新增图片和js

utils/signature_pad.js

@@ -0,0 +1,390 @@
+/*!
+ * 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;
+
+})));