text: ﻿(function (root, factory) {
      if (typeof define === 'function' && define.amd) {
          // AMD. Register as an anonymous module unless amdModuleId is set
          define([], function () {
              return (root['SignaturePad'] = factory());
          });
      } else if (typeof exports === 'object') {
          // Node. Does not work with strict CommonJS, but
          // only CommonJS-like environments that support module.exports,
          // like Node.
          module.exports = factory();
      } else {
          root['SignaturePad'] = factory();
      }
  }(this, function () {
  
      /*!
       * Signature Pad v1.5.2
       * https://github.com/szimek/signature_pad
       *
       * Copyright 2015 Szymon Nowak
       * Released under the MIT license
       *
       * The main idea and some parts of the code (e.g. drawing variable width Bézier curve) are taken from:
       * http://corner.squareup.com/2012/07/smoother-signatures.html
       *
       * Implementation of interpolation using cubic Bézier curves is taken from:
       * http://benknowscode.wordpress.com/2012/09/14/path-interpolation-using-cubic-bezier-and-control-point-estimation-in-javascript
       *
       * Algorithm for approximated length of a Bézier curve is taken from:
       * http://www.lemoda.net/maths/bezier-length/index.html
       *
       */
      var SignaturePad = (function (document) {
          "use strict";
  
          var SignaturePad = function (canvas, options) {
              var self = this,
                  opts = options || {};
  
              this.velocityFilterWeight = opts.velocityFilterWeight || 0.7;
              this.minWidth = opts.minWidth || 0.5;
              this.maxWidth = opts.maxWidth || 2.5;
              this.dotSize = opts.dotSize || function () {
                  return (this.minWidth + this.maxWidth) / 2;
              };
              this.penColor = opts.penColor || "black";
              this.backgroundColor = opts.backgroundColor || "rgba(0,0,0,0)";
              this.onEnd = opts.onEnd;
              this.onBegin = opts.onBegin;
  
              this._canvas = canvas;
              this._ctx = canvas.getContext("2d");
              this.clear();
  
              // we need add these inline so they are available to unbind while still having
              //  access to 'self' we could use _.bind but it's not worth adding a dependency
              this._handleMouseDown = function (event) {
                  if (event.which === 1) {
                      self._mouseButtonDown = true;
                      self._strokeBegin(event);
                  }
              };
  
              this._handleMouseMove = function (event) {
                  if (self._mouseButtonDown) {
                      self._strokeUpdate(event);
                  }
              };
  
              this._handleMouseUp = function (event) {
                  if (event.which === 1 && self._mouseButtonDown) {
                      self._mouseButtonDown = false;
                      self._strokeEnd(event);
                  }
              };
  
              this._handleTouchStart = function (event) {
                  if (event.targetTouches.length == 1) {
                      var touch = event.changedTouches[0];
                      self._strokeBegin(touch);
                  }
              };
  
              this._handleTouchMove = function (event) {
                  // Prevent scrolling.
                  event.preventDefault();
  
                  var touch = event.targetTouches[0];
                  self._strokeUpdate(touch);
              };
  
              this._handleTouchEnd = function (event) {
                  var wasCanvasTouched = event.target === self._canvas;
                  if (wasCanvasTouched) {
                      event.preventDefault();
                      self._strokeEnd(event);
                  }
              };
  
              this._handleMouseEvents();
              this._handleTouchEvents();
          };
  
          SignaturePad.prototype.clear = function () {
              var ctx = this._ctx,
                  canvas = this._canvas;
  
              ctx.fillStyle = this.backgroundColor;
              ctx.clearRect(0, 0, canvas.width, canvas.height);
              ctx.fillRect(0, 0, canvas.width, canvas.height);
              this._reset();
          };
  
          SignaturePad.prototype.toDataURL = function (imageType, quality) {
              var canvas = this._canvas;
              return canvas.toDataURL.apply(canvas, arguments);
          };
  
          SignaturePad.prototype.fromDataURL = function (dataUrl) {
              var self = this,
                  image = new Image(),
                  ratio = window.devicePixelRatio || 1,
                  width = this._canvas.width / ratio,
                  height = this._canvas.height / ratio;
  
              this._reset();
              image.src = dataUrl;
              image.onload = function () {
                  self._ctx.drawImage(image, 0, 0, width, height);
              };
              this._isEmpty = false;
          };
  
          SignaturePad.prototype._strokeUpdate = function (event) {
              var point = this._createPoint(event);
              this._addPoint(point);
          };
  
          SignaturePad.prototype._strokeBegin = function (event) {
              this._reset();
              this._strokeUpdate(event);
              if (typeof this.onBegin === 'function') {
                  this.onBegin(event);
              }
          };
  
          SignaturePad.prototype._strokeDraw = function (point) {
              var ctx = this._ctx,
                  dotSize = typeof (this.dotSize) === 'function' ? this.dotSize() : this.dotSize;
  
              ctx.beginPath();
              this._drawPoint(point.x, point.y, dotSize);
              ctx.closePath();
              ctx.fill();
          };
  
          SignaturePad.prototype._strokeEnd = function (event) {
              var canDrawCurve = this.points.length > 2,
                  point = this.points[0];
  
              if (!canDrawCurve && point) {
                  this._strokeDraw(point);
              }
              if (typeof this.onEnd === 'function') {
                  this.onEnd(event);
              }
          };
  
          SignaturePad.prototype._handleMouseEvents = function () {
              this._mouseButtonDown = false;
  
              this._canvas.addEventListener("mousedown", this._handleMouseDown);
              this._canvas.addEventListener("mousemove", this._handleMouseMove);
              document.addEventListener("mouseup", this._handleMouseUp);
          };
  
          SignaturePad.prototype._handleTouchEvents = function () {
              // Pass touch events to canvas element on mobile IE.
              this._canvas.style.msTouchAction = 'none';
  
              this._canvas.addEventListener("touchstart", this._handleTouchStart);
              this._canvas.addEventListener("touchmove", this._handleTouchMove);
              document.addEventListener("touchend", this._handleTouchEnd);
          };
  
          SignaturePad.prototype.on = function () {
              this._handleMouseEvents();
              this._handleTouchEvents();
          };
  
          SignaturePad.prototype.off = function () {
              this._canvas.removeEventListener("mousedown", this._handleMouseDown);
              this._canvas.removeEventListener("mousemove", this._handleMouseMove);
              document.removeEventListener("mouseup", this._handleMouseUp);
  
              this._canvas.removeEventListener("touchstart", this._handleTouchStart);
              this._canvas.removeEventListener("touchmove", this._handleTouchMove);
              document.removeEventListener("touchend", this._handleTouchEnd);
          };
  
          SignaturePad.prototype.isEmpty = function () {
              return this._isEmpty;
          };
  
          SignaturePad.prototype._reset = function () {
              this.points = [];
              this._lastVelocity = 0;
              this._lastWidth = (this.minWidth + this.maxWidth) / 2;
              this._isEmpty = true;
              this._ctx.fillStyle = this.penColor;
          };
  
          SignaturePad.prototype._createPoint = function (event) {
              var rect = this._canvas.getBoundingClientRect();
              return new Point(
                  event.clientX - rect.left,
                  event.clientY - rect.top
              );
          };
  
          SignaturePad.prototype._addPoint = function (point) {
              var points = this.points,
                  c2, c3,
                  curve, tmp;
  
              points.push(point);
  
              if (points.length > 2) {
                  // To reduce the initial lag make it work with 3 points
                  // by copying the first point to the beginning.
                  if (points.length === 3) points.unshift(points[0]);
  
                  tmp = this._calculateCurveControlPoints(points[0], points[1], points[2]);
                  c2 = tmp.c2;
                  tmp = this._calculateCurveControlPoints(points[1], points[2], points[3]);
                  c3 = tmp.c1;
                  curve = new Bezier(points[1], c2, c3, points[2]);
                  this._addCurve(curve);
  
                  // Remove the first element from the list,
                  // so that we always have no more than 4 points in points array.
                  points.shift();
              }
          };
  
          SignaturePad.prototype._calculateCurveControlPoints = function (s1, s2, s3) {
              var dx1 = s1.x - s2.x, dy1 = s1.y - s2.y,
                  dx2 = s2.x - s3.x, dy2 = s2.y - s3.y,
  
                  m1 = { x: (s1.x + s2.x) / 2.0, y: (s1.y + s2.y) / 2.0 },
                  m2 = { x: (s2.x + s3.x) / 2.0, y: (s2.y + s3.y) / 2.0 },
  
                  l1 = Math.sqrt(dx1 * dx1 + dy1 * dy1),
                  l2 = Math.sqrt(dx2 * dx2 + dy2 * dy2),
  
                  dxm = (m1.x - m2.x),
                  dym = (m1.y - m2.y),
  
                  k = l2 / (l1 + l2),
                  cm = { x: m2.x + dxm * k, y: m2.y + dym * k },
  
                  tx = s2.x - cm.x,
                  ty = s2.y - cm.y;
  
              return {
                  c1: new Point(m1.x + tx, m1.y + ty),
                  c2: new Point(m2.x + tx, m2.y + ty)
              };
          };
  
          SignaturePad.prototype._addCurve = function (curve) {
              var startPoint = curve.startPoint,
                  endPoint = curve.endPoint,
                  velocity, newWidth;
  
              velocity = endPoint.velocityFrom(startPoint);
              velocity = this.velocityFilterWeight * velocity
                  + (1 - this.velocityFilterWeight) * this._lastVelocity;
  
              newWidth = this._strokeWidth(velocity);
              this._drawCurve(curve, this._lastWidth, newWidth);
  
              this._lastVelocity = velocity;
              this._lastWidth = newWidth;
          };
  
          SignaturePad.prototype._drawPoint = function (x, y, size) {
              var ctx = this._ctx;
  
              ctx.moveTo(x, y);
              ctx.arc(x, y, size, 0, 2 * Math.PI, false);
              this._isEmpty = false;
          };
  
          SignaturePad.prototype._drawCurve = function (curve, startWidth, endWidth) {
              var ctx = this._ctx,
                  widthDelta = endWidth - startWidth,
                  drawSteps, width, i, t, tt, ttt, u, uu, uuu, x, y;
  
              drawSteps = Math.floor(curve.length());
              ctx.beginPath();
              for (i = 0; i < drawSteps; i++) {
                  // Calculate the Bezier (x, y) coordinate for this step.
                  t = i / drawSteps;
                  tt = t * t;
                  ttt = tt * t;
                  u = 1 - t;
                  uu = u * u;
                  uuu = uu * u;
  
                  x = uuu * curve.startPoint.x;
                  x += 3 * uu * t * curve.control1.x;
                  x += 3 * u * tt * curve.control2.x;
                  x += ttt * curve.endPoint.x;
  
                  y = uuu * curve.startPoint.y;
                  y += 3 * uu * t * curve.control1.y;
                  y += 3 * u * tt * curve.control2.y;
                  y += ttt * curve.endPoint.y;
  
                  width = startWidth + ttt * widthDelta;
                  this._drawPoint(x, y, width);
              }
              ctx.closePath();
              ctx.fill();
          };
  
          SignaturePad.prototype._strokeWidth = function (velocity) {
              return Math.max(this.maxWidth / (velocity + 1), this.minWidth);
          };
  
  
          var Point = function (x, y, time) {
              this.x = x;
              this.y = y;
              this.time = time || new Date().getTime();
          };
  
          Point.prototype.velocityFrom = function (start) {
              return (this.time !== start.time) ? this.distanceTo(start) / (this.time - start.time) : 1;
          };
  
          Point.prototype.distanceTo = function (start) {
              return Math.sqrt(Math.pow(this.x - start.x, 2) + Math.pow(this.y - start.y, 2));
          };
  
          var Bezier = function (startPoint, control1, control2, endPoint) {
              this.startPoint = startPoint;
              this.control1 = control1;
              this.control2 = control2;
              this.endPoint = endPoint;
          };
  
          // Returns approximated length.
          Bezier.prototype.length = function () {
              var steps = 10,
                  length = 0,
                  i, t, cx, cy, px, py, xdiff, ydiff;
  
              for (i = 0; i <= steps; i++) {
                  t = i / steps;
                  cx = this._point(t, this.startPoint.x, this.control1.x, this.control2.x, this.endPoint.x);
                  cy = this._point(t, this.startPoint.y, this.control1.y, this.control2.y, this.endPoint.y);
                  if (i > 0) {
                      xdiff = cx - px;
                      ydiff = cy - py;
                      length += Math.sqrt(xdiff * xdiff + ydiff * ydiff);
                  }
                  px = cx;
                  py = cy;
              }
              return length;
          };
  
          Bezier.prototype._point = function (t, start, c1, c2, end) {
              return start * (1.0 - t) * (1.0 - t) * (1.0 - t)
                     + 3.0 * c1 * (1.0 - t) * (1.0 - t) * t
                     + 3.0 * c2 * (1.0 - t) * t * t
                     + end * t * t * t;
          };
  
          return SignaturePad;
      })(document);
  
      return SignaturePad;
  
  }));
  