原文: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）
<!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;
width: 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>