2022将至，前端程序员们应该一起放个烟花庆祝一下，走起
作者：互联网
前言：小时候，在我印象中，每到快过年的时候就有很多卖炮仗的，一般也就是阳历的12月份到明年的正月15号卖炮仗的商家比较多，省下买辣条的钱去买炮仗，在老家也就过年和除夕两天及正月15日这几天放烟花和炮仗比较猛，现在年纪大了，听不得炮仗那种噪声了，也考虑到环保，工作之后的程序员以代码的形式演绎一下烟花的效果。
目录
效果图
首先我们下看一段小视频
<iframe allowfullscreen="true" data-mediaembed="bilibili" id="4ahlGM15-1642087155466" src="https://player.bilibili.com/player.html?aid=423136333"></iframe>前端程序员自制春节元宵烟花
项目结构
一个网页+两个配图
html
引入两个背景图片衬托一下，先写几段话用于在播放烟花的字幕，可以根据自己的兴趣随意添加，直接复制粘帖修改文字即可。
<canvas id='cas' style="background-color:rgba(0,5,24,1)">浏览器不支持canvas</canvas>
<div class="city"><img src="city.png" alt="" /></div>
<img src="moon.png" alt="" id="moon" style="visibility: hidden;"/>
<div style="display:none">
<div class="shape">孙叫兽祝大家</div>
<div class="shape">2022年</div>
<div class="shape">新年快乐</div>
<div class="shape">财富自由</div>
<div class="shape">合家幸福</div>
<div class="shape">万事如意</div>
<div class="shape">心想事成</div>
<div class="shape">财源广进</div>
</div>javascript
主要控制文字显示的位置，文字及烟花出现的频率。
var canvas = document.getElementById("cas");
var ocas = document.createElement("canvas");
var octx = ocas.getContext("2d");
var ctx = canvas.getContext("2d");
ocas.width = canvas.width = window.innerWidth;
ocas.height = canvas.height = window.innerHeight;
var bigbooms = [];
window.onload = function(){
initAnimate()
}
function initAnimate(){
drawBg();
lastTime = new Date();
animate();
}
var lastTime;
function animate(){
ctx.save();
ctx.fillStyle = "rgba(0,5,24,0.1)";
ctx.fillRect(0,0,canvas.width,canvas.height);
ctx.restore();
var newTime = new Date();
if(newTime-lastTime>500+(window.innerHeight-767)/2){
var random = Math.random()*100>2?true:false;
var x = getRandom(canvas.width/5 , canvas.width*4/5);
var y = getRandom(50 , 200);
if(random){
var bigboom = new Boom(getRandom(canvas.width/3,canvas.width*2/3) ,2,"#FFF" , {x:x , y:y});
bigbooms.push(bigboom)
}
else {
var bigboom = new Boom(getRandom(canvas.width/3,canvas.width*2/3) ,2,"#FFF" , {x:canvas.width/2 , y:200} , document.querySelectorAll(".shape")[parseInt(getRandom(0, document.querySelectorAll(".shape").length))]);
bigbooms.push(bigboom)
}
lastTime = newTime;
console.log(bigbooms)
}
stars.foreach(function(){
this.paint();
})
drawMoon();
bigbooms.foreach(function(index){
var that = this;
if(!this.dead){
this._move();
this._drawLight();
}
else{
this.booms.foreach(function(index){
if(!this.dead) {
this.moveTo(index);
}
else if(index === that.booms.length-1){
bigbooms[bigbooms.indexOf(that)] = null;
}
})
}
});
raf(animate);
}
function drawMoon(){
var moon = document.getElementById("moon");
var centerX = canvas.width-200 , centerY = 100 , width = 80;
if(moon.complete){
ctx.drawImage(moon , centerX , centerY , width , width )
}
else {
moon.onload = function(){
ctx.drawImage(moon ,centerX , centerY , width , width)
}
}
var index = 0;
for(var i=0;i<10;i++){
ctx.save();
ctx.beginPath();
ctx.arc(centerX+width/2 , centerY+width/2 , width/2+index , 0 , 2*Math.PI);
ctx.fillStyle="rgba(240,219,120,0.005)";
index+=2;
ctx.fill();
ctx.restore();
}
}
Array.prototype.foreach = function(callback){
for(var i=0;i<this.length;i++){
if(this[i]!==null) callback.apply(this[i] , [i])
}
}
var raf = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function (callback) { window.setTimeout(callback, 1000 / 60); };
canvas.onclick = function(){
var x = event.clientX;
var y = event.clientY;
var bigboom = new Boom(getRandom(canvas.width/3,canvas.width*2/3) ,2,"#FFF" , {x:x , y:y});
bigbooms.push(bigboom)
}
// canvas.addEventLisener("touchstart" , function(event){
// var touch = event.targetTouches[0];
// var x = event.pageX;
// var y = event.pageY;
// var bigboom = new Boom(getRandom(canvas.width/3,canvas.width*2/3) ,2,"#FFF" , {x:x , y:y});
// bigbooms.push(bigboom)
// })
var Boom = function(x,r,c,boomArea,shape){
this.booms = [];
this.x = x;
this.y = (canvas.height+r);
this.r = r;
this.c = c;
this.shape = shape || false;
this.boomArea = boomArea;
this.theta = 0;
this.dead = false;
this.ba = parseInt(getRandom(80 , 100));
}
Boom.prototype = {
_paint:function(){
ctx.save();
ctx.beginPath();
ctx.arc(this.x,this.y,this.r,0,2*Math.PI);
ctx.fillStyle = this.c;
ctx.fill();
ctx.restore();
},
_move:function(){
var dx = this.boomArea.x - this.x , dy = this.boomArea.y - this.y;
this.x = this.x+dx*0.01;
this.y = this.y+dy*0.01;
if(Math.abs(dx)<=this.ba && Math.abs(dy)<=this.ba){
if(this.shape){
this._shapBoom();
}
else this._boom();
this.dead = true;
}
else {
this._paint();
}
},
_drawLight:function(){
ctx.save();
ctx.fillStyle = "rgba(255,228,150,0.3)";
ctx.beginPath();
ctx.arc(this.x , this.y , this.r+3*Math.random()+1 , 0 , 2*Math.PI);
ctx.fill();
ctx.restore();
},
_boom:function(){
var fragNum = getRandom(30 , 200);
var style = getRandom(0,10)>=5? 1 : 2;
var color;
if(style===1){
color = {
a:parseInt(getRandom(128,255)),
b:parseInt(getRandom(128,255)),
c:parseInt(getRandom(128,255))
}
}
var fanwei = parseInt(getRandom(300, 400));
for(var i=0;i<fragNum;i++){
if(style===2){
color = {
a:parseInt(getRandom(128,255)),
b:parseInt(getRandom(128,255)),
c:parseInt(getRandom(128,255))
}
}
var a = getRandom(-Math.PI, Math.PI);
var x = getRandom(0, fanwei) * Math.cos(a) + this.x;
var y = getRandom(0, fanwei) * Math.sin(a) + this.y;
var radius = getRandom(0 , 2)
var frag = new Frag(this.x , this.y , radius , color , x , y );
this.booms.push(frag);
}
},
_shapBoom:function(){
var that = this;
putValue(ocas , octx , this.shape , 5, function(dots){
var dx = canvas.width/2-that.x;
var dy = canvas.height/2-that.y;
for(var i=0;i<dots.length;i++){
color = {a:dots[i].a,b:dots[i].b,c:dots[i].c}
var x = dots[i].x;
var y = dots[i].y;
var radius = 1;
var frag = new Frag(that.x , that.y , radius , color , x-dx , y-dy);
that.booms.push(frag);
}
})
}
}
function putValue(canvas , context , ele , dr , callback){
context.clearRect(0,0,canvas.width,canvas.height);
var img = new Image();
if(ele.innerHTML.indexOf("img")>=0){
img.src = ele.getElementsByTagName("img")[0].src;
imgload(img , function(){
context.drawImage(img , canvas.width/2 - img.width/2 , canvas.height/2 - img.width/2);
dots = getimgData(canvas , context , dr);
callback(dots);
})
}
else {
var text = ele.innerHTML;
context.save();
var fontSize =200;
context.font = fontSize+"px 宋体 bold";
context.textAlign = "center";
context.textBaseline = "middle";
context.fillStyle = "rgba("+parseInt(getRandom(128,255))+","+parseInt(getRandom(128,255))+","+parseInt(getRandom(128,255))+" , 1)";
context.fillText(text , canvas.width/2 , canvas.height/2);
context.restore();
dots = getimgData(canvas , context , dr);
callback(dots);
}
}
function imgload(img , callback){
if(img.complete){
callback.call(img);
}
else {
img.onload = function(){
callback.call(this);
}
}
}
function getimgData(canvas , context , dr){
var imgData = context.getImageData(0,0,canvas.width , canvas.height);
context.clearRect(0,0,canvas.width , canvas.height);
var dots = [];
for(var x=0;x<imgData.width;x+=dr){
for(var y=0;y<imgData.height;y+=dr){
var i = (y*imgData.width + x)*4;
if(imgData.data[i+3] > 128){
var dot = {x:x , y:y , a:imgData.data[i] , b:imgData.data[i+1] , c:imgData.data[i+2]};
dots.push(dot);
}
}
}
return dots;
}
function getRandom(a , b){
return Math.random()*(b-a)+a;
}
var maxRadius = 1 , stars=[];
function drawBg(){
for(var i=0;i<100;i++){
var r = Math.random()*maxRadius;
var x = Math.random()*canvas.width;
var y = Math.random()*2*canvas.height - canvas.height;
var star = new Star(x , y , r);
stars.push(star);
star.paint()
}
}
var Star = function(x,y,r){
this.x = x;this.y=y;this.r=r;
}
Star.prototype = {
paint:function(){
ctx.save();
ctx.beginPath();
ctx.arc(this.x , this.y , this.r , 0 , 2*Math.PI);
ctx.fillStyle = "rgba(255,255,255,"+this.r+")";
ctx.fill();
ctx.restore();
}
}
var focallength = 250;
var Frag = function(centerX , centerY , radius , color ,tx , ty){
this.tx = tx;
this.ty = ty;
this.x = centerX;
this.y = centerY;
this.dead = false;
this.centerX = centerX;
this.centerY = centerY;
this.radius = radius;
this.color = color;
}
Frag.prototype = {
paint:function(){
ctx.save();
ctx.beginPath();
ctx.arc(this.x , this.y , this.radius , 0 , 2*Math.PI);
ctx.fillStyle = "rgba("+this.color.a+","+this.color.b+","+this.color.c+",1)";
ctx.fill()
ctx.restore();
},
moveTo:function(index){
this.ty = this.ty+0.3;
var dx = this.tx - this.x , dy = this.ty - this.y;
this.x = Math.abs(dx)<0.1 ? this.tx : (this.x+dx*0.1);
this.y = Math.abs(dy)<0.1 ? this.ty : (this.y+dy*0.1);
if(dx===0 && Math.abs(dy)<=80){
this.dead = true;
}
this.paint();
}
}完整代码及必要的配图
好啦，本期内容就分享到这里，我们下期见！
标签：function,canvas,context,width,getRandom,程序员,放个,2022,var 来源： https://blog.csdn.net/weixin_41937552/article/details/122484504