root/lang/javascript/userscripts/flickraddsfocallengthona35mm.user.js

// ==UserScript==
// @name        Flickr Adds Focal Length on a 35mm
// @namespace   http://codefairy.org/ns/userscripts
// @include     http://www.flickr.com/*/meta/*
// @include     http://flickr.com/*/meta/*
// @version     0.2.5
// @license     MIT License
// ==/UserScript==

new function() {
        var cacheable = (typeof GM_setValue == 'function' && typeof GM_getValue == 'function');

        var camera      = $X('id("Inbox")//tr/td[preceding-sibling::td/b[text()="Camera:"]]/b');
        var focalLength = $X('id("Inbox")//tr/td[preceding-sibling::td/b[text()="Focal Length:"]]/b');
        if (!camera || !focalLength) return;
        camera = camera[0];
        focalLength = focalLength[0];

        var w = typeof unsafeWindow != 'undefined' ? unsafeWindow : window;
        var now = new Date().getTime();
        var uri = 'http://wedata.net/databases/AngleOfView/items';

        var callback = function(data) {
                var text = 'unknown on a 35mm camera. <a href="'+uri+'">add angle of view data?</a>';
                for (var i = 0, length = data.length; i < length; i++) {
                        var item = data[i];
                        if (item.name == camera.textContent) {
                                if (item.data.ratio == 1)
                                        text = 'with a full-frame';
                                else {
                                        var angleOfView = Math.round(parseFloat(focalLength.textContent) * parseFloat(item.data.ratio));
                                        text = angleOfView+' mm on a 35 mm camera'; 
                                }
                                break;
                        }
                }
                focalLength.innerHTML += ' ('+text+')';
        };

        var load = function() {
                return eval(GM_getValue('stash'));
        };

        var save = function(data) {
                var stash = data ?
                        uneval({
                                data   : data,
                                expires: now + 1000 * 60 * 60 * 24
                        }) :
                        '';
                GM_setValue('stash', stash);
                return data;
        };


        if (cacheable && typeof GM_registerMenuCommand == 'function')
                GM_registerMenuCommand('Clear Angle of View Data Cache', save); 

        var api = uri+'.json';
        if (cacheable) {
                var complete = false;
                var stash = load();

                if (stash && stash.expires >= now)
                        callback(stash.data);
                else {
                        GM_xmlhttpRequest({
                                method: 'GET',
                                url   : api,
                                onload: function(r) {
                                        var data = eval(r.responseText);
                                        save(data);
                                        if (!complete) callback(data);
                                }
                        });
                        if (stash)
                                setTimeout(function() {
                                        complete = true;
                                        callback(save(stash.data));
                                }, 1000 * 30);
                }
        }
        else {
                w['jsonp'+now] = callback;

                var s = document.createElement('script');
                s.type    = 'text/javascript';
                s.src     = api+'?callback=jsonp'+now;
                s.charset = 'utf-8';
                document.body.appendChild(s);
        }


        // @source http://gist.github.com/29681.txt
        function $X (exp, context, resolver, result_type) {
                context || (context = document);
                var Doc = context.ownerDocument || context;
                var result = Doc.evaluate(exp, context, resolver, result_type || XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
                if (result_type) return result;
                for (var i = 0, len = result.snapshotLength, res = []; i < len; i++) {
                        res.push(result.snapshotItem(i));
                }
                return res;
        }
};