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