55 lines
1.9 KiB
Plaintext
55 lines
1.9 KiB
Plaintext
---
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id: lifecycle
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title: Lifecycle
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sidebar_label: Lifecycle
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---
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import useBaseUrl from '@docusaurus/useBaseUrl';
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<div>
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<img align="right" width="283" src={useBaseUrl("img/example.png")} />
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</div>
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### The `isActive` prop
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The Camera's `isActive` property can be used to _pause_ the session (`isActive={false}`) while still keeping the session "warm". This is more desirable than completely unmounting the camera, since _resuming_ the session (`isActive={true}`) will be **much faster** than re-mounting the camera view.
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For example, you want to **pause the camera** when the user **navigates to another page** or **minimizes the app** since otherwise the camera continues to run in the background without the user seeing it, causing **siginificant battery drain**. Also, on iOS a green dot indicates the user that the camera is still active, possibly causing the user to raise privacy concerns. (🔗 See ["About the orange and green indicators in your iPhone status bar"](https://support.apple.com/en-us/HT211876))
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This example demonstrates how you could pause the camera stream once the app goes into background using a [custom `useIsAppForeground` hook](https://github.com/mrousavy/react-native-vision-camera/blob/main/example/src/hooks/useIsForeground.ts):
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```tsx
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function App() {
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const devices = useCameraDevices()
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const device = devices.back
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const isAppForeground = useIsAppForeground()
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if (device == null) return <LoadingView />
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return (
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<Camera
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style={StyleSheet.absoluteFill}
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device={device}
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isActive={isAppForeground}
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/>
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)
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}
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```
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#### Usage with `react-navigation`
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To automatically pause the Camera when the user navigates to a different page, use the [`useIsFocused`](https://reactnavigation.org/docs/use-is-focused/) function:
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```tsx {4}
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function App() {
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// ...
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const isFocused = useIsFocused()
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return <Camera {...props} isActive={isFocused} />
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}
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```
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<br />
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#### 🚀 Next section: [Camera Formats](formats)
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