This example shows you how to draw on a Google Map, without having to explicitly know any latitude or longitude. This makes it really easy to draw on a map that has been adjusted as required by a user, and can then be annotated using only the pixel size of the map as reference points.
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August 1, 2012 10:07
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Drawing a Google Map using pixel space
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| <!DOCTYPE html> | |
| <head> | |
| <meta chartset="UTF-8"> | |
| <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> | |
| <meta name="author" content="Scott Mebberson"> | |
| <title>scottmebberson.com example</title> | |
| <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1"> | |
| <link rel="stylesheet" href="http://scottmebberson.com/css/examples.css" type="text/css" media="screen"> | |
| <style> | |
| #mapcanvas { | |
| width: 100%; | |
| height: 240px; | |
| } | |
| </style> | |
| <script src="http://code.jquery.com/jquery-1.7.2.min.js"></script> | |
| <script src="http://maps.googleapis.com/maps/api/js?key=&sensor=false"></script> | |
| </head> | |
| <body> | |
| <header> | |
| <h1>scottmebberson.com</h1> | |
| </header> | |
| <div class="content"> | |
| <article> | |
| <header> | |
| <h1>Drawing on a Google Map using pixel space</h1> | |
| </header> | |
| <script type="text/javascript"> | |
| (function() { | |
| var convertPixels, initialiseGoogleMap, | |
| _this = this; | |
| initialiseGoogleMap = function() { | |
| var mapOptions; | |
| mapOptions = { | |
| center: new google.maps.LatLng(-34.397, 150.644), | |
| zoom: 8, | |
| mapTypeId: google.maps.MapTypeId.ROADMAP | |
| }; | |
| this.map = new google.maps.Map(document.getElementById('mapcanvas'), mapOptions); | |
| this.overlay = new google.maps.OverlayView(); | |
| this.overlay.draw = function() {}; | |
| this.overlay.setMap(this.map); | |
| return setTimeout(getCenter, 100); | |
| }; | |
| this.lineSymbol = { | |
| path: 'M 0,-1 0, 1', | |
| strokeOpacity: 1, | |
| strokeWeight: 1, | |
| scale: 3 | |
| }; | |
| this.getCenter = function() { | |
| var bottom, center, middle, polyline; | |
| center = map.getCenter(); | |
| middle = $('#mapcanvas').width() / 2; | |
| bottom = $('#mapcanvas').height(); | |
| _this.aLines = [convertPixels(middle, 0), convertPixels(middle, bottom)]; | |
| return polyline = new google.maps.Polyline({ | |
| path: aLines, | |
| strokeOpacity: 0, | |
| icons: [ | |
| { | |
| icon: lineSymbol, | |
| offset: '0', | |
| repeat: '10px' | |
| } | |
| ], | |
| map: map | |
| }); | |
| }; | |
| convertPixels = function(x, y) { | |
| return overlay.getProjection().fromDivPixelToLatLng(new google.maps.Point(x, y)); | |
| }; | |
| window.addEventListener('load', initialiseGoogleMap); | |
| }).call(this); | |
| </script> | |
| <div id="mapcanvas"></div> | |
| <p>This example draws on a Google Map using pixel space, rather than specific knowledge of lat/lng or map zoom and center. You should see a vertical dashed line straight through the center of the map above.</p> | |
| <p class="highlight">To make this example work, you'll need to add your Google Maps API key to this example.</p> | |
| </article> | |
| </div> | |
| </body></html> |
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