515 lines
15 KiB
JavaScript
515 lines
15 KiB
JavaScript
/*!
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* Signature Pad v1.6.0-beta.5
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* https://github.com/szimek/signature_pad
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*
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* Copyright 2017 Szymon Nowak
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* Released under the MIT license
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*
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* The main idea and some parts of the code (e.g. drawing variable width Bézier curve) are taken from:
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* http://corner.squareup.com/2012/07/smoother-signatures.html
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*
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* Implementation of interpolation using cubic Bézier curves is taken from:
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* http://benknowscode.wordpress.com/2012/09/14/path-interpolation-using-cubic-bezier-and-control-point-estimation-in-javascript
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*
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* Algorithm for approximated length of a Bézier curve is taken from:
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* http://www.lemoda.net/maths/bezier-length/index.html
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*
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*/
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(function (global, factory) {
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typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
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typeof define === 'function' && define.amd ? define(factory) :
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(global.SignaturePad = factory());
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}(this, (function () { 'use strict';
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function Point(x, y, time) {
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this.x = x;
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this.y = y;
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this.time = time || new Date().getTime();
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}
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Point.prototype.velocityFrom = function (start) {
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return this.time !== start.time ? this.distanceTo(start) / (this.time - start.time) : 1;
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};
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Point.prototype.distanceTo = function (start) {
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return Math.sqrt(Math.pow(this.x - start.x, 2) + Math.pow(this.y - start.y, 2));
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};
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function Bezier(startPoint, control1, control2, endPoint) {
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this.startPoint = startPoint;
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this.control1 = control1;
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this.control2 = control2;
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this.endPoint = endPoint;
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}
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// Returns approximated length.
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Bezier.prototype.length = function () {
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var steps = 10;
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var length = 0;
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var px = void 0;
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var py = void 0;
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for (var i = 0; i <= steps; i += 1) {
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var t = i / steps;
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var cx = this._point(t, this.startPoint.x, this.control1.x, this.control2.x, this.endPoint.x);
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var cy = this._point(t, this.startPoint.y, this.control1.y, this.control2.y, this.endPoint.y);
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if (i > 0) {
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var xdiff = cx - px;
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var ydiff = cy - py;
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length += Math.sqrt(xdiff * xdiff + ydiff * ydiff);
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}
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px = cx;
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py = cy;
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}
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return length;
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};
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/* eslint-disable no-multi-spaces, space-in-parens */
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Bezier.prototype._point = function (t, start, c1, c2, end) {
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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;
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};
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function SignaturePad(canvas, options) {
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var self = this;
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var opts = options || {};
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this.velocityFilterWeight = opts.velocityFilterWeight || 0.7;
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this.minWidth = opts.minWidth || 0.5;
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this.maxWidth = opts.maxWidth || 2.5;
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this.dotSize = opts.dotSize || function () {
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return (this.minWidth + this.maxWidth) / 2;
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};
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this.penColor = opts.penColor || 'black';
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this.backgroundColor = opts.backgroundColor || 'rgba(0,0,0,0)';
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this.onBegin = opts.onBegin;
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this.onEnd = opts.onEnd;
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this._canvas = canvas;
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this._ctx = canvas.getContext('2d');
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this.clear();
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// We need add these inline so they are available to unbind while still having
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// access to 'self' we could use _.bind but it's not worth adding a dependency.
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this._handleMouseDown = function (event) {
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if (event.which === 1) {
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self._mouseButtonDown = true;
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self._strokeBegin(event);
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}
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};
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this._handleMouseMove = function (event) {
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if (self._mouseButtonDown) {
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self._strokeUpdate(event);
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}
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};
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this._handleMouseUp = function (event) {
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if (event.which === 1 && self._mouseButtonDown) {
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self._mouseButtonDown = false;
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self._strokeEnd(event);
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}
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};
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this._handleTouchStart = function (event) {
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if (event.targetTouches.length === 1) {
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var touch = event.changedTouches[0];
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self._strokeBegin(touch);
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}
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};
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this._handleTouchMove = function (event) {
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// Prevent scrolling.
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event.preventDefault();
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var touch = event.targetTouches[0];
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self._strokeUpdate(touch);
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};
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this._handleTouchEnd = function (event) {
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var wasCanvasTouched = event.target === self._canvas;
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if (wasCanvasTouched) {
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event.preventDefault();
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self._strokeEnd(event);
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}
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};
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// Enable mouse and touch event handlers
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this.on();
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}
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// Public methods
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SignaturePad.prototype.clear = function () {
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var ctx = this._ctx;
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var canvas = this._canvas;
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ctx.fillStyle = this.backgroundColor;
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ctx.clearRect(0, 0, canvas.width, canvas.height);
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ctx.fillRect(0, 0, canvas.width, canvas.height);
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this._data = [];
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this._reset();
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this._isEmpty = true;
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};
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SignaturePad.prototype.fromDataURL = function (dataUrl) {
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var _this = this;
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var image = new Image();
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var ratio = window.devicePixelRatio || 1;
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var width = this._canvas.width / ratio;
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var height = this._canvas.height / ratio;
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this._reset();
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image.src = dataUrl;
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image.onload = function () {
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_this._ctx.drawImage(image, 0, 0, width, height);
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};
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this._isEmpty = false;
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};
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SignaturePad.prototype.toDataURL = function (type) {
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var _canvas;
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switch (type) {
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case 'image/svg+xml':
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return this._toSVG();
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default:
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for (var _len = arguments.length, options = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
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options[_key - 1] = arguments[_key];
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}
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return (_canvas = this._canvas).toDataURL.apply(_canvas, [type].concat(options));
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}
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};
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SignaturePad.prototype.on = function () {
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this._handleMouseEvents();
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this._handleTouchEvents();
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};
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SignaturePad.prototype.off = function () {
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this._canvas.removeEventListener('mousedown', this._handleMouseDown);
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this._canvas.removeEventListener('mousemove', this._handleMouseMove);
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document.removeEventListener('mouseup', this._handleMouseUp);
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this._canvas.removeEventListener('touchstart', this._handleTouchStart);
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this._canvas.removeEventListener('touchmove', this._handleTouchMove);
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this._canvas.removeEventListener('touchend', this._handleTouchEnd);
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};
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SignaturePad.prototype.isEmpty = function () {
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return this._isEmpty;
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};
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// Private methods
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SignaturePad.prototype._strokeBegin = function (event) {
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this._data.push([]);
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this._reset();
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this._strokeUpdate(event);
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if (typeof this.onBegin === 'function') {
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this.onBegin(event);
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}
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};
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SignaturePad.prototype._strokeUpdate = function (event) {
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var x = event.clientX;
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var y = event.clientY;
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var point = this._createPoint(x, y);
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var _addPoint = this._addPoint(point),
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curve = _addPoint.curve,
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widths = _addPoint.widths;
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if (curve && widths) {
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this._drawCurve(curve, widths.start, widths.end);
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}
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this._data[this._data.length - 1].push({
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x: point.x,
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y: point.y,
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time: point.time
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});
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};
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SignaturePad.prototype._strokeEnd = function (event) {
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var canDrawCurve = this.points.length > 2;
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var point = this.points[0];
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if (!canDrawCurve && point) {
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this._drawDot(point);
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}
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if (typeof this.onEnd === 'function') {
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this.onEnd(event);
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}
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};
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SignaturePad.prototype._handleMouseEvents = function () {
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this._mouseButtonDown = false;
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this._canvas.addEventListener('mousedown', this._handleMouseDown);
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this._canvas.addEventListener('mousemove', this._handleMouseMove);
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document.addEventListener('mouseup', this._handleMouseUp);
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};
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SignaturePad.prototype._handleTouchEvents = function () {
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// Pass touch events to canvas element on mobile IE11 and Edge.
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this._canvas.style.msTouchAction = 'none';
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this._canvas.style.touchAction = 'none';
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this._canvas.addEventListener('touchstart', this._handleTouchStart);
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this._canvas.addEventListener('touchmove', this._handleTouchMove);
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this._canvas.addEventListener('touchend', this._handleTouchEnd);
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};
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SignaturePad.prototype._reset = function () {
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this.points = [];
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this._lastVelocity = 0;
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this._lastWidth = (this.minWidth + this.maxWidth) / 2;
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this._ctx.fillStyle = this.penColor;
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};
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SignaturePad.prototype._createPoint = function (x, y, time) {
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var rect = this._canvas.getBoundingClientRect();
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return new Point(x - rect.left, y - rect.top, time || new Date().getTime());
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};
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SignaturePad.prototype._addPoint = function (point) {
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var points = this.points;
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var tmp = void 0;
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points.push(point);
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if (points.length > 2) {
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// To reduce the initial lag make it work with 3 points
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// by copying the first point to the beginning.
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if (points.length === 3) points.unshift(points[0]);
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tmp = this._calculateCurveControlPoints(points[0], points[1], points[2]);
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var c2 = tmp.c2;
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tmp = this._calculateCurveControlPoints(points[1], points[2], points[3]);
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var c3 = tmp.c1;
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var curve = new Bezier(points[1], c2, c3, points[2]);
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var widths = this._calculateCurveWidths(curve);
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// Remove the first element from the list,
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// so that we always have no more than 4 points in points array.
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points.shift();
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return { curve: curve, widths: widths };
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}
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return {};
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};
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SignaturePad.prototype._calculateCurveControlPoints = function (s1, s2, s3) {
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var dx1 = s1.x - s2.x;
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var dy1 = s1.y - s2.y;
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var dx2 = s2.x - s3.x;
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var dy2 = s2.y - s3.y;
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var m1 = { x: (s1.x + s2.x) / 2.0, y: (s1.y + s2.y) / 2.0 };
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var m2 = { x: (s2.x + s3.x) / 2.0, y: (s2.y + s3.y) / 2.0 };
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var l1 = Math.sqrt(dx1 * dx1 + dy1 * dy1);
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var l2 = Math.sqrt(dx2 * dx2 + dy2 * dy2);
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var dxm = m1.x - m2.x;
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var dym = m1.y - m2.y;
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var k = l2 / (l1 + l2);
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var cm = { x: m2.x + dxm * k, y: m2.y + dym * k };
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var tx = s2.x - cm.x;
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var ty = s2.y - cm.y;
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return {
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c1: new Point(m1.x + tx, m1.y + ty),
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c2: new Point(m2.x + tx, m2.y + ty)
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};
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};
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SignaturePad.prototype._calculateCurveWidths = function (curve) {
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var startPoint = curve.startPoint;
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var endPoint = curve.endPoint;
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var widths = { start: null, end: null };
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var velocity = this.velocityFilterWeight * endPoint.velocityFrom(startPoint) + (1 - this.velocityFilterWeight) * this._lastVelocity;
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var newWidth = this._strokeWidth(velocity);
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widths.start = this._lastWidth;
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widths.end = newWidth;
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this._lastVelocity = velocity;
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this._lastWidth = newWidth;
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return widths;
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};
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SignaturePad.prototype._strokeWidth = function (velocity) {
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return Math.max(this.maxWidth / (velocity + 1), this.minWidth);
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};
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SignaturePad.prototype._drawPoint = function (x, y, size) {
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var ctx = this._ctx;
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ctx.moveTo(x, y);
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ctx.arc(x, y, size, 0, 2 * Math.PI, false);
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this._isEmpty = false;
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};
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SignaturePad.prototype._drawCurve = function (curve, startWidth, endWidth) {
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var ctx = this._ctx;
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var widthDelta = endWidth - startWidth;
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var drawSteps = Math.floor(curve.length());
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ctx.beginPath();
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for (var i = 0; i < drawSteps; i += 1) {
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// Calculate the Bezier (x, y) coordinate for this step.
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var t = i / drawSteps;
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var tt = t * t;
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var ttt = tt * t;
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var u = 1 - t;
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var uu = u * u;
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var uuu = uu * u;
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var x = uuu * curve.startPoint.x;
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x += 3 * uu * t * curve.control1.x;
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x += 3 * u * tt * curve.control2.x;
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x += ttt * curve.endPoint.x;
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var y = uuu * curve.startPoint.y;
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y += 3 * uu * t * curve.control1.y;
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y += 3 * u * tt * curve.control2.y;
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y += ttt * curve.endPoint.y;
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var width = startWidth + ttt * widthDelta;
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this._drawPoint(x, y, width);
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}
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ctx.closePath();
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ctx.fill();
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};
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SignaturePad.prototype._drawDot = function (point) {
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var ctx = this._ctx;
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var width = typeof this.dotSize === 'function' ? this.dotSize() : this.dotSize;
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ctx.beginPath();
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this._drawPoint(point.x, point.y, width);
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ctx.closePath();
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ctx.fill();
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};
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SignaturePad.prototype._fromData = function (pointGroups, drawCurve, drawDot) {
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for (var i = 0; i < pointGroups.length; i += 1) {
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var group = pointGroups[i];
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if (group.length > 1) {
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for (var j = 0; j < group.length; j += 1) {
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var rawPoint = group[j];
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var point = new Point(rawPoint.x, rawPoint.y, rawPoint.time);
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if (j === 0) {
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// First point in a group. Nothing to draw yet.
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this._reset();
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this._addPoint(point);
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} else if (j !== group.length - 1) {
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// Middle point in a group.
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var _addPoint2 = this._addPoint(point),
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curve = _addPoint2.curve,
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widths = _addPoint2.widths;
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if (curve && widths) {
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drawCurve(curve, widths);
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}
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} else {
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// Last point in a group. Do nothing.
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}
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}
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} else {
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this._reset();
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var _rawPoint = group[0];
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drawDot(_rawPoint);
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}
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}
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};
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SignaturePad.prototype._toSVG = function () {
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var _this2 = this;
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var pointGroups = this._data;
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var canvas = this._canvas;
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var minX = 0;
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var minY = 0;
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var maxX = canvas.width;
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var maxY = canvas.height;
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var svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
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svg.setAttributeNS(null, 'width', canvas.width);
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svg.setAttributeNS(null, 'height', canvas.height);
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this._fromData(pointGroups, function (curve, widths) {
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var path = document.createElementNS('http;//www.w3.org/2000/svg', 'path');
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// Need to check curve for NaN values, these pop up when drawing
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// lines on the canvas that are not continuous. E.g. Sharp corners
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// or stopping mid-stroke and than continuing without lifting mouse.
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if (!isNaN(curve.control1.x) && !isNaN(curve.control1.y) && !isNaN(curve.control2.x) && !isNaN(curve.control2.y)) {
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var attr = 'M ' + curve.startPoint.x.toFixed(3) + ',' + curve.startPoint.y.toFixed(3) + ' ' + ('C ' + curve.control1.x.toFixed(3) + ',' + curve.control1.y.toFixed(3) + ' ') + (curve.control2.x.toFixed(3) + ',' + curve.control2.y.toFixed(3) + ' ') + (curve.endPoint.x.toFixed(3) + ',' + curve.endPoint.y.toFixed(3));
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path.setAttribute('d', attr);
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path.setAttributeNS(null, 'stroke-width', (widths.end * 2.25).toFixed(3));
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path.setAttributeNS(null, 'stroke', _this2.penColor);
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path.setAttributeNS(null, 'fill', 'none');
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path.setAttributeNS(null, 'stroke-linecap', 'round');
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svg.appendChild(path);
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}
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}, function (rawPoint) {
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var circle = document.createElementNS('http://www.w3.org/2000/svg', 'circle');
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var dotSize = typeof _this2.dotSize === 'function' ? _this2.dotSize() : _this2.dotSize;
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circle.setAttributeNS(null, 'r', dotSize);
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circle.setAttributeNS(null, 'cx', rawPoint.x);
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circle.setAttributeNS(null, 'cy', rawPoint.y);
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circle.setAttributeNS(null, 'fill', _this2.penColor);
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svg.appendChild(circle);
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});
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var prefix = 'data:image/svg+xml;base64,';
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var header = '<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="' + minX + ' ' + minY + ' ' + maxX + ' ' + maxY + '">';
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var body = svg.innerHTML;
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var footer = '</svg>';
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var data = header + body + footer;
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return prefix + btoa(data);
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};
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SignaturePad.prototype.fromData = function (pointGroups) {
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var _this3 = this;
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this.clear();
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this._fromData(pointGroups, function (curve, widths) {
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return _this3._drawCurve(curve, widths.start, widths.end);
|
|
}, function (rawPoint) {
|
|
return _this3._drawDot(rawPoint);
|
|
});
|
|
};
|
|
|
|
SignaturePad.prototype.toData = function () {
|
|
return this._data;
|
|
};
|
|
|
|
return SignaturePad;
|
|
|
|
})));
|