电脑上用小程序工具调试正常，用真机测试的时候就获取不到，有没有人遇到过
query.select(selector).fields({node: true,size: true}).exec(res => {
console.log('yzl--小程序里获取canvas',res);
const canvas = res[0].node;
const ctx = canvas.getContext('2d');
resolve({
canvas,
ctx,
width: res[0].width,
height: res[0].height
});
});
