Index template

index.html

{% extends 'base.html' %}
{% load static %}

{% block title %}{{ index.title }}{% endblock %}

{% block head %}
    <style>
        html {
            background: {{ index.bg_color }} url("{{ index.image.url }}") no-repeat center fixed;
            background-size: cover;
            height: 100%;
            overflow: hidden;
        }
        a {
            position: relative !important;
            left: 0px;
            top: 0px;
        }
        .section {
            position: absolute !important;
            border-radius: 1000px;
        }
        .section .label {
            position: relative;
            left: -50%;
            top: 80%;
            background-color: white;
            opacity: 0.5;
            font-size: 2em;
            text-align: center;
        }
        .section:hover .label {
            opacity: 1;
        }
    </style>
{% endblock %}

{% block content %}
{% for index_ref in index.indexrefs_set.all %}
    <a href="{{ index_ref.ref }}" class="menu">
        <div class="section d-none" data-x="{{ index_ref.x }}" data-y="{{ index_ref.y }}" data-radius="{{ index_ref.radius }}">
            <div class="label">{{ index_ref.title }}</div>
        </div>
    </a>
{% endfor %}
{% endblock %}

{% block scripts %}
    <script>
        window.addEventListener('load', function() {
            var sections = document.querySelectorAll('.section'),
                forEach = Array.prototype.forEach;

            activate();

            function activate() {
                window.addEventListener('resize', resize_handler);
                forEach.call(sections, function (section) {
                    section.classList.remove('d-none');
                });
                resize_handler();
            }

            function resize_handler(event) {
                forEach.call(sections, function(section) {
                    var left = parseInt(section.dataset.x),
                        top = parseInt(section.dataset.y),
                        radius = parseInt(section.dataset.radius);

                    var width = parseInt("{{ index.image.width }}"),
                        height = parseInt("{{ index.image.height }}"),
                        img_proportions = width / height,
                        win_width = window.innerWidth,
                        win_height = window.innerHeight,
                        win_proportions = win_width / win_height;

                    var scale = img_proportions > win_proportions
                        ? win_height / height
                        : win_width / width;

                    left *= scale;
                    top *= scale;
                    radius *= scale;

                    if (img_proportions > win_proportions) {
                        left -= (width * scale - win_width) / 2;
                    }
                    else {
                        top -= (height * scale - win_height) / 2;
                    }

                    top -= radius;
                    left -= radius;

                    section.style.width = section.style.height = 2 * radius + 'px';
                    section.style.left = left + 'px';
                    section.style.top = top + 'px';
                });
            }
        });
    </script>
{% endblock %}