zoomHandler.js

var ZoomHandler = (function() {

    if(typeof require === 'undefined') {
        return {};
    }

    // Private
    const defaultZoom = 1;
    const defaultWidth = 1030;
    const maxZoom = 2;
    const maxAutoZoom = 1.5;
    const minZoom = 0.9;
    const zoomStep = 0.1;

    var webFrame = require('web-frame');

    function getZoomLevel() {
        var zoomFactor = webFrame.getZoomFactor();
        var width = window.innerWidth * zoomFactor;
        var zoom = normalizeAuto(width / defaultWidth);
        return zoom;
    };

    function setZoom() {
        var zoom = getZoomLevel();
        webFrame.setZoomFactor(zoom);
        localStorage.setItem('zoomLevel', zoom);
    };

    function boundedNormalize(zoom, min, max) {
        if(typeof zoom === 'undefined') {
            return defaultZoom;
        }

        if(isNaN(zoom)) {
            return defaultZoom;
        }

        if (zoom < min) {
            return min;
        } else if (zoom > max) {
            return max;
        } else {
            return zoom;
        }
    };

    function normalize(zoom) {
        return boundedNormalize(zoom, minZoom, maxZoom);
    };

    function normalizeAuto(zoom) {
        return boundedNormalize(zoom, minZoom, maxAutoZoom);
    }

    function increaseZoom() {
        disableAutoResize();
        localStorage.setItem('zoomAuto', 0);

        var zoom = normalize(webFrame.getZoomFactor() + zoomStep);
        webFrame.setZoomFactor(zoom);
        localStorage.setItem('zoomLevel', zoom);
    };

    function decreaseZoom() {
        disableAutoResize();
        localStorage.setItem('zoomAuto', 0);

        var zoom = normalize(webFrame.getZoomFactor() - zoomStep);
        webFrame.setZoomFactor(zoom);
        localStorage.setItem('zoomLevel', zoom);
    };

    function resetZoom() {
        webFrame.setZoomFactor(defaultZoom);
        localStorage.setItem('zoomLevel', defaultZoom);
    };

    // event handlers
    function enableAutoResize() {
        $(window).on('resize.zoomHandler', setZoom);
        setZoom();
        localStorage.setItem('zoomAuto', 1);        
    };

    function manualResizeKeybinds(e) {
        if ((e.which == 107 || e.which == 187 ) && e.ctrlKey) {
            increaseZoom();
        } else if ((e.which == 109 || e.which == 189 ) && e.ctrlKey) {
            decreaseZoom();
        } else if ((e.which == 48 || e.which == 96) && e.ctrlKey) {
            resetZoom();
        }
    };

    function disableAutoResize() {
        localStorage.setItem('zoomAuto', 0);
        $(window).off('resize.zoomHandler');
    };

    function enableManualResize() {
        $(function() {
            $(document).on('keydown.zoomHandler', manualResizeKeybinds);
        });
    };

    function disableManualResize() {
        $(document).off('keydown.zoomHandler');
    }

    function init() {
        var autoResizeEnabled = localStorage.getItem('zoomAuto');

        if(autoResizeEnabled === null) {
            autoResizeEnabled = '1';
            localStorage.setItem('zoomAuto', 1);
        }

        if(autoResizeEnabled === '1') {
            enableAutoResize();
        }

        enableManualResize();

        var zoom = parseInt(localStorage.getItem('zoomLevel'), 10);
        zoom = normalize(zoom);
        webFrame.setZoomFactor(zoom);

        // Fix odd menu issue
        var menufix = $('.desktop-close').parent();
        menufix.hide();
        setTimeout(function() { menufix.show(); }, 100);
    }

    // Public
    var zoomHandler = {
        getZoom: webFrame.getZoomFactor,
        increaseZoom,
        decreaseZoom,
        resetZoom,
        enableAutoResize,
        disableAutoResize,
        enableManualResize,
        disableManualResize,
        init
    };

    return zoomHandler;

})();

if(typeof jQuery !== 'undefined') {
    ZoomHandler.init();
}