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在 Jetpack Compose 中解锁 CameraX 的强大功能

谷歌开发者 · 公众号 · 科技媒体 · 2025-02-24 17:30

正文

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{

..


   
    
     implementation(libs.androidx.camera.core)


   
    
     implementation(libs.androidx.camera.compose)


   
    
     implementation(libs.androidx.camera.lifecycle)


   
    
     implementation(libs.androidx.camera.camera2)


   
    
     implementation(libs.accompanist.permissions)

为了授予相机权限，我们添加了所有依赖项，然后实际显示相机预览。接下来，让我们看看如何授予正确的权限。

授予相机权限

通过使用 Accompanist 权限库，我们可以轻松地授予正确的相机权限。首先，我们需要设置 AndroidManifest.xml ：

<manifest xmlns:android="http://schemas.android.com/apk/res/android">    <uses-feature android:name="android.hardware.camera" android:required="true" />    <uses-permission android:name="android.permission.CAMERA" />
    ..
manifest>

Accompanist 权限库

https://google.github.io/accompanist/permissions/

现在，我们只需按照库的说明授予正确的权限：

class MainActivity : ComponentActivity() {    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        enableEdgeToEdge()        setContent {            MyApplicationTheme {                CameraPreviewScreen()            }        }    }}
@OptIn(ExperimentalPermissionsApi::class)@Composablefun CameraPreviewScreen(modifier: Modifier = Modifier) {    val cameraPermissionState = rememberPermissionState(android.Manifest.permission.CAMERA)    if (cameraPermissionState.status.isGranted) {        CameraPreviewContent(modifier)    } else {        Column(            modifier = modifier.fillMaxSize().wrapContentSize().widthIn(max = 480.dp),            horizontalAlignment = Alignment.CenterHorizontally        ) {            val textToShow = if (cameraPermissionState.status.shouldShowRationale) {                // If the user has denied the permission but the rationale can be shown,                // then gently explain why the app requires this permission                "Whoops! Looks like we need your camera to work our magic!" +                    "Don't worry, we just wanna see your pretty face (and maybe some cats).  "