Thursday, March 22, 2007

Google’s New Picasa API

One of the most straightforward, read-only uses is to simply request the contents of a public album to display its images. You'll use the following URL return a "REST"-style XML:

http://picasaweb.google.com/data/feed/api/
 user/philipp.lenssen/album/55WaysToHaveFunWithGoogle

... where the first bold parameter is the user ID, and the second bold parameter is the album name. Here's a small sample function in PHP5, which generates this output:

function showAlbumContent($userId, $albumName)
{
    $url = 'http://picasaweb.google.com/data/feed/api/user/' .
            urlencode($userId) . '/album/' . urlencode($albumName);

    $xml = file_get_contents($url); // a workaround needed on my server
    $xml = str_replace("xmlns='http://www.w3.org/2005/Atom'", '', $xml);

    $dom = new domdocument;
    $dom->loadXml($xml);
    
    $xpath = new domxpath($dom);
    $nodes = $xpath->query('//entry');
    foreach ($nodes as $node) {
        echo '<p>';
        $imageUrl = $xpath->query('.//media:thumbnail/@url', $node)->item(0)->textContent;
        $keywords = $xpath->query('.//media:keywords', $node)->item(0)->firstChild->data;
        echo '<img src="' . htmlentities($imageUrl) . '" alt="" />'; 
        echo '<br />Tags: <em>' . htmlentities($keywords) . '</em>';
        echo '</p>';
    }
}

Image editor Picnik, which needs Flash 9, is a (very cool) third-party sample application making use of this API already. The problem? To connect to your Picasa album, Picnik requires you to enter your Google Account login & password. There's no way I'll do that on a non-Google domain (outside of Orkut, I guess, but even at Orkut the login Iframe is hosted at Google.com). A better way to implement this might be to forward to a Google.com page – one that promises your credentials won't be shared with the site – which then only passes back a token to the application.

[Hat tip to Zmarties and Google Code Blog!]

Google’s New Picasa API by Philipp Lenssen | Comments (12)

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