Is there a way to target the first and last element in each row using jQuery isotope?

Question

I have an masonry isotope grid that has n number of rows with two column sizes: 160px by 160px and 320px by 320px and I'd like to assign different styles to the first and last element of each row. My rows could have anywhere from 4 elements to 7 elements. I've been struggling with this for a bit, and wondering if it's possible.

HTML

<div id="grid" style="position: relative; overflow: hidden; height: 960px;"
class="isotope">
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="two_by_two">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_two">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="two_by_two">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_two">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="two_by_two">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_two">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
    <div class="one_by_one">
        <img class="thumb" src="https://s3.amazonaws.com/stitch-images/products/gucci.png"
        />
    </div>
</div>

CSS

#grid {
    margin:auto;
    margin-top:55px;
    margin-bottom:200px;
    width:1140px
}
#grid .thumb {
    width:97%;
    height:97%
}
#grid .one_by_one {
    width:160px;
    height:160px;
    background:url(https://s3.amazonaws.com/stitch-images/assets/cell_1x1.png);
    cursor:pointer
}
#grid .one_by_two {
    width:160px;
    height:320px;
    background:url(https://s3.amazonaws.com/stitch-images/assets/cell_1x2.png);
    cursor:pointer
}
#grid .two_by_two {
    width:320px;
    height:320px;
    background:url(https://s3.amazonaws.com/stitch-images/assets/cell_2x2.png);
    cursor:pointer
}

JS

$("#grid").isotope masonry: layoutMode: 'fitRows'

View my Jsfiddle http://jsfiddle.net/TDma4/

Thanks. I don't think I have an answer ready for you, but adding the sample code makes your question a lot clearer :). Will respond if I do come up with an answer — thaJeztah, Jan 27 '13 at 22:08

score 11 · Accepted Answer · edited May 23 '17 at 12:33

Here's one way to approach the problem.

Working Solution: http://jsbin.com/ufuleb/21/

CSS

.first, .last {
  border:2px dashed blue;
  opacity:.75;
}

JavaScript

$("#grid").isotope(
    { layoutMode : 'fitRows' });

// Last div element
$("#grid div:last-child").addClass("last");

var maxWidth = 0;

// Use max to handle last div
$("#grid div").each(function (i) {  
  matrix = matrixToArray($(this).css("-transform"));

  // identify first elements
  if ( parseInt(matrix[4],10) == 0 ) {
    $(this).addClass("first");
  }

  // identify last elements
  if ( parseInt(matrix[4],10) > parseInt(maxWidth,10) ) { 
    maxWidth = matrix[4];
  } else {      
    $(this).prev().addClass("last");
    maxWidth = 0;
  } 
});

// Util function for parsing -webkit-transform
function matrixToArray(matrix) {    
    return matrix.substr(7, matrix.length-8).split(', ');
}

Loop through each div and track the current xT value (CSS -webkit-transform). Whenever the maximum value is passed, just update the previous value which should be the last element of each row. The very last element is handled with :last-child. Note that this solution also handles the overall #grid width changing.

Example Output

Example output

This could probably be optimized further but at least provides a starting point.

I got some help from this answer: https://stackoverflow.com/a/5968313/1085891

For reference:

If you change `-webkit-transform` to `transform`, it should work in other browsers (e.g. Firefox). Also, is the last child (in DOM order) guaranteed to be the last element in the last row? — Jeffery To, Feb 06 '13 at 04:55
Updated my code. Also, I couldn't find a test case where the last child element wasn't the element in the last row with `layoutMode: 'fitRows'`. — JSuar, Feb 06 '13 at 12:49

Jeffery To · Answer 2 · 2013-02-06T01:54:22.530

Isotope has a itemPositionDataEnabled option that exposes the position of each element. Using this, along with a onLayout handler, you can compute the first and last elements of each row (demo):

$('#grid').isotope({
    itemPositionDataEnabled: true,
    onLayout: function (elems, instance) {
        var items, rows, numRows, row, prev, i;

        // gather info for each element
        items = elems.map(function () {
            var el = $(this), pos = el.data('isotope-item-position');
            return {
                x: pos.x,
                y: pos.y,
                w: el.width(),
                h: el.height(),
                el: el
            };
        });

        // first pass to find the first and last items of each row
        rows = [];
        i = {};
        items.each(function () {
            var y = this.y, r = i[y];
            if (!r) {
                r = {
                    y: y,
                    first: null,
                    last: null
                };
                rows.push(r);
                i[y] = r;
            }
            if (!r.first || this.x < r.first.x) {
                r.first = this;
            }
            if (!r.last || this.x > r.last.x) {
                r.last = this;
            }
        });
        rows.sort(function (a, b) { return a.y - b.y; });
        numRows = rows.length;

        // compare items for each row against the previous row
        for (prev = rows[0], i = 1; i < numRows; prev = row, i++) {
            row = rows[i];
            if (prev.first.x < row.first.x &&
                    prev.first.y + prev.first.h > row.y) {
                row.first = prev.first;
            }
            if (prev.last.x + prev.last.w > row.last.x + row.last.w &&
                    prev.last.y + prev.last.h > row.y) {
                row.last = prev.last;
            }
        }

        // assign classes to first and last elements
        elems.removeClass('first last');
        $.each(rows, function () {
            this.first.el.addClass('first');
            this.last.el.addClass('last');
        });
    }
});

Update: Fixed algorithm based on JSuar's feedback

Update #2: Fixed an issue when items are taller than 2 rows

@JSuar can you provide an example? The onLayout handler is called every time Isotope lays out the elements — Jeffery To, Feb 05 '13 at 12:24
It's an edge case but if you set `width:520px;` one of the larger elements won't be caught as a last element. — JSuar, Feb 05 '13 at 12:37

score 1 · Answer 3 · answered Jan 31 '13 at 19:45

Mike, If you are feeling adventurous you can extend Isotop to do this. I pulled the following from http://isotope.metafizzy.co/docs/extending-isotope.html

Any additional properties you are looking to do you can do in the .each block

_fitRowsLayout : function( $elems ) {
  var instance = this,
      containerWidth = this.element.width(),
      props = this.fitRows;

  $elems.each( function() {
    var $this = $(this),
        atomW = $this.outerWidth(true),
        atomH = $this.outerHeight(true);

    if ( props.x !== 0 && atomW + props.x > containerWidth ) {
      // if this element cannot fit in the current row
      props.x = 0;
      props.y = props.height;
    } 

    // position the atom
    instance._pushPosition( $this, props.x, props.y );

    props.height = Math.max( props.y + atomH, props.height );
    props.x += atomW;

  });
},

am05mhz · Answer 4 · 2013-02-05T01:06:45.413

use this: http://jsfiddle.net/86WVw/1/

Edit: isotope now uses translate3d, edited to use both translate n translate3d http://jsfiddle.net/86WVw/3/

additional css:

[style*="translate(0px"], [style*="translate3d(0px"], .border { // .border is class for end of row item, you can change it to whatever you want
    border: 3px dotted #f00;
}

additioan js:

gw = $('#grid').width(); // get grid width
w = $('#grid').width(); // to find smallest width, take a big number first
$('#grid>div').each(function(){ // iterate through tiles
    if ($(this).width()<w) // if width smaller then assumed smallest width
        w = $(this).width(); // change smallest width
});

var x;
for (x = w; x < gw; x += w) // iterate translated tiles from smallest width to grid width
{
    var elms = $('[style*="translate3d('+x+'px"], [style*="translate('+x+'px"]');
    $(elms).each(function(){
        if ((x+$(this).width())>(gw-w)) // if tiles left + tile width reach end of grid
        $(this).addClass('border'); // apply class
    });
}

score 0 · Answer 5 · answered Jan 28 '14 at 21:13

The question is much simpler than it seems.
The size of the box is a multiple of a common matrix.

This is my approach.

var columnsWidth = 100; // the base matrix width
var columns = 8; // the number of columns available (container.width / columnsWidth)

$.each(box, function() {
    var box = $(this) // the current box
    var boxSize = [2,2] // obtained subdividing size by matrix
    var maximumXChord = (columns - boxSize[0]) * columnsWidth // the maximum X available

    if (box.x == maximumXChord) { // check if the current X Chords is equal to the maximum
        console.log('the box is the last of this row!')
    } else if (box.x == 0) { // check if the the X is 0
        console.log('the box is the first of this row!') 
    }
})

That's all!

Is there a way to target the first and last element in each row using jQuery isotope?

5 Answers5