react-native/Examples/UIExplorer/LayoutEventsExample.js

165 lines
4.5 KiB
JavaScript

/**
* The examples provided by Facebook are for non-commercial testing and
* evaluation purposes only.
*
* Facebook reserves all rights not expressly granted.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON INFRINGEMENT. IN NO EVENT SHALL
* FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* @flow
*/
'use strict';
var React = require('react');
var ReactNative = require('react-native');
var {
Image,
LayoutAnimation,
StyleSheet,
Text,
View,
} = ReactNative;
type Layout = {
x: number;
y: number;
width: number;
height: number;
};
type LayoutEvent = {
nativeEvent: {
layout: Layout,
};
};
type State = {
containerStyle?: { width: number },
extraText?: string,
imageLayout?: Layout,
textLayout?: Layout,
viewLayout?: Layout,
viewStyle: { margin: number },
};
var LayoutEventExample = React.createClass({
getInitialState(): State {
return {
viewStyle: {
margin: 20,
},
};
},
animateViewLayout: function() {
LayoutAnimation.configureNext(
LayoutAnimation.Presets.spring,
() => {
console.log('layout animation done.');
this.addWrapText();
}
);
this.setState({
viewStyle: {
margin: this.state.viewStyle.margin > 20 ? 20 : 60,
}
});
},
addWrapText: function() {
this.setState(
{extraText: ' And a bunch more text to wrap around a few lines.'},
this.changeContainer
);
},
changeContainer: function() {
this.setState({containerStyle: {width: 280}});
},
onViewLayout: function(e: LayoutEvent) {
console.log('received view layout event\n', e.nativeEvent);
this.setState({viewLayout: e.nativeEvent.layout});
},
onTextLayout: function(e: LayoutEvent) {
console.log('received text layout event\n', e.nativeEvent);
this.setState({textLayout: e.nativeEvent.layout});
},
onImageLayout: function(e: LayoutEvent) {
console.log('received image layout event\n', e.nativeEvent);
this.setState({imageLayout: e.nativeEvent.layout});
},
render: function() {
var viewStyle = [styles.view, this.state.viewStyle];
var textLayout = this.state.textLayout || {width: '?', height: '?'};
var imageLayout = this.state.imageLayout || {x: '?', y: '?'};
return (
<View style={this.state.containerStyle}>
<Text>
layout events are called on mount and whenever layout is recalculated. Note that the layout event will typically be received <Text style={styles.italicText}>before</Text> the layout has updated on screen, especially when using layout animations.{' '}
<Text style={styles.pressText} onPress={this.animateViewLayout}>
Press here to change layout.
</Text>
</Text>
<View ref="view" onLayout={this.onViewLayout} style={viewStyle}>
<Image
ref="img"
onLayout={this.onImageLayout}
style={styles.image}
source={{uri: 'https://fbcdn-dragon-a.akamaihd.net/hphotos-ak-prn1/t39.1997/p128x128/851561_767334496626293_1958532586_n.png'}}
/>
<Text>
ViewLayout: {JSON.stringify(this.state.viewLayout, null, ' ') + '\n\n'}
</Text>
<Text ref="txt" onLayout={this.onTextLayout} style={styles.text}>
A simple piece of text.{this.state.extraText}
</Text>
<Text>
{'\n'}
Text w/h: {textLayout.width}/{textLayout.height + '\n'}
Image x/y: {imageLayout.x}/{imageLayout.y}
</Text>
</View>
</View>
);
}
});
var styles = StyleSheet.create({
view: {
padding: 12,
borderColor: 'black',
borderWidth: 0.5,
backgroundColor: 'transparent',
},
text: {
alignSelf: 'flex-start',
borderColor: 'rgba(0, 0, 255, 0.2)',
borderWidth: 0.5,
},
image: {
width: 50,
height: 50,
marginBottom: 10,
alignSelf: 'center',
},
pressText: {
fontWeight: 'bold',
},
italicText: {
fontStyle: 'italic',
},
});
exports.title = 'Layout Events';
exports.description = 'Examples that show how Layout events can be used to ' +
'measure view size and position.';
exports.examples = [
{
title: 'LayoutEventExample',
render: function(): ReactElement {
return <LayoutEventExample />;
},
}];