// ==UserScript==
// @license     弗莱克斯
// @name         snow
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  屏保
// @match        *://*/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=tampermonkey.net
// @grant        none
// ==/UserScript==
(function() {
'use strict';
// Your code here...
//创建canvas标签
let snow=document.createElement("canvas");
snow.setAttribute('id','snow');
let maxh = window.innerHeight;
let maxw = window.innerWidth;
//获取图片
//     let nimg=new Image()
//     nimg.src='http://img.netbian.com/file/2021/0304/24f1b123ff78de994241c8822fef48f3.jpg'
//判断动画执行
let flag=1;
snow.style.cssText=`
width: ${maxw}px;
height: ${maxh}px;
position:fixed;
top:0;
left:0;
opacity:1;
background:rgba(19, 15, 64,0.6);
transition:all .5s;
z-index:99999;
`;
const PI = Math.PI
const num = 100;
snow.height = maxh
snow.width = maxw
let ctx = snow.getContext('2d');
//粒子集合
let arr = [];
//页面改变时样式
window.onresize=function(){
ctx.clearRect(0, 0, maxw, maxh)
maxw=window.innerWidth;
maxh=window.innerHeight;
snow.style.cssText=`
width: ${maxw}px;
height: ${maxh}px;
position:fixed;
top:0;
left:0;
opacity:1;
transition:all .3s;
background:rgba(19, 15, 64,0.6);
z-index:99999;
`;
snow.width = maxw;
snow.height = maxh;
}
//粒子类
class snow_point {
constructor(x, y, r) {
this.x = x;
this.y = y;
this.r = r;
this.offset = randomOffset();
this.speed = getRandom(0.4, 0.7);
this.opacity=0.5+Math.random()*0.5;
this.offspeed = getRandom(0.025, 0.1);
}
//绘制
draw() {
this.change()
ctx.save()
ctx.beginPath()
ctx.arc(this.x, this.y, this.r, 0, 2 * PI)
ctx.fillStyle = `rgba(245, 246, 250,${this.opacity})`;
ctx.shadowColor = 'rgba(255, 190, 118,1.0)';
ctx.shadowBlur = 20;
ctx.fill();
ctx.restore();
}
//变化
change() {
this.x += this.offset * this.offspeed
this.y += this.speed
this.r-=0.0005
this.opacity-=0.0005;
this.opacity<0?this.opacity=0:0;
this.r<0?this.r=0:0;
if (this.y > maxh) {
this.y = -20
}
}
}
//横向偏移
function randomOffset() {
let a = Math.sin(Math.random() * PI * 2)
return a
}
//获取两个值直接的随机数
function getRandom(min, max) {
return Math.random() * (max - min) + min
}
//创建粒子
function create() {
for (let i = 0; i < num; i++) {
let a = new snow_point(getRandom(0, maxw), getRandom(-maxh,maxh), getRandom(1.5, 4.5))
arr.push(a)
}
}
//动画
function animate() {
ctx.clearRect(0,0,maxw,maxh)
arr.forEach((item,index,arr) => {
if(item.opacity == 0 || item.r == 0){
arr.splice(index,1);
if(arr.length<200){ //限制最多同屏200个
let a = new snow_point(getRandom(0, maxw), getRandom(-maxh, 0), getRandom(1.5, 4.5))
arr.push(a)
}
}
})
arr.forEach((item,index) => {
item.draw()
})
flag?window.requestAnimationFrame(animate):0
}
create()
animate()
function fn(){
snow.removeEventListener('click',fn)
//透明
snow.style.opacity=0
setTimeout(()=>{
document.body.removeChild(snow)
},300)
flag=0;
}
//再次执行动画
function doAgain(){
if(!flag){
flag=1
//显示
snow.style.opacity=1
animate()
}
}
//切换页面出现
document.onvisibilitychange = function() {
if (document.visibilityState === 'hidden') {
document.body.appendChild(snow)
doAgain()
}else{
if(document.getElementById('snow')){
snow.addEventListener('click',fn)
}
}
}
})();