CSS 对象适合：包含；在布局中保持原始图像宽度

Question

我正在尝试使用 object-fit: contain 使我的图像在某些 flexbox 容器内响应，虽然图像确实调整了大小，但布局似乎保持了原始图像大小，导致出现滚动条。

使用ChromeDev Tools检查图片的宽度，显示宽度仍然是1024（但是高度已经适当减小了。）

（我的灵感来自 FlexBox 布局中的自动调整图像大小并保持纵横比？到此为止）

我是否遗漏了一些额外的 CSS 属性？

JSFiddle：https://jsfiddle.net/w6hgqf18/1/

html,
body {
  margin: 0;
  height: 100%;
}

.page {
  height: 100%;
  display: flex;
}

.main-container {
  flex: 1 1 0;
  display: flex;
  flex-direction: column;
}

.half-containers {
  flex: 0 1 50%;
  overflow: auto;
  box-sizing: border-box;
  border: 0.5px solid red;
  display: flex;
}

.page-header {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

.page-footer {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

img {
  object-fit: contain;
}

<div class="page">
  <div class="main-container">
    <div class="page-header">
      This is a header
    </div>
    <div class="half-containers">
      <img src='https://i.imgur.com/tqQvuFr.jpg' />
    </div>
    <div class="half-containers">
      <img src='https://i.imgur.com/tqQvuFr.jpg' />
    </div>
    <div class="page-footer">
      This is a footer
    </div>
  </div>
</div>

Answer 1

您可以用 div 和 width: 100% 包装 img 标签，并将图像 height 设置为 100%，并且在没有 object-fit 的情况下执行此操作:

html,
body {
  margin: 0;
  height: 100%;
}

.page {
  height: 100%;
  display: flex;
}

.main-container {
  flex: 1 1 0;
  display: flex;
  flex-direction: column;
}

.half-containers {
  flex: 0 1 50%;
  overflow: auto;
  box-sizing: border-box;
  border: 0.5px solid red;
  display: flex;
}

.page-header {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

.page-footer {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}


.img-container {
  width: 100%;
}

img {
  height: 100%;
}

<div class="page">
  <div class="main-container">
    <div class="page-header">
      This is a header
    </div>
    <div class="half-containers">
      <div class="img-container">
        <img src='https://i.imgur.com/tqQvuFr.jpg' />
      </div>
    </div>
    <div class="half-containers">
      <div class="img-container">
        <img src='https://i.imgur.com/tqQvuFr.jpg' />
       </div>
    </div>
    <div class="page-footer">
      This is a footer
    </div>
  </div>
</div>

Answer 2

您所拥有的是合乎逻辑的，您只需要了解 object-fit 是如何工作的。让我们从一个更简单的例子开始：

.box {
  width:300px;
  height:300px;
  border:1px solid;
}
img {
 width:100%;
 height:100%;
 object-fit:contain;
}

<div class="box">
  <img src="https://picsum.photos/300/200?image=1069">
</div>

如你所见，我使用了 300x200 图像，我在 300x300 框内拉伸，因此我打破了它的比例，如果你检查图像的 width/height 你会看到它的尺寸仍然是 300x300（应用 object-fit 之前的尺寸）。

来自 the specification:

The object-fit property specifies how the contents of a replaced element should be fitted to the box established by its used height and width.

基本上，我们在视觉上 更改图像的内容，使其适合图像建立的space。 object-fit 不会改变图像的大小，但会使用该大小作为参考来更改其内部内容。

我们还是举个例子，用50%代替：

.box {
  width:300px;
  height:300px;
  border:1px solid;
}
img {
 width:50%;
 height:50%;
 object-fit:contain;
}

<div class="box">
  <img src="https://picsum.photos/300/200?image=1069">
</div>

现在图像的尺寸为 150x150，我们在其中更改内容以具有 contain 效果。

所有值都会发生相同的逻辑

.box {
  width:300px;
  height:300px;
  border:1px solid;
}
img {
 width:50%;
 height:50%;
}

<div class="box">
  <img src="https://picsum.photos/300/200?image=1069" style="object-fit:contain;">
</div>
<div class="box">
  <img src="https://picsum.photos/300/200?image=1069" style="object-fit:cover;">
</div>

在你的例子中你有同样的事情。没有 object-fit 图像如下

html,
body {
  margin: 0;
  height: 100%;
}

.page {
  height: 100%;
  display: flex;
}

.main-container {
  flex: 1 1 0;
  display: flex;
  flex-direction: column;
}

.half-containers {
  flex: 0 1 50%;
  overflow: auto;
  box-sizing: border-box;
  border: 0.5px solid red;
  display: flex;
}

.page-header {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

.page-footer {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

img {
  /*object-fit: contain;*/
}

<div class="page">
  <div class="main-container">
    <div class="page-header">
      This is a header
    </div>
    <div class="half-containers">
      <img src='https://i.imgur.com/tqQvuFr.jpg' />
    </div>
    <div class="half-containers">
      <img src='https://i.imgur.com/tqQvuFr.jpg' />
    </div>
    <div class="page-footer">
      This is a footer
    </div>
  </div>
</div>

添加 object-fit 不会改变它的大小，只会改变我们看到的：

html,
body {
  margin: 0;
  height: 100%;
}

.page {
  height: 100%;
  display: flex;
}

.main-container {
  flex: 1 1 0;
  display: flex;
  flex-direction: column;
}

.half-containers {
  flex: 0 1 50%;
  overflow: auto;
  box-sizing: border-box;
  border: 0.5px solid red;
  display: flex;
}

.page-header {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

.page-footer {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

img {
  object-fit: contain;
}

<div class="page">
  <div class="main-container">
    <div class="page-header">
      This is a header
    </div>
    <div class="half-containers">
      <img src='https://i.imgur.com/tqQvuFr.jpg' />
    </div>
    <div class="half-containers">
      <img src='https://i.imgur.com/tqQvuFr.jpg' />
    </div>
    <div class="page-footer">
      This is a footer
    </div>
  </div>
</div>

现在，另一个问题是您的图像的宽度为 1024px 而弹性项目不会因此您需要添加以获得所需的效果 min-width:0。这样做你将不再有溢出问题然后你的图像将包含在 flexbox 布局定义的区域内。

html,
body {
  margin: 0;
  height: 100%;
}

.page {
  height: 100%;
  display: flex;
}

.main-container {
  flex: 1 1 0;
  display: flex;
  min-width: 0; /*added*/
  flex-direction: column;
}

.half-containers {
  flex: 0 1 50%;
  overflow: auto;
  box-sizing: border-box;
  border: 0.5px solid red;
  display: flex;
}

.page-header {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

.page-footer {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

img {
  object-fit: contain;
  min-width: 0; /*added*/
}

<div class="page">
  <div class="main-container">
    <div class="page-header">
      This is a header
    </div>
    <div class="half-containers">
      <img src='https://i.imgur.com/tqQvuFr.jpg' />
    </div>
    <div class="half-containers">
      <img src='https://i.imgur.com/tqQvuFr.jpg' />
    </div>
    <div class="page-footer">
      This is a footer
    </div>
  </div>
</div>

考虑到 background-image 和 background-size:contain，您也可以得到相同的输出，因为没有更多的内容

，您不再需要为 min-width 约束而烦恼

html,
body {
  margin: 0;
  height: 100%;
}

.page {
  height: 100%;
  display: flex;
}

.main-container {
  flex: 1 1 0;
  display: flex;
  flex-direction: column;
}

.half-containers {
  flex: 0 1 50%;
  overflow: auto;
  box-sizing: border-box;
  border: 0.5px solid red;
  display: flex;
  background:url(https://i.imgur.com/tqQvuFr.jpg) center/contain no-repeat;
}

.page-header {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

.page-footer {
  flex: 0 0 auto;
  background-color: #dcdcdc;
}

<div class="page">
  <div class="main-container">
    <div class="page-header">
      This is a header
    </div>
    <div class="half-containers">
    </div>
    <div class="half-containers">
    </div>
    <div class="page-footer">
      This is a footer
    </div>
  </div>
</div>

CSS 对象适合：包含；在布局中保持原始图像宽度

CSS object-fit: contain; is keeping original image width in layout

html

css

flexbox

object-fit