Develop Reference

Custom overlay in google maps area clicked then zoom in

So I tried to draw grid line on my map and I found a good example on google api documentation here : https://developers.google.com/maps/documentation/javascript/examples/maptype-base
it works , now I have another problem in every area or rectangle which built by grid line, I want them to have a listener on click event and then zoom to area that has been clicked. I have tried like this
google.maps.event.addListener(map, "click", function (e) {
var latLng = e.latLng;
map.setCenter(new google.maps.LatLng(latLng.lat(), latLng.lng()));
map.setZoom(17);
});
it works either, but as you can see the latitude and longitude are the exact location where the cursor / pointer clicked, it's not in the middle of the rectangle or area it means the map after zoomed in is wrong. Could anyone help me with this?

I think the problem is because you are using the overlay(as your grid line), when using the tile overlay Google Maps API breaks up the imagery at each zoom level into a set of square map tiles arranged in a grid. When a map moves to a new location, or to a new zoom level, the Maps API determines which tiles are needed and translates that information into a set of tiles to retrieve.
For example each zoom level increases the magnification by a factor of two. So, at zoom level 1 the map will be rendered as a 2x2 grid of tiles. At zoom level 2, it's a 4x4 grid. At zoom level 3, it's an 8x8 grid, and so on.
So when you zoom in, the coordinates that you click is not always in the middle because tile overlay is not set because of your coordinate.
Check this page for more information about overlay.
You can also check this SO question for more information.

Leaflet center popup AND marker to the map

I want center my marker on popup open.. and centering map not in marker latlng, but on center of marker and popup!
The problem is that popup has dinamic content(loaded on click).
The map size is full display size in a mobile device!
I'm just used autoPanPadding option in popup but not sufficient
Refer to follow picture:

Using fitzpaddy's answer I was able to make this code which works and is much more flexible.
map.on('popupopen', function(e) {
var px = map.project(e.target._popup._latlng); // find the pixel location on the map where the popup anchor is
px.y -= e.target._popup._container.clientHeight/2; // find the height of the popup container, divide by 2, subtract from the Y axis of marker location
map.panTo(map.unproject(px),{animate: true}); // pan to new center
});

Ciao Stefano,
This is untested pseudocode, but Leaflet project/unproject functions should provide assistance.
i.e;
// Obtain latlng from mouse event
var latlng;
// Convert latlng to pixels
var px = project(latlng);
// Add pixel height offset to converted pixels (screen origin is top left)
px.y -= mypopup.height/2
// Convert back to coordinates
latlng = unproject(px);
// Pan map
map.panTo(latlng,{animate: true});
This depends on zoom scale being constant during calculation, so you might be required to pan the map and then calculate the pan offset to update correctly (using animation, this will only be a gentle transition).
Good luck!

Here's an easy solution:
First you center the map to your marker.
map.setView(marker.latLng);
Then you open the popup.
var popup.openOn(map); = L.popup()
.setLatLng(marker.latLng)
.setContent(dynamic-content)
.openOn(map);
Leaflet will automatically pan the map so the popup fits on the map. To make it look more beautiful you can add a margin-top to the popup with CSS.

My very simple solution keeps the current zoom level as well for better usability.
map.on('popupopen', function (e) {
map.setView(e.target._popup._latlng, e.target._zoom);
});

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.

setCenter() and then move marker vertically higher on the map canvas

I have a simple question, and hopefully there is a simple answer . . . I just can't find it after a couple of hours of searching.
I've got a standard google map with a bunch of markers. I have a click event on each marker so that when clicked, the map pans the marker to the center and zooms in on it. No issues there.
Now I want to change the event handler so that when a marker is clicked the map recenters so that the marker is centered horizontally, but it is vertically towards the top of the map canvas. Is there a relatively straight forward way of doing this that works across different zoom levels?
Thanks,
Chuck

There may be many ways, e.g.
google.maps.event.addListener(marker, 'click', function() {
this.getMap().setCenter(this.getPosition());
this.getMap().panBy(0,(this.getMap().getDiv().offsetHeight/2)+this.anchorPoint.y);
});
It puts the marker in the center and then pans the map vertically by (mapHeight/2-markerHeight)

You could also muck around with getProjection() and the fromContainerPixelToLatLon and fromLatLonToContainerPixel to set a specific position within the viewable point of the math.
Both of those will give you pixel measurements from the <div> element you're using as the map canvas.
c.f. fromDivPixel and ToDivPixel which will give you the pixel position of the item on the infinite div of the map. Say you've got your map focussed on Africa, right? And you've got a pin in NYC. Using the *DivPixel* variants will keep your pin in NYC, and then you can pan towards it. Using *ContainerPixel* will move your pin into view on the map regardless of whatever Lat/Lon you've set it to.

How would I position a marker at the bottom of the map in Google Maps v2?

I have a webpage that finds a store by postcode or name.
I have just released an update to it so that contact details display in an info window coming from the marker. Due to the small size of the info window, after centering to the marker, the map pans down until it can fit the marker and info window in leaving the marker near the bottom.
Wondering if there is an easy way to set this offset immediately so that the marker appears at the bottom of the map window and it doesn't have to pan?
Thanks.

You could center the map appropriately before you add the marker:
var someZoom = 13;
var center = new GLatLng(37.4419, -122.1419);
map.setCenter(center, someZoom);
The zoom is optional too. You can just leave the zoom on whatever it is:
map.setCenter(center);
If you would like to center on a particular pixel, instead of a lat/lng, then you can use this function to convert:
fromContainerPixelToLatLng(pixel:GPoint)
I feel like you should spend half an hour and review the docs: http://code.google.com/apis/maps/documentation/reference.html. I read the documentation extensively while working on my website: www.trailbehind.com

Perhaps the auto-panning is caused by an internal addoverlay event handler. Have you tried handling the addoverlay event and returning false from it?
GEvent.addListener(map, "addoverlay", function() {
return false;
});
where 'map' is the name of your GMap2 object.