需求很简单代码也很简单，就是效果出不来，心好累。。。老铁们，怎么办 takePhoto() {     this.data.camera.takePhoto({         quality: 'high',         success: (res) => {             let cv =  wx.createCanvasContext("abc");     //canvas-id='abc'             let w = this.data.canvasW;                            //<canvas>宽             let h = this.data.canvasH;             cv.drawImage(res.tempImagePath, 0, 0, w, h);    //res.tempImagePath是http://tmp/xxx.jpg             cv.draw();         }     }) },