具有横向和纵向的幻灯片

Question

我正在关注有关制作幻灯片网页的这个 w3c 学校教程。

对我来说，唯一的要求不同是我的横向和纵向图像具有相同的垂直分辨率（1280x720 和 420x720）。

当我加载纵向图像时，它们会放大很多，因为图像仅受最大宽度约束。真的我想限制为垂直最大高度，所以当我循环通过它们时，高度是恒定的。

问题是，当我在 .slideshow-container 上指定 max-height 并删除 max-width 时，图像会在页面上左对齐。所以看起来我必须在其中设置 max-heigth 以使其保持居中对齐。

当我同时定义最大高度和最大宽度时，它会优先考虑宽度而不是高度。

那么我怎样才能让幻灯片图像都强制保持一致的高度，同时仍然让所有内容都在页面中正确居中绘制？

var slideIndex = 1;
showSlides(slideIndex);

function plusSlides(n) {
  showSlides(slideIndex += n);
}

function currentSlide(n) {
  showSlides(slideIndex = n);
}

function showSlides(n) {
  var i;
  var slides = document.getElementsByClassName("mySlides");
  var dots = document.getElementsByClassName("dot");
  if (n > slides.length) {
    slideIndex = 1
  }
  if (n < 1) {
    slideIndex = slides.length
  }
  for (i = 0; i < slides.length; i++) {
    slides[i].style.display = "none";
  }
  for (i = 0; i < dots.length; i++) {
    dots[i].className = dots[i].className.replace(" active", "");
  }
  slides[slideIndex - 1].style.display = "block";
  dots[slideIndex - 1].className += " active";
}

* {
  box-sizing: border-box
}

body {
  font-family: Verdana, sans-serif;
  margin: 0
}

.mySlides {
  display: none
}


/* Slideshow container */

.slideshow-container {
  max-width: 1000px;
  position: relative;
  margin: auto;
}


/* Next & previous buttons */

.prev,
.next {
  cursor: pointer;
  position: absolute;
  top: 50%;
  width: auto;
  padding: 16px;
  margin-top: -22px;
  color: white;
  font-weight: bold;
  font-size: 18px;
  transition: 0.6s ease;
  border-radius: 0 3px 3px 0;
}


/* Position the "next button" to the right */

.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}


/* On hover, add a black background color with a little bit see-through */

.prev:hover,
.next:hover {
  background-color: rgba(0, 0, 0, 0.8);
}


/* Caption text */

.text {
  color: #f2f2f2;
  font-size: 15px;
  padding: 8px 12px;
  position: absolute;
  bottom: 8px;
  width: 100%;
  text-align: center;
}


/* Number text (1/3 etc) */

.numbertext {
  color: #f2f2f2;
  font-size: 12px;
  padding: 8px 12px;
  position: absolute;
  top: 0;
}


/* The dots/bullets/indicators */

.dot {
  cursor: pointer;
  height: 15px;
  width: 15px;
  margin: 0 2px;
  background-color: #bbb;
  border-radius: 50%;
  display: inline-block;
  transition: background-color 0.6s ease;
}

.active,
.dot:hover {
  background-color: #717171;
}


/* Fading animation */

.fade {
  -webkit-animation-name: fade;
  -webkit-animation-duration: 1.5s;
  animation-name: fade;
  animation-duration: 1.5s;
}

@-webkit-keyframes fade {
  from {
    opacity: .4
  }
  to {
    opacity: 1
  }
}

@keyframes fade {
  from {
    opacity: .4
  }
  to {
    opacity: 1
  }
}


/* On smaller screens, decrease text size */

@media only screen and (max-width: 300px) {
  .prev,
  .next,
  .text {
    font-size: 11px
  }
}

<div class="slideshow-container">

  <div class="mySlides fade">
    <div class="numbertext">1 / 3</div>
    <img src="img_nature_wide.jpg" style="width:100%">
    <div class="text">Caption Text</div>
  </div>

  <div class="mySlides fade">
    <div class="numbertext">2 / 3</div>
    <img src="img_fjords_wide.jpg" style="width:100%">
    <div class="text">Caption Two</div>
  </div>

  <div class="mySlides fade">
    <div class="numbertext">3 / 3</div>
    <img src="img_mountains_wide.jpg" style="width:100%">
    <div class="text">Caption Three</div>
  </div>

  <a class="prev" onclick="plusSlides(-1)">&#10094;</a>
  <a class="next" onclick="plusSlides(1)">&#10095;</a>

</div>
<br>

<div style="text-align:center">
  <span class="dot" onclick="currentSlide(1)"></span>
  <span class="dot" onclick="currentSlide(2)"></span>
  <span class="dot" onclick="currentSlide(3)"></span>
</div>

Answer 1

您可以应用以下样式来保持幻灯片高度：

.mySlides {
  position: relative;
  overflow: hidden;
  height: 100vh; /* whatever height you want it to be */
}

.mySlides img {
  /* centre the image */
  height: 100%;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%); 
}

var slideIndex = 1;
showSlides(slideIndex);

function plusSlides(n) {
  showSlides(slideIndex += n);
}

function currentSlide(n) {
  showSlides(slideIndex = n);
}

function showSlides(n) {
  var i;
  var slides = document.getElementsByClassName("mySlides");
  var dots = document.getElementsByClassName("dot");
  if (n > slides.length) {
    slideIndex = 1
  }
  if (n < 1) {
    slideIndex = slides.length
  }
  for (i = 0; i < slides.length; i++) {
    slides[i].style.display = "none";
  }
  for (i = 0; i < dots.length; i++) {
    dots[i].className = dots[i].className.replace(" active", "");
  }
  slides[slideIndex - 1].style.display = "block";
  dots[slideIndex - 1].className += " active";
}

* {
  box-sizing: border-box
}

body {
  font-family: Verdana, sans-serif;
  margin: 0
}

.mySlides {
  display: none
}


/* Slideshow container */

.slideshow-container {
  max-width: 1000px;
  position: relative;
  margin: auto;
}


/* Next & previous buttons */

.prev,
.next {
  cursor: pointer;
  position: absolute;
  top: 50%;
  width: auto;
  padding: 16px;
  margin-top: -22px;
  color: white;
  font-weight: bold;
  font-size: 18px;
  transition: 0.6s ease;
  border-radius: 0 3px 3px 0;
}


/* Position the "next button" to the right */

.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}


/* On hover, add a black background color with a little bit see-through */

.prev:hover,
.next:hover {
  background-color: rgba(0, 0, 0, 0.8);
}


/* Caption text */

.text {
  color: #f2f2f2;
  font-size: 15px;
  padding: 8px 12px;
  position: absolute;
  bottom: 8px;
  width: 100%;
  text-align: center;
}


/* Number text (1/3 etc) */

.numbertext {
  color: #f2f2f2;
  font-size: 12px;
  padding: 8px 12px;
  position: absolute;
  top: 0;
}


/* The dots/bullets/indicators */

.dot {
  cursor: pointer;
  height: 15px;
  width: 15px;
  margin: 0 2px;
  background-color: #bbb;
  border-radius: 50%;
  display: inline-block;
  transition: background-color 0.6s ease;
}

.active,
.dot:hover {
  background-color: #717171;
}


/* Fading animation */

.fade {
  -webkit-animation-name: fade;
  -webkit-animation-duration: 1.5s;
  animation-name: fade;
  animation-duration: 1.5s;
}

@-webkit-keyframes fade {
  from {
    opacity: .4
  }
  to {
    opacity: 1
  }
}

@keyframes fade {
  from {
    opacity: .4
  }
  to {
    opacity: 1
  }
}


/* On smaller screens, decrease text size */

@media only screen and (max-width: 300px) {
  .prev,
  .next,
  .text {
    font-size: 11px
  }
}

.mySlides {
  position: relative;
  overflow: hidden;
  height: 100vh;
}

.mySlides img {
  /* centre the image */
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  height: 100%;
}

<div class="slideshow-container">

  <div class="mySlides fade">
    <div class="numbertext">1 / 3</div>
    <img src="https://i.imgur.com/hd6AbVQ.jpg">
    <div class="text">Caption Text</div>
  </div>

  <div class="mySlides fade">
    <div class="numbertext">2 / 3</div>
    <img src="https://i.imgur.com/ZXwfiH2.jpg">
    <div class="text">Caption Two</div>
  </div>

  <div class="mySlides fade">
    <div class="numbertext">3 / 3</div>
    <img src="https://i.imgur.com/hd6AbVQ.jpg">
    <div class="text">Caption Three</div>
  </div>

  <a class="prev" onclick="plusSlides(-1)">&#10094;</a>
  <a class="next" onclick="plusSlides(1)">&#10095;</a>

</div>
<br>

<div style="text-align:center">
  <span class="dot" onclick="currentSlide(1)"></span>
  <span class="dot" onclick="currentSlide(2)"></span>
  <span class="dot" onclick="currentSlide(3)"></span>
</div>