/**
 * Copyright 2004-present Facebook. All Rights Reserved.
 *
 * @providesModule PixelRatio
 */
'use strict';

var Dimensions = require('Dimensions');

/**
 * PixelRatio class gives access to the device pixel density.
 *
 * Some examples:
 *   - PixelRatio.get() === 2
 *     - iPhone 4, 4S
 *     - iPhone 5, 5c, 5s
 *     - iPhone 6
 *
 *   - PixelRatio.get() === 3
 *     - iPhone 6 plus
 *
 * There are a few use cases for using PixelRatio:
 *
 * == Displaying a line that's as thin as the device permits
 *
 * A width of 1 is actually pretty thick on an iPhone 4+, we can do one that's
 * thinner using a width of 1 / PixelRatio.get(). It's a technique that works
 * on all the devices independent of their pixel density.
 *
 *   style={{ borderWidth: 1 / PixelRatio.get() }}
 *
 * == Fetching a correctly sized image
 *
 * You should get a higher resolution image if you are on a high pixel density
 * device. A good rule of thumb is to multiply the size of the image you display
 * by the pixel ratio.
 *
 *   var image = getImage({
 *     width: 200 * PixelRatio.get(),
 *     height: 100 * PixelRatio.get()
 *   });
 *   <Image source={image} style={{width: 200, height: 100}} />
 */
class PixelRatio {
  static get() {
    return Dimensions.get('window').scale;
  }

  static startDetecting() {
    // no-op for iOS, but this is useful for other platforms
  }
};

module.exports = PixelRatio;