124 lines
4.1 KiB
JavaScript
124 lines
4.1 KiB
JavaScript
/**
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @format
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* @flow
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*/
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import RCTDeviceEventEmitter from '../EventEmitter/RCTDeviceEventEmitter';
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import EventEmitter, {
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type EventSubscription,
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} from '../vendor/emitter/EventEmitter';
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import NativeDeviceInfo, {
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type DimensionsPayload,
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type DisplayMetrics,
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type DisplayMetricsAndroid,
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} from './NativeDeviceInfo';
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import invariant from 'invariant';
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const eventEmitter = new EventEmitter<{
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change: [DimensionsPayload],
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}>();
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let dimensionsInitialized = false;
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let dimensions: DimensionsPayload;
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class Dimensions {
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/**
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* NOTE: `useWindowDimensions` is the preferred API for React components.
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*
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* Initial dimensions are set before `runApplication` is called so they should
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* be available before any other require's are run, but may be updated later.
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*
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* Note: Although dimensions are available immediately, they may change (e.g
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* due to device rotation) so any rendering logic or styles that depend on
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* these constants should try to call this function on every render, rather
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* than caching the value (for example, using inline styles rather than
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* setting a value in a `StyleSheet`).
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*
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* Example: `const {height, width} = Dimensions.get('window');`
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*
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* @param {string} dim Name of dimension as defined when calling `set`.
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* @returns {DisplayMetrics? | DisplayMetricsAndroid?} Value for the dimension.
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*/
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static get(dim: string): DisplayMetrics | DisplayMetricsAndroid {
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// $FlowFixMe[invalid-computed-prop]
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invariant(dimensions[dim], 'No dimension set for key ' + dim);
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return dimensions[dim];
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}
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/**
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* This should only be called from native code by sending the
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* didUpdateDimensions event.
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*
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* @param {DimensionsPayload} dims Simple string-keyed object of dimensions to set
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*/
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static set(dims: $ReadOnly<DimensionsPayload>): void {
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// We calculate the window dimensions in JS so that we don't encounter loss of
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// precision in transferring the dimensions (which could be non-integers) over
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// the bridge.
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let {screen, window} = dims;
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const {windowPhysicalPixels} = dims;
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if (windowPhysicalPixels) {
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window = {
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width: windowPhysicalPixels.width / windowPhysicalPixels.scale,
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height: windowPhysicalPixels.height / windowPhysicalPixels.scale,
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scale: windowPhysicalPixels.scale,
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fontScale: windowPhysicalPixels.fontScale,
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};
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}
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const {screenPhysicalPixels} = dims;
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if (screenPhysicalPixels) {
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screen = {
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width: screenPhysicalPixels.width / screenPhysicalPixels.scale,
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height: screenPhysicalPixels.height / screenPhysicalPixels.scale,
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scale: screenPhysicalPixels.scale,
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fontScale: screenPhysicalPixels.fontScale,
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};
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} else if (screen == null) {
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screen = window;
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}
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dimensions = {window, screen};
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if (dimensionsInitialized) {
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// Don't fire 'change' the first time the dimensions are set.
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eventEmitter.emit('change', dimensions);
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} else {
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dimensionsInitialized = true;
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}
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}
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/**
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* Add an event handler. Supported events:
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*
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* - `change`: Fires when a property within the `Dimensions` object changes. The argument
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* to the event handler is an object with `window` and `screen` properties whose values
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* are the same as the return values of `Dimensions.get('window')` and
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* `Dimensions.get('screen')`, respectively.
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*/
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static addEventListener(
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type: 'change',
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handler: Function,
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): EventSubscription {
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invariant(
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type === 'change',
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'Trying to subscribe to unknown event: "%s"',
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type,
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);
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return eventEmitter.addListener(type, handler);
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}
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}
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// Subscribe before calling getConstants to make sure we don't miss any updates in between.
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RCTDeviceEventEmitter.addListener(
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'didUpdateDimensions',
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(update: DimensionsPayload) => {
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Dimensions.set(update);
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},
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);
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Dimensions.set(NativeDeviceInfo.getConstants().Dimensions);
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export default Dimensions;
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