如何在移动视图上更改Bootstrap Carousel图像?

Question

/*Carousel CSS for Mobile View*/
@media (max-width: 425px){
#banner-one img{
background-image: url("/images/mobile_banner1.jpg") !important;
}

#banner-two img{
background-image: url("/images/mobile_banner2.jpg") !important;
}

#banner-three img{
background-image: url("/images/mobile_banner3.jpg") !important;
}

#banner-four img{
background-image: url("/images/mobile_banner4.jpg") !important;
}
}

<div id="carouselExampleControls" class="carousel slide" data-ride="carousel">
<div class="carousel-inner">
<div id="banner-one" class="carousel-item active">
<img class="d-block w-100" src="/images/banner-one.jpg" alt="First slide">
</div>
<div id="banner-two" class="carousel-item">
<img class="d-block w-100" src="/images/banner-two.jpg" alt="Second slide">
</div>
<div id="banner-three" class="carousel-item">
<img class="d-block w-100" src="/images/banner-three.jpg" alt="Third slide">
</div>
<div id="banner-four" class="carousel-item">
<img class="d-block w-100" src="/images/banner-four.jpg" alt="Third slide">
</div>
</div>
<a class="carousel-control-prev" href="#carouselExampleControls" role="button" data-slide="prev">
<span class="carousel-control-prev-icon" aria-hidden="true"></span>
<span class="sr-only">Previous</span>
</a>
<a class="carousel-control-next" href="#carouselExampleControls" role="button" data-slide="next">
<span class="carousel-control-next-icon" aria-hidden="true"></span>
<span class="sr-only">Next</span>
</a>
</div>

我在我的项目中有一个Bootstrap Carousel，它在每个视图中都是完美的。但我想改变移动视图中每张幻灯片的旋转图像。我什么都试过了，但都失败了。

Answer 1

你可以设置这两个图像，并发挥其可见性的css。

参见下面的代码片段(使用全屏在视图之间切换):

.desk-img {
display: block;
}
.mobile-img {
display: none;
}
@media (max-width: 700px) {
.desk-img {
display: none !important;
}
.mobile-img {
display: block;
}
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css" rel="stylesheet" />
<div id="carouselExampleControls" class="carousel slide" data-ride="carousel">
<div class="carousel-inner">
<div id="banner-one" class="carousel-item active">
<img class=" w-100  desk-img" src="https://via.placeholder.com/800x380?text=slide%201" alt="First slide">
<img class=" w-100  mobile-img" src="https://via.placeholder.com/800x380?text=mobile slide%201" alt="First slide">
</div>
<div id="banner-two" class="carousel-item">
<img class=" w-100 desk-img" src="https://via.placeholder.com/800x380?text=slide%202" alt="Second slide">
<img class=" w-100  mobile-img" src="https://via.placeholder.com/800x380?text=mobile slide%202" alt="Second slide">
</div>
<div id="banner-three" class="carousel-item">
<img class=" w-100 desk-img" src="https://via.placeholder.com/800x380?text=slide%203" alt="Third slide">
<img class=" w-100  mobile-img" src="https://via.placeholder.com/800x380?text=mobile slide%203" alt="Third slide">
</div>
</div>
<a class="carousel-control-prev" href="#carouselExampleControls" role="button" data-slide="prev">
<span class="carousel-control-prev-icon" aria-hidden="true"></span>
<span class="sr-only">Previous</span>
</a>
<a class="carousel-control-next" href="#carouselExampleControls" role="button" data-slide="next">
<span class="carousel-control-next-icon" aria-hidden="true"></span>
<span class="sr-only">Next</span>
</a>
</div>

Answer 2

我认为你可以直接使用picture元素，

<picture>
<source media="(max-width: 425px)" srcset="mobile-img.jpg" />
<source media="(max-width: 768px)" srcset="tablet-img.jpg" />
<img src="desktop-or-default-img.jpg" class="d-block w-100" alt="..." />
</picture>

在这种情况下，mobile-img.jpg将在屏幕低于425px时使用，tablet-img.jpg将在屏幕低于768px-425px时使用，desktop-or-default-img.jpg将在屏幕在(任意)px-768px时使用。