trying to do each function on a certain class

Question

Hey community im doing this centering of pictures in a frame so the center of the image is in the center of the frame despite its size. (frame is fixed)

 $('.item-box').each(function () {
    var fwidth = $('.gmask').width();
    var iwidth = $('.gmask img').width();
    var fheight = $('.gmask').height();
    var iheight = $('.gmask img').height();

    $('.gmask img').css('margin-left', Math.floor((fwidth - iwidth) / 2) - 3);
    $('.gmask img').css('margin-top', Math.floor((fheight - iheight) / 2) - 3);
});

I wanna do this as a loop for each of my '.item-box' can anyone tell me what im doing wrong

*EDIT

btw im doing jquery template

<script id="resultTemplate" type="text/x-jquery-tmpl "> 
    {{for Product}}

    <div class="item-box" id="{{if #index < 5 }}itemboxTeaser{{else}}itemboxRest{{/if}}{{:#index+1}}">
        <div class="visual-gallery">
            <div class="gmask">
                <ul class="replaceClass">
                    <a href="/lejemaal/{{:Urlname}}/#/Lejemaal">
                        <img src="{{:PhysicalPathToFrontPhotoUseWebFront300Px}}" alt="">
                    </a>
                </ul>
            </div>
        </div>
     </div>
     {{/for}}
</script>

Answer 1

I suppose .gmask and it's relative img are children of $(this) (your .item-box)
Try like:

$('.item-box').each(function () {
        var $gmask = $(this).find('.gmask');
        var $gmaskImg = $gmask.find('img');

        var fwidth = $gmask.width();
        var iwidth = $gmaskImg.width();
        var fheight = $gmask.height();
        var iheight = $gmaskImg.height();

        $gmaskImg.css('margin-left', Math.floor((fwidth - iwidth) / 2) - 3);
        $gmaskImg.css('margin-top', Math.floor((fheight - iheight) / 2) - 3);
});

EDIT after reading OP comment

$(window).load(function(){
    $('.item-box').find('.gmask').each(function () {
            var $gmask = $(this);
            var $gmaskImg = $gmask.find('img');

            var fwidth = $gmask.width();
            var iwidth = $gmaskImg.width();
            var fheight = $gmask.height();
            var iheight = $gmaskImg.height();

            $gmaskImg.css('margin-left', Math.floor((fwidth - iwidth) / 2) - 3);
            $gmaskImg.css('margin-top', Math.floor((fheight - iheight) / 2) - 3);
    });
});

Answer 2

Since the img is what you're after, why not .each-loop over those elements?

$('.item-box .gmask img').each(function ()
{
    var parent, fwidth,fheight,iwidth,iheight;
    parent = $(this);
    while(!parent.attr('class').match(/\bgmask\b/))
    {//get the .gmask parent of current img
        parent = parent.parent();
    }
    iwidth = $(this).width();
    iheight = $(this).height;
    fwidth = parent.width();
    fheight = parent.height();
    $(this).css('margin-left', Math.floor((fwidth - iwidth) / 2) - 3);
    $(this).css('margin-top', Math.floor((fheight - iheight) / 2) - 3);
});

This reduces the amount of selectors used, thus increasing overall performance. IMHO, it's also easier to read and maintain.

Answer 3

Those lines are taking the first element of the page, whatever the current .item-box :

var fwidth = $('.gmask').width();
var iwidth = $('.gmask img').width();
var fheight = $('.gmask').height();
var iheight = $('.gmask img').height();

You need to do $(this).find('.element');

Answer 4

I guess you want to center the image inside each .item-box, so you need to refer to 'this' :

 $('.item-box').each(function () {
    var fwidth = $(this).find('.gmask').width();
    var iwidth = $(this).find('.gmask img').width();
    var fheight = $(this).find('.gmask').height();
    var iheight = $(this).find('.gmask img').height();

    $(this).find('.gmask img').css('margin-left', Math.floor((fwidth - iwidth) / 2) - 3);
    $(this).find('.gmask img').css('margin-top', Math.floor((fheight - iheight) / 2) - 3);
});