想用一個(gè)網(wǎng)上現(xiàn)成的canvas效果引入到vue中,不知道為何失效,求大神解答,代碼直接用是可以運(yùn)行的,不知道怎么引到vue中使用
var wave = (function () {
var ctx
var waveImage
var canvasWidth
var canvasHeight
var needAnimate = false
function init (callback) {
var wave = document.getElementById('wave')
var canvas = document.createElement('canvas')
if (!canvas.getContext) return
ctx = canvas.getContext('2d')
canvasWidth = 200
canvasHeight = 200
canvas.setAttribute('width', canvasWidth)
canvas.setAttribute('height', canvasHeight)
wave.appendChild(canvas)
waveImage = new Image()
waveImage.onload = function () {
waveImage.onload = null
callback()
}
waveImage.src = '../images/wave.png'
}
function animate () {
var waveX = 0
var waveY = 0
var waveXmin = -203
var waveYmax = canvasHeight * 0.7
var requestAnimationFrame =
window.requestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function (callback) { window.setTimeout(callback, 1000 / 60) }
function loop () {
ctx.clearRect(0, 0, canvasWidth, canvasHeight)
if (!needAnimate) return
if (waveY < waveXmin) waveY += 1.5
if (waveX < waveYmax) waveX = 0; else waveX -= 3
ctx.globalCompositeOperation = 'source-over'
ctx.beginPath()
ctx.arc(canvasWidth / 2, canvasHeight / 2, canvasHeight / 2, 0, Math.PI * 2, true)
ctx.closePath()
ctx.fill()
ctx.globalCompositeOperation = 'source-in'
ctx.drawImage(waveImage, waveX, canvasHeight - waveY)
requestAnimationFrame(loop)
}
loop()
}
function start () {
if (!ctx) return init(start)
needAnimate = true
setTimeout(function () {
if (needAnimate) animate()
}, 500)
}
function stop () {
needAnimate = false
}
return {start: start, stop: stop}
}())
export default wave
這是JS代碼
<div id="wave" class="wave"><span>60%</span></div>
.wave{width:200px;height:200px;overflow:hidden;border-radius:50%;background:rgba(255,203,103,.6);margin:100px auto;position:relative;text-align:center;display:table-cell;vertical-align:middle;}
.wave span{display:inline-block;color:#fff;font-size:20px;position:relative;z-index:2;}
.wave canvas{position:absolute;left:0;top:0;z-index:1;}
這是HTML
import wave from '../assets/js/circle'
export default {
name: 'home',
created: function () {
wave.start()
},
}
沒有報(bào)錯(cuò),但是效果就是不出來(lái),這是引用,麻煩可以告訴我什么問(wèn)題嗎?但我把mounted改成created的時(shí)候會(huì)報(bào)Cannot read property 'appendChild' of null",謝謝各位大佬啦
但我把mounted改成created的時(shí)候會(huì)報(bào)Cannot read property 'appendChild' of null"
這是因?yàn)閏reated的時(shí)候,Dom節(jié)點(diǎn)還沒有渲染出來(lái)到頁(yè)面上,這個(gè)時(shí)候是找不到id=wave的DIV的。
改成Vue的插件
import wavePng from './wave.png'
export default {
install(Vue){
Vue.directive('wave', {
inserted: function(el){
start(el)
}
})
}
}
var ctx;
var waveImage;
var canvasWidth;
var canvasHeight;
var needAnimate = false;
function init (callback, wave) {
// var wave = document.getElementById('wave');
var canvas = document.createElement('canvas');
if (!canvas.getContext) return;
ctx = canvas.getContext('2d');
canvasWidth = wave.offsetWidth;
canvasHeight = wave.offsetHeight;
canvas.setAttribute('width', canvasWidth);
canvas.setAttribute('height', canvasHeight);
wave.appendChild(canvas);
waveImage = new Image();
waveImage.onload = function () {
console.log('000')
waveImage.onload = null;
callback(wave);
}
waveImage.src = wavePng;
}
function animate () {
var waveX = 0;
var waveY = 0;
var waveX_min = -203;
var waveY_max = canvasHeight * 0.7;
var requestAnimationFrame =
window.requestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function (callback) { window.setTimeout(callback, 1000 / 60); };
function loop () {
ctx.clearRect(0, 0, canvasWidth, canvasHeight);
if (!needAnimate) return;
if (waveY < waveY_max) waveY += 1.5;
if (waveX < waveX_min) waveX = 0; else waveX -= 3;
ctx.globalCompositeOperation = 'source-over';
ctx.beginPath();
ctx.arc(canvasWidth/2, canvasHeight/2, canvasHeight/2, 0, Math.PI*2, true);
ctx.closePath();
ctx.fill();
ctx.globalCompositeOperation = 'source-in';
ctx.drawImage(waveImage, waveX, canvasHeight - waveY);
requestAnimationFrame(loop);
}
loop();
}
function start (el) {
console.log(1)
if (!ctx) return init(start, el);
needAnimate = true;
setTimeout(function () {
if (needAnimate) animate();
}, 500);
}
function stop () {
needAnimate = false;
}
上述的代碼,把原先插件的閉包去掉了,因?yàn)檫@個(gè)改成vue的插件webpack打包完本身就是一個(gè)閉包了。
然后使用的話,就用指令的形式
<template>
<div id="wave" class="wave" v-wave><span>60%</span></div>
</template>
<script>
import wave from './a'
export default {
}
</script>
<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
.wave{width:200px;height:200px;overflow:hidden;border-radius:50%;background:rgba(255,203,103,.6);margin:100px auto;position:relative;text-align:center;display:table-cell;vertical-align:middle;}
.wave span{display:inline-block;color:#fff;font-size:20px;position:relative;z-index:2;}
.wave canvas{position:absolute;left:0;top:0;z-index:1;}
</style>
main.js
import Vue from 'vue'
import App from './App'
import router from './router'
import wave from './components/a'
Vue.config.productionTip = false
Vue.use(wave)
/* eslint-disable no-new */
new Vue({
el: '#app',
router,
components: { App },
template: '<App/>'
})
這樣就可以了。
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