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KeyboardAvoidingView.js
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KeyboardAvoidingView.js
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/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @format
* @flow
*/
'use strict';
const Keyboard = require('./Keyboard');
const LayoutAnimation = require('../../LayoutAnimation/LayoutAnimation');
const Platform = require('../../Utilities/Platform');
const React = require('react');
const StyleSheet = require('../../StyleSheet/StyleSheet');
const View = require('../View/View');
import type {ViewStyleProp} from '../../StyleSheet/StyleSheet';
import type EmitterSubscription from '../../vendor/emitter/EmitterSubscription';
import type {
ViewProps,
ViewLayout,
ViewLayoutEvent,
} from '../View/ViewPropTypes';
import type {KeyboardEvent} from './Keyboard';
type Props = $ReadOnly<{|
...ViewProps,
/**
* Specify how to react to the presence of the keyboard.
*/
behavior?: ?('height' | 'position' | 'padding'),
/**
* Style of the content container when `behavior` is 'position'.
*/
contentContainerStyle?: ?ViewStyleProp,
/**
* Controls whether this `KeyboardAvoidingView` instance should take effect.
* This is useful when more than one is on the screen. Defaults to true.
*/
enabled: ?boolean,
/**
* Distance between the top of the user screen and the React Native view. This
* may be non-zero in some cases. Defaults to 0.
*/
keyboardVerticalOffset: number,
|}>;
type State = {|
bottom: number,
|};
/**
* View that moves out of the way when the keyboard appears by automatically
* adjusting its height, position, or bottom padding.
*/
class KeyboardAvoidingView extends React.Component<Props, State> {
static defaultProps: {|enabled: boolean, keyboardVerticalOffset: number|} = {
enabled: true,
keyboardVerticalOffset: 0,
};
_frame: ?ViewLayout = null;
_subscriptions: Array<EmitterSubscription> = [];
viewRef: {current: React.ElementRef<any> | null, ...};
_initialFrameHeight: number = 0;
constructor(props: Props) {
super(props);
this.state = {bottom: 0};
this.viewRef = React.createRef();
}
_relativeKeyboardHeight(keyboardFrame): number {
const frame = this._frame;
if (!frame || !keyboardFrame) {
return 0;
}
const keyboardY = keyboardFrame.screenY - this.props.keyboardVerticalOffset;
// Calculate the displacement needed for the view such that it
// no longer overlaps with the keyboard
return Math.max(frame.y + frame.height - keyboardY, 0);
}
_onKeyboardChange = (event: ?KeyboardEvent) => {
if (event == null) {
this.setState({bottom: 0});
return;
}
const {duration, easing, endCoordinates} = event;
const height = this._relativeKeyboardHeight(endCoordinates);
if (this.state.bottom === height) {
return;
}
if (duration && easing) {
LayoutAnimation.configureNext({
// We have to pass the duration equal to minimal accepted duration defined here: RCTLayoutAnimation.m
duration: duration > 10 ? duration : 10,
update: {
duration: duration > 10 ? duration : 10,
type: LayoutAnimation.Types[easing] || 'keyboard',
},
});
}
this.setState({bottom: height});
};
_onLayout = (event: ViewLayoutEvent) => {
this._frame = event.nativeEvent.layout;
if (!this._initialFrameHeight) {
// save the initial frame height, before the keyboard is visible
this._initialFrameHeight = this._frame.height;
}
};
componentDidMount(): void {
if (Platform.OS === 'ios') {
this._subscriptions = [
Keyboard.addListener('keyboardWillChangeFrame', this._onKeyboardChange),
];
} else {
this._subscriptions = [
Keyboard.addListener('keyboardDidHide', this._onKeyboardChange),
Keyboard.addListener('keyboardDidShow', this._onKeyboardChange),
];
}
}
componentWillUnmount(): void {
this._subscriptions.forEach(subscription => {
subscription.remove();
});
}
render(): React.Node {
const {
behavior,
children,
contentContainerStyle,
enabled,
keyboardVerticalOffset,
style,
...props
} = this.props;
const bottomHeight = enabled ? this.state.bottom : 0;
switch (behavior) {
case 'height':
let heightStyle;
if (this._frame != null && this.state.bottom > 0) {
// Note that we only apply a height change when there is keyboard present,
// i.e. this.state.bottom is greater than 0. If we remove that condition,
// this.frame.height will never go back to its original value.
// When height changes, we need to disable flex.
heightStyle = {
height: this._initialFrameHeight - bottomHeight,
flex: 0,
};
}
return (
<View
ref={this.viewRef}
style={StyleSheet.compose(
style,
heightStyle,
)}
onLayout={this._onLayout}
{...props}>
{children}
</View>
);
case 'position':
return (
<View
ref={this.viewRef}
style={style}
onLayout={this._onLayout}
{...props}>
<View
style={StyleSheet.compose(
contentContainerStyle,
{
bottom: bottomHeight,
},
)}>
{children}
</View>
</View>
);
case 'padding':
return (
<View
ref={this.viewRef}
style={StyleSheet.compose(
style,
{paddingBottom: bottomHeight},
)}
onLayout={this._onLayout}
{...props}>
{children}
</View>
);
default:
return (
<View
ref={this.viewRef}
onLayout={this._onLayout}
style={style}
{...props}>
{children}
</View>
);
}
}
}
module.exports = KeyboardAvoidingView;