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A (partial) implementation of the CSS box and flexbox layout algorithm.

Project description

A (partial) implementation of the CSS box and flexbox layout algorithm.

The following CSS attributes and value types are supported:

Name Value
width, height positive number
left, right, top, bottom number
margin, marginLeft, marginRight, marginTop, marginBottom number
padding, paddingLeft, paddingRight, paddingTop, paddingBottom positive number
borderWidth, borderLeftWidth, borderRightWidth, borderTopWidth, borderBottomWidth positive number
flexDirection "column", "row"
justifyContent "flex-start", "center", "flex-end", "space-between", "space-around"
alignItems, alignSelf "flex-start", "center", "flex-end", "stretch"
flex positive number
flexWrap "wrap", "nowrap"
position "relative", "absolute"


In your virtualenv, install Colosseum:

$ pip install colosseum

Then, you can instantiate CSS nodes, and query the layout that results:

>>> from colosseum import CSSNode
>>> node = CSSNode(width=1000, height=1000, flexDirection='row')
>>> node.children.add(CSSNode(width=100, height=200))
>>> node.children.add(CSSNode(width=300, height=150))
>>> layout = node.layout
>>> print(layout)
<Layout (1000x1000 @ 0,0)>
>>> layout.width
>>> layout.height
>>> layout.left
>>> for child in node.children:
...     print(child.layout)
<Layout (100x200 @ 0,0)>
<Layout (300x150 @ 100,0)>

Requesting the layout attribute of a CSSNode forces the box model to be evaluated. Once evaluated, the layout will be cached. Modifying any CSS property on a node will mark the layout as dirty, and the layout will be recomputed the next time the layout is accessed. For example, if we switch the outer node to be a “column” flexBox, rather than a “row” flexBox, you’ll see the coordinates of the child boxes update to reflect a vertical, rather than horizontal layout:

>>> node.flexDirection = 'column'
>>> print(node.layout)
<Layout (1000x1000 @ 0,0)>
>>> for child in node.children:
...     print(child.layout)
<Layout (100x200 @ 0,0)>
<Layout (300x150 @ 0,200)>


Colosseum is part of the BeeWare suite. You can talk to the community through:


If you experience problems with Colosseum, log them on GitHub. If you want to contribute code, please fork the code and submit a pull request.


The algorithm and test suite for this library is a language port of CSS-layout project, open-sourced by Facebook.

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Filename, size & hash SHA256 hash help File type Python version Upload date
colosseum-0.0.1-py2.py3-none-any.whl (12.5 kB) Copy SHA256 hash SHA256 Wheel py2.py3 Mar 29, 2015
colosseum-0.0.1.tar.gz (23.4 kB) Copy SHA256 hash SHA256 Source None Mar 29, 2015

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