HTML5 Canvas简简单单实现手机九宫格手势密码解锁

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HTML5 Canvas简简单单实现手机九宫格手势密码解锁

早上花了一个半小时写了一个基于HTML Canvas的手势解锁，主要是为了好玩，可能以后会用到。

思路：根据配置计算出九个点的位置，存入一个数组，当然存入数组的顺序的索引是：

　　　第一行：0 1 2 　　第二行：3 4 5 　　第三行：6 7 8

然后就根据这个坐标数组去绘制九个点

再则我们需要一个保存选中点的数组，每当touchmove事件就判断当前触摸点和那个点的距离小于圆的半径

　　如果为真的话那么就添加进入选中点的数组

　　在绘制过程中就根据该数据去绘制线条。就这么简单

上代码：（需要chrome浏览器或者火狐浏览器模拟手机状态才有触摸效果）

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<!DOCTYPE html> <html> <head lang="en"> <meta content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0" name="viewport"/> <meta charset="UTF-8"> <title></title> <style type="text/css"> html, body { margin: 0; padding: 0; 100%; height: 100%; } </style> <script type="text/javascript"> var R = 26, CW = 400, CH = 320, OffsetX = 30, OffsetY = 30; function CaculateNinePointLotion(diffX, diffY) { var Re = []; for (var row = 0; row < 3; row++) { for (var col = 0; col < 3; col++) { var Point = { X: (OffsetX + col * diffX + ( col * 2 + 1) * R), Y: (OffsetY + row * diffY + (row * 2 + 1) * R) }; Re.push(Point); } } return Re; } var PointLocationArr = []; window.onload = function () { var c = document.getElementById("myCanvas"); CW = document.body.offsetWidth; c.width = CW; c.height = CH; var cxt = c.getContext("2d"); //两个圆之间的外距离就是说两个圆心的距离去除两个半径 var X = (CW - 2 * OffsetX - R * 2 * 3) / 2; var Y = (CH - 2 * OffsetY - R * 2 * 3) / 2; PointLocationArr = CaculateNinePointLotion(X, Y); InitEvent(c, cxt); //CW=2*offsetX+R*2*3+2*X Draw(cxt, PointLocationArr, [],null); } function Draw(cxt, _PointLocationArr, _LinePointArr,touchPoint) { if (_LinePointArr.length > 0) { cxt.beginPath(); for (var i = 0; i < _LinePointArr.length; i++) { var pointIndex = _LinePointArr[i]; cxt.lineTo(_PointLocationArr[pointIndex].X, _PointLocationArr[pointIndex].Y); } cxt.lineWidth = 10; cxt.strokeStyle = "#627eed"; cxt.stroke(); cxt.closePath(); if(touchPoint!=null) { var lastPointIndex=_LinePointArr[_LinePointArr.length-1]; var lastPoint=_PointLocationArr[lastPointIndex]; cxt.beginPath(); cxt.moveTo(lastPoint.X,lastPoint.Y); cxt.lineTo(touchPoint.X,touchPoint.Y); cxt.stroke(); cxt.closePath(); } } for (var i = 0; i < _PointLocationArr.length; i++) { var Point = _PointLocationArr[i]; cxt.fillStyle = "#627eed"; cxt.beginPath(); cxt.arc(Point.X, Point.Y, R, 0, Math.PI * 2, true); cxt.closePath(); cxt.fill(); cxt.fillStyle = "#ffffff"; cxt.beginPath(); cxt.arc(Point.X, Point.Y, R - 3, 0, Math.PI * 2, true); cxt.closePath(); cxt.fill(); if(_LinePointArr.indexOf(i)>=0) { cxt.fillStyle = "#627eed"; cxt.beginPath(); cxt.arc(Point.X, Point.Y, R -16, 0, Math.PI * 2, true); cxt.closePath(); cxt.fill(); } } } function IsPointSelect(touches,LinePoint) { for (var i = 0; i < PointLocationArr.length; i++) { var currentPoint = PointLocationArr[i]; var xdiff = Math.abs(currentPoint.X - touches.pageX); var ydiff = Math.abs(currentPoint.Y - touches.pageY); var dir = Math.pow((xdiff * xdiff + ydiff * ydiff), 0.5); if (dir < R ) { if(LinePoint.indexOf(i) < 0){ LinePoint.push(i);} break; } } } function InitEvent(canvasContainer, cxt) { var LinePoint = []; canvasContainer.addEventListener("touchstart", function (e) { IsPointSelect(e.touches[0],LinePoint); }, false); canvasContainer.addEventListener("touchmove", function (e) { e.preventDefault(); var touches = e.touches[0]; IsPointSelect(touches,LinePoint); cxt.clearRect(0,0,CW,CH); Draw(cxt,PointLocationArr,LinePoint,{X:touches.pageX,Y:touches.pageY}); }, false); canvasContainer.addEventListener("touchend", function (e) { cxt.clearRect(0,0,CW,CH); Draw(cxt,PointLocationArr,LinePoint,null); alert("密码结果是："+LinePoint.join("->")); LinePoint=[]; }, false); } </script> </head> <body> <canvas id="myCanvas"></canvas> </body> </html>
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原文地址：https://www.cnblogs.com/amylis_chen/p/4142588.html