Question

我试图创建一个频谱图，我需要调用自身的函数，但是setTimeOut不接受＆＃34; stream＆＃34;绘图功能需要的参数。这是我的代码（我知道它不完整）。

var yAxis=0;
var n=0;
var canvas = document.getElementById("can");
var ctx = canvas.getContext("2d");
var context = new AudioContext();
navigator.getUserMedia = navigator.getUserMedia || 
navigator.webkitGetUserMedia;
var analyzer = context.createAnalyser();
var node;
var input;

function gra(){

navigator.getUserMedia({ audio: true }, spect,error);
analyzer.fftSize = 1024;
}

function spect (stream) {

node = context.createScriptProcessor(2048, 1, 1);
input = context.createMediaStreamSource(stream);
input.connect(analyzer);
analyzer.connect(node);
node.connect(context.destination);
var frequencyData = new Uint8Array(analyzer.frequencyBinCount);

if (n==2047){

    yAxis=yAxis+1;
    n=0;
    setTimeOut("spect()",10,stream);
} else {
    analyzer.getByteFrequencyData(frequencyData);
    ctx.strokeStyle = frequencyData[n];
    ctx.moveTo(yAxis,n);
    ctx.lineTo(yAxis,n+1);
    ctx.stroke();
    ctx.beginPath();
    n=n+1;  
    setTimeOut("spect()",10, stream);
}



}

function error () {

    alert("The action cannot be completed!")

}

Answer 1

错字。它应该是setTimeout而不是setTimeOut

Answer 2

将函数引用传递给setTimeout而不是字符串

setTimeout(spect, 10, stream);

Answer 3

像这样使用setTimeout：

setTimeout(function(){
  spect(stream)
},10)

或以es6风格）

setTimeout(() => spect(stream),10)

setTimeOut无法将流作为参数传递

3 个答案: