mirror of
https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Website Deployment Script
157 lines
39 KiB
HTML
157 lines
39 KiB
HTML
<!DOCTYPE html><html><head><title>Direct Manipulation</title><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"><meta name="viewport" content="width=device-width"><meta property="fb:app_id" content="1677033832619985"><meta property="fb:admins" content="121800083"><meta property="og:site_name" content="React Native"><meta property="og:title" content="Direct Manipulation"><meta property="og:url" content="https://facebook.github.io/react-native/index.html"><meta property="og:image" content="https://facebook.github.io/react-native/img/opengraph.png"><meta property="og:description" content="A framework for building native apps using React"><meta name="twitter:site" content="@reactnative"><meta name="twitter:card" content="summary_large_image"><meta property="og:type" content="website"><base href="/react-native/"><link rel="stylesheet" href="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.css"><link rel="shortcut icon" href="img/favicon.png?2"><link rel="stylesheet" href="css/react-native.css"><link rel="alternate" type="application/rss+xml" title="React Native Blog" href="https://facebook.github.io/react-native/blog/feed.xml"><link href="//cdn-images.mailchimp.com/embedcode/horizontal-slim-10_7.css" rel="stylesheet" type="text/css"><script type="text/javascript" src="//use.typekit.net/vqa1hcx.js"></script><script type="text/javascript">try{Typekit.load();}catch(e){}</script></head><body><script>window.fbAsyncInit = function() {FB.init({appId:'1677033832619985',xfbml:true,version:'v2.7'});};(function(d, s, id){var js, fjs = d.getElementsByTagName(s)[0];if (d.getElementById(id)) {return;}js = d.createElement(s); js.id = id;js.src = '//connect.facebook.net/en_US/sdk.js';fjs.parentNode.insertBefore(js, fjs);}(document, 'script','facebook-jssdk'));</script><script>window.twttr=(function(d,s, id){var js,fjs=d.getElementsByTagName(s)[0],t=window.twttr||{};if(d.getElementById(id))return t;js=d.createElement(s);js.id=id;js.src='https://platform.twitter.com/widgets.js';fjs.parentNode.insertBefore(js, fjs);t._e = [];t.ready = function(f) {t._e.push(f);};return t;}(document, 'script', 'twitter-wjs'));</script><div class="container"><div class="nav-main"><div class="wrap"><a class="nav-home" href=""><img src="img/header_logo.png">React Native</a><a class="nav-version" href="/react-native/versions.html">0.40</a><div class="nav-site-wrapper"><ul class="nav-site nav-site-internal"><li><a href="docs/getting-started.html" class="active" data-target=".nav-docs">Docs</a></li><li><a href="/react-native/support.html" class="">Help</a></li><li><a href="/react-native/showcase.html" class="">Showcase</a></li><li><a href="/react-native/blog/" class="">Blog</a></li></ul><div class="algolia-search-wrapper"><input id="algolia-doc-search" tabindex="0" type="text" placeholder="Search docs..."></div><ul class="nav-site nav-site-external"><li><a href="https://github.com/facebook/react-native" class="">GitHub</a></li><li><a href="http://facebook.github.io/react" class="">React</a></li></ul></div></div></div><section class="content wrap documentationContent"><div class="nav-docs"><div class="nav-docs-viewport"><div class="nav-docs-section"><h3>The Basics</h3><ul><li><a style="margin-left:0;" class="" href="docs/getting-started.html">Getting Started</a></li><li><a style="margin-left:0;" class="" href="docs/tutorial.html">Tutorial</a></li><li><a style="margin-left:0;" class="" href="docs/props.html">Props</a></li><li><a style="margin-left:0;" class="" href="docs/state.html">State</a></li><li><a style="margin-left:0;" class="" href="docs/style.html">Style</a></li><li><a style="margin-left:0;" class="" href="docs/height-and-width.html">Height and Width</a></li><li><a style="margin-left:0;" class="" href="docs/flexbox.html">Layout with Flexbox</a></li><li><a style="margin-left:0;" class="" href="docs/handling-text-input.html">Handling Text Input</a></li><li><a style="margin-left:0;" class="" href="docs/using-a-scrollview.html">Using a ScrollView</a></li><li><a style="margin-left:0;" class="" href="docs/using-a-listview.html">Using a ListView</a></li><li><a style="margin-left:0;" class="" href="docs/network.html">Networking</a></li><li><a style="margin-left:0;" class="" href="docs/using-navigators.html">Using Navigators</a></li><li><a style="margin-left:0;" class="" href="docs/more-resources.html">More Resources</a></li></ul></div><div class="nav-docs-section"><h3>Guides</h3><ul><li><a style="margin-left:0;" class="" href="docs/integration-with-existing-apps.html">Integration With Existing Apps</a></li><li><a style="margin-left:0;" class="" href="docs/colors.html">Colors</a></li><li><a style="margin-left:0;" class="" href="docs/images.html">Images</a></li><li><a style="margin-left:0;" class="" href="docs/handling-touches.html">Handling Touches</a></li><li><a style="margin-left:0;" class="" href="docs/animations.html">Animations</a></li><li><a style="margin-left:0;" class="" href="docs/accessibility.html">Accessibility</a></li><li><a style="margin-left:0;" class="" href="docs/timers.html">Timers</a></li><li><a style="margin-left:0;" class="active" href="docs/direct-manipulation.html">Direct Manipulation</a></li><li><a style="margin-left:0;" class="" href="docs/debugging.html">Debugging</a></li><li><a style="margin-left:0;" class="" href="docs/testing.html">Testing</a></li><li><a style="margin-left:0;" class="" href="docs/running-on-device.html">Running On Device</a></li><li><a style="margin-left:0;" class="" href="docs/javascript-environment.html">JavaScript Environment</a></li><li><a style="margin-left:0;" class="" href="docs/navigation.html">Navigation</a></li><li><a style="margin-left:0;" class="" href="docs/performance.html">Performance</a></li><li><a style="margin-left:0;" class="" href="docs/understanding-cli.html">Understanding the CLI</a></li><li><a style="margin-left:0;" class="" href="docs/upgrading.html">Upgrading</a></li><li><a style="margin-left:0;" class="" href="docs/platform-specific-code.html">Platform Specific Code</a></li><li><a style="margin-left:0;" class="" href="docs/gesture-responder-system.html">Gesture Responder System</a></li></ul></div><div class="nav-docs-section"><h3>Guides (iOS)</h3><ul><li><a style="margin-left:0;" class="" href="docs/native-modules-ios.html">Native Modules</a></li><li><a style="margin-left:0;" class="" href="docs/native-components-ios.html">Native UI Components</a></li><li><a style="margin-left:0;" class="" href="docs/linking-libraries-ios.html">Linking Libraries</a></li><li><a style="margin-left:0;" class="" href="docs/running-on-simulator-ios.html">Running On Simulator</a></li><li><a style="margin-left:0;" class="" href="docs/communication-ios.html">Communication between native and React Native</a></li></ul></div><div class="nav-docs-section"><h3>Guides (Android)</h3><ul><li><a style="margin-left:0;" class="" href="docs/native-modules-android.html">Native Modules</a></li><li><a style="margin-left:0;" class="" href="docs/native-components-android.html">Native UI Components</a></li><li><a style="margin-left:0;" class="" href="docs/headless-js-android.html">Headless JS</a></li><li><a style="margin-left:0;" class="" href="docs/signed-apk-android.html">Generating Signed APK</a></li><li><a style="margin-left:0;" class="" href="docs/android-ui-performance.html">Profiling Android UI Performance</a></li><li><a style="margin-left:0;" class="" href="docs/android-building-from-source.html">Building React Native from source</a></li></ul></div><div class="nav-docs-section"><h3>components</h3><ul><li><a style="margin-left:0;" class="" href="docs/activityindicator.html">ActivityIndicator</a></li><li><a style="margin-left:0;" class="" href="docs/button.html">Button</a></li><li><a style="margin-left:0;" class="" href="docs/datepickerios.html">DatePickerIOS</a></li><li><a style="margin-left:0;" class="" href="docs/drawerlayoutandroid.html">DrawerLayoutAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/image.html">Image</a></li><li><a style="margin-left:0;" class="" href="docs/keyboardavoidingview.html">KeyboardAvoidingView</a></li><li><a style="margin-left:0;" class="" href="docs/listview.html">ListView</a></li><li><a style="margin-left:0;" class="" href="docs/mapview.html">MapView</a></li><li><a style="margin-left:0;" class="" href="docs/modal.html">Modal</a></li><li><a style="margin-left:0;" class="" href="docs/navigator.html">Navigator</a></li><li><a style="margin-left:0;" class="" href="docs/navigatorios.html">NavigatorIOS</a></li><li><a style="margin-left:0;" class="" href="docs/picker.html">Picker</a></li><li><a style="margin-left:0;" class="" href="docs/pickerios.html">PickerIOS</a></li><li><a style="margin-left:0;" class="" href="docs/progressbarandroid.html">ProgressBarAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/progressviewios.html">ProgressViewIOS</a></li><li><a style="margin-left:0;" class="" href="docs/refreshcontrol.html">RefreshControl</a></li><li><a style="margin-left:0;" class="" href="docs/scrollview.html">ScrollView</a></li><li><a style="margin-left:0;" class="" href="docs/segmentedcontrolios.html">SegmentedControlIOS</a></li><li><a style="margin-left:0;" class="" href="docs/slider.html">Slider</a></li><li><a style="margin-left:0;" class="" href="docs/snapshotviewios.html">SnapshotViewIOS</a></li><li><a style="margin-left:0;" class="" href="docs/statusbar.html">StatusBar</a></li><li><a style="margin-left:0;" class="" href="docs/switch.html">Switch</a></li><li><a style="margin-left:0;" class="" href="docs/tabbarios.html">TabBarIOS</a></li><li><a style="margin-left:0;" class="" href="docs/tabbarios-item.html">TabBarIOS.Item</a></li><li><a style="margin-left:0;" class="" href="docs/text.html">Text</a></li><li><a style="margin-left:0;" class="" href="docs/textinput.html">TextInput</a></li><li><a style="margin-left:0;" class="" href="docs/toolbarandroid.html">ToolbarAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/touchablehighlight.html">TouchableHighlight</a></li><li><a style="margin-left:0;" class="" href="docs/touchablenativefeedback.html">TouchableNativeFeedback</a></li><li><a style="margin-left:0;" class="" href="docs/touchableopacity.html">TouchableOpacity</a></li><li><a style="margin-left:0;" class="" href="docs/touchablewithoutfeedback.html">TouchableWithoutFeedback</a></li><li><a style="margin-left:0;" class="" href="docs/view.html">View</a></li><li><a style="margin-left:0;" class="" href="docs/viewpagerandroid.html">ViewPagerAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/webview.html">WebView</a></li></ul></div><div class="nav-docs-section"><h3>apis</h3><ul><li><a style="margin-left:0;" class="" href="docs/actionsheetios.html">ActionSheetIOS</a></li><li><a style="margin-left:0;" class="" href="docs/adsupportios.html">AdSupportIOS</a></li><li><a style="margin-left:0;" class="" href="docs/alert.html">Alert</a></li><li><a style="margin-left:0;" class="" href="docs/alertios.html">AlertIOS</a></li><li><a style="margin-left:0;" class="" href="docs/animated.html">Animated</a></li><li><a style="margin-left:0;" class="" href="docs/appregistry.html">AppRegistry</a></li><li><a style="margin-left:0;" class="" href="docs/appstate.html">AppState</a></li><li><a style="margin-left:0;" class="" href="docs/asyncstorage.html">AsyncStorage</a></li><li><a style="margin-left:0;" class="" href="docs/backandroid.html">BackAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/cameraroll.html">CameraRoll</a></li><li><a style="margin-left:0;" class="" href="docs/clipboard.html">Clipboard</a></li><li><a style="margin-left:0;" class="" href="docs/datepickerandroid.html">DatePickerAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/dimensions.html">Dimensions</a></li><li><a style="margin-left:0;" class="" href="docs/easing.html">Easing</a></li><li><a style="margin-left:0;" class="" href="docs/geolocation.html">Geolocation</a></li><li><a style="margin-left:0;" class="" href="docs/imageeditor.html">ImageEditor</a></li><li><a style="margin-left:0;" class="" href="docs/imagepickerios.html">ImagePickerIOS</a></li><li><a style="margin-left:0;" class="" href="docs/imagestore.html">ImageStore</a></li><li><a style="margin-left:0;" class="" href="docs/interactionmanager.html">InteractionManager</a></li><li><a style="margin-left:0;" class="" href="docs/keyboard.html">Keyboard</a></li><li><a style="margin-left:0;" class="" href="docs/layoutanimation.html">LayoutAnimation</a></li><li><a style="margin-left:0;" class="" href="docs/linking.html">Linking</a></li><li><a style="margin-left:0;" class="" href="docs/nativemethodsmixin.html">NativeMethodsMixin</a></li><li><a style="margin-left:0;" class="" href="docs/netinfo.html">NetInfo</a></li><li><a style="margin-left:0;" class="" href="docs/panresponder.html">PanResponder</a></li><li><a style="margin-left:0;" class="" href="docs/permissionsandroid.html">PermissionsAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/pixelratio.html">PixelRatio</a></li><li><a style="margin-left:0;" class="" href="docs/pushnotificationios.html">PushNotificationIOS</a></li><li><a style="margin-left:0;" class="" href="docs/settings.html">Settings</a></li><li><a style="margin-left:0;" class="" href="docs/share.html">Share</a></li><li><a style="margin-left:0;" class="" href="docs/statusbarios.html">StatusBarIOS</a></li><li><a style="margin-left:0;" class="" href="docs/stylesheet.html">StyleSheet</a></li><li><a style="margin-left:0;" class="" href="docs/systrace.html">Systrace</a></li><li><a style="margin-left:0;" class="" href="docs/timepickerandroid.html">TimePickerAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/toastandroid.html">ToastAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/vibration.html">Vibration</a></li><li><a style="margin-left:0;" class="" href="docs/vibrationios.html">VibrationIOS</a></li><li><a style="margin-left:0;" class="" href="docs/layout-props.html">Layout Props</a></li><li><a style="margin-left:0;" class="" href="docs/shadow-props.html">Shadow Props</a></li></ul></div></div></div><div class="inner-content"><a id="content"></a><h1><a class="anchor" name="direct-manipulation"></a>Direct Manipulation <a class="hash-link" href="docs/direct-manipulation.html#direct-manipulation">#</a></h1><div><p>It is sometimes necessary to make changes directly to a component
|
|
without using state/props to trigger a re-render of the entire subtree.
|
|
When using React in the browser for example, you sometimes need to
|
|
directly modify a DOM node, and the same is true for views in mobile
|
|
apps. <code>setNativeProps</code> is the React Native equivalent to setting
|
|
properties directly on a DOM node.</p><blockquote><p>Use setNativeProps when frequent re-rendering creates a performance bottleneck</p><p>Direct manipulation will not be a tool that you reach for
|
|
frequently; you will typically only be using it for creating
|
|
continuous animations to avoid the overhead of rendering the component
|
|
hierarchy and reconciling many views. <code>setNativeProps</code> is imperative
|
|
and stores state in the native layer (DOM, UIView, etc.) and not
|
|
within your React components, which makes your code more difficult to
|
|
reason about. Before you use it, try to solve your problem with <code>setState</code>
|
|
and <a href="http://facebook.github.io/react/docs/advanced-performance.html#shouldcomponentupdate-in-action" target="_blank">shouldComponentUpdate</a>.</p></blockquote><h2><a class="anchor" name="setnativeprops-with-touchableopacity"></a>setNativeProps with TouchableOpacity <a class="hash-link" href="docs/direct-manipulation.html#setnativeprops-with-touchableopacity">#</a></h2><p><a href="https://github.com/facebook/react-native/blob/master/Libraries/Components/Touchable/TouchableOpacity.js" target="_blank">TouchableOpacity</a>
|
|
uses <code>setNativeProps</code> internally to update the opacity of its child
|
|
component:</p><div class="prism language-javascript"><span class="token function">setOpacityTo<span class="token punctuation">(</span></span>value<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token comment" spellcheck="true"> // Redacted: animation related code
|
|
</span> <span class="token keyword">this</span><span class="token punctuation">.</span>refs<span class="token punctuation">[</span>CHILD_REF<span class="token punctuation">]</span><span class="token punctuation">.</span><span class="token function">setNativeProps<span class="token punctuation">(</span></span><span class="token punctuation">{</span>
|
|
opacity<span class="token punctuation">:</span> value
|
|
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
|
<span class="token punctuation">}</span><span class="token punctuation">,</span></div><p>This allows us to write the following code and know that the child will
|
|
have its opacity updated in response to taps, without the child having
|
|
any knowledge of that fact or requiring any changes to its implementation:</p><div class="prism language-javascript"><TouchableOpacity onPress<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>_handlePress<span class="token punctuation">}</span><span class="token operator">></span>
|
|
<View style<span class="token operator">=</span><span class="token punctuation">{</span>styles<span class="token punctuation">.</span>button<span class="token punctuation">}</span><span class="token operator">></span>
|
|
<Text<span class="token operator">></span>Press me<span class="token operator">!</span><<span class="token operator">/</span>Text<span class="token operator">></span>
|
|
<<span class="token operator">/</span>View<span class="token operator">></span>
|
|
<<span class="token operator">/</span>TouchableOpacity<span class="token operator">></span></div><p>Let's imagine that <code>setNativeProps</code> was not available. One way that we
|
|
might implement it with that constraint is to store the opacity value
|
|
in the state, then update that value whenever <code>onPress</code> is fired:</p><div class="prism language-javascript"><span class="token function">constructor<span class="token punctuation">(</span></span>props<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token function">super<span class="token punctuation">(</span></span>props<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
|
<span class="token keyword">this</span><span class="token punctuation">.</span>state <span class="token operator">=</span> <span class="token punctuation">{</span> myButtonOpacity<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
|
|
<span class="token punctuation">}</span>
|
|
|
|
<span class="token function">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token keyword">return</span> <span class="token punctuation">(</span>
|
|
<TouchableOpacity onPress<span class="token operator">=</span><span class="token punctuation">{</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState<span class="token punctuation">(</span></span><span class="token punctuation">{</span>myButtonOpacity<span class="token punctuation">:</span> <span class="token number">0.5</span><span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">}</span>
|
|
onPressOut<span class="token operator">=</span><span class="token punctuation">{</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState<span class="token punctuation">(</span></span><span class="token punctuation">{</span>myButtonOpacity<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">}</span><span class="token operator">></span>
|
|
<View style<span class="token operator">=</span><span class="token punctuation">{</span><span class="token punctuation">[</span>styles<span class="token punctuation">.</span>button<span class="token punctuation">,</span> <span class="token punctuation">{</span>opacity<span class="token punctuation">:</span> <span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>myButtonOpacity<span class="token punctuation">}</span><span class="token punctuation">]</span><span class="token punctuation">}</span><span class="token operator">></span>
|
|
<Text<span class="token operator">></span>Press me<span class="token operator">!</span><<span class="token operator">/</span>Text<span class="token operator">></span>
|
|
<<span class="token operator">/</span>View<span class="token operator">></span>
|
|
<<span class="token operator">/</span>TouchableOpacity<span class="token operator">></span>
|
|
<span class="token punctuation">)</span>
|
|
<span class="token punctuation">}</span></div><p>This is computationally intensive compared to the original example -
|
|
React needs to re-render the component hierarchy each time the opacity
|
|
changes, even though other properties of the view and its children
|
|
haven't changed. Usually this overhead isn't a concern but when
|
|
performing continuous animations and responding to gestures, judiciously
|
|
optimizing your components can improve your animations' fidelity.</p><p>If you look at the implementation of <code>setNativeProps</code> in
|
|
<a href="https://github.com/facebook/react/blob/master/src/renderers/native/NativeMethodsMixin.js" target="_blank">NativeMethodsMixin.js</a>
|
|
you will notice that it is a wrapper around <code>RCTUIManager.updateView</code> -
|
|
this is the exact same function call that results from re-rendering -
|
|
see <a href="https://github.com/facebook/react/blob/master/src/renderers/native/ReactNativeBaseComponent.js" target="_blank">receiveComponent in
|
|
ReactNativeBaseComponent.js</a>.</p><h2><a class="anchor" name="composite-components-and-setnativeprops"></a>Composite components and setNativeProps <a class="hash-link" href="docs/direct-manipulation.html#composite-components-and-setnativeprops">#</a></h2><p>Composite components are not backed by a native view, so you cannot call
|
|
<code>setNativeProps</code> on them. Consider this example:</p><div class="prism language-javascript">class <span class="token class-name">MyButton</span> extends <span class="token class-name">React<span class="token punctuation">.</span>Component</span> <span class="token punctuation">{</span>
|
|
<span class="token function">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token keyword">return</span> <span class="token punctuation">(</span>
|
|
<View<span class="token operator">></span>
|
|
<Text<span class="token operator">></span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span>label<span class="token punctuation">}</span><<span class="token operator">/</span>Text<span class="token operator">></span>
|
|
<<span class="token operator">/</span>View<span class="token operator">></span>
|
|
<span class="token punctuation">)</span>
|
|
<span class="token punctuation">}</span>
|
|
<span class="token punctuation">}</span>
|
|
|
|
class <span class="token class-name">App</span> extends <span class="token class-name">React<span class="token punctuation">.</span>Component</span> <span class="token punctuation">{</span>
|
|
<span class="token function">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token keyword">return</span> <span class="token punctuation">(</span>
|
|
<TouchableOpacity<span class="token operator">></span>
|
|
<MyButton label<span class="token operator">=</span><span class="token string">"Press me!"</span> <span class="token operator">/</span><span class="token operator">></span>
|
|
<<span class="token operator">/</span>TouchableOpacity<span class="token operator">></span>
|
|
<span class="token punctuation">)</span>
|
|
<span class="token punctuation">}</span>
|
|
<span class="token punctuation">}</span></div><p><a href="https://rnplay.org/apps/JXkgmQ" target="_blank">Run this example</a></p><p>If you run this you will immediately see this error: <code>Touchable child
|
|
must either be native or forward setNativeProps to a native component</code>.
|
|
This occurs because <code>MyButton</code> isn't directly backed by a native view
|
|
whose opacity should be set. You can think about it like this: if you
|
|
define a component with <code>React.createClass</code> you would not expect to be
|
|
able to set a style prop on it and have that work - you would need to
|
|
pass the style prop down to a child, unless you are wrapping a native
|
|
component. Similarly, we are going to forward <code>setNativeProps</code> to a
|
|
native-backed child component.</p><h4><a class="anchor" name="forward-setnativeprops-to-a-child"></a>Forward setNativeProps to a child <a class="hash-link" href="docs/direct-manipulation.html#forward-setnativeprops-to-a-child">#</a></h4><p>All we need to do is provide a <code>setNativeProps</code> method on our component
|
|
that calls <code>setNativeProps</code> on the appropriate child with the given
|
|
arguments.</p><div class="prism language-javascript">class <span class="token class-name">MyButton</span> extends <span class="token class-name">React<span class="token punctuation">.</span>Component</span> <span class="token punctuation">{</span>
|
|
<span class="token function">setNativeProps<span class="token punctuation">(</span></span>nativeProps<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token keyword">this</span><span class="token punctuation">.</span>_root<span class="token punctuation">.</span><span class="token function">setNativeProps<span class="token punctuation">(</span></span>nativeProps<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
|
<span class="token punctuation">}</span>
|
|
|
|
<span class="token function">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token keyword">return</span> <span class="token punctuation">(</span>
|
|
<View ref<span class="token operator">=</span><span class="token punctuation">{</span>component <span class="token operator">=</span><span class="token operator">></span> <span class="token keyword">this</span><span class="token punctuation">.</span>_root <span class="token operator">=</span> component<span class="token punctuation">}</span> <span class="token punctuation">{</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">}</span><span class="token operator">></span>
|
|
<Text<span class="token operator">></span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span>label<span class="token punctuation">}</span><<span class="token operator">/</span>Text<span class="token operator">></span>
|
|
<<span class="token operator">/</span>View<span class="token operator">></span>
|
|
<span class="token punctuation">)</span>
|
|
<span class="token punctuation">}</span>
|
|
<span class="token punctuation">}</span></div><p><a href="https://rnplay.org/apps/YJxnEQ" target="_blank">Run this example</a></p><p>You can now use <code>MyButton</code> inside of <code>TouchableOpacity</code>! A sidenote for
|
|
clarity: we used the <a href="https://facebook.github.io/react/docs/more-about-refs.html#the-ref-callback-attribute" target="_blank">ref callback</a> syntax here, rather than the traditional string-based ref.</p><p>You may have noticed that we passed all of the props down to the child
|
|
view using <code>{...this.props}</code>. The reason for this is that
|
|
<code>TouchableOpacity</code> is actually a composite component, and so in addition
|
|
to depending on <code>setNativeProps</code> on its child, it also requires that the
|
|
child perform touch handling. To do this, it passes on <a href="docs/view.html#onmoveshouldsetresponder" target="_blank">various
|
|
props</a>
|
|
that call back to the <code>TouchableOpacity</code> component.
|
|
<code>TouchableHighlight</code>, in contrast, is backed by a native view and only
|
|
requires that we implement <code>setNativeProps</code>.</p><h2><a class="anchor" name="setnativeprops-to-clear-textinput-value"></a>setNativeProps to clear TextInput value <a class="hash-link" href="docs/direct-manipulation.html#setnativeprops-to-clear-textinput-value">#</a></h2><p>Another very common use case of <code>setNativeProps</code> is to clear the value
|
|
of a TextInput. The <code>controlled</code> prop of TextInput can sometimes drop
|
|
characters when the <code>bufferDelay</code> is low and the user types very
|
|
quickly. Some developers prefer to skip this prop entirely and instead
|
|
use <code>setNativeProps</code> to directly manipulate the TextInput value when
|
|
necessary. For example, the following code demonstrates clearing the
|
|
input when you tap a button:</p><div class="prism language-javascript">class <span class="token class-name">App</span> extends <span class="token class-name">React<span class="token punctuation">.</span>Component</span> <span class="token punctuation">{</span>
|
|
<span class="token function">constructor<span class="token punctuation">(</span></span>props<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token function">super<span class="token punctuation">(</span></span>props<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
|
<span class="token keyword">this</span><span class="token punctuation">.</span>clearText <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>clearText<span class="token punctuation">.</span><span class="token function">bind<span class="token punctuation">(</span></span><span class="token keyword">this</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
|
<span class="token punctuation">}</span>
|
|
|
|
<span class="token function">clearText<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token keyword">this</span><span class="token punctuation">.</span>_textInput<span class="token punctuation">.</span><span class="token function">setNativeProps<span class="token punctuation">(</span></span><span class="token punctuation">{</span>text<span class="token punctuation">:</span> <span class="token string">''</span><span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
|
<span class="token punctuation">}</span>
|
|
|
|
<span class="token function">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
|
<span class="token keyword">return</span> <span class="token punctuation">(</span>
|
|
<View style<span class="token operator">=</span><span class="token punctuation">{</span>styles<span class="token punctuation">.</span>container<span class="token punctuation">}</span><span class="token operator">></span>
|
|
<TextInput ref<span class="token operator">=</span><span class="token punctuation">{</span>component <span class="token operator">=</span><span class="token operator">></span> <span class="token keyword">this</span><span class="token punctuation">.</span>_textInput <span class="token operator">=</span> component<span class="token punctuation">}</span>
|
|
style<span class="token operator">=</span><span class="token punctuation">{</span>styles<span class="token punctuation">.</span>textInput<span class="token punctuation">}</span> <span class="token operator">/</span><span class="token operator">></span>
|
|
<TouchableOpacity onPress<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>clearText<span class="token punctuation">}</span><span class="token operator">></span>
|
|
<Text<span class="token operator">></span>Clear text<<span class="token operator">/</span>Text<span class="token operator">></span>
|
|
<<span class="token operator">/</span>TouchableOpacity<span class="token operator">></span>
|
|
<<span class="token operator">/</span>View<span class="token operator">></span>
|
|
<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
|
<span class="token punctuation">}</span>
|
|
<span class="token punctuation">}</span></div><p><a href="https://rnplay.org/plays/pOI9bA" target="_blank">Run this example</a></p><h2><a class="anchor" name="avoiding-conflicts-with-the-render-function"></a>Avoiding conflicts with the render function <a class="hash-link" href="docs/direct-manipulation.html#avoiding-conflicts-with-the-render-function">#</a></h2><p>If you update a property that is also managed by the render function,
|
|
you might end up with some unpredictable and confusing bugs because
|
|
anytime the component re-renders and that property changes, whatever
|
|
value was previously set from <code>setNativeProps</code> will be completely
|
|
ignored and overridden. <a href="https://rnplay.org/apps/bp1DvQ" target="_blank">See this example</a>
|
|
for a demonstration of what can happen if these two collide - notice
|
|
the jerky animation each 250ms when <code>setState</code> triggers a re-render.</p><h2><a class="anchor" name="setnativeprops-shouldcomponentupdate"></a>setNativeProps & shouldComponentUpdate <a class="hash-link" href="docs/direct-manipulation.html#setnativeprops-shouldcomponentupdate">#</a></h2><p>By <a href="https://facebook.github.io/react/docs/advanced-performance.html#avoiding-reconciling-the-dom" target="_blank">intelligently applying
|
|
<code>shouldComponentUpdate</code></a>
|
|
you can avoid the unnecessary overhead involved in reconciling unchanged
|
|
component subtrees, to the point where it may be performant enough to
|
|
use <code>setState</code> instead of <code>setNativeProps</code>.</p></div><div class="docs-prevnext"><a class="docs-prev" href="docs/timers.html#content">← Prev</a><a class="docs-next" href="docs/debugging.html#content">Next →</a></div><p class="edit-page-block">You can <a target="_blank" href="https://github.com/facebook/react-native/blob/master/docs/DirectManipulation.md">edit the content above on GitHub</a> and send us a pull request!</p></div></section><footer class="nav-footer"><section class="sitemap"><a href="/react-native" class="nav-home"><img src="img/header_logo.png" alt="React Native" width="66" height="58"></a><div><h5><a href="docs/">Docs</a></h5><a href="docs/getting-started.html">Getting Started</a><a href="docs/tutorial.html">Tutorial</a><a href="docs/integration-with-existing-apps.html">Integration With Existing Apps</a><a href="docs/more-resources.html">More Resources</a></div><div><h5><a href="/react-native/support.html">Community</a></h5><a href="/react-native/showcase.html">Showcase</a><a href="http://www.meetup.com/topics/react-native/" target="_blank">Upcoming Events</a><a href="https://www.facebook.com/groups/react.native.community" target="_blank">Facebook Group</a><a href="https://twitter.com/reactnative" target="_blank">Twitter</a></div><div><h5><a href="/react-native/support.html">Help</a></h5><a href="http://stackoverflow.com/questions/tagged/react-native" target="_blank">Stack Overflow</a><a href="https://discord.gg/0ZcbPKXt5bZjGY5n">Reactiflux Chat</a><a href="/react-native/versions.html" target="_blank">Latest Releases</a><a href="https://productpains.com/product/react-native/" target="_blank">Feature Requests</a></div><div><h5>More</h5><a href="/react-native/blog">Blog</a><a href="https://github.com/facebook/react-native" target="_blank">GitHub</a><a href="http://facebook.github.io/react/" target="_blank">React</a></div></section><section class="newsletter"><div id="mc_embed_signup"><form action="//reactnative.us10.list-manage.com/subscribe/post?u=db0dd948e2b729ee62625b1a8&id=47cd41008f" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" target="_blank" novalidate><div id="mc_embed_signup_scroll"><label for="mce-EMAIL"><h5>Get the React Native Newsletter</h5></label><input type="email" value="" name="EMAIL" class="email" id="mce-EMAIL" placeholder="email address" required><div style="position:absolute;left:-5000px;" aria-hidden="true"><input type="text" name="b_db0dd948e2b729ee62625b1a8_47cd41008f" tabindex="-1" value=""></div><div class="clear"><input type="submit" value="Sign up" name="subscribe" id="mc-embedded-subscribe" class="button"></div></div></form></div></section><a href="https://code.facebook.com/projects/" target="_blank" class="fbOpenSource"><img src="img/oss_logo.png" alt="Facebook Open Source" width="170" height="45"></a><section class="copyright">Copyright © 2017 Facebook Inc.</section></footer></div><div id="fb-root"></div><script type="text/javascript" src="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.js"></script><script>
|
|
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
|
|
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
|
|
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
|
|
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
|
|
ga('create', 'UA-41298772-2', 'facebook.github.io');
|
|
ga('send', 'pageview');
|
|
|
|
!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)
|
|
){js=d.createElement(s);js.id=id;js.src="https://platform.twitter.com/widgets.js";
|
|
fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");
|
|
|
|
docsearch({
|
|
apiKey: '2c98749b4a1e588efec53b2acec13025',
|
|
indexName: 'react-native-versions',
|
|
inputSelector: '#algolia-doc-search',
|
|
algoliaOptions: { facetFilters: [ "tags:0.40" ], hitsPerPage: 5 }
|
|
});
|
|
</script><script src="js/scripts.js"></script><script type="text/javascript" src="//s3.amazonaws.com/downloads.mailchimp.com/js/mc-validate.js"></script><script type="text/javascript">(function($) {window.fnames = new Array(); window.ftypes = new Array();fnames[0]='EMAIL';ftypes[0]='email';fnames[1]='FNAME';ftypes[1]='text';fnames[2]='LNAME';ftypes[2]='text';}(jQuery));var $mcj = jQuery.noConflict(true);</script></body></html> |