<bin-packing-grid>

This is a custom element that fit elements into a grid using a bin-packing algorithm. The result is similar to the grid used on pinterest and other sites.

It will try to fit everything and leave no spaces, but in case there are gaps left, it will create div elements to fill them.

And just for the record, the size of the elements are never changed at all; the elements are only reordered.

Also, this element is responsive.

It is created using only vanilla js and it has no dependencies! (except, of course, the webcomponents.js polyfill)

Demo

Check it live!

Changelog

• 0.2.3

• Using the HTML5 hidden attribute to make an bin-packing-item element to not use space on the grid.

• 0.2.2

• Fix: It was incorrectly using the rows instead of cols while checking for the wide elements.

• 0.2.1

• New detect-size attribute. Using it, is not necessary to manually set the rows and cols and instead, it tries to automatically detect how many are necessary.
• Added a simple border to each bin-packing-item, to make visible the elements if no custom css is added.

• 0.2.0

• Removed Polymer as dependency. Now is a vanilla js component!
• The dist file is vulcanized.

• 0.1.2

• Now is possible to create dynamically <bin-packing-item> elements and call the reflow method on the grid element to repackage and reorder the grid.

• 0.1.1

• Bug fixes

• 0.1.0

• First version

Algorithm

This uses a variation of the best-fit algorithm; it tries to fit each element and check the possible positions but it first gives priority to the one that keeps the height of the grid smaller.

Install

Install the component using Bower:

$ bower install bin-packing-grid --save

Or download as ZIP.

Usage

1. Import Web Components' polyfill:

   <script src="bower_components/webcomponentsjs/webcomponents.min.js"></script>

2. Import the bin-packing-grid element:

   <link rel="import" href="bower_components/bin-packing-grid/dist/bin-packing-grid.html">

3. Start using it!

   <bin-packing-grid cell-size="150">
     <bin-packing-item rows="1" cols="2">2x1</bin-packing-item>
     <bin-packing-item rows="2" cols="1">1x2</bin-packing-item>
     <bin-packing-item detect-size><img src="someimage.jpg"></bin-packing-item>
     <bin-packing-item rows="2" cols="3">3x2</bin-packing-item>
   </bin-packing-grid>

How it works

The <bin-packing-grid> creates a grid formed by squares, which each side has the measure of cell-size in pixels (default 100). Each one of those squares is separated by a gutter determined by gutter-size also in pixels (default 5).

The size of each <bin-packing-item> element is determined by the amount of rows (number of squares, plus gutter space, vertically) and cols (number of squares, plus gutter space, horizontally).

Instead of manually specifying rows and cols, is possible to add the detect-size attribute (with any or no value) to try to detect the required number of rows and cols.

The <bin-packing-item> elements don't have colours, backgrounds or any visual style by default (except a border to make it visible). The only style properties added are the ones required to set the size and positionate the element into the grid. Is up to the developer to add any other desired style. By using the transition css property, is possible to animate the movement of elements.

To fill the gaps, <div> elements with the bin-packing-filler class will be created. Those elements are created into the shadow dom. You can target that element for styling with a rule like this:

bin-packing-grid::shadow .bin-packing-filler {
  background-color: blue;
}

Dynamically create elements

Just create a <bin-packing-item> element, attach it to the grid, and call reflow.

var item, grid;

grid = document.getElementsByTagName('bin-packing-grid')[0];

item = document.createElement('bin-packing-item');
item.rows = 3;
item.cols = 3;
grid.appendChild(item);
grid.reflow();

Options

For <bin-packing-grid>:

Property	Attribute	Type	Default	Description
cellSize	cell-size	number	100	Size in pixels for each cell
gutterSize	gutter-size	number	5	Size in pixels for the space used to separate elements

For <bin-packing-item>:

Property	Attribute	Type	Default	Description
rows	rows	number	1	Height of the item, using the cellSize of the <bin-packing-grid> parent as unit.
cols	cols	number	1	Width of the item, using the cellSize of the <bin-packing-grid> parent as unit.
detectSize	detect-size	boolean	false	Automatically set the rows and cols required for the content inside of the <bin-packing-item> element.
hidden	hidden	boolean	false	Using the attribute hidden will cause the element not only to be not displayed, but also it will not use space on the grid.

Contributing

1. Fork it!
2. Create your feature branch: git checkout -b my-new-feature
3. Commit your changes: git commit -m 'Add some feature'
4. Push to the branch: git push origin my-new-feature
5. Submit a pull request :D

License

MIT License