Develop Reference

CSS position elements along ring of a circle [duplicate]

How can I position several <img> elements into a circle around another and have those elements all be clickable links as well? I want it to look like the picture below, but I have no idea how to achieve that effect.
Is this even possible?

2020 solution
Here's a more modern solution I use these days.
I start off by generating the HTML starting from an array of images. Whether the HTML is generated using PHP, JS, some HTML preprocessor, whatever... this matters less as the basic idea behind is the same.
Here's the Pug code that would do this:
//- start with an array of images, described by url and alt text
- let imgs = [
- {
- src: 'image_url.jpg',
- alt: 'image alt text'
- } /* and so on, add more images here */
- ];
- let n_imgs = imgs.length;
- let has_mid = 1; /* 0 if there's no item in the middle, 1 otherwise */
- let m = n_imgs - has_mid; /* how many are ON the circle */
- let tan = Math.tan(Math.PI/m); /* tangent of half the base angle */
.container(style=`--m: ${m}; --tan: ${+tan.toFixed(2)}`)
- for(let i = 0; i < n_imgs; i++)
a(href='#' style=i - has_mid >= 0 ? `--i: ${i}` : null)
img(src=imgs[i].src alt=imgs[i].alt)
The generated HTML looks as follows (and yes, you can write the HTML manually too, but it's going to be a pain to make changes afterwards):
<div class="container" style="--m: 8; --tan: 0.41">
<a href='#'>
<img src="image_mid.jpg" alt="alt text"/>
</a>
<a style="--i: 1">
<img src="first_img_on_circle.jpg" alt="alt text"/>
</a>
<!-- the rest of those placed on the circle -->
</div>
In the CSS, we decide on a size for the images, let's say 8em. The --m items are positioned on a circle and it's if they're in the middle of the edges of a polygon of --m edges, all of which are tangent to the circle.
If you have a hard time picturing that, you can play with this interactive demo which constructs the incircle and circumcircle for various polygons whose number of edges you pick by dragging the slider.
This tells us that the size of the container must be twice the radius of the circle plus twice half the size of the images.
We don't yet know the radius, but we can compute it if we know the number of edges (and therefore the tangent of half the base angle, precomputed and set as a custom property --tan) and the polygon edge. We probably want the polygon edge to be a least the size of the images, but how much we leave on the sides is arbitrary. Let's say we have half the image size on each side, so the polygon edge is twice the image size. This gives us the following CSS:
.container {
--d: 6.5em; /* image size */
--rel: 1; /* how much extra space we want between images, 1 = one image size */
--r: calc(.5*(1 + var(--rel))*var(--d)/var(--tan)); /* circle radius */
--s: calc(2*var(--r) + var(--d)); /* container size */
position: relative;
width: var(--s); height: var(--s);
background: silver /* to show images perfectly fit in container */
}
.container a {
position: absolute;
top: 50%; left: 50%;
margin: calc(-.5*var(--d));
width: var(--d); height: var(--d);
--az: calc(var(--i)*1turn/var(--m));
transform:
rotate(var(--az))
translate(var(--r))
rotate(calc(-1*var(--az)))
}
img { max-width: 100% }
See the old solution for an explanation of how the transform chain works.
This way, adding or removing an image from the array of images automatically arranges the new number of images on a circle such that they're equally spaced out and also adjusts the size of the container. You can test this in this demo.
OLD solution (preserved for historical reasons)
Yes, it is very much possible and very simple using just CSS. You just need to have clear in mind the angles at which you want the links with the images (I've added a piece of code at the end just for showing the angles whenever you hover one of them).
You first need a wrapper. I set its diameter to be 24em (width: 24em; height: 24em; does that), you can set it to whatever you want. You give it position: relative;.
You then position your links with the images in the center of that wrapper, both horizontally and vertically. You do that by setting position: absolute; and then top: 50%; left: 50%; and margin: -2em; (where 2em is half the width of the link with the image, which I've set to be 4em - again, you can change it to whatever you wish, but don't forget to change the margin in that case).
You then decide on the angles at which you want to have your links with the images and you add a class deg{desired_angle} (for example deg0 or deg45 or whatever). Then for each such class you apply chained CSS transforms, like this:
.deg{desired_angle} {
transform: rotate({desired_angle}) translate(12em) rotate(-{desired_angle});
}
where you replace {desired_angle} with 0, 45, and so on...
The first rotate transform rotates the object and its axes, the translate transform translates the object along the rotated X axis and the second rotate transform brings back the object into position.
The advantage of this method is that it is flexible. You can add new images at different angles without altering the current structure.
CODE SNIPPET
.circle-container {
position: relative;
width: 24em;
height: 24em;
padding: 2.8em;
/*2.8em = 2em*1.4 (2em = half the width of a link with img, 1.4 = sqrt(2))*/
border: dashed 1px;
border-radius: 50%;
margin: 1.75em auto 0;
}
.circle-container a {
display: block;
position: absolute;
top: 50%; left: 50%;
width: 4em; height: 4em;
margin: -2em;
}
.circle-container img { display: block; width: 100%; }
.deg0 { transform: translate(12em); } /* 12em = half the width of the wrapper */
.deg45 { transform: rotate(45deg) translate(12em) rotate(-45deg); }
.deg135 { transform: rotate(135deg) translate(12em) rotate(-135deg); }
.deg180 { transform: translate(-12em); }
.deg225 { transform: rotate(225deg) translate(12em) rotate(-225deg); }
.deg315 { transform: rotate(315deg) translate(12em) rotate(-315deg); }
<div class='circle-container'>
<a href='#' class='center'><img src='image.jpg'></a>
<a href='#' class='deg0'><img src='image.jpg'></a>
<a href='#' class='deg45'><img src='image.jpg'></a>
<a href='#' class='deg135'><img src='image.jpg'></a>
<a href='#' class='deg180'><img src='image.jpg'></a>
<a href='#' class='deg225'><img src='image.jpg'></a>
<a href='#' class='deg315'><img src='image.jpg'></a>
</div>
Also, you could further simplify the HTML by using background images for the links instead of using img tags.
EDIT: example with fallback for IE8 and older (tested in IE8 and IE7)

Here is the easy solution without absolute positioning:
.container .row {
margin: 20px;
text-align: center;
}
.container .row img {
margin: 0 20px;
}
<div class="container">
<div class="row">
<img src="https://ssl.gstatic.com/s2/oz/images/faviconr2.ico" alt="" width="64" height="64">
<img src="https://ssl.gstatic.com/s2/oz/images/faviconr2.ico" alt="" width="64" height="64">
</div>
<div class="row">
<img src="https://ssl.gstatic.com/s2/oz/images/faviconr2.ico" alt="" width="64" height="64">
<img src="https://ssl.gstatic.com/s2/oz/images/faviconr2.ico" alt="" width="64" height="64">
<img src="https://ssl.gstatic.com/s2/oz/images/faviconr2.ico" alt="" width="64" height="64">
</div>
<div class="row">
<img src="https://ssl.gstatic.com/s2/oz/images/faviconr2.ico" alt="" width="64" height="64">
<img src="https://ssl.gstatic.com/s2/oz/images/faviconr2.ico" alt="" width="64" height="64">
</div>
</div>
http://jsfiddle.net/mD6H6/

Using the solution proposed by #Ana:
transform: rotate(${angle}deg) translate(${radius}px) rotate(-${angle}deg)
I created the following jsFiddle that places circles dynamically using plain JavaScript (jQuery version also available).
The way it works is rather simple:
document.querySelectorAll( '.ciclegraph' ).forEach( ( ciclegraph )=>{
let circles = ciclegraph.querySelectorAll( '.circle' )
let angle = 360-90, dangle = 360 / circles.length
for( let i = 0; i < circles.length; ++i ){
let circle = circles[i]
angle += dangle
circle.style.transform = `rotate(${angle}deg) translate(${ciclegraph.clientWidth / 2}px) rotate(-${angle}deg)`
}
})
.ciclegraph {
position: relative;
width: 500px;
height: 500px;
margin: calc(100px / 2 + 0px);
}
.ciclegraph:before {
content: "";
position: absolute;
top: 0; left: 0;
border: 2px solid teal;
width: calc( 100% - 2px * 2);
height: calc( 100% - 2px * 2 );
border-radius: 50%;
}
.ciclegraph .circle {
position: absolute;
top: 50%; left: 50%;
width: 100px;
height: 100px;
margin: calc( -100px / 2 );
background: teal;
border-radius: 50%;
}
<div class="ciclegraph">
<div class="circle"></div>
<div class="circle"></div>
<div class="circle"></div>
<div class="circle"></div>
<div class="circle"></div>
<div class="circle"></div>
</div>

Building off #Ana's excellent answer, I created this dynamic version that allows you to add and remove elements from the DOM and maintain proportionate spacing between the elements - check out my fiddle: https://jsfiddle.net/skwidbreth/q59s90oy/
var list = $("#list");
var updateLayout = function(listItems) {
for (var i = 0; i < listItems.length; i++) {
var offsetAngle = 360 / listItems.length;
var rotateAngle = offsetAngle * i;
$(listItems[i]).css("transform", "rotate(" + rotateAngle + "deg) translate(0, -200px) rotate(-" + rotateAngle + "deg)")
};
};
$(document).on("click", "#add-item", function() {
var listItem = $("<li class='list-item'>Things go here<button class='remove-item'>Remove</button></li>");
list.append(listItem);
var listItems = $(".list-item");
updateLayout(listItems);
});
$(document).on("click", ".remove-item", function() {
$(this).parent().remove();
var listItems = $(".list-item");
updateLayout(listItems);
});
#list {
background-color: blue;
height: 400px;
width: 400px;
border-radius: 50%;
position: relative;
}
.list-item {
list-style: none;
background-color: red;
height: 50px;
width: 50px;
position: absolute;
top: 50%;
left: 50%;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<ul id="list"></ul>
<button id="add-item">Add item</button>

Here is a version I made in React from the examples here.
CodeSandbox Example
import React, { useRef, useEffect } from "react";
import "./styles.css";
export default function App() {
const graph = useRef(null);
useEffect(() => {
const ciclegraph = graph.current;
const circleElements = ciclegraph.childNodes;
let angle = 360 - 90;
let dangle = 360 / circleElements.length;
for (let i = 0; i < circleElements.length; i++) {
let circle = circleElements[i];
angle += dangle;
circle.style.transform = `rotate(${angle}deg) translate(${ciclegraph.clientWidth /
2}px) rotate(-${angle}deg)`;
}
}, []);
return (
<div className="App">
<div className="ciclegraph" ref={graph}>
<div className="circle" />
<div className="circle" />
<div className="circle" />
<div className="circle" />
<div className="circle" />
<div className="circle" />
</div>
</div>
);
}

You can certainly do it with pure css or use JavaScript. My suggestion:
If you already know that the images number will never change just calculate your styles and go with plain css (pros: better performances, very reliable)
If the number can vary either dynamically in your app or just may vary in the future go with a Js solution (pros: more future-proof)
I had a similar job to do, so I created a script and open sourced it here on Github for anyone who might need it. It just accepts some configuration values and simply outputs the CSS code you need.
If you want to go for the Js solution here's a simple pointer that can be useful to you. Using this html as a starting point being #box the container and .dot the image/div in the middle you want all your other images around:
Starting html:
<div id="box">
<div class="dot"></div>
<img src="my-img.jpg">
<!-- all the other images you need-->
</div>
Starting Css:
#box{
width: 400px;
height: 400px;
position: relative;
border-radius: 100%;
border: 1px solid teal;
}
.dot{
position: absolute;
border-radius: 100%;
width: 40px;
height: 40px;
left: 50%;
top: 50%;
margin-left: -20px;
margin-top: -20px;
background: rebeccapurple;
}
img{
width: 40px;
height: 40px;
position: absolute;
}
You can create a quick function along these lines:
var circle = document.getElementById('box'),
imgs = document.getElementsByTagName('img'),
total = imgs.length,
coords = {},
diam, radius1, radius2, imgW;
// get circle diameter
// getBoundingClientRect outputs the actual px AFTER transform
// using getComputedStyle does the job as we want
diam = parseInt( window.getComputedStyle(circle).getPropertyValue('width') ),
radius = diam/2,
imgW = imgs[0].getBoundingClientRect().width,
// get the dimensions of the inner circle we want the images to align to
radius2 = radius - imgW
var i,
alpha = Math.PI / 2,
len = imgs.length,
corner = 2 * Math.PI / total;
// loop over the images and assign the correct css props
for ( i = 0 ; i < total; i++ ){
imgs[i].style.left = parseInt( ( radius - imgW / 2 ) + ( radius2 * Math.cos( alpha ) ) ) + 'px'
imgs[i].style.top = parseInt( ( radius - imgW / 2 ) - ( radius2 * Math.sin( alpha ) ) ) + 'px'
alpha = alpha - corner;
}
You can see a live example here

There is no way to magically place clickable items in a circle around another element with CSS.
The way how I would do this is by using a container with position:relative;. And then place all the elements with position:absolute; and using top and left to target it's place.
Even though you haven't placed jquery in your tags it might be best to use jQuery / javascript for this.
First step is placing your center image perfectly in the center of the container using position:relative;.
#centerImage {
position:absolute;
top:50%;
left:50%;
width:200px;
height:200px;
margin: -100px 0 0 -100px;
}
After that you can place the other elements around it by using an offset() of the centerImage minus the offset() of the container. Giving you the exact top and left of the image.
var left = $('#centerImage').offset().left - $('#centerImage').parent().offset().left;
var top = $('#centerImage').offset().top - $('#centerImage').parent().offset().top;
$('#surroundingElement1').css({
'left': left - 50,
'top': top - 50
});
$('#surroundingElement2').css({
'left': left - 50,
'top': top
});
$('#surroundingElement3').css({
'left': left - 50,
'top': top + 50
});
What I've done here is placing the elements relative to the centerImage. Hope this helps.

You could do it like this: fiddle
Don't mind the positioning, its a quick example

The first step is to have 6 long columnar boxes:
The second step is to use position: absolute and move them all into the middle of your container:
And now rotate them around the pivot point located at the bottom center. Use :nth-child to vary rotation angles:
div {
transform-origin: bottom center;
#for $n from 0 through 7 {
&:nth-child(#{$n}) {
rotate: (360deg / 6) * $n;
}
}
Now all you have to do is to locate your images at the far end of every column, and compensate the rotation with an anti-rotation :)
Full source:
<div class="flower">
<div class="petal">1</div>
<div class="petal">2</div>
<div class="petal">3</div>
<div class="petal">4</div>
<div class="petal">5</div>
<div class="petal">6</div>
</div>
.flower {
width: 300px;
height: 300px;
// We need a relative position
// so that children can have "position:abolute"
position: relative;
.petal {
// Make sure petals are visible
border: 1px solid #999;
// Position them all in one point
position: absolute; top: 0; left: 50%;
display: inline-block;
width: 30px; height: 150px;
// Rotation
transform-origin: bottom center;
#for $n from 0 through 7 {
&:nth-child(#{$n}) {
// Petal rotation
$angle: (360deg / 6) * $n;
rotate: $angle;
// Icon anti-rotation
.icon { rotate: -$angle; }
}
}
}
}
See CodePen

How to not make div stack?

I am using this code to make the images and text move around the screen. My problem is that sometimes the images and text land on eachother and stack up, how do i make it so its not possible to land on eachother?
$(document).ready(function() {
animateDiv('.a');
animateDiv('.b');
animateDiv('.c');
animateDiv('.d');
animateDiv('.e');
animateDiv('.f');
animateDiv('.g');
animateDiv('.h');
animateDiv('.i');
});
function makeNewPosition() {
var h = $(window).height() - 60;
var w = $(window).width() - 60;
var nh = Math.floor(Math.random() * h);
var nw = Math.floor(Math.random() * w);
return [nh, nw];
}
function animateDiv(myclass) {
var newq = makeNewPosition();
$(myclass).animate({
top: newq[0],
left: newq[1]
}, 2000, function() {
animateDiv(myclass);
});
};
div.a {
width: 50px;
height: 50px;
position: fixed;
color: Navy;
}
div.b {
width: 50px;
height: 50px;
position: fixed;
color: red;
}
div.c {
width: 50px;
height: 50px;
position: fixed;
color: Fuchsia;
}
div.d {
width: 50px;
height: 50px;
position: fixed;
color: SpringGreen;
}
div.e {
position: fixed;
}
div.f {
position: fixed;
}
div.g {
position: fixed;
}
div.h {
position: fixed;
}
div.i {
position: fixed;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class='a'>MOCKO</div>
<div class='b'>MOCKO</div>
<div class='c'>MOCKO</div>
<div class='d'>MOCKO</div>
<div class='e'><img src="image/image1.png"></div>
<div class='f'><img src="image/image2.png"></div>
<div class='g'><img src="image/image3.png"></div>
<div class='h'><img src="image/image4.png"></div>
<div class='i'><img src="image/image5.png"></div>
Thanks beforehand, if you can help me, please do! My name is Lukas and I am not so good at coding.

So you are effectively randomly placing fixed elements on the screen, that's why they overlap occasionally.
There are several different ways to prevent that, but it just depends on what your end goal is.
If you really want the random placement approach without overlaps, you will have to run a check in makeNewPosition against all existing locations to determine if their coordinates are overlapping, and if so then regenerate coordinates. You would need to determine the edges of both the new placement and the old placement then compare them.
Personally, I think that will be a fragile and overly complicated way to do things. I would encourage you to look at other possible solutions other than the random generation, perhaps a different layout.
Also #hungerstar has a great comment. This is essentially collision detection. It can get heavily involved to do this well and answer your particular problems.
Here is a helpful SO link that explains a basic approach: jQuery/JavaScript collision detection
And here is a working example on jsfiddle: https://jsfiddle.net/ryanoc/TG2M7/
I can dive into a specific use case if you'd like. Not sure what all to post since I'm not sure what your end goal is.

Make div fly with animation to another DOM position

I am moving an <img> element (the octopus) from the large gray <div> above (#large) to the small orange <div> below (#small) using
$(document).on("click", "#large > img", function() {
$(this).appendTo("#small");
});
This works great but I want it to transition smoothly and to 'fly' over so it will slowly interpolate its coordinates and size.
I tried adding a CSS transition
img { transition: all 3s; }
to my <img>, but that won't work as the image is readded to the DOM and not moved.
How can such animation be established?
JS Fiddle

Using the jQuery .append method won't allow you to animate the element between the 2 states.
Here is an example with an animation using CSS transition and the scale() function. This example also uses the transform-origin property to change the position the of the image on the "big" state. Fiddle here.
$(document).on("click", "img", function() {
$(this).toggleClass("big");
});
div {
margin: 20px;
padding: 10px;
}
#large {
width: 600px;
height: 400px;
background-color: gray;
}
#small {
width: 120px;
height: 90px;
background-color: orange;
}
img {
width: 100%;
height: 100%;
transition: transform .3s ease-out;
transform-origin: 0 129px;
}
img.big {
transform: scaleX(5) scaleY(4.4);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="large">
</div>
<div id="small">
<img src="https://ak.picdn.net/assets/cms/5bb580387901a83212e3028ab5a2fa8fb1153d7b-img_offset_2x.jpg" />
</div>
Note that :
you will need to add vendor prefixes to the transition, transform and transform-origin properties depending on the browsers you need to support.
this technique relies on the fact you are using hard values (in pixels). It would be possible to make this responsive (using percent values for widths, margins and paddings) but it will need more calculations.

i made a responsive solution ( so i think ) using JQ . check it out below or in jsFiddle
first i cached all the necessary selectors for cleaner and concise code .
the -20 is because of the div { margin-top:20px}`
there i calculated the TOP offset of both divs in relation to the document, then got the width and height of the small div
in the click function first i got the image's top offset so i could compare that with the #small's offset .
so if the image's distance to top is smaller than the #small's distance to top, it means that the img is in the #large div and so i move it using transform:translate giving it an Y-axis value equal to the TOP offset of the #small Div, so the img offset.top ( iOffset ) will become equal to the #small offset.top ( sOffset )
also adding width and height of the #small div to the image
else ( if iOffset is = or bigger than sOffset ) then it means that the image is not in the large div, so i need to translate it back to the offset of the #large div and add width:100% and height:100%
hope i got it right and explained correctly.
let me know if it helps
var Large = $("#large"),
Small = $("#small"),
lOffset = $(Large).offset().top - 20 + 'px',
sOffset = $(Small).offset().top - 20 + 'px',
sWidth = $(Small).width(),
sHeight = $(Small).height()
$(document).on("click", "img", function() {
var iOffset = $(this).offset().top + 'px'
if (iOffset < sOffset) {
$(this).css('transform', 'translate(0,' + sOffset + ')')
.width(sWidth).height(sHeight)
} else {
$(this).css('transform', 'translate(0,' + lOffset + ')')
.width("100%").height("100%")
}
})
div {
margin: 20px;
padding: 10px;
}
#large {
width: 600px;
height: 400px;
background-color: gray;
}
#small {
width: 120px;
height: 90px;
background-color: orange;
}
img {
width: 100%;
height: 100%;
transition: 5s;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="large">
<img src="https://ak.picdn.net/assets/cms/5bb580387901a83212e3028ab5a2fa8fb1153d7b-img_offset_2x.jpg" />
</div>
<div id="small">
</div>

You need to compute the current dimensions of the image, the target dimensions, and calculate the needed transform.
To make it easier, I will calculate the transform needed to make the new element (the cloned one) look like it is still at the current position.
Later, a standard animation (that just resets scale and position) will do the trick.
I avoided using jQuery so the solution is easier to port
function func (target) {
var image = document.getElementById('image');
var current = image.parentNode;
var rectImage = current.getBoundingClientRect();
var rectTarget = target.getBoundingClientRect();
evalRect (rectImage);
evalRect (rectTarget);
var scaleX = rectImage.width / rectTarget.width;
var scaleY = rectImage.height / rectTarget.height;
var translateX = rectImage.centerX - rectTarget.centerX;
var translateY = rectImage.centerY - rectTarget.centerY;
var dup = image.cloneNode();
var scale = 'scale(' + scaleX + ', ' + scaleY + ') ';
var translate = 'translate(' + translateX + 'px, ' + translateY + 'px) ';
target.appendChild(dup);
dup.style.transform = translate + scale;
current.removeChild(image);
}
function evalRect (rect) {
rect.centerX = rect.left + rect.width * 0.5;
rect.centerY = rect.top + rect.height * 0.5;
}
.container {
border: solid 1px black;
position: relative;
display: inline-block;
}
#container1 {
width: 200px;
height: 100px;
}
#container2 {
width: 400px;
height: 200px;
}
#container3 {
width: 200px;
height: 200px;
}
#image {
background: linear-gradient(45deg, yellow, tomato);
width: 100%;
height: 100%;
position: absolute;
left: 0px;
top: 0px;
animation: adjust 1s forwards;
}
#keyframes adjust {
to {transform: translate(0px, 0px);}
}
<div id="container1" class="container" onclick="func(this)">click me
<div id="image"></div>
</div>
<div id="container2" class="container" onclick="func(this)">click me</div>
<div id="container3" class="container" onclick="func(this)">click me</div>

appendto do not accept animations, but this question maybe helpful for you
appendTo() animation

Just add a transition and change the size and position to match the target. On the transitionend event, append the image to the target element.
// when transition completes
$('img').on('webkitTransitionEnd otransitionend oTransitionEnd msTransitionEnd transitionend', function(){
// place in container
$('#target').append($('img'));
// set to corner of container
$('img').css({
top: '0',
left: '0'
});
});
// position in corner of target and make size the same
$('img').css({
position: 'absolute',
top: $('#target').offset().top + 'px',
left: $('#target').offset().left + 'px',
height: $('#target').css('height'),
width: $('#target').css('width')
});
#target {
height: 150px;
width: 150px;
border: 1px solid grey;
position: absolute;
top: 350px;
left: 5px;
z-index: 1;
}
img {
position: absolute;
top: 0;
left: 5px;
transition: all 1s;
height: 300px;
width: 300px;
z-index: 5;
}
<script src="https://code.jquery.com/jquery-3.2.1.min.js" integrity="sha256-hwg4gsxgFZhOsEEamdOYGBf13FyQuiTwlAQgxVSNgt4=" crossorigin="anonymous"></script>
<img src="https://placeholdit.imgix.net/~text?txtsize=33&txt=300%C3%97300&w=300&h=300" />
<div id="target">
</div>

How to user controlled overlap images in JS

I'm desperately searching for solution for my client. I have graphic - something like that:
And I want to be able to take the line with circle in the center and drag it to right or left. And it will be hiding and unhiding my two full images. It's basically two images on the same place, just with another z-index I think.
I think it's possible to do it with JavaScript, but I don't know of any functions or methods for this option.

Here is my solution:
The HTML is pretty simple, just two divs for the images and one for the drag:
<div class="img" id="img1"></div>
<div class="img" id="img2"></div>
<div id="drag"></div>
For the CSS, the important part is to absolute position all the divs and give a background image.
As for the Javascript, with a little help from jQuery, we listen for the mouse events, make some calculations and adjust the CSS of the second image:
$('#drag').on('mousedown', function(e){
var $self = $(this),
dragPos = $self.position().left + $self.width()/2,
imgWidth = $('#img1').width();
$(document).on('mouseup', function(e){
$(document).off('mouseup').off('mousemove');
});
$(document).on('mousemove', function(me){
var mx = me.pageX - e.pageX + dragPos
$self.css({ left: mx });
$('#img2').css({
width: imgWidth - mx,
left: mx,
backgroundPosition: -mx + 'px 0px',
});
});
});
From there, I believe it's pretty easy to customize it and give it a unique look.
Hope this helps!
JsFiddle Demo

Something like this alphamask plugin may do the trick, though I'm not sure how simple it would be for you to implement in the manner of your slider example.

Actually quite simple. The first step is to make it work manually. I'd set it up as follows:
<div class="wrap" id="wrap1">
<div class="img-wrap img1"></div>
<div class="img-wrap img2"></div>
<div>
With CSS as follows:
.wrap {
position: relative;
width: 300px;
height: 300px;
}
.img-wrap {
width: 100%;
height: 100%;
position: absolute;
top: 0px;
left: 0px;
}
.img1 {
z-index: 1;
background: url(bg1.png) no-repeat 0px 0px;
}
.img2 {
z-index: 2;
background: url(bg1.png) no-repeat 0px 0px;
}
Now some JavaScript (with jQuery) to set a position (you can call this when you move a slider over the top later):
function setPosition(percentage){
// get the width of the container
var w = $('#wrap1').width();
// work out the width of left panel
var w1 = Math.floor(w * percentage);
// and the right panel
var w2 = w - w1;
// set the width of the right panel
// move it right by the width of the left panel
// and move the background back by the width of the left panel
$('#wrap1 .img2').css({
width: w2,
left: w1,
backgroundPosition: -w1 + 'px 0px',
});
}
You now just have to decide how to do the dragging. You could even just do it on mouseOver. Easy!

how to i get the image to center in my gallery

I have made a simple slider gallery for my site but have found that when I click next the image updates but it does not centre until I have done a full cycle of the images
how can i get the images to align from the start?
HERE IS THE JS FIDDLE > http://jsfiddle.net/8pScd/4
HTML
<div class="view_gallery">view gallery</div>
<div class="prev control"><<</div>
<div class="next control">>></div>
<div class="gallery">
</div>
<div class="overlay"></div>
CSS
.overlay{
display: none;
position: absolute; top: 0; right: 0; bottom: 0; left: 0;
width: 100%; height: 100%;
background: rgba(0,0,0,0.8);
z-index: 100;
}
.gallery{
z-index: 200;
padding: 10px;
position: absolute;
left: 50%;
background: #fff;
}
.control{
position: absolute;
top: 200px;
z-index: 300;
color: #fff;
text-transform: capitalize;
font-size: 2em;
cursor: pointer;
}
.prev{left: 0;}
.next{right:0;}
JQUERY
//images
var pics = new Array();
pics[0] = "cars.jpg";
pics[1] = "cats.png";
pics[2] = "dogs.png";
pics[3] = "bus.jpg"
//total amount of pictures to display
var pictot = pics.length-1;
var nxt = $(".next"),
prv = $(".prev"),
view = $(".view_gallery"),
gal = $(".gallery"),
overlay = $(".overlay"),
num = 0;
//view gallery
view.click(function(){
overlay.show();
gal.show();
// Start gallery off on the first image
gal.html('<img src="' + pics[0] + '" />');
});
nxt.click(function(){
// If on the last image set value to 0. Else add 1
if (num == pictot){num = 0;}else{num++;};
update();
});
prv.click(function(){
// If on first image set value to last image number. Else minus 1
if (num == 0){num = pictot;}else{num--;}
update();
});
function update () {
// update image with next/previous
gal.html('<img src="' + pics[num] + '" />');
//center image (not working very well)
var x = gal.width()/2;
gal.css("marginLeft", -x);
};
//hide
overlay.click(function(){
gal.hide();
$(this).hide();
});

The problem you have is that the "update" function is called immediately after clicking on prev/next. The image has not yet been loaded, so the code does not actually know the new gal.width yet. That's why it works after a full round: the images are now in the cache, and therefore already available.
The best solution would be to use javascript Image objects to preload the pictures; an easier way but possibly problematic is to use the 'load' event (it may not work well in all browsers).

You can align your gallery div with some simple css hack.
1)first define width. (you can define dynamic width with jquery).
2)add position:absolute;
3)add left:0 , right:0;
4)add margin:0 auto;
final code looks like this.
.gallery {
background: none repeat scroll 0 0 #FFFFFF;
left: 0;
margin: 0 auto !important;
padding: 10px;
position: absolute;
right: 0;
width: 600px;
z-index: 200;
}

your math is wrong, look at this example http://jsfiddle.net/8pScd/6/
i've just need to change your math at
var x = $('body').width()/2 - gal.width()/2;
gal.css("margin-left", x + 'px');
and i removed this line at your css
left: 50%;
.gallery{
z-index: 200;
padding: 10px;
position: absolute;
background: #fff;
}

Knowing that .gallery is 920px wide, set left: 50%; margin-left: -470px. Also remove the line in javascript which updates margin-left of the gallery container - gal.css("marginLeft", -x);