如何将整个图像比较滑块居中

Question

当我设法移动图像比较滑块时，实际的"滑块"留下了。滑块 JS 代码来自 https://www.w3schools.com/howto/howto_js_image_comparison.asp

并且可以很容易地在那里检查，但我也会在这里粘贴代码。 我尝试使用 Css 网格移动滑块，但如前所述，滑块图标不会随图像移动。

function initComparisons() {
var x, i;
/* Find all elements with an "overlay" class: */
x = document.getElementsByClassName("img-comp-overlay");
for (i = 0; i < x.length; i++) {
/* Once for each "overlay" element:
pass the "overlay" element as a parameter when executing the compareImages function: */
compareImages(x[i]);
}
function compareImages(img) {
var slider, img, clicked = 0, w, h;
/* Get the width and height of the img element */
w = img.offsetWidth;
h = img.offsetHeight;
/* Set the width of the img element to 50%: */
img.style.width = (w / 2) + "px";
/* Create slider: */
slider = document.createElement("DIV");
slider.setAttribute("class", "img-comp-slider");
/* Insert slider */
img.parentElement.insertBefore(slider, img);
/* Position the slider in the middle: */
slider.style.top = (h / 2) - (slider.offsetHeight / 2) + "px";
slider.style.left = (w / 2) - (slider.offsetWidth / 2) + "px";
/* Execute a function when the mouse button is pressed: */
slider.addEventListener("mousedown", slideReady);
/* And another function when the mouse button is released: */
window.addEventListener("mouseup", slideFinish);
/* Or touched (for touch screens: */
slider.addEventListener("touchstart", slideReady);
/* And released (for touch screens: */
window.addEventListener("touchstop", slideFinish);
function slideReady(e) {
/* Prevent any other actions that may occur when moving over the image: */
e.preventDefault();
/* The slider is now clicked and ready to move: */
clicked = 1;
/* Execute a function when the slider is moved: */
window.addEventListener("mousemove", slideMove);
window.addEventListener("touchmove", slideMove);
}
function slideFinish() {
/* The slider is no longer clicked: */
clicked = 0;
}
function slideMove(e) {
var pos;
/* If the slider is no longer clicked, exit this function: */
if (clicked == 0) return false;
/* Get the cursor's x position: */
pos = getCursorPos(e)
/* Prevent the slider from being positioned outside the image: */
if (pos < 0) pos = 0;
if (pos > w) pos = w;
/* Execute a function that will resize the overlay image according to the cursor: */
slide(pos);
}
function getCursorPos(e) {
var a, x = 0;
e = e || window.event;
/* Get the x positions of the image: */
a = img.getBoundingClientRect();
/* Calculate the cursor's x coordinate, relative to the image: */
x = e.pageX - a.left;
/* Consider any page scrolling: */
x = x - window.pageXOffset;
return x;
}
function slide(x) {
/* Resize the image: */
img.style.width = x + "px";
/* Position the slider: */
slider.style.left = img.offsetWidth - (slider.offsetWidth / 2) + "px";
}
}
}
initComparisons();

.img-comp-container {
margin:auto;
position: relative;
height: 100vh; 
width: 100vw
}
.img-comp-img {
position: absolute;
width: auto;
height: auto;
overflow:hidden;
}
.img-comp-img img {
display: block;
vertical-align: middle;
}

.img-comp-slider {
position: absolute;
z-index: 9;
cursor: ew-resize;
width: 0;
height: 0;
border-style: solid;
border-width: 9px 0 9px 14px;
border-color: transparent transparent transparent #ffffff;
}

<div class="img-comp-container">
<div class="img-comp-img">
<img src="img/ysl_before.jpg" width="650" height="450">
</div>
<div class="img-comp-img img-comp-overlay">
<img src="img/ysl_after.jpg" width="650" height="450">
</div>
</div>

Answer 1

我相信这可以解决您正在寻找的内容：

将现有容器包装在另一个div(img-comp-outer-container(中，从img-comp-container中删除边距，并将img-comp-container的高度/宽度设置为auto。

然后，您可以设置外部容器的样式，以按照您喜欢的方式对齐组件

<div class="img-comp-outer-container"> <!--new div -->
<div class="img-comp-container">
<div class="img-comp-img">
<img src="img_snow.jpg" width="650" height="450">
</div>
<div class="img-comp-img img-comp-overlay">
<img src="img_forest.jpg" width="650" height="450">
</div>
</div>
</div> <!--new div end -->

.img-comp-outer-container {
/* add your styles to move around component */
}
.img-comp-container {
/* margin: auto; */
position: relative;
height: auto; /* was 100vh */
width: auto; /* was 100vw */
}

Answer 2

我想将我使用图像比较滑块进行比较的两个图像带到页面中心。W3Schools上可用的代码，用于使用滑块比较图像，但没有建议将其居中。所以我所做的是放置div id框并将所有其他类添加到其中，并将该框样式设置为具有高度和宽度的白色，并将float-right添加到img-comp-container中。您可以相应地更改框的宽度和高度以使滑块居中。

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
* {box-sizing: border-box;}
.img-comp-container {
float: right; /*new change*/
position: relative;
height: 200px; /*should be the same height as the images*/
}
.img-comp-img {
position: absolute;
width: auto;
height: auto;
overflow:hidden;
}
.img-comp-img img {
display:block;
vertical-align:middle;
}
.img-comp-slider {
position: absolute;
z-index:9;
cursor: ew-resize;
/*set the appearance of the slider:*/
width: 40px;
height: 40px;
background-color: #2196F3;
opacity: 0.7;
border-radius: 50%;
}
/*new change*/
#box{ 
background: white;
width: 150px;
height: 200px;
}
</style>
<script>
function initComparisons() {
var x, i;
/*find all elements with an "overlay" class:*/
x = document.getElementsByClassName("img-comp-overlay");
for (i = 0; i < x.length; i++) {
/*once for each "overlay" element:
pass the "overlay" element as a parameter when executing the compareImages function:*/
compareImages(x[i]);
}
function compareImages(img) {
var slider, img, clicked = 0, w, h;
/*get the width and height of the img element*/
w = img.offsetWidth;
h = img.offsetHeight;
/*set the width of the img element to 50%:*/
img.style.width = (w / 2) + "px";
/*create slider:*/
slider = document.createElement("DIV");
slider.setAttribute("class", "img-comp-slider");
/*insert slider*/
img.parentElement.insertBefore(slider, img);
/*position the slider in the middle:*/
slider.style.top = (h / 2) - (slider.offsetHeight / 2) + "px";
slider.style.left = (w / 2) - (slider.offsetWidth / 2) + "px";
/*execute a function when the mouse button is pressed:*/
slider.addEventListener("mousedown", slideReady);
/*and another function when the mouse button is released:*/
window.addEventListener("mouseup", slideFinish);
/*or touched (for touch screens:*/
slider.addEventListener("touchstart", slideReady);
/*and released (for touch screens:*/
window.addEventListener("touchend", slideFinish);
function slideReady(e) {
/*prevent any other actions that may occur when moving over the image:*/
e.preventDefault();
/*the slider is now clicked and ready to move:*/
clicked = 1;
/*execute a function when the slider is moved:*/
window.addEventListener("mousemove", slideMove);
window.addEventListener("touchmove", slideMove);
}
function slideFinish() {
/*the slider is no longer clicked:*/
clicked = 0;
}
function slideMove(e) {
var pos;
/*if the slider is no longer clicked, exit this function:*/
if (clicked == 0) return false;
/*get the cursor's x position:*/
pos = getCursorPos(e)
/*prevent the slider from being positioned outside the image:*/
if (pos < 0) pos = 0;
if (pos > w) pos = w;
/*execute a function that will resize the overlay image according to the cursor:*/
slide(pos);
}
function getCursorPos(e) {
var a, x = 0;
e = e || window.event;
/*get the x positions of the image:*/
a = img.getBoundingClientRect();
/*calculate the cursor's x coordinate, relative to the image:*/
x = e.pageX - a.left;
/*consider any page scrolling:*/
x = x - window.pageXOffset;
return x;
}
function slide(x) {
/*resize the image:*/
img.style.width = x + "px";
/*position the slider:*/
slider.style.left = img.offsetWidth - (slider.offsetWidth / 2) + "px";
}
}
}
</script>
</head>
<body>
<h1>Compare Two Images</h1>
<p>Click and slide the blue slider to compare two images:</p>
<div id="box">/*new change*/
<div class="img-comp-container">
<div class="img-comp-img">
<img src="img_snow.jpg" width="300" height="200">
</div>
<div class="img-comp-img img-comp-overlay">
<img src="img_forest.jpg" width="300" height="200">
</div>
</div>
</div>
<script>
/*Execute a function that will execute an image compare function for each element with the img-comp-overlay class:*/
initComparisons();
</script>
</body>
</html>