Google Maps Remember Last location

Using GMap2.savePosition() and GMap2.returnToSavedPosition()			Using cookies via Javascript

Description

A demonstration of two methods for saving and reloading a position on a Google Map. This allows a preset location to be brought up quickly without the user spending time remembering or panning and zooming to the position. A position is assumed to be a combination all all the following:

• Latitude
• Longitude
• Level of Zoom

Using GMap2.savePosition() and GMap2.returnToSavedPosition()

How To Use

1. Once the map has fully loaded on the page, pan and zoom to find a particular location
2. Click Save
3. Move the map to somewhere else
4. Click Load
5. The map should return to its saved state

How it Works

The methods GMap2.savePosition() and GMap2.returnToSavedPosition() are included in the Google Maps API and are very easy to use in the required events.

The code use to call these methods is...

function Load() { map.returnToSavedPosition(); } function Save() { map.savePosition(); }

Advantages and Disadvantages

• A: Simple to implement
• A: Does not use cookies
• D: Will not remember if the user leaves the page

Using Cookies

How To Use

1. Once the map has fully loaded on the page, pan and zoom to find a particular location
2. Click Save
3. Move the map to somewhere else
4. Click Load
5. The map should return to its saved state
6. Then try navigating away from this page and then try to load again

How it Works

The code use save and load the location is...

function Save() { var mapzoom=map.getZoom(); var mapcenter=map.getCenter(); var maplat=mapcenter.lat(); var maplng=mapcenter.lng(); var cookiestring=maplat+"_"+maplng+"_"+mapzoom; var exp = new Date(); //set new date object exp.setTime(exp.getTime() + (1000 * 60 * 60 * 24 * 30)); //set it 30 days ahead setCookie("DaftLogicGMRLL",cookiestring, exp); } function Load() { var loadedstring=getCookie("DaftLogicGMRLL"); var splitstr = loadedstring.split("_"); map.setCenter(new GLatLng(parseFloat(splitstr[0]), parseFloat(splitstr[1])), parseFloat(splitstr[2])); } function setCookie(name, value, expires) { document.cookie = name + "=" + escape(value) + "; path=/" + ((expires == null) ? "" : "; expires=" + expires.toGMTString()); } function getCookie(c_name) { if (document.cookie.length>0) { c_start=document.cookie.indexOf(c_name + "="); if (c_start!=-1) { c_start=c_start + c_name.length+1; c_end=document.cookie.indexOf(";",c_start); if (c_end==-1) c_end=document.cookie.length; return unescape(document.cookie.substring(c_start,c_end)); } } return ""; }

Advantages and Disadvantages

• A: Can save location even if the user leaves the page and comes back
• D: Require extra javascript
• D: Uses cookie which can be blocked or deleted on the client machine
• A: Available for customised expansion i.e. remember additional data such as...
  • a name for that saved location
  • multiple saved locations
  • The map state (Map /Satellite / Hybrid)

Version History

• Version 1 (16/12/2008) - You are here

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