marginalia/resources/app.js

// hackity-hack

$(document).ready(function() {
    var ft = $("#floating-toc")
    var ul = ft.find('ul')
    var lis = ft.find('li')

    ul.css('maring', '0px')

    var liHeight = $(lis.get(0)).height()

    ft.css('height', (liHeight) + 'px')


    showNs = function(ns) {
        //this is killing performance, lookup table.
        //var el = $("[id='floating-toc_" + ns + "']")
        //var index = lis.index(el)

        var index = 0

        for(i in nsPositions.nss) {
            if(ns == nsPositions.nss[i]) index = i
        }

        console.log(index)

        if(index == lastNsIndex) return;

        lastNsIndex = index


        ul.animate({marginTop: (-1 * liHeight * index) + 'px'},
               300)
        //        ul.css('margin-top', (-1 * liHeight * index) + 'px')

    }

    var calcNsPositions = function() {
        var nss = []
        var anchors = []
        var positions = []
        $.each(lis, function(i, el) {
            var ns = $(el).attr('id').split('_')[1]
            nss.push(ns)
            var a = $("a[name='"+ns+"']")
            anchors.push(a)
            positions.push(a.offset().top)
            console.log(a.offset().top)
        });

        return {nss: nss, positions: positions}
    }

    var nsPositions = calcNsPositions()

    console.log(nsPositions)

    var lastNsIndex = -1

    var $window = $(window)

    var currentSection = function(nsp) {

        var ps = nsp.positions
        var nss = nsp.nss
        var scroll = $window.scrollTop() + 300
        var nsIndex = -1
        for(var i in ps) {
            var p = ps[i]
            if(p >= scroll) {
                nsIndex = i-1
                break;
            }
                
        }

        if(nsIndex == -1 && scroll >= ps[0]) {
            nsIndex = ps.length-1
        }

        if(nsIndex == -1) nsIndex = 0

        return nss[nsIndex]
    }

    $(window).scroll(function(e) {
        showNs(currentSection(nsPositions))
    })

    ul.css('margin-top', '0px')

})