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今天小編通過(guò)：“如何使用前端中canvas實(shí)現(xiàn)手勢(shì)解鎖？”這個(gè)問(wèn)題來(lái)教大家怎么實(shí)現(xiàn)手勢(shì)解鎖的技能，有想學(xué)其他的實(shí)現(xiàn)方法可以和小編說(shuō)噢！
先放圖：
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>手勢(shì)解鎖</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動(dòng)態(tài)生成canvas標(biāo)簽
// 4、js方式動(dòng)態(tài)生成h4標(biāo)簽和canvas標(biāo)簽
new canvasLock({chooseType:3}).init();
</script>
</body>
</html>index.js：
(function(){
/**
* 實(shí)現(xiàn)畫圓和劃線：
* 1、添加事件touchstart、touchmove、touchend
* 2、touchstart判斷是否點(diǎn)擊的位置處于圓內(nèi)getPosition，處于則初始化
* lastpoint、restPoint
* 3、touchmove做的就是：畫圓drawPoint和畫線drawLine
*
* 實(shí)現(xiàn)自動(dòng)畫圓的效果
* 1、檢測(cè)手勢(shì)移動(dòng)的位置是否處于圓內(nèi)
* 2、圓內(nèi)的話則畫圓 drawPoint
* 3、已經(jīng)畫過(guò)實(shí)心圓的圓，無(wú)需重復(fù)檢測(cè)
*
* 實(shí)現(xiàn)解鎖成功：
* 1、檢測(cè)路徑是否是對(duì)的
* 2、如果是對(duì)的就重置，圓圈變綠
* 3、不對(duì)也重置，圓圈變紅
* 4、重置
*/
window.canvasLock = function(obj){
this.height = obj.height;
this.width = obj.width;
this.chooseType = obj.chooseType;
};
// js方式動(dòng)態(tài)生成dom
canvasLock.prototype.initDom = function(){
var wrap = document.createElement('div');
var str = '<h4 id="title" class="title">繪制解鎖圖案</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);
// 高清屏鎖放
canvas.style.width = width + "px";
canvas.style.height = height + "px";
canvas.width = width;
canvas.height = height;
}
canvasLock.prototype.drawCle = function(x, y) { // 初始化解鎖密碼面板
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() {// 創(chuàng)建解鎖點(diǎn)的坐標(biāo)，根據(jù)canvas的大小來(lái)平均分配半徑
var n = this.chooseType;
var count = 0;
this.r = this.ctx.canvas.width / (2 + 4 * n);// 公式計(jì)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++) {
// 畫圓函數(shù)
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、確定半徑
// 2、確定每一個(gè)圓的中心坐標(biāo)點(diǎn)
// 3、一行3個(gè)圓14個(gè)半徑，一行4個(gè)圓有18個(gè)半徑
this.createCircle();
this.bindEvent();
}
canvasLock.prototype.bindEvent = function(){
var self = this;
this.canvas.addEventListener("touchstart", function (e) {
// 2、touchstart判斷是否點(diǎn)擊的位置處于圓內(nèi)getPosition，處于則初始化
// * lastpoint、restPoint
// po有x和y，并且是相較于canvas邊距
var po = self.getPosition(e);
console.log(po.x)
// 判斷是否在圓內(nèi)的原理：多出來(lái)的這條 x/y < r 在圓內(nèi)
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存放的就是選中的圓圈的x/y坐標(biāo)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：畫圓drawPoint和劃線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) {// 獲取touch點(diǎn)相對(duì)于canvas的坐標(biāo)
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) {// 核心變換方法在touchmove時(shí)候調(diào)用
this.ctx.clearRect(0, 0, this.ctx.canvas.width, this.ctx.canvas.height);
// 重新畫9個(gè)圓圈
for (var i = 0 ; i < this.arr.length ; i++) { // 每幀先把面板畫出來(lái)
this.drawCle(this.arr[i].x, this.arr[i].y);
}
this.drawPoint();// 畫圓
this.drawLine(po);// 畫線
// 1、檢測(cè)手勢(shì)移動(dòng)的位置是否處于下一個(gè)圓內(nèi)
// 2、圓內(nèi)的話則畫圓 drawPoint
// 3、已經(jīng)畫過(guò)實(shí)心圓的圓，無(wú)需重復(fù)檢測(cè)
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) {// 解鎖軌跡
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() { // 初始化圓心
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、檢測(cè)路徑是否是對(duì)的
// 2、如果是對(duì)的就重置，圓圈變綠
// 3、不對(duì)也重置，圓圈變紅
// 4、重置
canvasLock.prototype.storePass = function() {
if (this.checkPass()) {
document.getElementById('title').innerHTML = '解鎖成功';
this.drawStatusPoint('#2CFF26');
}else{
document.getElementById('title').innerHTML = '解鎖失敗';
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();
}
})();總結(jié)
那么以上所述是小編給大家介紹有關(guān)于“如何使用前端中canvas實(shí)現(xiàn)手勢(shì)解鎖？”這方面的相關(guān)內(nèi)容，希望對(duì)大家有所幫助更多的內(nèi)容也可以在W3Cschool網(wǎng)站進(jìn)行學(xué)習(xí)！
