/** * 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 Dimensions * @flow */ 'use strict'; var EventEmitter = require('EventEmitter'); var Platform = require('Platform'); var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter'); var invariant = require('fbjs/lib/invariant'); var eventEmitter = new EventEmitter(); var dimensionsInitialized = false; var dimensions = {}; var dimensionsProvider: ?(() => {[key:string]: Object}); class Dimensions { static setProvider(value: () => {[key:string]: Object}): void { dimensionsProvider = value; dimensionsInitialized = false; dimensions = {}; } static getDimensions(): {[key:string]: Object} { if (dimensionsInitialized) { return dimensions; } // We calculate the window dimensions in JS so that we don't encounter loss of // precision in transferring the dimensions (which could be non-integers) over // the bridge. const dims = (dimensionsProvider || defaultDimProvider)(); const result = Dimensions.updateDimensions(dims); RCTDeviceEventEmitter.addListener('didUpdateDimensions', function(update) { Dimensions.updateDimensions(update); }); return result; } /** * Initial dimensions are set before `runApplication` is called so they should * be available before any other require's are run, but may be updated later. * * Note: Although dimensions are available immediately, they may change (e.g * due to device rotation) so any rendering logic or styles that depend on * these constants should try to call this function on every render, rather * than caching the value (for example, using inline styles rather than * setting a value in a `StyleSheet`). * * Example: `var {height, width} = Dimensions.get('window');` * * @param {string} dim Name of dimension as defined when calling `set`. * @returns {Object?} Value for the dimension. */ static get(dim: string): Object { const dims = Dimensions.getDimensions(); invariant(dims[dim], 'No dimension set for key ' + dim); return dims[dim]; } static updateDimensions(dims: ?{[key:string]: Object}): {[key:string]: Object} { if (dims && dims.windowPhysicalPixels) { // parse/stringify => Clone hack dims = JSON.parse(JSON.stringify(dims)); const windowPhysicalPixels = dims.windowPhysicalPixels; dims.window = { width: windowPhysicalPixels.width / windowPhysicalPixels.scale, height: windowPhysicalPixels.height / windowPhysicalPixels.scale, scale: windowPhysicalPixels.scale, fontScale: windowPhysicalPixels.fontScale, }; if (Platform.OS === 'android') { // Screen and window dimensions are different on android const screenPhysicalPixels = dims.screenPhysicalPixels; dims.screen = { width: screenPhysicalPixels.width / screenPhysicalPixels.scale, height: screenPhysicalPixels.height / screenPhysicalPixels.scale, scale: screenPhysicalPixels.scale, fontScale: screenPhysicalPixels.fontScale, }; // delete so no callers rely on this existing delete dims.screenPhysicalPixels; } else { dims.screen = dims.window; } // delete so no callers rely on this existing delete dims.windowPhysicalPixels; } Object.assign(dimensions, dims); if (dimensionsInitialized) { // Don't fire 'change' the first time the dimensions are set. eventEmitter.emit('change', { window: dimensions.window, screen: dimensions.screen }); } else { dimensionsInitialized = true; } return dimensions; } /** * Add an event handler. Supported events: * * - `change`: Fires when a property within the `Dimensions` object changes. The argument * to the event handler is an object with `window` and `screen` properties whose values * are the same as the return values of `Dimensions.get('window')` and * `Dimensions.get('screen')`, respectively. */ static addEventListener( type: string, handler: Function ) { invariant( type === 'change', 'Trying to subscribe to unknown event: "%s"', type ); eventEmitter.addListener(type, handler); } /** * Remove an event handler. */ static removeEventListener( type: string, handler: Function ) { invariant( type === 'change', 'Trying to remove listener for unknown event: "%s"', type ); eventEmitter.removeListener(type, handler); } } function defaultDimProvider(): {[key:string]: Object} { return require('DeviceInfo').Dimensions; } module.exports = Dimensions;