刚学习微信小游戏，使用原生引擎与基础库，做了一个简单画布添上背景图；然后再添加了一个离屏画布，画了一个矩形，接着2秒延迟将矩形清除一部分。看了几遍api文档，问了几个AI工具，都没有解决问题。  请大神帮忙分析一下问题，非常感谢。 [图片] 预期效果： [图片] 但实际效果没有做到清除，日志正常。 完整代码如下（清除逻辑bindEvent函数): const WINDOW_INFO = wx.getWindowInfo(); const IMAGE_SRC="images/index_bg2.jpg"; const BACKGROUND_WIDTH = 1312; const BACKGROUND_HEIGHT = 736;  /** //  * 游戏主函数  */ export default class Main {      constructor() {          //解决重新进入游戏出现黑屏问题         console.log('高性能模式',GameGlobal.isIOSHighPerformanceMode);           this.init();     }          /**      * 初始化      */     init(){          //创建画布          this.canvas = wx.createCanvas();          this.canvas.width = WINDOW_INFO.screenWidth;          this.canvas.height = WINDOW_INFO.screenHeight;          //获取canvas的2D绘图上下文，画笔          this.context  = this.canvas.getContext("2d");           //设置背景图片          this.image = wx.createImage();          this.image.src= IMAGE_SRC;          this.imageLoaded = false;          this.image.onload=()=>{               this.imageLoaded = true;          };          //将图片绘制到画布上， 并且渲染至屏幕          requestAnimationFrame(this.render.bind(this));              }     /**      * 绘制      */     render(){           const timeId= setInterval(() => {                    if(this.imageLoaded){                         console.log('图片加载成功了');                         clearInterval(timeId);                         this.context.drawImage(                             this.image,                             0,                             0,                             BACKGROUND_WIDTH,                             BACKGROUND_HEIGHT,                             0,                             0,                             this.canvas.width,                             this.canvas.height                                           );                          this.bindEvent();                   }else{                       console.log('图片加载中');                   }            }, 100);     }     /**      * 测试离屏清除      */     bindEvent(){              //创建离屏画布             const secondScreenCanvas = wx.createCanvas();              secondScreenCanvas.width = 100;             secondScreenCanvas.height = 100;             this.secondScreenCtx = secondScreenCanvas.getContext('2d');             //在离屏左上角绘制红色100*100矩形             this.secondScreenCtx.fillStyle ='red';             this.secondScreenCtx.fillRect(0, 0, 100, 100);             //同步至主屏             this.context.drawImage(secondScreenCanvas, 0, 0);                          //二秒后清除一小块50*50红色区域             setTimeout(()=>{                 this.secondScreenCtx.clearRect(0, 0, 50, 50);                 //重新绘制到主画布，确保清除效果可见                 requestAnimationFrame(()=>{                     this.context.drawImage(secondScreenCanvas, 0, 0);                     console.log('清除完成');                 });              },2000);     }      }

刚学习小游戏开发，参考模板小游戏，做一个简单的页面，放置一个背景图，模拟器上面可以呈现： [图片] 但上传体验版，就显示不了，黑屏： [图片] 请教问题出在哪里。 以下完整代码： const WINDOW_INFO = wx.getWindowInfo(); const IMAGE_SRC="./images/index_bg.jpg"; const BACKGROUND_WIDTH = 1312; const BACKGROUND_HEIGHT = 736;  /**  * 游戏主函数  */ export default class Main {      constructor() {         this.init();     }          /**      * 初始化      */     init(){          //创建画布          this.canvas = wx.createCanvas();          //获取canvas的2D绘图上下文，画笔                     this.canvas.width = WINDOW_INFO.screenWidth;          this.canvas.height = WINDOW_INFO.screenHeight;          this.context  = this.canvas.getContext("2d");          //设置背景图片          this.image = wx.createImage();          this.image.src= IMAGE_SRC;          this.imageLoaded = false;          this.image.onload=()=>{               this.imageLoaded = true;          };          //将图片绘制到画布上， 并且渲染至屏幕          requestAnimationFrame(this.render.bind(this));               }     /**      * 绘制      */     render(){           const timeId= setInterval(() => {                    if(this.imageLoaded){                         console.log('图片加载成功了');                         clearInterval(timeId);                         this.context.drawImage(                             this.image,                             0,                             0,                             BACKGROUND_WIDTH,                             BACKGROUND_HEIGHT,                             0,                             0,                             this.canvas.width,                             this.canvas.height                                           );                    }else{                       console.log('图片加载中');                   }            }, 100);     } }