Thursday, September 24, 2009

Gecoder response structure

I made simple test pages for version 2 and version 3 that display the geocoder response object contents prettyprinted.

First I was using toSource() method of Firefox which is a handy way to have a look inside objects. You could say that is opposite to eval().

Using non-standard toSource() debugging method means that the pages would work only with FF. I think that all the browsers have a similar method internally, but it is exposed only in Gecko browsers.

I switched to JSON.stringify(). That is also built in FF3.1+ and even in IE but only in IE8 mode. The function is made cross-browser by loading Douglas Crockfords json2.js script. You can get it from

The line breaks, spaces and indents are generated by beautify.js from

Monday, September 14, 2009

Zoom events

The following concerns version 2 of API.

There is a single zoomend(old, new) event in documentation. However there are a few additional undocumented events that return a lot of data about zoom action.

'zoomto' is triggered always when user changes zoom setting. It returns two parameters. The first one is a string that indicates how the zoom was started. The second is an object {infoWindow: boolean} that tells if the info window is open. Following string values are discovered:

- "zi" or "zo" When zoom button is clicked
- "zs_drag_zi " or "zs_drag_zo" When zoom slider is moved
- "zb_click_zi" or "zb_click_zo" When zoom bar is clicked
- "wl_zi" or "wl_zo" By scrollwheel zoom
- "key_zi" or "key_zo" When zoomed by keyboard +/-

If we have continuousZoom enabled, we get more events: 'zoomstart' and 'zooming'.

'zooming' is triggered repeatedly while animated zoom is under progress. The interval is a few tens of milliseconds.

'zoomstart' is triggered when continuous zoom is started by dblclick or scrollwheel. Its first parameter is -1 or 1 indicating the direction of the started zoom. The second parameter is a GLatLng mouse pointer position. By double rightclick zoomout the second parameter is a blank object.

I have discovered a third parameter, a boolean that is true only by dblclick-zoom-in?

When triggering a continuous zoom, we get a series of events:
  • zoomstart
  • zoomto
  • zooming
  • zooming
  • zooming
  • zoomend
And a lot of data with them.