[Qt-interest] QWebView: getting events from javascript

Tue Jul 21 17:32:40 CEST 2009

Hi,

I'm working on a simple application, which would display different maps of 
same location in same scale. When I change scale or location on one map, 
others should change it automatically as well.

I'm trying to solve a following problem. 

I have a (Qt 4.5) QWebView object which displays following page with google map:

<html>
<head>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<script type="text/javascript" 
	src="http://maps.google.com/maps/api/js?sensor=false"></script>

<script type="text/javascript">
	var map;

	function changed() {
		***MAP CHANGED***
	}

	function initialize() {
		var latlng = new google.maps.LatLng(-34.397, 150.644);
		var myOptions = {
			zoom: 8,
			center: latlng,
			mapTypeId: google.maps.MapTypeId.ROADMAP
		};
		map = new google.maps.Map(document.getElementById("map_canvas"), 
					myOptions);
		google.maps.event.addListener(map, 'bounds_changed', changed);
	}
</script>

</head>
<body onload="initialize()" onunload="GUnload()">
	<div id="map_canvas" style="width:100%; height:100%"></div>
</body>
</html>

I am able to control the map from the outside with
qwebview->page()->mainFrame()->evaluateJavaScript(). But I need also
the other way. When the user drags a map or changes the zoom level, the
map object triggers a bounds_changed event, which I can process inside
javascript (shown in the code above). Is there some way to "propagate" 
it from javascript to the QWebView so I can handle it in the Qt application?

I've found only one possible solution so far - polling: the event in
javascript sets some js variable and Qt application polls this variable
in regular time intervals...

Is there any better way?

TIA

Best regards,

-- 
Lukas Lipavsky, QA Developer

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