// Tâmia © 2013 Artem Sapegin http://sapegin.me
// Images, sprites, Retina support

//
// Configuration
//

// Enable Retina support (default: false).
retinafy ?= false

// Path to calculate file system image path based on CSS path (default: .).
images_relative_root ?= '.'

// Default sprite image file (default: ../build/sprite.png).
sprite_image ?= '../build/sprite.png';
sprite_image = sprite_image + '?' + sprite_fingerprint  if sprite_fingerprint

// Sprite step size (default: 20px).
sprite_step ?= 20px;


//
// Functions
//

// background-image with Retina variant.
//
// path - Image file path.
// x - background-position x (default: 0).
// y - background-position y (default: 0).
//
// Retina image file should be named path@2x.png.
if retinafy
	image(path, x=0, y=0)
		background: url(path) x y
		+retina()
			ext = extname(path)
			hdpath = dirname(path) + '/' + basename(path, ext) + '@2x' + ext
			background: url(hdpath) x y
			background-size: image-size(pathjoin(images_relative_root, path))
else
	image(path, x=0, y=0)
		background: url(path) x y


// Sprite (to use in pseudo element).
//
// Sprite generated by grunt-squirrelsprite:
// img - Sprite image variable.
//
// Manually created sprite:
// x - Horizontal position in sprite grid.
// y - Vertical position in sprite grid.
// w - Sprite width, pixels.
// h - sprite height, pixels.
//
// Example:
//
//   .elem
//     sprite(sprite_pony);
//
//   .elem2
//     sprite(5, 6, 36, 22);
sprite(img)
	if not @content and match(":(before|after)", selector())
		content: ""
	if not @display
		display: inline-block
	if length(img) > 1
		image(sprite_image, img[0], img[1])
		width: img[2]
		height: img[3]
	else
		image(sprite_image, sprite-x(arguments[0]), sprite-y(arguments[1]))
		width: arguments[2]
		height: arguments[3]

// Horizontal position of sprite image.
//
// x - Horizontal position in sprite grid.
//
// Returns pixels.
sprite-x(x)
	(-((x - 1)*sprite_step+1));

// Vertical position of sprite image.
//
// y - Vertical position in sprite grid.
//
// Returns pixels.
sprite-y(y)
	(-((y - 1)*sprite_step+1));

// background-position for sprite.
//
// x - Horizontal position in sprite grid.
// y - Vertical position in sprite grid.
//
// Example:
//
//   .elem
//     sprite-bg()
//     sprite-pos(5,6)
//     sprite-pos(sprite_pony-hover)
sprite-pos(img)
	if length(img) > 1
		background-position: img[0] img[1]
	else
		background-position: sprite-x(img[0]) sprite-y(img[1])

// background-image for sprite.
//
// Sprite generated by grunt-squirrelsprite:
// img - Sprite image variable.
//
// Manually created sprite:
// x - Horizontal position in sprite grid (default: 0).
// y - Vertical position in sprite grid (default: 0).
sprite-bg(x=0, y=0)
	image(sprite_image, x, x)

// Element width for sprite.
//
// Returns pixels
sprite-width(img)
	img[2]

// Element height for sprite.
//
// Returns pixels
sprite-height(img)
	img[3]

// Element width/height for sprite.
//
// Example:
//
//   .elem
//     sprite-size(sprite_pony);
sprite-size(img)
	width: sprite-width(img)
	height: sprite-height(img)

// Shifts element half height to top
//
sprite-shift-top(img)
	margin-top: (-(round(sprite-height(img)/2)))