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					59 lines
				
				1.6 KiB
			
		
		
			
		
	
	
					59 lines
				
				1.6 KiB
			| 
											3 years ago
										 | // @flow | ||
|  | import hiDPI from './hiDPI' | ||
|  | import PolishedError from '../internalHelpers/_errors' | ||
|  | 
 | ||
|  | import type { Styles } from '../types/style' | ||
|  | 
 | ||
|  | /** | ||
|  |  * A helper to generate a retina background image and non-retina | ||
|  |  * background image. The retina background image will output to a HiDPI media query. The mixin uses | ||
|  |  * a _2x.png filename suffix by default. | ||
|  |  * | ||
|  |  * @example | ||
|  |  * // Styles as object usage | ||
|  |  * const styles = { | ||
|  |  *  ...retinaImage('my-img') | ||
|  |  * } | ||
|  |  * | ||
|  |  * // styled-components usage | ||
|  |  * const div = styled.div` | ||
|  |  *   ${retinaImage('my-img')} | ||
|  |  * ` | ||
|  |  * | ||
|  |  * // CSS as JS Output | ||
|  |  * div { | ||
|  |  *   backgroundImage: 'url(my-img.png)', | ||
|  |  *   '@media only screen and (-webkit-min-device-pixel-ratio: 1.3), | ||
|  |  *    only screen and (min--moz-device-pixel-ratio: 1.3), | ||
|  |  *    only screen and (-o-min-device-pixel-ratio: 1.3/1), | ||
|  |  *    only screen and (min-resolution: 144dpi), | ||
|  |  *    only screen and (min-resolution: 1.5dppx)': { | ||
|  |  *     backgroundImage: 'url(my-img_2x.png)', | ||
|  |  *   } | ||
|  |  * } | ||
|  |  */ | ||
|  | export default function retinaImage( | ||
|  |   filename: string, | ||
|  |   backgroundSize?: string, | ||
|  |   extension?: string = 'png', | ||
|  |   retinaFilename?: string, | ||
|  |   retinaSuffix?: string = '_2x', | ||
|  | ): Styles { | ||
|  |   if (!filename) { | ||
|  |     throw new PolishedError(58) | ||
|  |   } | ||
|  |   // Replace the dot at the beginning of the passed extension if one exists | ||
|  |   const ext = extension.replace(/^\./, '') | ||
|  |   const rFilename = retinaFilename | ||
|  |     ? `${retinaFilename}.${ext}` | ||
|  |     : `${filename}${retinaSuffix}.${ext}` | ||
|  | 
 | ||
|  |   return { | ||
|  |     backgroundImage: `url(${filename}.${ext})`, | ||
|  |     [hiDPI()]: { | ||
|  |       backgroundImage: `url(${rFilename})`, | ||
|  |       ...(backgroundSize ? { backgroundSize } : {}), | ||
|  |     }, | ||
|  |   } | ||
|  | } |