Overlay img with css - visualization issues from different devices - javascript

I am looking to make digital wedding invitations, even though I'm not a web developer.
I'm trying to create a page with a very simple animation where there is an envelope that shows the invitation. I have three simple images overlapped using html and css:
the front envelope - https://i.ibb.co/HBZsxLt/optipng.png
the invitation - https://i.ibb.co/h7SfR5L/part.png
the opend envelope - https://i.ibb.co/HtkgNPy/all.png
I was able to create the code (listed below) for what I want to achieve.
There are the three images overlapped and I'm able to shift the envelope with two simple lines of JavaScript. The overlapping works perfectly when I open it with Chrome. However, my issues came with the following point:
When I open the website with Firefox some pixels of the invitation come out the envelope
When I open the website from any smartphone in addition to the envelope-invitation dimension problems all the images are zoomed or moved on the left.
I tried to search if there is any way to overlap the images in an adaptive way (from the device/browser point of view), maybe using only JavaScript but I didn't find anything. I found only the css and html approach the I implemented already below. The simplest thing that I found for solving the issues was to insert a gif in the body but I don't like it very much.
My simple code is:
<!DOCTYPE html>
<html lang="it">
<head>
<title>Invitation wedding</title>
<style>
body {
margin: 0;
background-color: white;
}
#container {
height: 100vh;
display: flex;
justify-content: center;
align-items: center;
position: relative;
}
img {
height: 50%;
padding: 80px 0;
overflow: visible; /* For Firefox */
}
.env {
position: absolute;
}
.partecipazione{
height: 130%;
padding-top: 20%;
position: absolute;
padding-right: 22px;
}
.allEnvelope{
padding-top: 20%;
position: absolute;
}
</style>
</head>
<body>
<div id="container">
<div class="allEnvelope">
<img id="allEnv" src="all.png"></img>
</div>
<div class="partecipazione">
<img id="part" src="part.png"></img>
</div>
<div class="env">
<img id="envelope" src="optipng.png"></img>
</div>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/1.20.2/TweenMax.min.js"></script>
<script>
var timeline = new TimelineMax();
timeline.to('#envelope, #allEnv', .6, {y:290}, '+=.7');
</script>
</body>
</html>

Here I changed some things:
I removed
img {
height: 50%;
padding: 80px 0;
overflow: visible; /* For Firefox */
}
Then added a extra container around all divs inside the envelope for placement:
<div id="container">
<div class="envelopeWrapper">
<div class="allEnvelope">
<img id="allEnv" src="all.png"></img>
</div>
<div class="partecipazione">
<img id="part" src="part.png"></img>
</div>
<div class="env">
<img id="envelope" src="optipng.png"></img>
</div>
</div>
</div>
The styles:
.envelopeWrapper{
width: 603px;
max-width: 95%;
height: 500px;
position: relative;
}
the height here is just to place it in the middle of the screen.
The max-width is for mobile devices o if its smaller than the width of 603px it will adapt. Also added position: relative to adjust the div's within.
Added the styles for all divs/images inside the new wrapper:
.env, .partecipazione, .allEnvelope {
position: absolute;
right: 0;
left: 0;
bottom: 0;
}
.envelopeWrapper img{
max-width: 100%;
height: auto;
}
.partecipazione{
padding-left: 2%;
padding-right: 6%;
padding-bottom: 7%;
}
With position absolute I placed it at the corners of the bottom of the new wrapper-div.
I needed to add padding with percent for .partecipazione because the images wherent properly cut out. It's in percent so it will scale right for mobile devices.
Heres your changed code:
<!DOCTYPE html>
<html lang="it">
<head>
<title>Invitation wedding</title>
<style>
body {
margin: 0;
background-color: white;
}
#container {
height: 100vh;
display: flex;
justify-content: center;
align-items: center;
position: relative;
}
.envelopeWrapper{
width: 603px;
max-width: 95%;
height: 500px;
position: relative;
}
.env, .partecipazione, .allEnvelope {
position: absolute;
right: 0;
left: 0;
bottom: 0;
}
.envelopeWrapper img{
max-width: 100%;
height: auto;
}
.partecipazione{
padding-left: 2%;
padding-right: 6%;
padding-bottom: 7%;
}
</style>
</head>
<body>
<div id="container">
<div class="envelopeWrapper">
<div class="allEnvelope">
<img id="allEnv" src="all.png"></img>
</div>
<div class="partecipazione">
<img id="part" src="part.png"></img>
</div>
<div class="env">
<img id="envelope" src="optipng.png"></img>
</div>
</div>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/1.20.2/TweenMax.min.js"></script>
<script>
var timeline = new TimelineMax();
timeline.to('#envelope, #allEnv', .6, {y:290}, '+=.7');
</script>
</body>
</html>
But I think now you jsut have to adjust the script for the animation a little bit.

You can add browser prefix with your CSS. Here is new CSS code.
<style type="text/css">
body {
margin: 0;
background-color: white;
}
#container {
height: 100vh;
display: -webkit-box;
display: -webkit-flex;
display: -ms-flexbox;
display: flex;
-webkit-box-pack: center;
-webkit-justify-content: center;
-ms-flex-pack: center;
justify-content: center;
-webkit-box-align: center;
-webkit-align-items: center;
-ms-flex-align: center;
align-items: center;
position: relative;
}
img {
height: 50%;
padding: 80px 0;
overflow: visible; /* For Firefox */
}
.env {
position: absolute;
}
.partecipazione{
height: 130%;
padding-top: 20%;
position: absolute;
padding-right: 22px;
}
.allEnvelope{
padding-top: 20%;
position: absolute;
}
</style>

Elements can overlap for a variety of reasons, by using the property z-index we can make sure that the Letter stays in the vertical order we want it. It is the same as Layers in Photoshop if you have used that.
Using the above example by Puschi, we can add z-index to the following classes:
.partecipazione {
z-index: 1
}
.env {
z-index: 2;
}
The .env class will stay in the default layer at the bottom, placing the letter above it, then the open envelope above that again. This makes sure that the elements don't overlap.
Here is a Codesandbox using CSS & Javascript
https://codesandbox.io/s/sparkling-resonance-49b2w?file=/index.html:591-627
By using JavaScript we can fire off the animations after the browser is done loading all the images, making sure that it plays well.
Or we could add interactivity so that when the user clicks or hovers the Envelope it opens.

Related

Centering via setAttribute for Firefox [duplicate]

How can I horizontally center a <div> within another <div> using CSS?
<div id="outer">
<div id="inner">Foo foo</div>
</div>
With flexbox it is very easy to style the div horizontally and vertically centered.
#inner {
border: 0.05em solid black;
}
#outer {
border: 0.05em solid red;
width:100%;
display: flex;
justify-content: center;
}
<div id="outer">
<div id="inner">Foo foo</div>
</div>
To align the div vertically centered, use the property align-items: center.
Other Solutions
You can apply this CSS to the inner <div>:
#inner {
width: 50%;
margin: 0 auto;
}
Of course, you don't have to set the width to 50%. Any width less than the containing <div> will work. The margin: 0 auto is what does the actual centering.
If you are targeting Internet Explorer 8 (and later), it might be better to have this instead:
#inner {
display: table;
margin: 0 auto;
}
It will make the inner element center horizontally and it works without setting a specific width.
Working example here:
#inner {
display: table;
margin: 0 auto;
border: 1px solid black;
}
#outer {
border: 1px solid red;
width:100%
}
<div id="outer">
<div id="inner">Foo foo</div>
</div>
If you don't want to set a fixed width on the inner div you could do something like this:
#outer {
width: 100%;
text-align: center;
}
#inner {
display: inline-block;
}
<div id="outer">
<div id="inner">Foo foo</div>
</div>
That makes the inner div into an inline element that can be centered with text-align.
The best approaches are with CSS3.
The old box model (deprecated)
display: box and its properties box-pack, box-align, box-orient, box-direction etc. have been replaced by flexbox. While they may still work, they are not recommended to be used in production.
#outer {
width: 100%;
/* Firefox */
display: -moz-box;
-moz-box-pack: center;
-moz-box-align: center;
/* Safari and Chrome */
display: -webkit-box;
-webkit-box-pack: center;
-webkit-box-align: center;
/* W3C */
display: box;
box-pack: center;
box-align: center;
}
#inner {
width: 50%;
}
<div id="outer">
<div id="inner">Foo foo</div>
</div>
According to your usability you may also use the box-orient, box-flex, box-direction properties.
The modern box model with Flexbox
#outer {
display: flex;
flex-direction: row;
flex-wrap: wrap;
justify-content: center;
align-items: center;
}
Read more about centering the child elements
CSS Box Model Module Level 3
Box model (CSS2)
box-align on MDN
And this explains why the box model is the best approach:
Why is the W3C box model considered better?
#centered {
position: absolute;
left: 50%;
margin-left: -100px;
}
<div id="outer" style="width:200px">
<div id="centered">Foo foo</div>
</div>
Make sure the parent element is positioned, i.e., relative, fixed, absolute, or sticky.
If you don't know the width of your div, you can use transform:translateX(-50%); instead of the negative margin.
With CSS calc(), the code can get even simpler:
.centered {
width: 200px;
position: absolute;
left: calc(50% - 100px);
}
The principle is still the same; put the item in the middle and compensate for the width.
I've created this example to show how to vertically and horizontally align.
The code is basically this:
#outer {
position: relative;
}
and...
#inner {
margin: auto;
position: absolute;
left:0;
right: 0;
top: 0;
bottom: 0;
}
And it will stay in the center even when you resize your screen.
Some posters have mentioned the CSS 3 way to center using display:box.
This syntax is outdated and shouldn't be used anymore. [See also this post].
So just for completeness here is the latest way to center in CSS 3 using the Flexible Box Layout Module.
So if you have simple markup like:
<div class="box">
<div class="item1">A</div>
<div class="item2">B</div>
<div class="item3">C</div>
</div>
...and you want to center your items within the box, here's what you need on the parent element (.box):
.box {
display: flex;
flex-wrap: wrap; /* Optional. only if you want the items to wrap */
justify-content: center; /* For horizontal alignment */
align-items: center; /* For vertical alignment */
}
.box {
display: flex;
flex-wrap: wrap;
/* Optional. only if you want the items to wrap */
justify-content: center;
/* For horizontal alignment */
align-items: center;
/* For vertical alignment */
}
* {
margin: 0;
padding: 0;
}
html,
body {
height: 100%;
}
.box {
height: 200px;
display: flex;
flex-wrap: wrap;
justify-content: center;
align-items: center;
border: 2px solid tomato;
}
.box div {
margin: 0 10px;
width: 100px;
}
.item1 {
height: 50px;
background: pink;
}
.item2 {
background: brown;
height: 100px;
}
.item3 {
height: 150px;
background: orange;
}
<div class="box">
<div class="item1">A</div>
<div class="item2">B</div>
<div class="item3">C</div>
</div>
If you need to support older browsers which use older syntax for flexbox here's a good place to look.
If you don't want to set a fixed width and don't want the extra margin, add display: inline-block to your element.
You can use:
#element {
display: table;
margin: 0 auto;
}
Centering a div of unknown height and width
Horizontally and vertically. It works with reasonably modern browsers (Firefox, Safari/WebKit, Chrome, Internet & Explorer & 10, Opera, etc.)
.content {
position: absolute;
left: 50%;
top: 50%;
transform: translate(-50%, -50%);
}
<div class="content">This works with any content</div>
Tinker with it further on Codepen or on JSBin.
Set the width and set margin-left and margin-right to auto. That's for horizontal only, though. If you want both ways, you'd just do it both ways. Don't be afraid to experiment; it's not like you'll break anything.
It cannot be centered if you don't give it a width. Otherwise, it will take, by default, the whole horizontal space.
CSS 3's box-align property
#outer {
width: 100%;
height: 100%;
display: box;
box-orient: horizontal;
box-pack: center;
box-align: center;
}
The way I usually do it is using absolute position:
#inner{
left: 0;
right: 0;
margin-left: auto;
margin-right: auto;
position: absolute;
}
The outer div doesn't need any extra properties for this to work.
I recently had to center a "hidden" div (i.e., display:none;) that had a tabled form within it that needed to be centered on the page. I wrote the following jQuery code to display the hidden div and then update the CSS content to the automatic generated width of the table and change the margin to center it. (The display toggle is triggered by clicking on a link, but this code wasn't necessary to display.)
NOTE: I'm sharing this code, because Google brought me to this Stack Overflow solution and everything would have worked except that hidden elements don't have any width and can't be resized/centered until after they are displayed.
$(function(){
$('#inner').show().width($('#innerTable').width()).css('margin','0 auto');
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="inner" style="display:none;">
<form action="">
<table id="innerTable">
<tr><td>Name:</td><td><input type="text"></td></tr>
<tr><td>Email:</td><td><input type="text"></td></tr>
<tr><td>Email:</td><td><input type="submit"></td></tr>
</table>
</form>
</div>
For Firefox and Chrome:
<div style="width:100%;">
<div style="width: 50%; margin: 0px auto;">Text</div>
</div>
For Internet Explorer, Firefox, and Chrome:
<div style="width:100%; text-align:center;">
<div style="width: 50%; margin: 0px auto; text-align:left;">Text</div>
</div>
The text-align: property is optional for modern browsers, but it is necessary in Internet Explorer Quirks Mode for legacy browsers support.
Use:
#outerDiv {
width: 500px;
}
#innerDiv {
width: 200px;
margin: 0 auto;
}
<div id="outerDiv">
<div id="innerDiv">Inner Content</div>
</div>
Another solution for this without having to set a width for one of the elements is using the CSS 3 transform attribute.
#outer {
position: relative;
}
#inner {
position: absolute;
left: 50%;
transform: translateX(-50%);
}
The trick is that translateX(-50%) sets the #inner element 50 percent to the left of its own width. You can use the same trick for vertical alignment.
Here's a Fiddle showing horizontal and vertical alignment.
More information is on Mozilla Developer Network.
Chris Coyier who wrote an excellent post on 'Centering in the Unknown' on his blog. It's a roundup of multiple solutions. I posted one that isn't posted in this question. It has more browser support than the Flexbox solution, and you're not using display: table; which could break other things.
/* This parent can be any width and height */
.outer {
text-align: center;
}
/* The ghost, nudged to maintain perfect centering */
.outer:before {
content: '.';
display: inline-block;
height: 100%;
vertical-align: middle;
width: 0;
overflow: hidden;
}
/* The element to be centered, can
also be of any width and height */
.inner {
display: inline-block;
vertical-align: middle;
width: 300px;
}
I recently found an approach:
#outer {
position: absolute;
left: 50%;
}
#inner {
position: relative;
left: -50%;
}
Both elements must be the same width to function correctly.
For example, see this link and the snippet below:
div#outer {
height: 120px;
background-color: red;
}
div#inner {
width: 50%;
height: 100%;
background-color: green;
margin: 0 auto;
text-align: center; /* For text alignment to center horizontally. */
line-height: 120px; /* For text alignment to center vertically. */
}
<div id="outer" style="width:100%;">
<div id="inner">Foo foo</div>
</div>
If you have a lot of children under a parent, so your CSS content must be like this example on fiddle.
The HTML content look likes this:
<div id="outer" style="width:100%;">
<div class="inner"> Foo Text </div>
<div class="inner"> Foo Text </div>
<div class="inner"> Foo Text </div>
<div class="inner"> </div>
<div class="inner"> </div>
<div class="inner"> </div>
<div class="inner"> </div>
<div class="inner"> </div>
<div class="inner"> Foo Text </div>
</div>
Then see this example on fiddle.
Centering only horizontally
In my experience, the best way to center a box horizontally is to apply the following properties:
The container:
should have text-align: center;
The content box:
should have display: inline-block;
Demo:
.container {
width: 100%;
height: 120px;
background: #CCC;
text-align: center;
}
.centered-content {
display: inline-block;
background: #FFF;
padding: 20px;
border: 1px solid #000;
}
<div class="container">
<div class="centered-content">
Center this!
</div>
</div>
See also this Fiddle!
Centering both horizontally & vertically
In my experience, the best way to center a box both vertically and horizontally is to use an additional container and apply the following properties:
The outer container:
should have display: table;
The inner container:
should have display: table-cell;
should have vertical-align: middle;
should have text-align: center;
The content box:
should have display: inline-block;
Demo:
.outer-container {
display: table;
width: 100%;
height: 120px;
background: #CCC;
}
.inner-container {
display: table-cell;
vertical-align: middle;
text-align: center;
}
.centered-content {
display: inline-block;
background: #FFF;
padding: 20px;
border: 1px solid #000;
}
<div class="outer-container">
<div class="inner-container">
<div class="centered-content">
Center this!
</div>
</div>
</div>
See also this Fiddle!
Flexbox
display: flex behaves like a block element and lays out its content according to the flexbox model. It works with justify-content: center.
Please note: Flexbox is compatible all browsers exept Internet Explorer. See display: flex not working on Internet Explorer for a complete and up to date list of browsers compatibility.
#inner {
display: inline-block;
}
#outer {
display: flex;
justify-content: center;
}
<div id="outer">
<div id="inner">Foo foo</div>
</div>
Text-align: center
Applying text-align: center the inline contents are centered within the line box. However since the inner div has by default width: 100% you have to set a specific width or use one of the following:
display: block
display: inline
display: inline-block
#inner {
display: inline-block;
}
#outer {
text-align: center;
}
<div id="outer">
<div id="inner">Foo foo</div>
</div>
Margin: 0 auto
Using margin: 0 auto is another option and it is more suitable for older browsers compatibility. It works together with display: table.
#inner {
display: table;
margin: 0 auto;
}
<div id="outer">
<div id="inner">Foo foo</div>
</div>
Transform
transform: translate lets you modify the coordinate space of the CSS visual formatting model. Using it, elements can be translated, rotated, scaled, and skewed. To center horizontally it require position: absolute and left: 50%.
#inner {
position: absolute;
left: 50%;
transform: translate(-50%, 0%);
}
<div id="outer">
<div id="inner">Foo foo</div>
</div>
<center> (Deprecated)
The tag <center> is the HTML alternative to text-align: center. It works on older browsers and most of the new ones but it is not considered a good practice since this feature is obsolete and has been removed from the Web standards.
#inner {
display: inline-block;
}
<div id="outer">
<center>
<div id="inner">Foo foo</div>
</center>
</div>
This method also works just fine:
div.container {
display: flex;
justify-content: center; /* For horizontal alignment */
align-items: center; /* For vertical alignment */
}
For the inner <div>, the only condition is that its height and width must not be larger than the ones of its container.
The easiest way:
#outer {
width: 100%;
text-align: center;
}
#inner {
margin: auto;
width: 200px;
}
<div id="outer">
<div id="inner">Blabla</div>
</div>
Flex have more than 97% browser support coverage and might be the best way to solve these kind of problems within few lines:
#outer {
display: flex;
justify-content: center;
}
If width of the content is unknown you can use the following method. Suppose we have these two elements:
.outer -- full width
.inner -- no width set (but a max-width could be specified)
Suppose the computed width of the elements are 1000 pixels and 300 pixels respectively. Proceed as follows:
Wrap .inner inside .center-helper
Make .center-helper an inline block; it becomes the same size as .inner making it 300 pixels wide.
Push .center-helper 50% right relative to its parent; this places its left at 500 pixels wrt. outer.
Push .inner 50% left relative to its parent; this places its left at -150 pixels wrt. center helper which means its left is at 500 - 150 = 350 pixels wrt. outer.
Set overflow on .outer to hidden to prevent horizontal scrollbar.
Demo:
body {
font: medium sans-serif;
}
.outer {
overflow: hidden;
background-color: papayawhip;
}
.center-helper {
display: inline-block;
position: relative;
left: 50%;
background-color: burlywood;
}
.inner {
display: inline-block;
position: relative;
left: -50%;
background-color: wheat;
}
<div class="outer">
<div class="center-helper">
<div class="inner">
<h1>A div with no defined width</h1>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.<br>
Duis condimentum sem non turpis consectetur blandit.<br>
Donec dictum risus id orci ornare tempor.<br>
Proin pharetra augue a lorem elementum molestie.<br>
Nunc nec justo sit amet nisi tempor viverra sit amet a ipsum.</p>
</div>
</div>
</div>
You can do something like this
#container {
display: table;
width: <width of your container>;
height: <height of your container>;
}
#inner {
width: <width of your center div>;
display: table-cell;
margin: 0 auto;
text-align: center;
vertical-align: middle;
}
This will also align the #inner vertically. If you don't want to, remove the display and vertical-align properties;
Here is what you want in the shortest way.
JSFIDDLE
#outer {
margin - top: 100 px;
height: 500 px; /* you can set whatever you want */
border: 1 px solid# ccc;
}
#inner {
border: 1 px solid# f00;
position: relative;
top: 50 % ;
transform: translateY(-50 % );
}
You can use display: flex for your outer div and to horizontally center you have to add justify-content: center
#outer{
display: flex;
justify-content: center;
}
or you can visit w3schools - CSS flex Property for more ideas.
Well, I managed to find a solution that maybe will fit all situations, but uses JavaScript:
Here's the structure:
<div class="container">
<div class="content">Your content goes here!</div>
<div class="content">Your content goes here!</div>
<div class="content">Your content goes here!</div>
</div>
And here's the JavaScript snippet:
$(document).ready(function() {
$('.container .content').each( function() {
container = $(this).closest('.container');
content = $(this);
containerHeight = container.height();
contentHeight = content.height();
margin = (containerHeight - contentHeight) / 2;
content.css('margin-top', margin);
})
});
If you want to use it in a responsive approach, you can add the following:
$(window).resize(function() {
$('.container .content').each( function() {
container = $(this).closest('.container');
content = $(this);
containerHeight = container.height();
contentHeight = content.height();
margin = (containerHeight - contentHeight) / 2;
content.css('margin-top', margin);
})
});
One option existed that I found:
Everybody says to use:
margin: auto 0;
But there is another option. Set this property for the parent div. It
works perfectly anytime:
text-align: center;
And see, child go center.
And finally CSS for you:
#outer{
text-align: center;
display: block; /* Or inline-block - base on your need */
}
#inner
{
position: relative;
margin: 0 auto; /* It is good to be */
}

How to show load spinner for particular div content load instead of whole page load

I have some web page to fetch the user related data and huge count of images. The problem is while load the page it took more time due to images , Images are rendered in separate div in the page. So i want loader spinner for that particular div.
Note: I know how to implement for page load. Just need for particular div.
Just look the below my implementation idea.
<body>
<div id="divUserContent">
</div>
<div id="divuserimages">
</div>
</body>
Just make sure the parent element to the loading element has a position set to relative. See this example below.
body {
margin: 0px;
font-size: 16px;
}
.container {
background: rgba(0,0,0,.2);
height: 100vh;
align-items: center;
justify-content: center;
display: flex;
position: relative;
}
.loading-container {
padding: 10rem;
border: 1px solid #000;
position: relative; /* this keeps .loading-text inside it */
width: 5rem;
}
.loading-text {
position: absolute;
top: 50%;
left: 50%;
margin-top: -9px; /* take .loading-text height, divide by -2 */
margin-left: -35px; /* take .loading-text width, dividide by -2*/
}
<div class="container">
<div class="loading-container">
<div class="loading-text">Loading...</div>
</div>
</div>

CSS performance issue during manual resizing of a div

I have a div that acts as drawer that the user can pull down from the top of the window, that contains a dozen of buttons with some styling.
the code for expanding/collapsing that div while pulling on it is:
drawer.style.height = `${Math.min(drawerParams.maxheight,drawerParams.startHeight + event.y - drawerParams.startY)}px`;
It works fine on a computer, but I have serious lagging on a mobile phone. Here is a picture of the chrome devtools for mobile devices:
Here is the structure and CSS for that layout:
<style>
.main {
position: relative;
width: 100%;
height: 100%;
}
.drawer {
position: absolute;
top: 0;
width: 100vw;
background-color: lightgreen;
min-height: 7px;
z-index: 4;
}
.drawer-content {
position: absolute;
bottom: 7px;
display: flex;
flex-wrap: wrap-reverse;
justify-content: space-between;
}
.handle {
position: absolute;
width: 100%;
bottom: 0;
height: 7px;
}
</style>
<div class="main">
<div class="drawer">
<div class="drawer-content">
<div class="button">button1</div>
<div class="button">button2</div>
<div class="button">button3</div>
<div class="button">button...</div>
<div class="button">button10</div>
</div>
<div class="handle">
<!-- some svg -->
</div>
</div>
</div>
If I set the initial drawer's position to "top:200px", I see that the content is already there, and when pulling on it from that position, I have the same performance issues.
I tried to use transform:translateY() like in this article:link, but it had no effect. (I assume it is because instead of having one translate from the begining of the transition to the end, I have one for each pixel of mouse movement..?)
So the questions are (from the picture):
1: is the browser repainting the div each time the drawer element's height changes?
2: why?
3: what can I change to avoid that?

How to keep my custom range/slider follower div perfectly centered with range thumb in Vanilla JavaScript

I've spent some time working on a slider that has a div follow the thumb of slider. I did this by creating a relatively positioned container for the follower (called #slider-follower-cntnr). I then adjust the position of the follower div (#slider-follower) according to the value of the range input. The problem is that as you move the thumb across the track the follower does not stay perfectly centered against the position of the thumb. I've tried adjusting the width of the #slider-follower-cntnr but I don't no how to find the correct width to keep it perfectly centered. Thanks for any help.
TL/DR: How can I keep follower div centered perfectly to the thumb of the range input across all range values?
Heres a codepen. You may need to full screen to see it get off center as you pull it along the range.
HTML
<div id="slider-cntnr">
<input type="range" id="frame-slider" oninput="updateFollowerValue(this.value)" />
<div id="slider-follow-cntnr">
<div id="slider-follow">
<div id="slider-val-cntnr">
<span id="slider-val"></span>
</div>
</div>
</div>
</div>
JS
var follower = document.getElementById('slider-follow');
var follower_val = document.getElementById('slider-val');
var slider = document.getElementById('frame-slider');
var updateFollowerValue = function(val) {
follower_val.innerHTML = val;
follower.style.left = (val*1) + '%';
};
updateFollowerValue(slider.value);
CSS
html, body {
width: 100%;
height: 100%;
}
#slider-cntnr {
width: 80%;
margin: 40px;
position: relative;
display: flex;
flex-direction: column;
background: orange;
}
#frame-slider {
width: 100%;
margin: 0;
}
#slider-follow-cntnr {
position: relative;
background-color: blue;
height: 10px;
margin: 0 auto;
width: 98%;
}
#slider-follow {
background-color: black;
width: 30px;
height: 50px;
display: flex;
justify-content: center;
align-items: center;
position: absolute;
margin-left: -15px;
}
#slider-val-cntnr {
background-color: white;
width: 25px;
height: 20px;
}
#slider-val {
margin-left: 9px;
}
Few ways you can fix this:
(1) In the HTML
<div id="slider-val-cntnr">
<center>
<span id="slider-val"></span>
</center>
</div>
(2) In the CSS
#slider-val {
margin-left: auto;
margin-right: auto;
}
(1) The HTML method probably works the best, but it's generally not best practice to have <center> tags throughout your HTML.
(2) This will make sure that the number never goes beyond the bounds of the white box that it resides in. If you don't care that it is absolutely centered, and just want the number to not exit the box, then this is a suitable solution.

How to center an image created in Javascript?

I have this very simple code, the problem is it doesn't give the same output using Firefox and IE: in Firefox, the images are superposed but right-aligned, and in IE they are superposed and left aligned.
What I want is that the images will be centered and superposed.
I have to create images using Javascript to use a special library in creating the images.
Thank you for your help.
HTML
<body>
<div id="Container">
<script type="text/javascript">
document.write('<img id="image1" src="image1.jpg">')
document.write('<img id="image1" src="image2.jpg">')
</script>
</div>
</body>
CSS
body {
text-align: center;
background-color: #e8e6e7;
margin-left: auto;
margin-right: auto;
}
#Container {
position: relative;
text-align: center;
margin-left: auto;
margin-right: auto;
}
#image1 {
position : absolute;
margin-left: auto;
margin-right: auto;
}
#image2 {
position : absolute;
margin-left: auto;
margin-right: auto;
}
Since you are making #image1 and #image2 be absolutely positionined, they will not adjust the width/height of the #Container. This means you can't center it, because it doesn't have the proportions to center.
The code below makes only one image be absolutely positioned. This lets your other image act as expected. You can do whatever you want with the "overlay" image.
I also included z-index, which can let you change the order of the images. This isn't necessary for this example, but if you add more images, it may be useful.
HTML
<div id="Container">
<div class="image-wrap">
<img id="image1" src="http://dummyimage.com/200x200/fa00fa/fff.png"/>
<img id="image2" src="http://dummyimage.com/200x200/00ff33/000000.png"/>
</div>
</div>
CSS
#Container .image-wrap {
position: relative;
display: inline-block;
}
#image1 {
position : relative;
z-index: 10;
}
#image2 {
position : absolute; /* Different than #image1 */
z-index: 20; /* On top of #image2 */
top: 0;
left: 0;
/* Assuming width/height of both images are the same */
}
JS Fiddle
http://jsfiddle.net/n496j/1/
First change second image id to image2.
2 tricks for centering your images is:
add one of these classes to your images:
.center {
display: block; /*can remove this line*/
margin: 0 auto;
left: 0;
right: 0;
}
.center {
left: 50%;
margin-left: -[your image width / 2]
}
Use the css
img{ display:block; margin: auto; }
well, it will help if the images would sit in some container with text-align:center;.
something like this:
// body can be be replaced with any element which contains the images
body{ text-align:center; }
body > img{ display:inline-block; max-width:49%; }
Demo page:
http://jsbin.com/hehot/1/edit

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