先看一下效果：
代码奉上：
<template>
<canvas id="canvas" />
</template>
<script>
export default {
name: "BackCanvas",
props: {
height: {
type: Number,
default: 500
}
},
data() {
return {
settings: {
COL_WIDTH: 15,
COL_HEIGHT: 15,
// 速度参数 最小值:4 - 最大值:8
VELOCITY_PARAMS: {
min: 3,
max: 8
},
// 代码长度参数 最小值 20 - 最大值 40
CODE_LENGTH_PARAMS: {
min: 20,
max: 40
}
},
animation: null,
c: null,
ctx: null,
lineC: null,
ctx2: null,
WIDTH: window.innerWidth,
HEIGHT: window.innerHeight,
COLUMNS: null,
canvii: [],
// font from here https://www.dafont.com/matrix-code-nfi.font
font: '24px matrix-code',
letters: ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'this', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '$', '+', '-', '*', '/', '=', '%', '"', '\'', '#', '&', '_', '(', ')', ',', '.', ';', ':', '?', '!', '\\', '|', '{', '}', '<', '>', '[', ']', '^', '~'],
codes: [],
createCodeLoop: null,
codesCounter: 0
}
},
mounted() {
this.init();
},
methods: {
init () {
this.c = document.getElementById( 'canvas' );
this.ctx = this.c.getContext( '2d' );
this.c.width = this.WIDTH;
this.c.height = this.HEIGHT;
this.ctx.shadowBlur = 0;
this.ctx.fillStyle = '#000';
this.ctx.fillRect(0, 0, this.WIDTH, this.HEIGHT);
this.ctx.font = this.font;
this.COLUMNS = Math.ceil(this.WIDTH / this.settings.COL_WIDTH);
for (let i = 0; i < this.COLUMNS; i++) {
this.codes[i] = [];
this.codes[i][0] = {
'open': true,
'position': {'x': 0, 'y': 0},
'strength': 0
};
}
this.loop();
this.createLines();
this.createCode();
window.onresize = function () {
window.cancelAnimationFrame(this.animation);
this.animation = null;
this.ctx.clearRect(0, 0, this.WIDTH, this.HEIGHT);
this.codesCounter = 0;
this.ctx2.clearRect(0, 0, this.WIDTH, this.HEIGHT);
this.WIDTH = window.innerWidth;
this.HEIGHT = window.innerHeight;
this.init();
};
},
loop () {
this.animation = requestAnimationFrame( () => { this.loop(); } );
this.draw();
},
draw () {
let velocity, height, x, y, c, ctx;
// slow fade BG colour
this.ctx.shadowColor = 'rgba(0, 0, 0, 0.5)';
this.ctx.fillStyle = 'rgba(0, 0, 0, 0.5)';
this.ctx.fillRect(0, 0, this.WIDTH, this.HEIGHT);
this.ctx.globalCompositeOperation = 'source-over';
for (let i = 0; i < this.COLUMNS; i++) {
if (this.codes[i][0].canvas) {
velocity = this.codes[i][0].velocity;
height = this.codes[i][0].canvas.height;
x = this.codes[i][0].position.x;
y = this.codes[i][0].position.y - height;
c = this.codes[i][0].canvas;
ctx = c.getContext('2d');
this.ctx.drawImage(c, x, y, this.settings.COL_WIDTH, height);
if ((this.codes[i][0].position.y - height) < this.HEIGHT){
this.codes[i][0].position.y += velocity;
} else {
this.codes[i][0].position.y = 0;
}
}
}
},
createCode () {
if (this.codesCounter > this.COLUMNS) {
clearTimeout(this.createCodeLoop);
return;
}
let randomInterval = this.randomFromInterval(0, 100);
let column = this.assignColumn();
if (column) {
let codeLength = this.randomFromInterval(this.settings.CODE_LENGTH_PARAMS.min, this.settings.CODE_LENGTH_PARAMS.max);
let codeVelocity = (Math.random() * (this.settings.VELOCITY_PARAMS.max - this.settings.VELOCITY_PARAMS.min)) + this.settings.VELOCITY_PARAMS.min;
let lettersLength = this.letters.length;
this.codes[column][0].position = {'x': (column * this.settings.COL_WIDTH), 'y': 0};
this.codes[column][0].velocity = codeVelocity;
this.codes[column][0].strength = this.codes[column][0].velocity / this.settings.VELOCITY_PARAMS.max;
for (let i = 1; i <= codeLength; i++) {
let newLetter = this.randomFromInterval(0, (lettersLength - 1));
this.codes[column][i] = this.letters[newLetter];
}
this.createCanvii(column);
this.codesCounter++;
}
this.createCodeLoop = setTimeout(this.createCode, randomInterval);
},
createCanvii (i) {
let codeLen = this.codes[i].length - 1;
let canvHeight = codeLen * this.settings.COL_HEIGHT;
let velocity = this.codes[i][0].velocity;
let strength = this.codes[i][0].strength;
let text, fadeStrength;
let newCanv = document.createElement('canvas');
let newCtx = newCanv.getContext('2d');
newCanv.width = this.settings.COL_WIDTH;
newCanv.height = canvHeight;
for (let j = 1; j < codeLen; j++) {
text = this.codes[i][j];
newCtx.globalCompositeOperation = 'source-over';
newCtx.font = '24px matrix-code';
if (j < 5) {
newCtx.shadowColor = 'hsl(104, 79%, 74%)';
newCtx.shadowOffsetX = 0;
newCtx.shadowOffsetY = 0;
// 设置模糊程度
newCtx.shadowBlur = 6;
newCtx.fillStyle = 'hsla(104, 79%, ' + (100 - (j * 5)) + '%, ' + strength + ')';
} else if (j > (codeLen - 4)) {
fadeStrength = j / codeLen;
fadeStrength = 1 - fadeStrength;
newCtx.shadowOffsetX = 0;
newCtx.shadowOffsetY = 0;
newCtx.shadowBlur = 0;
newCtx.fillStyle = 'hsla(104, 79%, 74%, ' + (fadeStrength + 0.3) + ')';
} else {
newCtx.shadowOffsetX = 0;
newCtx.shadowOffsetY = 0;
newCtx.shadowBlur = 0;
newCtx.fillStyle = 'hsla(104, 79%, 74%, ' + strength + ')';
}
newCtx.fillText(text, 0, (canvHeight - (j * this.settings.COL_HEIGHT)));
}
this.codes[i][0].canvas = newCanv;
},
createLines () {
this.linesC = document.createElement('canvas');
this.linesC.width = this.WIDTH;
this.linesC.height = this.HEIGHT;
this.linesC.style.position = 'fixed';
this.linesC.style.top = 0;
this.linesC.style.left = 0;
this.linesC.style.zIndex = 10;
document.body.appendChild(this.linesC);
let linesYBlack = 0;
let linesYWhite = 0;
this.ctx2 = this.linesC.getContext('2d');
this.ctx2.beginPath();
this.ctx2.lineWidth = 1;
this.ctx2.strokeStyle = 'rgba(0, 0, 0, 0.7)';
while (linesYBlack < this.HEIGHT) {
this.ctx2.moveTo(0, linesYBlack);
this.ctx2.lineTo(this.WIDTH, linesYBlack);
linesYBlack += 5;
}
this.ctx2.lineWidth = 0.15;
this.ctx2.strokeStyle = 'rgba(255, 255, 255, 0)';
while (linesYWhite < this.HEIGHT) {
this.ctx2.moveTo(0, linesYWhite+1);
this.ctx2.lineTo(this.WIDTH, linesYWhite+1);
linesYWhite += 5;
}
this.ctx2.stroke();
},
assignColumn () {
let randomColumn = this.randomFromInterval(0, (this.COLUMNS - 1));
if (this.codes[randomColumn][0].open) {
this.codes[randomColumn][0].open = false;
} else {
return false;
}
return randomColumn;
},
randomFromInterval (from, to) {
return Math.floor(Math.random() * (to - from+ 1 ) + from);
}
}
}
</script>
<style scoped>
/** 让这个背景固定在页面不随着滚动而滚动 */
#canvas {
position: fixed;
top: 0;
left: 0;
}
</style>
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