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- /*!
- * Signature Pad v2.2.0
- * https://github.com/szimek/signature_pad
- *
- * Copyright 2017 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
- *
- */
-
- (function(global, factory) {
- typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
- typeof define === 'function' && define.amd ? define(factory) :
- (global.SignaturePad = factory());
- }(this, (function() {
- 'use strict';
-
- function Point(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));
- };
-
- function Bezier(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;
- var length = 0;
- var px = void 0;
- var py = void 0;
-
- for (var i = 0; i <= steps; i += 1) {
- var t = i / steps;
- var cx = this._point(t, this.startPoint.x, this.control1.x, this.control2.x, this.endPoint.x);
- var cy = this._point(t, this.startPoint.y, this.control1.y, this.control2.y, this.endPoint.y);
- if (i > 0) {
- var xdiff = cx - px;
- var ydiff = cy - py;
- length += Math.sqrt(xdiff * xdiff + ydiff * ydiff);
- }
- px = cx;
- py = cy;
- }
-
- return length;
- };
-
- /* eslint-disable no-multi-spaces, space-in-parens */
- 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;
- };
-
- /* eslint-disable */
-
- // http://stackoverflow.com/a/27078401/815507
- function throttle(func, wait, options) {
- var context, args, result;
- var timeout = null;
- var previous = 0;
- if (!options) options = {};
- var later = function later() {
- previous = options.leading === false ? 0 : Date.now();
- timeout = null;
- result = func.apply(context, args);
- if (!timeout) context = args = null;
- };
- return function() {
- var now = Date.now();
- if (!previous && options.leading === false) previous = now;
- var remaining = wait - (now - previous);
- context = this;
- args = arguments;
- if (remaining <= 0 || remaining > wait) {
- if (timeout) {
- clearTimeout(timeout);
- timeout = null;
- }
- previous = now;
- result = func.apply(context, args);
- if (!timeout) context = args = null;
- } else if (!timeout && options.trailing !== false) {
- timeout = setTimeout(later, remaining);
- }
- return result;
- };
- }
-
- function SignaturePad(canvas, options) {
- var self = this;
- var opts = options || {};
-
- this.velocityFilterWeight = opts.velocityFilterWeight || 0.7;
- this.minWidth = opts.minWidth || 0.5;
- this.maxWidth = opts.maxWidth || 2.5;
- this.throttle = 'throttle' in opts ? opts.throttle : 16; // in miliseconds
-
- if (this.throttle) {
- this._strokeMoveUpdate = throttle(SignaturePad.prototype._strokeUpdate, this.throttle);
- } else {
- this._strokeMoveUpdate = SignaturePad.prototype._strokeUpdate;
- }
-
- this.dotSize = opts.dotSize || function() {
- return (this.minWidth + this.maxWidth) / 2;
- };
- this.penColor = opts.penColor || 'black'; //签字板的颜色
- this.backgroundColor = opts.backgroundColor || 'rgba(0,0,0,0)';
- this.onBegin = opts.onBegin;
- this.onEnd = opts.onEnd;
- this.devicePixelRatio = opts.devicePixelRatio || 1;
- this.lineWidth = opts.lineWidth || 1; //签字板的粗细
- this._canvas = canvas;
- this._ctx = canvas;
- 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._handleTouchStart = function(event, data) {
- self.penColor = data.penColor || self.penColor;
- self.lineWidth = data.lineWidth || self.lineWidth;
- if (event.touches.length === 1) {
- var touch = event.changedTouches[0];
- self._strokeBegin(touch);
- }
- };
-
- this._handleTouchMove = function(event) {
- // Prevent scrolling.
- var touch = event.touches[0];
- self._strokeMoveUpdate(touch);
- };
-
- this._handleTouchEnd = function(event) {
- self._strokeEnd(event);
- };
- this.clear = function() {
- var ctx = this._ctx;
- var canvas = this._canvas;
-
- ctx.fillStyle = this.backgroundColor;
- ctx.clearRect(0, 0, canvas.width, canvas.height);
- ctx.fillRect(0, 0, canvas.width, canvas.height);
- ctx.draw()
- this._data = [];
- this._reset();
- this._isEmpty = true;
- };
- }
-
- // Public methods
- SignaturePad.prototype.clear = function() {
- var ctx = this._ctx;
- var canvas = this._canvas;
-
- ctx.fillStyle = this.backgroundColor;
- ctx.clearRect(0, 0, canvas.width, canvas.height);
- ctx.fillRect(0, 0, canvas.width, canvas.height);
-
- this._data = [];
- this._reset();
- this._isEmpty = true;
- };
-
- SignaturePad.prototype.isEmpty = function() {
- return this._isEmpty;
- };
-
- // Private methods
- SignaturePad.prototype._strokeBegin = function(event) {
- this._data.push([]);
- this._reset();
- this._strokeUpdate(event);
-
- if (typeof this.onBegin === 'function') {
- this.onBegin(event);
- }
- };
-
- SignaturePad.prototype._strokeUpdate = function(event) {
- var x = event.x;
- var y = event.y;
-
- var point = this._createPoint(x, y);
-
- var _addPoint = this._addPoint(point),
- curve = _addPoint.curve,
- widths = _addPoint.widths;
-
- if (curve && widths) {
- this._drawCurve(curve, widths.start, widths.end);
- }
- this._data[this._data.length - 1].push({
- x: point.x,
- y: point.y,
- time: point.time,
- color: this.penColor
- });
- };
-
- SignaturePad.prototype._strokeEnd = function(event) {
- var canDrawCurve = this.points.length > 2;
- var point = this.points[0];
-
- if (!canDrawCurve && point) {
- this._drawDot(point);
- }
-
- if (typeof this.onEnd === 'function') {
- this.onEnd(event);
- }
- };
-
- SignaturePad.prototype._reset = function() {
- this.points = [];
- this._lastVelocity = 0;
- this._lastWidth = (this.minWidth + this.maxWidth) / 2;
- this._ctx.fillStyle = this.penColor;
- };
-
- SignaturePad.prototype._createPoint = function(x, y, time) {
- var rect = {
- left: 10,
- top: 10
- };
- return new Point(x - rect.left, y - rect.top, time || new Date().getTime());
- };
-
- SignaturePad.prototype._addPoint = function(point) {
- var points = this.points;
- var tmp = void 0;
-
- 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]);
- var c2 = tmp.c2;
- tmp = this._calculateCurveControlPoints(points[1], points[2], points[3]);
- var c3 = tmp.c1;
- var curve = new Bezier(points[1], c2, c3, points[2]);
- var widths = this._calculateCurveWidths(curve);
- // Remove the first element from the list,
- // so that we always have no more than 4 points in points array.
- points.shift();
-
- return { curve: curve, widths: widths };
- }
-
- return {};
- };
-
- SignaturePad.prototype._calculateCurveControlPoints = function(s1, s2, s3) {
- var dx1 = s1.x - s2.x;
- var dy1 = s1.y - s2.y;
- var dx2 = s2.x - s3.x;
- var dy2 = s2.y - s3.y;
- var m1 = { x: (s1.x + s2.x) / 2.0, y: (s1.y + s2.y) / 2.0 };
- var m2 = { x: (s2.x + s3.x) / 2.0, y: (s2.y + s3.y) / 2.0 };
-
- var l1 = Math.sqrt(dx1 * dx1 + dy1 * dy1);
- var l2 = Math.sqrt(dx2 * dx2 + dy2 * dy2);
-
- var dxm = m1.x - m2.x;
- var dym = m1.y - m2.y;
-
- var k = l2 / (l1 + l2);
- var cm = { x: m2.x + dxm * k, y: m2.y + dym * k };
-
- var tx = s2.x - cm.x;
- var 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._calculateCurveWidths = function(curve) {
- var startPoint = curve.startPoint;
- var endPoint = curve.endPoint;
- var widths = { start: null, end: null };
-
- var velocity = this.velocityFilterWeight * endPoint.velocityFrom(startPoint) + (1 - this.velocityFilterWeight) * this._lastVelocity;
-
- var newWidth = this._strokeWidth(velocity);
-
- widths.start = this._lastWidth;
- widths.end = newWidth;
-
- this._lastVelocity = velocity;
- this._lastWidth = newWidth;
-
- return widths;
- };
-
- SignaturePad.prototype._strokeWidth = function(velocity) {
- return Math.max(this.maxWidth / (velocity + 1), this.minWidth);
- };
-
- SignaturePad.prototype._drawPoint = function(x, y, size) {
- var ctx = this._ctx;
- var lineWidth = this.lineWidth;
- ctx.moveTo(x, y);
- ctx.arc(x, y, size * lineWidth, 0, 2 * Math.PI, false);
- this._isEmpty = false;
- };
-
- SignaturePad.prototype._drawCurve = function(curve, startWidth, endWidth) {
- var ctx = this._ctx;
- var widthDelta = endWidth - startWidth;
- var drawSteps = Math.floor(curve.length());
-
- ctx.beginPath();
- for (var i = 0; i < drawSteps; i += 1) {
- // Calculate the Bezier (x, y) coordinate for this step.
- var t = i / drawSteps;
- var tt = t * t;
- var ttt = tt * t;
- var u = 1 - t;
- var uu = u * u;
- var uuu = uu * u;
-
- var x = uuu * curve.startPoint.x;
- x += 3 * uu * t * curve.control1.x;
- x += 3 * u * tt * curve.control2.x;
- x += ttt * curve.endPoint.x;
-
- var y = uuu * curve.startPoint.y;
- y += 3 * uu * t * curve.control1.y;
- y += 3 * u * tt * curve.control2.y;
- y += ttt * curve.endPoint.y;
-
- var width = startWidth + ttt * widthDelta;
- this._drawPoint(x, y, width);
- }
- var penColor = this.penColor;
- ctx.closePath();
- ctx.setStrokeStyle(penColor);
- ctx.setFillStyle(penColor);
- ctx.fill();
- ctx.stroke();
- ctx.draw(true)
- };
-
- SignaturePad.prototype._drawDot = function(point) {
- var ctx = this._ctx;
- var width = typeof this.dotSize === 'function' ? this.dotSize() : this.dotSize;
- var penColor = this.penColor;
- ctx.beginPath();
- this._drawPoint(point.x, point.y, width);
- ctx.closePath();
- ctx.setStrokeStyle(penColor);
- ctx.setFillStyle(penColor);
- ctx.fill();
- ctx.stroke();
- ctx.draw(true)
- };
-
- SignaturePad.prototype.toData = function() {
- return this._data;
- };
-
- return SignaturePad;
-
- })));
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