自定义image节点，无法显示图片

uniapp+vue2

iOS真机预览

**图片没有跨域也没有被拦截**

```js
...
shape = group.addShape('image', {
attrs: {
x: 0 - radius,
y: 0 - radius,
width: radius * 2,
height: radius * 2,
img: cfg.img, // 接口返回的http://.....png地址
},
name: 'avatar-image',
draggable: true,
clipCfg: { // 图片剪裁
show: true,
type: 'circle', // 裁个圆
r: radius // 半径
}
});
return shape
```
这样无法显示，把图片转成base64才可以，如何解决？

Start at the custom image-node entry point using group.addShape('image') in the issue, then reproduce it with an HTTP PNG URL during an iOS real-device preview. Compare that path with the working base64 case and inspect the image-shape handling. Done means the remote image renders correctly with the stated circular clipping configuration.

Written by the indexing model from the issue text.