I spent some time today, with the help of other developers on the iGoogle
team, coming up with a way to adapt an arbitrary gadget that relies on the
way user prefs used to be supplied with the url in type="url" gadgets. A
gadget ideally only needs the gadget API, and shouldn't rely on the way
iGoogle sends (or doesn't send) parameters in the URL query string.
Keep in mind that what I'm suggesting is just one way to adapt such a
gadget, it's up to individual gadget developers to detemine what works for
them. I have used this to adapt one of the reported gadgets and it seems to
work fine.
The crux of the idea is that instead of supplying an external page to wrap,
we use a type=html gadget and request the page that we want wrapped after
the gadget loads. The wrapping gadget will be cached by iGoogle. You can
consider this code a template and adapt it if you'd like to include a
loading animation or message for the user in case your server takes some
time to respond.
I've tested this with sample data in IE6 on Windows and on Firefox. It is
just an example though and I encourage anyone that sees room for improvement
to chime in.
The UserPrefs elements are the same as for the existing Content type=url
section, as are the Module and ModulePrefs elements.
In the Javascript, the wrappeduserprefs variable is an array of the values
of name attributes from the UserPref elements. So for this pretend gadget,
it has prefs myname and mycolor. The type of the UserPref doesn't matter.
The wrappedpage variable is the url of the page that your Content type=url
gadget pointed at - that is the value of the href attribute on the Content
element.
If your server code doesn't need the "up_" prefix on the parameter name then
change (most will but it could be a chance to clean up some server side
cruft)
params["up_"+userprefs[key]] = prefs.getArray(userprefs[key]);
to
params[userprefs[key]] = prefs.getArray(userprefs[key]);
Here's the code
<?xml version="1.0" encoding="UTF-8"?>
<Module>
<ModulePrefs title="example url iframed" />
<UserPref name="myname" display_name="Name" default_value=""/>
<UserPref name="mycolor" display_name="Color" default_value="Red"
datatype="enum" >
<EnumValue value="Red" />
<EnumValue value="Blue" />
</UserPref>
<Content type="html">
<![CDATA[
<script type="text/javascript">
var wrappedpage = "http://example.com/mygadget.php";;
var wrappeduserprefs = ["myname","mycolor"];
var prefs = new gadgets.Prefs();
var params = {};
function init() {
for (key in wrappeduserprefs) {
params["up_"+wrappeduserprefs[key]] =
prefs.getArray(wrappeduserprefs[key]);
}
document.getElementById("wrapped").src = wrappedpage + "?" +
gadgets.io.encodeValues(params);
}
gadgets.util.registerOnLoadHandler(init);
</script>
<style>
body {
margin: 0;
padding: 0;
overflow: hidden;
}
</style>
<iframe src="" name="wrapped" id="wrapped" width="100%" height="200px"
style="border:none; margin:0; overflow:hidden; padding:0;" scrolling="no"
frameborder=0 >
</iframe>
]]>
</Content>
</Module>
Rob Russell
Google Developer Relations
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