怎么使用前端中canvas实现手势解锁

本篇内容介绍了"怎么使用前端中canvas实现手势解锁"的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！

demo.html：

index.js：

(function(){        /**         * 实现画圆和划线：         * 1、添加事件touchstart、touchmove、touchend         * 2、touchstart判断是否点击的位置处于圆内getPosition，处于则初始化         * lastpoint、restPoint         * 3、touchmove做的就是：画圆drawPoint和画线drawLine         *         * 实现自动画圆的效果         * 1、检测手势移动的位置是否处于圆内         * 2、圆内的话则画圆 drawPoint         * 3、已经画过实心圆的圆，无需重复检测         *         * 实现解锁成功：         * 1、检测路径是否是对的         * 2、如果是对的就重置，圆圈变绿         * 3、不对也重置，圆圈变红         * 4、重置         */        window.canvasLock = function(obj){            this.height = obj.height;            this.width = obj.width;            this.chooseType = obj.chooseType;        };        // js方式动态生成dom        canvasLock.prototype.initDom = function(){            var wrap = document.createElement('div');            var str = '
绘制解锁图案
';            wrap.setAttribute('style','position: absolute;top:0;left:0;right:0;bottom:0;');            var canvas = document.createElement('canvas');            canvas.setAttribute('id','canvas');            canvas.style.cssText = 'background-color: #305066;display: inline-block;margin-top: 15px;';            wrap[xss_clean] = str;            wrap.appendChild(canvas);            var width = this.width || 300;            var height = this.height || 300;            document.body.appendChild(wrap);            // 高清屏锁放            canvas.style.width = width + "px";            canvas.style.height = height + "px";            canvas.width = width;            canvas.height = height;        }        canvasLock.prototype.drawCle = function(x, y) { // 初始化解锁密码面板            this.ctx.strokeStyle = '#CFE6FF';            this.ctx.lineWidth = 2;            this.ctx.beginPath();            this.ctx.arc(x, y, this.r, 0, Math.PI * 2, true);            this.ctx.closePath();            this.ctx.stroke();        }        canvasLock.prototype.createCircle = function() {// 创建解锁点的坐标，根据canvas的大小来平均分配半径            var n = this.chooseType;            var count = 0;            this.r = this.ctx.canvas.width / (2 + 4 * n);// 公式计算            this.lastPoint = [];            this.arr = [];            this.restPoint = [];            var r = this.r;            for (var i = 0 ; i < n ; i++) {                for (var j = 0 ; j < n ; j++) {                    count++;                    var obj = {                        x: j * 4 * r + 3 * r,                        y: i * 4 * r + 3 * r,                        index: count                    };                    this.arr.push(obj);                    this.restPoint.push(obj);                }            }            this.ctx.clearRect(0, 0, this.ctx.canvas.width, this.ctx.canvas.height);            for (var i = 0 ; i < this.arr.length ; i++) {                // 画圆函数                this.drawCle(this.arr[i].x, this.arr[i].y);            }            //return arr;        }        // 程序初始化        canvasLock.prototype.init = function() {            this.initDom();            this.canvas = document.getElementById('canvas');            this.ctx = this.canvas.getContext('2d');            this.touchFlag = false;            // 1、确定半径            // 2、确定每一个圆的中心坐标点            // 3、一行3个圆14个半径，一行4个圆有18个半径            this.createCircle();            this.bindEvent();        }        canvasLock.prototype.bindEvent = function(){            var self = this;            this.canvas.addEventListener("touchstart", function (e) {                // 2、touchstart判断是否点击的位置处于圆内getPosition，处于则初始化                //          * lastpoint、restPoint                                // po有x和y，并且是相较于canvas边距                var po = self.getPosition(e);                console.log(po.x)                // 判断是否在圆内的原理：多出来的这条 x/y < r 在圆内                for (var i = 0 ; i < self.arr.length ; i++) {                    if (Math.abs(po.x - self.arr[i].x) < self.r && Math.abs(po.y - self.arr[i].y) < self.r) {                                                 self.touchFlag = true;                        // lastPoint存放的就是选中的圆圈的x/y坐标值                        self.lastPoint.push(self.arr[i]);                        self.restPoint.splice(i,1);                        break;                    }                }            }, false);            this.canvas.addEventListener("touchmove", function (e) {               // touchmove做的就是：画圆drawPoint和划线drawLine               if (self.touchFlag) {                  self.update(self.getPosition(e));               }            }, false);            this.canvas.addEventListener("touchend", function(e){                if (self.touchFlag) {                    self.storePass(self.lastPoint);                    setTimeout(function(){                       self.reset();                   }, 300);                }            }, false);        }        canvasLock.prototype.getPosition = function(e) {// 获取touch点相对于canvas的坐标            var rect = e.currentTarget.getBoundingClientRect();            var po = {                x: (e.touches[0].clientX - rect.left),                y: (e.touches[0].clientY - rect.top)            };            return po;        }                canvasLock.prototype.update = function(po) {// 核心变换方法在touchmove时候调用            this.ctx.clearRect(0, 0, this.ctx.canvas.width, this.ctx.canvas.height);            // 重新画9个圆圈            for (var i = 0 ; i < this.arr.length ; i++) { // 每帧先把面板画出来                this.drawCle(this.arr[i].x, this.arr[i].y);            }            this.drawPoint();// 画圆            this.drawLine(po);// 画线            // 1、检测手势移动的位置是否处于下一个圆内            // 2、圆内的话则画圆 drawPoint            // 3、已经画过实心圆的圆，无需重复检测            for (var i = 0 ; i < this.restPoint.length ; i++) {                if (Math.abs(po.x - this.restPoint[i].x) < this.r && Math.abs(po.y - this.restPoint[i].y) < this.r) {                    this.drawPoint();                    this.lastPoint.push(this.restPoint[i]);                    this.restPoint.splice(i, 1);                    break;                }            }            console.log(this.lastPoint)        }        canvasLock.prototype.drawLine = function(po) {// 解锁轨迹            this.ctx.beginPath();            this.ctx.lineWidth = 3;            this.ctx.moveTo(this.lastPoint[0].x, this.lastPoint[0].y);            for (var i = 1 ; i < this.lastPoint.length ; i++) {                this.ctx.lineTo(this.lastPoint[i].x, this.lastPoint[i].y);            }            this.ctx.lineTo(po.x, po.y);            this.ctx.stroke();            this.ctx.closePath();        }        canvasLock.prototype.drawPoint = function() { // 初始化圆心             for (var i = 0 ; i < this.lastPoint.length ; i++) {                this.ctx.fillStyle = '#CFE6FF';                this.ctx.beginPath();                this.ctx.arc(this.lastPoint[i].x, this.lastPoint[i].y, this.r / 2, 0, Math.PI * 2, true);                this.ctx.closePath();                this.ctx.fill();            }        }        // 1、检测路径是否是对的        // 2、如果是对的就重置，圆圈变绿        // 3、不对也重置，圆圈变红        // 4、重置        canvasLock.prototype.storePass = function() {            if (this.checkPass()) {                document.getElementById('title')[xss_clean] = '解锁成功';                this.drawStatusPoint('#2CFF26');            }else{                document.getElementById('title')[xss_clean] = '解锁失败';                this.drawStatusPoint('red');            }        }        canvasLock.prototype.checkPass = function() {            var p1 = '123',            p2 = '';            for (var i = 0 ; i < this.lastPoint.length ; i++) {                p2 += this.lastPoint[i].index;            }            return p1 === p2;        }        canvasLock.prototype.drawStatusPoint = function(type) {            for (var i = 0 ; i < this.lastPoint.length ; i++) {                this.ctx.strokeStyle = type;                this.ctx.beginPath();                this.ctx.arc(this.lastPoint[i].x, this.lastPoint[i].y, this.r, 0, Math.PI * 2, true);                this.ctx.closePath();                this.ctx.stroke();            }        }        canvasLock.prototype.reset = function(){            this.createCircle();        }})();

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