64 lines
2.3 KiB
Markdown
64 lines
2.3 KiB
Markdown
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---
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id: basics-dimensions
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title: Dimensions
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layout: docs
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category: The Basics
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permalink: docs/basics-dimensions.html
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next: basics-layout
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---
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A component's dimensions determine its size on the screen.
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#### Fixed Dimensions
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The simplest way to set the dimensions of a component is by adding a fixed `width` and `height` to style. All dimensions in React Native are unitless, and represent density-independent pixels.
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```ReactNativeWebPlayer
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import React from 'react';
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import { AppRegistry, View } from 'react-native';
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class AwesomeProject {
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render() {
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return (
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<View>
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<View style={{width: 50, height: 50, backgroundColor: 'powderblue'}} />
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<View style={{width: 100, height: 100, backgroundColor: 'skyblue'}} />
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<View style={{width: 150, height: 150, backgroundColor: 'steelblue'}} />
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</View>
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);
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}
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};
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AppRegistry.registerComponent('AwesomeProject', () => AwesomeProject);
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```
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Setting dimensions this way is common for components that should always render at exactly the same size, regardless of screen dimensions.
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#### Flex Dimensions
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Use `flex` in a component's style to have the component expand and shrink dynamically based on available space. Normally you will use `flex: 1`, which tells a component to fill all available space, shared evenly amongst each other component with the same parent. The larger the `flex` given, the higher the ratio of space a component will take compared to its siblings.
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> A component can only expand to fill available space if its parent has dimensions greater than 0. If a parent does not have either a fixed `width` and `height` or `flex`, the parent will have dimensions of 0 and the `flex` children will not be visible.
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```ReactNativeWebPlayer
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import React from 'react';
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import { AppRegistry, View } from 'react-native';
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class AwesomeProject {
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render() {
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return (
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// Try removing the `flex: 1` on the parent View.
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// The parent will not have dimensions, so the children can't expand.
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// What if you add `height: 300` instead of `flex: 1`?
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<View style={{flex: 1}}>
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<View style={{flex: 1, backgroundColor: 'powderblue'}} />
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<View style={{flex: 2, backgroundColor: 'skyblue'}} />
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<View style={{flex: 3, backgroundColor: 'steelblue'}} />
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</View>
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);
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}
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};
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AppRegistry.registerComponent('AwesomeProject', () => AwesomeProject);
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```
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