Fit div size to background image

问题

I'm trying to set the size (both width and height) of a div to match it's background image size, but I can't get it working. The background image size has to be in percentages, because I'm dealing with a responsive website. On smaller screens, the background should be displayed completely (with less width, but still proportional), and the div who has the image should follow that size.

I tried various values of the background-size, such as auto 100%, cover, contain, etc. but nothing did the trick. There's a similar question here about this: scale div to background image size but it didn't solve my problem either.

I'd really appreciate if someone knows how to do it.

EDIT: I made a fiddle to show the behavior: http://jsfiddle.net/osv1v9re/5/ This line is what is making the background image so small:

background-size: auto 100%;

But if it is removed is removed, the background will fill the proper width, but not the height.

回答1:

tag cannot adapt to background-image size, you need to use an tag and choose between height: auto for the div or javascript

// **** Problem ****

// Wrong html :
<div class="my_class"><div>

// with css :
.my_class {
    width: 100%;
    height: 100%;
    background-image: url(/images/my-image.jpg);
    background-size: 100%;
    background-position: center;
    background-repeat: no-repeat;
}

//****  Solution ****

// use css:
.my_class {
    width: 100%;
    height: 100%;
    background-image: url(/images/my-image.jpg);
    background-size: contain;
}

回答2:

*{
    padding: 0;
    margin: 0;
}


div{
    width: 100%;
}
div figure{
    padding-top: 36.56%;  /* 702px/1920px = 0.3656 */
    display: block;
    background: url("https://st.fl.ru/images/landing/bg2.jpg") no-repeat center top;
    background-size: cover;  
}

<div>    
    <figure></figure>
</div>

回答3:

you can have a responsive height using the padding-bottom or padding-top because you can't fix an height property in '%' with a width in '%'.

div{

	background-image: url(url);
	background-repeat: no-repeat;
	background-size: 100% 100%;
	background-position: center;

	margin: 0 auto;

	width: 100%;
	padding-bottom:  heightPicure / widthPicture + %; //do it manually or using scss rules

}

回答4:

If you want to make height proportional to width and set background-image this will do the job. There is an easy solution without using JavaScript. Just add <svg> with specific proportions inside a container.

You must use image dimensions as viewBox <svg viewBox="0 0 960 628"></svg>

Example:

div{
  background-image:url('https://cdn.pixabay.com/photo/2018/06/30/09/31/background-image-3507320_960_720.jpg');
  background-size:cover;
  background-position:50%;
  background-repeat:no-repeat;
}
svg{
  width:100%;
  display:block;
  visibility:hidden;
}


.demo-1{width:100%}
.demo-2{width:40%}

<div class="demo-1">
  <svg viewBox="0 0 960 628"></svg>
</div>

<hr>

<div class="demo-2">
  <svg viewBox="0 0 960 628"></svg>
</div>

来源：https://stackoverflow.com/questions/30319743/fit-div-size-to-background-image

标签

css

responsive-design

background-size