Question

我正在围绕scriptProcessorNode振荡器构建类。我已将onaudioprocess事件处理程序包装在函数Gendy.prototype.process中。我可以从这个包装器函数中访问全局变量和函数，但是不能从onaudioprocess函数中访问它们。

我设计了一个解决属性的方法，在包装函数中重新定义它们，但是当尝试使用this.walk()调用另一个方法，随机游走方法时，这不起作用。

这是我的代码：

Gendy.prototype.process = function(){
    var point = 0;
    var index = 0;
    var y = 0;
    var breakpoint = this.breakpoint;
    var freq = this.freq;

    var walk = this.walk();

    this.scriptNode.onaudioprocess = function(audioProcessingEvent){

        var outputBuffer = audioProcessingEvent.outputBuffer;
        var outputData = outputBuffer.getChannelData(0);

        for(var j = 0; j < outputData.length;j++){
            // linearly interpolate between the new breakpoint positions
            // get the interp point by comparing index to the x distance
            var lerp = (index - breakpoint[point].x) / (breakpoint[point+1].x - breakpoint[point].x);

            y = lerp * (breakpoint[point+1].y - breakpoint[point].y) + breakpoint[point].y;
            if(point < breakpoint.length && index >= breakpoint[point+1].x) {
                point++;
            }

            outputData[j] = y;
            index+=freq; 
            if(index >= breakpoint[breakpoint.length-1].x){
                index = 0;
                point = 0;
                walk(); 
            }  
        }
    }

}

这会产生声音，但会返回错误：

Uncaught TypeError: walk is not a function

几行，然后

Uncaught TypeError: undefined is not a function

永远。

这是scriptProcessorNode的错误吗？任何见解都将不胜感激！

Answer 1

scriptProcessorNode中没有错误，问题是以下行：

this.scriptNode.onaudioprocess = function(audioProcessingEvent){

this内的onaudioprocess变量默认情况下会引用this.scriptNode对象，您可以通过以下两种方式之一处理它：

使用bind（正如您在答案中所做的那样）：

this.scriptNode.onaudioprocess = function(audioProcessingEvent){
    ...
}.bind(this)

使用局部变量来保存this的值，并使用该局部变量代替this：

var self = this;
this.scriptNode.onaudioprocess = function(audioProcessingEvent){
    ...

Answer 2

通过将this附加到onaudioprocess功能，我可以从.bind(this)功能中访问Gendy.prototype.process = function(){ this.scriptNode.onaudioprocess = function(audioProcessingEvent){ var outputBuffer = audioProcessingEvent.outputBuffer; var outputData = outputBuffer.getChannelData(0); for(var j = 0; j < outputData.length;j++){ // linearly interpolate between the new breakpoint positions // get the interp point by comparing index to the x distance var lerp = (this.index - this.breakpoint[this.point].x) / (this.breakpoint[this.point+1].x - this.breakpoint[this.point].x); this.y = lerp * (this.breakpoint[this.point+1].y - this.breakpoint[this.point].y) + this.breakpoint[this.point].y; if(this.point < this.breakpoint.length && this.index >= this.breakpoint[this.point+1].x) { this.point++; } outputData[j] = this.y; this.index+=this.freq; if(this.index >= this.breakpoint[this.breakpoint.length-1].x){ this.index = 0; this.point = 0; this.walk(); } } }.bind(this); }。

以下是代码：

None

scriptProcessorNode.onaudioprocess无法访问全局变量

2 个答案: