canvas如何实现手机的手势解锁

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具体如下：

按照国际惯例，先放效果图

1、js动态初始化Dom结构

首先在index.html中添加基本样式

body{background:pink;text-align: center;}

加个移动端meta头

<meta name="viewport" content="width=device-width,initial-scale=1.0,user-Scalable=no">

引入index.js脚本

<script src="index.js"></script>

index.js

// 匿名函数自执行(function(){    // canvasLock是全局对象    window.canvasLock=function(obj){        this.width=obj.width;        this.height=obj.height;    }    //动态生成DOM    canvasLock.prototype.initDom=function(){        //创建一个div        var div=document.createElement("div");        var h5="<h5 id='title' class='title'>绘制解锁图案</h5>";        div.innerHTML=h5;        div.setAttribute("style","position:absolute;top:0;left:0;right:0;bottom:0;");        //创建canvas        var canvas=document.createElement("canvas");        canvas.setAttribute("id","canvas");        //CSSText 的本质就是设置 HTML 元素的 style 属性值        canvas.style.cssText="background:pink;display:inine-block;margin-top:15px;";        div.appendChild(canvas);        document.body.appendChild(div);        //设置canvas默认宽高        var width=this.width||300;        var height=this.height||300;        canvas.style.width=width+"px";        canvas.style.height=height+"px";        canvas.width=width;        canvas.height=height;    }        //init代表初始化，程序的入口    canvasLock.prototype.init=function(){        //动态生成DOM        this.initDom();        //创建画布        this.canvas=document.getElementById("canvas");        this.ctx=this.canvas.getContext("2d");    }})();

在index.html中创建实例并初始化

new canvasLock({}).init();

效果图

2、 画圆函数

需要补充一下画布宽度与圆的半径的关系

如果一行3个圆，则有4个间距，间距的宽度与圆的直径相同，相当于7个直径，即14个半径

如果一行4个圆，则有5个间距，间距的宽度与圆的直径相同，相当于9个直径，即18个半径

如果一行n个圆，则有n+1个间距，间距的宽度与圆的直径相同，相当于2n+1个直径，即4n+2个半径

补充两个方法：

//以给定坐标点为圆心画出单个圆    canvasLock.prototype.drawCircle=function(x,y){        this.ctx.strokeStyle="#abcdef";        this.ctx.lineWidth=2;        this.ctx.beginPath();        this.ctx.arc(x,y,this.r,0,2*Math.PI,true);        this.ctx.closePath();        this.ctx.stroke();    }        //绘制出所有的圆    canvasLock.prototype.createCircle=function(){        var n=this.circleNum;//一行几个圆        var count=0;        this.r=this.canvas.width/(4*n+2);//公式计算出每个圆的半径        this.lastPoint=[];//储存点击过的圆的信息        this.arr=[];//储存所有圆的信息        this.restPoint=[];//储存未被点击的圆的信息        var r=this.r;        for(var i=0;i<n;i++){            for(var j=0;j<n;j++){                count++;                var obj={                    x:(4*j+3)*r,                    y:(4*i+3)*r,                    index:count//给每个圆标记索引                };                this.arr.push(obj);                this.restPoint.push(obj);//初始化时为所有点            }        }        //清屏        this.ctx.clearRect(0,0,this.canvas.width,this.canvas.height);        //以给定坐标点为圆心画出所有圆        for(var i=0;i<this.arr.length;i++){            //循环调用画单个圆的方法            this.drawCircle(this.arr[i].x,this.arr[i].y);        }    }

初始化的时候记得调用

canvasLock.prototype.init=function(){        //动态生成DOM        this.initDom();        //创建画布        this.canvas=document.getElementById("canvas");        this.ctx=this.canvas.getContext("2d");        //绘制出所有的圆        this.createCircle();    }

别忘了在index.html中实例化时传入参数（一行定义几个圆）

new canvasLock({circleNum:3}).init();

效果图

3、canvas事件操作——实现画圆和画线

getPosition方法用来得到鼠标触摸点离canvas的距离（左边和上边）

canvasLock.prototype.getPosition=function(e){        var rect=e.currentTarget.getBoundinGClientRect();//获得canvas距离屏幕的上下左右距离        var po={            //鼠标与视口的左距离 - canvas距离视口的左距离 = 鼠标与canvas的左距离            x:(e.touches[0].clientX-rect.left),            //鼠标与视口的上距离 - canvas距离视口的上距离 = 鼠标距离canvas的上距离            y:(e.touches[0].clientY-rect.top)        };        return po;    }

给canvas添加 touchstart 事件，判断触摸点是否在圆内

触摸点在圆内则允许拖拽，并将该圆添加到 lastPoint 中，从 restPoint 中剔除

this.canvas.addEventListener("touchstart",function(e){            var po=self.getPosition(e);//鼠标距离canvas的距离            //判断是否在圆内            for(var i=0;i<self.arr.lenth;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;//允许拖拽                    self.lastPoint.push(self.arr[i]);//点击过的点                    self.restPoint.splice(i,1);//剩下的点剔除这个被点击的点                    break;                }            }        },false);

判断是否在圆内的原理：

圆心的x轴偏移和鼠标点的x轴偏移的距离的绝对值小于半径

并且

圆心的y轴偏移和鼠标点的y轴偏移的距离的绝对值小于半径

则可以判断鼠标位于圆内

给touchmove绑定事件，在触摸点移动时给点击过的圆画上实心圆，并画线

//触摸点移动时的动画    canvasLock.prototype.update=function(po){        //清屏，canvas动画前必须清空原来的内容        this.ctx.clearRect(0,0,this.canvas.width,this.canvas.height);        //以给定坐标点为圆心画出所有圆        for(var i=0;i<this.arr.length;i++){            this.drawCircle(this.arr[i].x,this.arr[i].y);        }        this.drawPoint();//点击过的圆画实心圆        this.drawLine(po);//画线    }    //画实心圆    canvasLock.prototype.drawPoint=function(){        for(var i=0;i<this.lastPoint.length;i++){            this.ctx.fillStyle="#abcdef";            this.ctx.beginPath();            this.ctx.arc(this.lastPoint[i].x,this.lastPoint[i].y,this.r/2,0,2*Math.PI,true);            this.ctx.closePath();            this.ctx.fill();        }    }    //画线    canvasLock.prototype.drawLine=function(po){        this.ctx.beginPath();        this.lineWidth=3;        this.ctx.moveTo(this.lastPoint[0].x,this.lastPoint[0].y);//线条起点        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);//触摸点        this.ctx.stroke();        this.ctx.closePath();    }

效果图

4、canvas手势链接操作实现

在touchmove中补充当碰到下一个目标圆时的操作

//碰到下一个圆时只需要push到lastPoint当中去        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.lastPoint.push(this.restPoint[i]);//将这个新点击到的点存入lastPoint                this.restPoint.splice(i,1);//从restPoint中剔除这个新点击到的点                break;            }        }

效果图

5、解锁成功与否的判断

//设置密码    canvasLock.prototype.storePass=function(){        if(this.checkPass()){            document.getElementById("title").innerHTML="解锁成功";            this.drawStatusPoint("lightgreen");        }else{            document.getElementById("title").innerHTML="解锁失败";            this.drawStatusPoint("orange");        }    }    //判断输入的密码    canvasLock.prototype.checkPass=function(){        var p1="123",//成功的密码            p2="";        for(var i=0;i<this.lastPoint.length;i++){            p2+=this.lastPoint[i].index;        }        return p1===p2;    }    //绘制判断结束后的状态    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,0,2*Math.PI,true);            this.ctx.closePath();            this.ctx.stroke();        }    }    //程序全部结束后重置    canvasLock.prototype.reset=function(){        this.createCircle();    }

大功告成！！下面晒出所有代码

index.html

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title>手势解锁</title>    <!-- 移动端meta头 -->    <meta name="viewport" content="width=device-width,initial-scale=1.0,user-scalable=no">    <style>           body{background:pink;text-align: center;}    </style></head><body>    <script src="index.js"></script>    <script>        // circleNum:3 表示一行3个圆        new canvasLock({circleNum:3}).init();    </script>  </body></html>

index.js

// 匿名函数自执行(function(){    // canvasLock是全局对象    window.canvasLock=function(obj){        this.width=obj.width;        this.height=obj.height;        this.circleNum=obj.circleNum;    }    //动态生成DOM    canvasLock.prototype.initDom=function(){        //创建一个div        var div=document.createElement("div");        var h5="<h5 id='title' class='title'>绘制解锁图案</h5>";        div.innerHTML=h5;        div.setAttribute("style","position:absolute;top:0;left:0;right:0;bottom:0;");        //创建canvas        var canvas=document.createElement("canvas");        canvas.setAttribute("id","canvas");        //cssText 的本质就是设置 HTML 元素的 style 属性值        canvas.style.cssText="background:pink;display:inine-block;margin-top:15px;";        div.appendChild(canvas);        document.body.appendChild(div);        //设置canvas默认宽高        var width=this.width||300;        var height=this.height||300;        canvas.style.width=width+"px";        canvas.style.height=height+"px";        canvas.width=width;        canvas.height=height;    }    //以给定坐标点为圆心画出单个圆    canvasLock.prototype.drawCircle=function(x,y){        this.ctx.strokeStyle="#abcdef";        this.ctx.lineWidth=2;        this.ctx.beginPath();        this.ctx.arc(x,y,this.r,0,2*Math.PI,true);        this.ctx.closePath();        this.ctx.stroke();    }        //绘制出所有的圆    canvasLock.prototype.createCircle=function(){        var n=this.circleNum;//一行几个圆        var count=0;        this.r=this.canvas.width/(4*n+2);//公式计算出每个圆的半径        this.lastPoint=[];//储存点击过的圆的信息        this.arr=[];//储存所有圆的信息        this.restPoint=[];//储存未被点击的圆的信息        var r=this.r;        for(var i=0;i<n;i++){            for(var j=0;j<n;j++){                count++;                var obj={                    x:(4*j+3)*r,                    y:(4*i+3)*r,                    index:count//给每个圆标记索引                };                this.arr.push(obj);                this.restPoint.push(obj);//初始化时为所有点            }        }        //清屏        this.ctx.clearRect(0,0,this.canvas.width,this.canvas.height);        //以给定坐标点为圆心画出所有圆        for(var i=0;i<this.arr.length;i++){            //循环调用画单个圆的方法            this.drawCircle(this.arr[i].x,this.arr[i].y);        }    }    //添加事件    canvasLock.prototype.bindEvent=function(){        var self=this;        this.canvas.addEventListener("touchstart",function(e){            var po=self.getPosition(e);//鼠标距离canvas的距离            //判断是否在圆内            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;//允许拖拽                    self.lastPoint.push(self.arr[i]);//点击过的点                    self.restPoint.splice(i,1);//剩下的点剔除这个被点击的点                    break;                }            }        },false);        this.canvas.addEventListener("touchmove",function(e){            if(self.touchFlag){                //触摸点移动时的动画                self.update(self.getPosition(e));            }        },false);        //触摸离开时        this.canvas.addEventListener("touchend",function(e){            if(self.touchFlag){                self.storePass(self.lastPoint);                setTimeout(function(){                    self.reset();                },300);            }        },false);    }    //设置密码    canvasLock.prototype.storePass=function(){        if(this.checkPass()){            document.getElementById("title").innerHTML="解锁成功";            this.drawStatusPoint("lightgreen");        }else{            document.getElementById("title").innerHTML="解锁失败";            this.drawStatusPoint("orange");        }    }    //判断输入的密码    canvasLock.prototype.checkPass=function(){        var p1="123",//成功的密码            p2="";        for(var i=0;i<this.lastPoint.length;i++){            p2+=this.lastPoint[i].index;        }        return p1===p2;    }    //绘制判断结束后的状态    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,0,2*Math.PI,true);            this.ctx.closePath();            this.ctx.stroke();        }    }    //程序全部结束后重置    canvasLock.prototype.reset=function(){        this.createCircle();    }        //获取鼠标点击处离canvas的距离    canvasLock.prototype.getPosition=function(e){        var rect=e.currentTarget.getBoundingClientRect();//获得canvas距离屏幕的上下左右距离        var po={            //鼠标与视口的左距离 - canvas距离视口的左距离 = 鼠标与canvas的左距离            x:(e.touches[0].clientX-rect.left),            //鼠标与视口的上距离 - canvas距离视口的上距离 = 鼠标距离canvas的上距离            y:(e.touches[0].clientY-rect.top)        };        return po;    }    //触摸点移动时的动画    canvasLock.prototype.update=function(po){        //清屏，canvas动画前必须清空原来的内容        this.ctx.clearRect(0,0,this.canvas.width,this.canvas.height);        //以给定坐标点为圆心画出所有圆        for(var i=0;i<this.arr.length;i++){            this.drawCircle(this.arr[i].x,this.arr[i].y);        }        // 鼠标每移动一下都会重绘canvas,update操作相当于每一个move事件都会触发        this.drawPoint();//点击过的圆画实心圆        this.drawLine(po);//画线        //碰到下一个圆时只需要push到lastPoint当中去        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.lastPoint.push(this.restPoint[i]);//将这个新点击到的点存入lastPoint                this.restPoint.splice(i,1);//从restPoint中剔除这个新点击到的点                break;            }        }    }    //画实心圆    canvasLock.prototype.drawPoint=function(){        for(var i=0;i<this.lastPoint.length;i++){            this.ctx.fillStyle="#abcdef";            this.ctx.beginPath();            this.ctx.arc(this.lastPoint[i].x,this.lastPoint[i].y,this.r/2,0,2*Math.PI,true);            this.ctx.closePath();            this.ctx.fill();        }    }    //画线    canvasLock.prototype.drawLine=function(po){        this.ctx.beginPath();        this.lineWidth=3;        this.ctx.moveTo(this.lastPoint[0].x,this.lastPoint[0].y);//线条起点        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);//触摸点        this.ctx.stroke();        this.ctx.closePath();    }    //init代表初始化，程序的入口    canvasLock.prototype.init=function(){        //动态生成DOM        this.initDom();        //创建画布        this.canvas=document.getElementById("canvas");        this.ctx=this.canvas.getContext("2d");        //默认不允许拖拽        this.touchFlag=false;        //绘制出所有的圆        this.createCircle();        //添加事件        this.bindEvent();    }})();

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