ios打包之后canvas无法绘制显示白色

let ctx = uni.createCanvasContext('canvas-clipper', _this);  
console.log(ctx)  
console.log(_self.imgdata.Front)  
ctx.drawImage(  
'/static/login/idcard/idcard1.png',  
0,  
0,  
image.width,  
image.height  
);  
ctx.restore()  
ctx.draw()