今天小编通过：“如何使用前端中canvas实现手势解锁？”这个问题来教大家怎么实现手势解锁的技能，有想学其他的实现方法可以和小编说噢！
先放图：
demo.html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
<title>手势解锁</title>
<style type="text/css">
body{
text-align: center;
background: #305066;
}
h4{
color: #22C3AA;
}
</style>
</head>
<body>
<script type="text/javascript" src="src/index.js"></script>
<script type="text/javascript">
// 1、生成背景
// 2、title生成
// 3、用js动态生成canvas标签
// 4、js方式动态生成h4标签和canvas标签
new canvasLock({chooseType:3}).init();
</script>
</body>
</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 = '<h4 id="title" class="title">绘制解锁图案</h4>';
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.innerHTML = 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').innerHTML = '解锁成功';
this.drawStatusPoint('#2CFF26');
}else{
document.getElementById('title').innerHTML = '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();
}
})();总结
那么以上所述是小编给大家介绍有关于“如何使用前端中canvas实现手势解锁？”这方面的相关内容，希望对大家有所帮助更多的内容也可以在W3Cschool网站进行学习！
