text: /**
   * Copyright (c) 2015-present, Facebook, Inc.
   * All rights reserved.
   *
   * This source code is licensed under the BSD-style license found in the
   * LICENSE file in the root directory of this source tree. An additional grant
   * of patent rights can be found in the PATENTS file in the same directory.
   *
   * @providesModule PixelRatio
   * @flow
   */
  'use strict';
  
  var Dimensions = require('Dimensions');
  
  /**
   * PixelRatio class gives access to the device pixel density.
   *
   * ### 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: PixelRatio.getPixelSizeForLayoutSize(200),
   *   height: PixelRatio.getPixelSizeForLayoutSize(100),
   * });
   * <Image source={image} style={{width: 200, height: 100}} />
   * ```
   */
  class PixelRatio {
    /**
     * Returns the device pixel density. Some examples:
     *
     *   - PixelRatio.get() === 1
     *     - mdpi Android devices (160 dpi)
     *   - PixelRatio.get() === 1.5
     *     - hdpi Android devices (240 dpi)
     *   - PixelRatio.get() === 2
     *     - iPhone 4, 4S
     *     - iPhone 5, 5c, 5s
     *     - iPhone 6
     *     - xhdpi Android devices (320 dpi)
     *   - PixelRatio.get() === 3
     *     - iPhone 6 plus
     *     - xxhdpi Android devices (480 dpi)
     *   - PixelRatio.get() === 3.5
     *     - Nexus 6
     */
    static get(): number {
      return Dimensions.get('window').scale;
    }
  
    /**
     * Returns the scaling factor for font sizes. This is the ratio that is used to calculate the
     * absolute font size, so any elements that heavily depend on that should use this to do
     * calculations.
     *
     * If a font scale is not set, this returns the device pixel ratio.
     *
     * Currently this is only implemented on Android and reflects the user preference set in
     * Settings > Display > Font size, on iOS it will always return the default pixel ratio.
     * @platform android
     */
    static getFontScale(): number {
      return Dimensions.get('window').fontScale || PixelRatio.get();
    }
  
    /**
     * Converts a layout size (dp) to pixel size (px).
     *
     * Guaranteed to return an integer number.
     */
    static getPixelSizeForLayoutSize(layoutSize: number): number {
      return Math.round(layoutSize * PixelRatio.get());
    }
  
    /**
     * Rounds a layout size (dp) to the nearest layout size that corresponds to
     * an integer number of pixels. For example, on a device with a PixelRatio
     * of 3, `PixelRatio.roundToNearestPixel(8.4) = 8.33`, which corresponds to
     * exactly (8.33 * 3) = 25 pixels.
     */
    static roundToNearestPixel(layoutSize: number): number {
      var ratio = PixelRatio.get();
      return Math.round(layoutSize * ratio) / ratio;
    }
  
    // No-op for iOS, but used on the web. Should not be documented.
    static startDetecting() {}
  }
  
  module.exports = PixelRatio;
  