box-sizing

Utility module to accept a variety of left, top, width, height combinations and output true left, top, width, height positions as valid numbers.

This module exposes a single function which is intended to be used as an assistant for positioning screen widgets such as Windows in a similar way to how CSS block elements work.

var boxSizing = require('box-sizing');

var coords = boxSizing({
	left: "20",
	top: -20,
	width: '50%',
	height: 50,
}, {
	maxWidth: 100,
	maxHeight: 100,
});

// coords = {
//	left: 20, // Straight forward copy (with type conversion to Number)
// 	top: 40, // (i.e. negative values are bottom aligned)
//	width: 50, // (i.e. 50% of maxWidth)
//	height: 50, // Another straight copy
// }

The boxSizing function can also take predefined default values:

var coords = boxSizing({
	left: 20,
}, {
	top: 30,
	height: 40,
	width: 50,
});

// coords = {
//	left: 20,
// 	top: 30,
//	width: 40,
//	height: 50,
// }

Valid input formats

The four main keys can be specified in the following format:

• Number - The value is used as is. E.g. '10' => '10px' offset
• String + "%" The value is used as a percentage of the whole. E.g. '10%' => '10%' of horizontal or vertical space (depending on context)
• "middle" / "center" - (only applicable for 'left' and 'top' positions) Tries to center the window based on 'width' and 'height' keys.
• -Number - Any negative value will be right or bottom aligned. E.g. -10 => 10 pixels from the right or bottom of the screen