My gadget for Chess.com uses an enhanced version of this technique,
which I think may help a couple people out there with complex gadget
needs.
Our server delivers the same "pages" to iGoogle as we do to Facebook.
In Facebook, due to the Javascript sandboxing, we need to be in an
iframe. In iGoogle, due to the Javascript Open Social API (a lot like
the set prefs code), we need to be embedded in the gadget's domain and
not use a remote iframe. I achieved this duality by creating a gadget
that calls the page with makeRequest and then outputs the response
into an iframe without a domain created by the javascript. This is
effectively a Javascript-enforced proxy browser.
Why not dump it into a div? Because a lot of our legacy Javascript
(including all the ajax mumbo-jumbo our server framework spits out)
assumes its in its own window object.
Complex and twisted, yes. But it works. It's probably more complex
than needed for most people. On the off chance that someone reading
this (now or in the future) needs something like this solution, here's
the gadget definition:
http://ig.hosted.chesscomapps.com/api/gadget_def.php
Naturally, I can't support this as sample code, and I make no
pretenses about it's readability or elegance. But if someone finds
they need something like this, I'm the only one I know of with this
solution, and I'm happy to share.
On Apr 22, 2010, at 1:34 AM, Rob Russell wrote:
That's true, using set prefs from script in the inner iframe won't
work as far as I know.
If a gadget also sets preferences then they may be able to read the
content of the page and place it inside a div. This should allow
access to the API to set preferences. The thing is the content of
the page may include a root html element which could cause issues on
some browsers when inserted in a div. So if that's the case
developers might want to tailor the server side script that delivers
the page.
Rob Russell
Google Developer Relations
On Thu, Apr 22, 2010 at 1:19 AM, Edouard Fattal <[email protected]>
wrote:
Be careful, this method can only help to read the preferences but
the JS code in the iframe will be unable to modify the preferences.
2010/4/22 Gavin McDonald <[email protected]>
Rob,
This is an acceptable method to restore service to my broken gadget,
and thanks to your team for being proactive to find a solution.
Regards,
-G
Gavin McDonald
EVI Logistic Enterprises
604-313-3845 - VE7HXR
On Wed, Apr 21, 2010 at 7:02 PM, Rob Russell <[email protected]>
wrote:
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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