index.js

var jsdom = require('jsdom');
$ = require("jquery")(new jsdom.JSDOM().window);
var textSignature = {};

textSignature = function(options) {
    var self = this;
    self.isInitiated = false;
    self.imageData = null;

    this.init = function() {
        //inject custom font face from external url   
        $('head').find("#text-signature").remove();
        var linkElem = $('<link rel="stylesheet">');
        linkElem.attr('id', "text-signature");
        $('head').append(linkElem);

        linkElem.attr('href', options.customFont.url);
        if (linkElem[0].addEventListener) {
            linkElem[0].addEventListener('load', function() {

                // wait abit slonger and call again -  if first time

                self.generateImage(options);
                if (!self.isInitiated) {
                    setTimeout(function() {
                        $(options.canvasTargetDom).html(" ");
                        self.generateImage(options);
                    }, 2800);
                }

                self.isInitiated = true;
            }, false);
        }

    }
    this.formatInput = function(options) {
        //handle errror 
        if (!options || options == undefined) {
            throw "text-singature: parameter cannot be null or empty";
        }
        if (!options.font) {
            throw "text-singature: parameter font cannot be empty";
        }
        if (!options.textString) {
            throw "text-singature: parameter textString cannot be empty";
        }
        if (typeof options.font === "string") {
            return options;
        }

        options.font = (options.font) || ["12px", "Arial"];
        options.font = (options.font).join(" ");

        options.fillStyle = (options.color) || "black";
        options.textString = options.textString || "Text-Signature !";
        options.paddingX = options.paddingX || 0;
        options.paddingY = options.paddingY || 0;

        return options;

    };


    this.generateImage = function(options) {

        //parameter sanity and defaults
        options = this.formatInput(options);

        var uniquetime = new Date().getUTCMilliseconds();

        //generate canvas
        var canvasSelectorDom = $('<canvas></canvas>');
        canvasSelectorDom.attr('width', options.width);
        canvasSelectorDom.attr('height', options.height);
        canvasSelectorDom.attr('id', "text-signature-" + uniquetime);


        var context = canvasSelectorDom[0].getContext("2d");
        context.font = options.font;
        context.fillStyle = options.fillStyle;
        context.fillText(options.textString, options.paddingX, options.paddingY);


        var dataUrl = canvasSelectorDom[0].toDataURL();
        self.imageData = dataUrl;

        var img = $('<img>'); //Equivalent: $(document.createElement('img'))
        img.attr('src', dataUrl);
        img.attr('text-signature-timestamp', uniquetime);
        img.attr('id', "text-signature-" + uniquetime); 


        if (options.canvasTargetDom) {
            if (self.isInitiated) {
                $(options.canvasTargetDom).html(img);
            } else {
                $(options.canvasTargetDom).html();
            }

        } else {
            window.open(dataUrl, "text-signature image", "width=600, height=200");
        }

    };
    this.getImageData = function() {
        return self.imageData;
    };
    this.isDomObject = function(obj) {
        return (obj.tagName ? "true" : "false");
    };

    this.ping = function() {
        console.log("Yup. text-singature is working");
    };

    this.init();
};




module.exports = textSignature