如何使用CameraX在安卓系统中启动240fps的摄像头预览？

使用CameraX在安卓系统中启动240fps的摄像头预览，你需要按照以下步骤进行操作：

导入CameraX库：在项目的build.gradle文件中添加以下依赖项：

implementation 'androidx.camera:camera-core:1.1.0-alpha07'
implementation 'androidx.camera:camera-camera2:1.1.0-alpha07'
implementation 'androidx.camera:camera-lifecycle:1.1.0-alpha07'
implementation 'androidx.camera:camera-view:1.0.0-alpha19'

在布局文件中添加CameraView：在你的布局文件中添加一个CameraView视图，用于显示摄像头的预览画面。

<androidx.camera.view.CameraView
    android:id="@+id/cameraView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
/>

在Activity或Fragment中初始化CameraX：在你的Activity或Fragment中的onCreate()方法中，初始化CameraX并配置相应的用例。

private lateinit var cameraView: CameraView

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.your_layout)
    
    cameraView = findViewById(R.id.cameraView)
    cameraView.bindToLifecycle(this)
    
    val previewConfig = PreviewConfig.Builder().apply {
        setTargetResolution(Size(1920, 1080))
    }.build()
    
    val preview = Preview(previewConfig)
    
    preview.setOnPreviewOutputUpdateListener { previewOutput ->
        val parent = cameraView.parent as ViewGroup
        parent.removeView(cameraView)
        parent.addView(cameraView, 0)
        cameraView.surfaceTexture = previewOutput.surfaceTexture
    }
    
    CameraX.bindToLifecycle(this, preview)
}

启动高帧率摄像头预览：为了启动240fps的摄像头预览，你需要先获取所有可用的摄像头，并找到支持240fps帧率的摄像头。然后，将该摄像头的id传递给PreviewConfig的setCameraSelector()方法。

val cameraSelector = CameraSelector.Builder()
    .requireLensFacing(CameraSelector.LENS_FACING_BACK)
    .build()

val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
cameraProviderFuture.addListener(Runnable {
    val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
    val cameraInfo = cameraProvider.getCameraInfo(cameraSelector).get()
    
    val cameraId = cameraInfo.cameraId
    val cameraCharacteristics = cameraInfo.cameraCharacteristics
    
    // 检查是否支持240fps帧率
    val highSpeedFpsRanges = cameraCharacteristics.get(
        CameraCharacteristics.CONTROL_AE_AVAILABLE_TARGET_FPS_RANGES
    ).filter { it.upper == 240 }
    
    if (highSpeedFpsRanges.isNotEmpty()) {
        val highSpeedConfig = PreviewConfig.Builder().apply {
            setCameraSelector(cameraSelector)
            setTargetResolution(Size(1920, 1080))
            setTargetAspectRatio(AspectRatio.RATIO_16_9)
            setTargetRotation(cameraView.display.rotation)
            setTargetFpsRange(highSpeedFpsRanges[0])
        }.build()
        
        val highSpeedPreview = Preview(highSpeedConfig)
        
        highSpeedPreview.setOnPreviewOutputUpdateListener { previewOutput ->
            // 处理预览输出
        }
        
        CameraX.bindToLifecycle(this, cameraSelector, highSpeedPreview)
    } else {
        // 设备不支持240fps帧率
    }
}, ContextCompat.getMainExecutor(this))

以上就是使用CameraX在安卓系统中启动240fps的摄像头预览的步骤。通过这些步骤，你可以获取摄像头的预览画面，并且在设备支持的情况下，实现高帧率的预览效果。

如果你想了解更多关于CameraX的信息，你可以访问腾讯云的CameraX产品介绍页面：CameraX产品介绍