,
strokeColor: "#FF0000",
strokeOpacity: 1.0,
strokeWeight: 2
});
flightPath.setMap(map);
the idea is that user points his mouse on the marker-abstraction box on the left, and then he shown the line which goes from marker-abstraction to actual marker on the map. I already have everything except of the STARTING POINT(red dots on the image)
How do I find starting lat/long which is located next to the mouse pointer, when the mouse is pointed at the box on the left
Some details:
When the mouse is pointed to the box that sais PERSON1, I want the coordinates of the first red dot. When the mouse is pointed to the box that sais PERSON2, I want the coordinates of the second red dot. And so on. There is a trick part- left boxes are located outside the google maps div; in addition, if there are many boxes with PERSONS, the left div will allow to scroll those persons up and down, so the vertical correlation between the persons box, and the red dot is dynamic.
In theory, I think, I need an event that is triggered when I point to one of the boxes. When even is fired, I need to measure the vertical distance in pixels from the top to the mouse pointer. Then, when I have the vertical distance, I need to perform some action that would measure same vertical distance on the google map, and would get me that point on the map in lat/lon coordinates.
This should be the answer to your question :
You should be using markers to represent (persons) and then add a listener onMouseOver like in the below post :
var overlay = new google.maps.OverlayView();
overlay.draw = function() {};
overlay.setMap(map); // 'map' is new google.maps.Map(...)
Use overlay in the listener to get the projection and the pixel coordinates:
google.maps.event.addListener(marker, 'mouseover', function() {
var projection = overlay.getProjection();
var pixel = projection.fromLatLngToContainerPixel(marker.getPosition());
// use pixel.x, pixel.y ... (after some rounding)
});
copied from :
Get Position of Mouse Cursor on Mouseover of Google Maps V3 API Marker
#MehdiKaramosly answer is pretty spot on.
Only slightly furthering the above, to get what would be the lat lng of an element that is not part of the visible map (if the map was visible there) you can pass the events page X/Y to the line:
projection.fromLatLngToContainerPixel(marker.getPosition());
like so:
var pixelLatLng = overlay.getProjection().fromContainerPixelToLatLng(new google.maps.Point(e.pageX,e.pageY));
I have put a very basic example at: http://tinkerbin.com/p30yEXqH
If you click anywhere outside of the map (which equates to the same as clicking on a div that overlays it), you will see in the console log that the lat/lng for wherever you have clicked (even though it is not in the visible map space), is logged.
Cheers,
C.
Update with Working Example of this code
Second Update with JsFiddle Example of both ways click and open map window or mouseover map to highlight listing
As i understand the problem you are having is as following:
Persons are listed in the div separate from map
Persons have latitude and longitude associated to them on the map
Map displays location of person with markers on it using lat long (might be stored in db or something)
You want it so people can highlight a person on map as well as list with mouse over.
If you have lat/long available on map or from list you need to relate them together.
Solution is something like this but there are many ways to achieve this mapping
In your div where person is listed. Insert a data-mapid attribute to each person element when a person hovers over it you highlight it and get the data-mapid from there.
On your map when you render a marker you can additionally pass a parameter data-mapid or something else with same value and have a highlight function on map as well.
`jQuery("#gmap3ul li[data-gb='plist']").each(function(){
elemtopush = {
lat:jQuery(this).attr("data-lat"),
lng:jQuery(this).attr("data-long"),
data:{
"ht":jQuery(this).html(),
"id":jQuery(this).attr("data-mapid")
}
};
ulmarkerspgb.push(elemtopush);
});`
In above code i have html to show on map as well as id as data-mapid now this mapid can be person1 person2 and so on so you can relate back to div with lists. i am using ul and li to list them in the div.
On mouse over your markers events you can do something like this
mouseover: function(marker, event, data)
{
clearalllist();
var listelement = jQuery("td[data-mapid='"+data.id+"']");
jQuery(listelement).attr('style','background-color:#ccc');
var map = jQuery(this).gmap3('get'),
infowindow = jQuery(this).gmap3({action:'get', name:'infowindow'});
if (infowindow){
infowindow.open(map, marker);
infowindow.setContent(data.ht);
google.maps.event.addListener(infowindow, 'closeclick', function(event) {
jQuery(listelement).attr('style','');
});
google.maps.event.addListener(infowindow, 'close', function(event) {
jQuery(listelement).attr('style','');
});
} else {
jQuery(this).gmap3({action:'addinfowindow', anchor:marker, options:{content: data.ht}});
infowindow = jQuery(this).gmap3({action:'get', name:'infowindow'});
google.maps.event.addListener(infowindow, 'closeclick', function(event) {
jQuery(listelement).attr('style','');
});
google.maps.event.addListener(infowindow, 'close', function(event) {
jQuery(listelement).attr('style','');
});
}
}
There is a lot of redundant code i have copied pasted from 3 locations so you might just be able to get what you want out of it.
This can make both map linked to list and list linked to map. See my second update on top or click this JSFiddle example. When you click on list on top it opens the map window and when you mouse over the map icons it highlights the listing.
This also populates the map via list rather than hard coding lat longs in js.

Google Maps API V3 - KML Layer vs. JS created Polygons

I'm back with more work on the Google Map that I've been working on. Here is the situation:
I have a map of Virginia. It will have markers in it, but I need the markers to be added/removed/editable by several people. As a result, I created a Google map in "My Places" and I'm importing the resulting KML file into a map I'm loading into the API.
I'm also trying to "white out" neighboring states by drawing a polygon over them and adding a white layer over them with 75% opacity, in order to make the state of Virginia stand out more.
However, I've run into a problem where if a marker from the KML layer "overlaps" onto the polygon covering a bordering state, the opaque polygon covers the layer AND the marker becomes unclickable. If one zooms in enough, one can click the marker, but I want people to be able to click the marker from the original zoom.
I've tried making the markers first, then adding the KML, and doing the KML first then drawing the polygons, but it doesn't seem to matter. I even tried a variation of the solution here: Handle when drawing of polygons is complete in google maps api v3 where I put the trigger to add the KML layer inside of the listener event, but still no dice.
My searching on Google also hasn't led me to anything that looks useful. I don't know if this is still a problem with the order the layers are being ordered, or if polygons somehow "override" a KML layer, regardless of the order, or if there is some way to explicitly tell the KML markers to stay on top of the polygons.
First off, here is the main code I'm using to draw the layers right now:
function initialize() {
var mapOptions = {
zoom: 7,
center: new google.maps.LatLng(38, -79.5),
disableDefaultUI: true,
mapTypeId: google.maps.MapTypeId.TERRAIN
}
var map = new google.maps.Map(document.getElementById("map_canvas"), mapOptions);
borderingStates(map);
var participantsLayer = new google.maps.KmlLayer('https://maps.google.com/maps/ms?msa=0&msid=204048902337864904598.0004cc332e8034251c1db&ie=UTF8&ll=37.668046,-80.289717&spn=1.959603,5.642338&output=kml',{preserveViewport:true});
google.maps.event.addListener(map,'idle', function() {
participantsLayer.setMap(map);
});
}
function loadScript() {
var script = document.createElement("script");
script.type = "text/javascript";
script.src = "https://maps.googleapis.com/maps/api/js?key=abc.def&sensor=false&callback=initialize";
document.body.appendChild(script);
}
window.onload = loadScript;
Next, here is an example of the code I'm using to draw the polygons. This happens when I call the borderingStates function above:
//Delaware
DEpoints = [
new google.maps.LatLng(39.7188, -75.7919),
new google.maps.LatLng(39.5210, -75.7837),
...
new google.maps.LatLng(39.8296, -75.6477),
new google.maps.LatLng(39.7199, -75.7906)
];
// Construct the polygon
var Delaware = new google.maps.Polygon({
paths: DEpoints,
fillColor: invisColor,
strokeOpacity: 0,
fillOpacity: .75
});
Delaware.setMap(map);
And then I repeat that for each state I draw a polygon for - I think there are 6 or 7.
I can't tell that there is anything in particular about the code that wouldn't cause it to work other than perhaps how Google Maps inherently treats polygons and KML Layers.
I would suggest making your polygons with KmlLayer (or FusionTablesLayer) as well.
You can control the ordering of layers by the order that you add them to the map (first one is on the bottom). I believe native Google Maps API v3 Polygons will always appear above layers. Your other option would be to make the Polygons "unclickable" (clickable: false) [not sure if this will work or not].
This is my first submission and at the risk of being labelled a cowboy, this was my solution to this problem:
Remove the Polygon on the first click event
Set a timer to reinstate the Polygon (after 1 1/2 seconds)
Capture the click event on the KML element during the 1 1/2 second window of opportunity
google.maps.event.addListener(polygon, 'click', function () {
polygon.setMap(null); // hide polygon for a 1 1/2 seconds
window.setTimeout(function () {
polygon.setMap(map_canvas);
}, 1500);
// process polygon click now
});
This method does mean that you'll process both the Polygon and KML element click events but in our case that was fine.

Changing the area which counts as being fit to bounding box

Let's say I've got a full-screen google map, with a div which is on the left (but isn't, strictly speaking, an overlay or UI element of the map) and absolutely positioned.
Now let's say I have a bounding box (as in: [ [lat, lng], [lat, lng] ]which I want to have the map fit. What if I want it to take into consideration that div. I have the absolute position and the size of it in pixels. Is there something I can specify on the map to say "This area is off bounds, don't let the bounding box clash with it"?
Are you trying to place a bounding box around the map or are you trying to ensure that all markers are displayed within the map?
The api allows you to set up a bounding area so that when the map loads all points are visible within the map. The map will zoom or scale accordingly.
to setup bounds within your function add the following
(function(){
..existing code
var bounds = new google.maps.LatLngBounds();
var infowindow;
//Here I have an event listener that I have setup for the clicking of the markers
(function (i, marker) {
google.maps.event.addListener(marker, 'click', function () {
if (!infowindow) {
infowindow = new google.maps.InfoWindow();
}
infowindow.setContent('Location: ' + i);
infowindow.open(map, marker);
});
})(i, marker);
bounds.extend(places[i]);
}
map.fitBounds(bounds)
})();
There are a few things happening here. Map is the name of my DIV layer the anonymous function would just be used to wrap everything. The reason I added the click event code was to also show how I can get the map to auto position whenever I click on a marker to view the info window (using the bounds.extend(places[i]). Places is the array of coordinates that I have collected. I didn't add all the code such as for the marker generation but I would normally place this block of code following that. The bounds function as part of the api forces the map to auto position and zoom according to where the markers are located on the page. This ensures that when the map is rendered all markers are visible to the user.
Not sure if this is what you wanted but if you can clarify I may be able to elaborate more.
Best of luck

Categories

Resources