Comments on: How to make Google static maps interactive

By: Speeding tickets Toronto

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By: Nesan

Nesan — Tue, 28 Jul 2009 02:37:54 +0000

Thank you for your reply Tim.I got it correct now.

By: Tim

Tim — Wed, 22 Jul 2009 13:37:13 +0000

Hi Nesan – hard to know what problem you are having but I did notice I wrote some of the examples down wrong 2 to the power of a zoom of 2 is clearly 4 and 4 times 256 is 1024… if that is not the problem here is some example code for the dynamic api that shows the same equations in action (some rounding errors in there but gives a pretty good idea of what’s going on). Should work off the file system without a key – play around with the ideas and then ask if you have any problems.

Google Maps JavaScript API Example

function initialize() {
if (GBrowserIsCompatible()) {
var map = new GMap2(document.getElementById(“map_canvas”));
map.setCenter(new GLatLng(40.702147,-73.9986), 2);
map.setUIToDefault();

var leftEdge = new GPoint(0, 128);
var leftLatLng = map.fromContainerPixelToLatLng(leftEdge);
var rightEdge = new GPoint(255, 128);
var rightLatLng = map.fromContainerPixelToLatLng(rightEdge);

var degreesToLeftEdge = leftLatLng.lng()-map.getCenter().lng();
var degreesToRightEdge = rightLatLng.lng()-map.getCenter().lng();

var pixelWidth = (256 * Math.pow(2, map.getZoom()))/360;
var calcDegreesToEdge = 128/pixelWidth;

var radianPixelWidth = (256 * Math.pow(2, map.getZoom()))/(2*Math.PI);

var radianCalc = Math.log( (1+Math.sin(map.getCenter().latRadians())) / (1-Math.sin(map.getCenter().latRadians())) )/ 2;

var calcCentre = radianCalc * radianPixelWidth + 1;

alert(degreesToLeftEdge + “, ” + degreesToRightEdge + “, ” + calcDegreesToEdge + “, ” + calcCentre);

}

By: Philip Boyle

Philip Boyle — Wed, 22 Jul 2009 11:35:36 +0000

Hi Nesan,

I’ve asked Tim to take a look at this and I’ll have an answer for your later today.

Philip

By: Nesan

Nesan — Tue, 21 Jul 2009 08:55:20 +0000

Hi,
I followed the given formulas for calculating the pixel values of map.I have 256×256 pix map.Center is at 40.702147,-73.9986.I substituted in the given formula but i am not getting 128px i am geetting someother values.Can you please tell me where i am going wrong.