How to do equivalent of a linear-gradient with opacity on a seamless background image in CSS

问题

I want to do this essentially in CSS:

div {
  background: linear-gradient(to top, rgba(255,0,0,0), rgba(255,0,0,1), rgba(255,0,0,0));
  width: 1000px;
  height: 1000px;
}

<div>hello</div>

But instead of a color, I want to gradient-fade-in-and-out a background image, like this:

background: linear-gradient(to top, transparent, url(/myimage.png) repeat, transparent);

How to accomplish this in CSS, or if it's not possible in CSS, in JS.

My image is a seamless texture, so maybe that might factor into the equation since it is repeated. I also want to set the background-size to different sizes to figure it out, so if you could specify that too that would be nice.

回答1:

You can consider mask to do this. You can specify the same properties as background thus you can easily define your gradient.

.box {
  width: 1000px;
  height: 1000px;
  position:relative;
  z-index:0;
}
.box:before {
  content:"";
  position:absolute;
  z-index:-1;
  top:0;
  left:0;
  right:0;
  bottom:0;
  background:url(https://picsum.photos/id/42/10/10);
  -webkit-mask-image:linear-gradient(to top, transparent, #fff, transparent);
  mask-image:linear-gradient(to top, transparent, #fff, transparent);
}

<div class="box">hello</div>

Or you can simulate this using multiple background. You will not have transparency but you will have better support:

.box {
  width: 1000px;
  height: 1000px;
  background:
    linear-gradient(to top,#fff, transparent, #fff),
    url(https://picsum.photos/id/42/10/10);
}

<div class="box">hello</div>

来源：https://stackoverflow.com/questions/57245123/how-to-do-equivalent-of-a-linear-gradient-with-opacity-on-a-seamless-background

标签

css

background-image

linear-gradients