前言：馬上過年了，我打算在后臺里面偷偷地埋個新春祝福+放煙花的彩蛋。項目是基于react+typescript的，因此最后封裝成了一個組件，設置好開啟時間就可以顯示了。
目錄結構
目錄結構大致如下
我們將煙花分為兩個階段，一個是未炸開持續上升時期，另一個是炸開后分散的時期。
其中Vector表示一個坐標，Particle表示一個煙花的亮點，Firewor表示煙花未炸開時持續上升的亮點。index.tsx就是組件了，繪制了canvas，并執行了動畫。
Vector
這個坐標就很簡單，后面涉及到位置的變更都可以使用它的add方法進行偏移操作
export default class Vector {
constructor(public x: number, public y: number) {}
add(vec2: {x: number; y: number}) {
this.x = this.x + vec2.x;
this.y = this.y + vec2.y;
}
}
Particle
初始創建的時候給個坐標，后續每次更新的時候控制y坐標下落，gravity變量就是下落的值。timeSpan用于控制煙花展示的時長
import Vector from './Vector';
export default class Particle {
pos: Vector = null;
vel: {x: number; y: number} = null;
dead: boolean = false;
start: number = 0;
ctx: CanvasRenderingContext2D = null;
constructor(pos: {x: number; y: number}, vel: {x: number; y: number}, ctx: CanvasRenderingContext2D) {
this.pos = new Vector(pos.x, pos.y);
this.vel = vel;
this.dead = false;
this.start = 0;
this.ctx = ctx;
}
update(time: number, gravity: number) {
let timeSpan = time - this.start;
if (timeSpan > 500) {
this.dead = true;
}
if (!this.dead) {
this.pos.add(this.vel);
this.vel.y = this.vel.y + gravity;
}
}
draw() {
if (!this.dead) {
this.drawDot(this.pos.x, this.pos.y, Math.random() > 0.5 ? 1 : 2);
}
}
drawDot(x: number, y: number, size: number) {
this.ctx.beginPath();
this.ctx.arc(x, y, size, 0, Math.PI * 2);
this.ctx.fill();
this.ctx.closePath();
}
}
Firework
生成隨機的hsl顏色，hsl(' + rndNum(360) + ', 100%, 60%);Firework每次上升的距離是一個遞減的過程，我們初始設置一個上升的距離，之后每次繪制的時候，這個距離減gravity，當距離小于零的時候，說明該出現煙花綻放的動畫了。
import Vector from './Vector';
import Particle from './Particle';
let rnd = Math.random;
function rndNum(num: number) {
return rnd() * num + 1;
}
export default class Firework {
pos: Vector = null;
vel: Vector = null;
color: string = null;
size: number = 0;
dead: boolean = false;
start: number = 0;
ctx: CanvasRenderingContext2D = null;
gravity: number = null;
exParticles: Particle[] = [];
exPLen: number = 100;
rootShow: boolean = true;
constructor(x: number, y: number, gravity: number, ctx: CanvasRenderingContext2D) {
this.pos = new Vector(x, y);
this.vel = new Vector(0, -rndNum(10) - 3);
this.color = 'hsl(' + rndNum(360) + ', 100%, 60%)';
this.size = 4;
this.dead = false;
this.start = 0;
this.ctx = ctx;
this.gravity = gravity;
}
update(time: number, gravity: number) {
if (this.dead) {
return;
}
this.rootShow = this.vel.y < 0;
if (this.rootShow) {
this.pos.add(this.vel);
this.vel.y = this.vel.y + gravity;
} else {
if (this.exParticles.length === 0) {
for (let i = 0; i < this.exPLen; i++) {
let randomR = rndNum(5);
let randomX = -rndNum(Math.abs(randomR) * 2) + Math.abs(randomR);
let randomY =
Math.sqrt(Math.abs(Math.pow(randomR, 2) - Math.pow(randomX, 2))) *
(Math.random() > 0.5 ? 1 : -1);
this.exParticles.push(new Particle(this.pos, new Vector(randomX, randomY), this.ctx));
this.exParticles[this.exParticles.length - 1].start = time;
}
}
let numOfDead = 0;
for (let i = 0; i < this.exPLen; i++) {
let p = this.exParticles[i];
p.update(time, this.gravity);
if (p.dead) {
numOfDead++;
}
}
if (numOfDead === this.exPLen) {
this.dead = true;
}
}
}
draw() {
if (this.dead) {
return;
}
this.ctx.fillStyle = this.color;
if (this.rootShow) {
this.drawDot(this.pos.x, this.pos.y, this.size);
} else {
for (let i = 0; i < this.exPLen; i++) {
let p = this.exParticles[i];
p.draw();
}
}
}
drawDot(x: number, y: number, size: number) {
this.ctx.beginPath();
this.ctx.arc(x, y, size, 0, Math.PI * 2);
this.ctx.fill();
this.ctx.closePath();
}
}
FireworkComponent
組件本身就很簡單了，生成和繪制Firework。我們在這里面可以額外加一些文字
import React from 'react';
import Firework from './Firework';
import {autobind} from 'core-decorators';
let rnd = Math.random;
function rndNum(num: number) {
return rnd() * num + 1;
}
interface PropTypes {
onClick?: () => void;
}
@autobind
class FireworkComponent extends React.Component<PropTypes> {
canvas: HTMLCanvasElement = null;
ctx: CanvasRenderingContext2D = null;
snapTime: number = 0;
fireworks: Firework[] = [];
gravity: number = 0.1;
componentDidMount() {
this.canvas = document.querySelector('#fireworks');
this.canvas.width = window.innerWidth;
this.canvas.height = window.innerHeight;
this.ctx = this.canvas.getContext('2d');
this.init();
this.draw();
}
init() {
let numOfFireworks = 20;
for (let i = 0; i < numOfFireworks; i++) {
this.fireworks.push(new Firework(rndNum(this.canvas.width), this.canvas.height, this.gravity, this.ctx));
}
}
update(time: number) {
for (let i = 0, len = this.fireworks.length; i < len; i++) {
let p = this.fireworks[i];
p.update(time, this.gravity);
}
}
draw(time?: number) {
this.update(time);
this.ctx.fillStyle = 'rgba(0,0,0,0.3)';
this.ctx.fillStyle = 'rgba(0,0,0,0)';
this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
this.ctx.font = 'bold 30px cursive';
this.ctx.fillStyle = '#e91818';
let text = 'XX項目組給您拜個早年！';
let textWidth = this.ctx.measureText(text);
this.ctx.fillText(text, this.canvas.width / 2 - textWidth.width / 2, 200);
text = '在新年來臨之際，祝您：';
textWidth = this.ctx.measureText(text);
this.ctx.fillText(text, this.canvas.width / 2 - textWidth.width / 2, 260);
text = '工作順利，新春快樂!';
this.ctx.font = 'bold 48px STCaiyun';
this.ctx.fillStyle = 'orangered';
textWidth = this.ctx.measureText(text);
this.ctx.fillText(text, this.canvas.width / 2 - textWidth.width / 2, 340);
this.ctx.fillStyle = 'gray';
this.ctx.font = '18px Arial';
text = '點擊任意處關閉';
textWidth = this.ctx.measureText(text);
this.ctx.fillText(text, this.canvas.width - 20 - textWidth.width, 60);
this.snapTime = time;
this.ctx.fillStyle = 'blue';
for (let i = 0, len = this.fireworks.length; i < len; i++) {
let p = this.fireworks[i];
if (p.dead) {
p = this.fireworks[i] = new Firework(
rndNum(this.canvas.width),
this.canvas.height,
this.gravity,
this.ctx
);
p.start = time;
}
p.draw();
}
window.requestAnimationFrame(this.draw);
}
render() {
return (
<canvas
id="fireworks"
onClick={this.props.onClick}
style={{position: 'fixed', zIndex: 99, background: 'rgba(0,0,0, 0.8)'}}
width="400"
height="400"></canvas>
);
}
}
export default FireworkComponent;
大致效果
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持腳本之家。
