canvas的宽高怎么自适应?

https://www.zhihu.com/question/36458228

window.addEventListener("resize", resizeCanvas, false);

function resizeCanvas() {
    w = canvas.width = window.innerWidth;
    h = canvas.height = window.innerHeight;
}

https://blog.csdn.net/m0_48940868/article/details/116503331