Jetpack Compose中使用相机

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Jetpack Compose中使用相机

前言

官方文档

https://developer.android.google.cn/jetpack/androidx/releases/camera?hl

在 Jetpack Compose 中获取相机画面可以按照以下步骤进行：

添加权限

在 AndroidManifest.xml 文件中添加相机权限：

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<uses-permission android:name="android.permission.CAMERA" />

如果你的应用面向 Android 13 及以上版本，还需要在 AndroidManifest.xml 中声明相机使用情况：

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<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

权限申请

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import android.Manifest
import android.content.pm.PackageManager
import androidx.activity.compose.rememberLauncherForActivityResult
import androidx.activity.result.contract.ActivityResultContracts
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.setValue
import androidx.compose.ui.platform.LocalContext
import androidx.core.content.ContextCompat
import androidx.compose.foundation.layout.Column
import androidx.compose.material3.Button
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember

@Composable
fun CameraPermissionRequest(onPermissionGranted: () -> Unit) {
    val context = LocalContext.current
    var hasCameraPermission by remember {
        mutableStateOf(
            ContextCompat.checkSelfPermission(
                context,
                Manifest.permission.CAMERA
            ) == PackageManager.PERMISSION_GRANTED
        )
    }

    val launcher = rememberLauncherForActivityResult(
        contract = ActivityResultContracts.RequestPermission()
    ) { isGranted: Boolean ->
        hasCameraPermission = isGranted
    }

    if (hasCameraPermission) {
        onPermissionGranted()
    } else {
        Column {
            Text("需要相机权限才能使用相机功能。")
            Button(onClick = { launcher.launch(Manifest.permission.CAMERA) }) {
                Text("请求权限")
            }
        }
    }
}

添加依赖

向您的 libs.versions.toml 中添加以下内容：

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[versions]
camerax = "1.5.0-alpha03"
cameraView = "1.4.2"


[libraries]
# Contains the basic camera functionality such as SurfaceRequest
androidx-camera-core = { module = "androidx.camera:camera-core", version.ref = "camerax" }
# Contains the CameraXViewfinder composable
androidx-camera-compose = { module = "androidx.camera:camera-compose", version.ref = "camerax" }
# Allows us to bind the camera preview to our UI lifecycle
androidx-camera-lifecycle = { group = "androidx.camera", name = "camera-lifecycle", version.ref = "camerax" }
# The specific camera implementation that renders the preview
androidx-camera-camera2 = { module = "androidx.camera:camera-camera2", version.ref = "camerax" }
androidx-camera-view = { group = "androidx.camera", name = "camera-view", version.ref = "cameraView" }

依赖

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dependencies {
    implementation(libs.androidx.camera.core)
    implementation(libs.androidx.camera.compose)
    implementation(libs.androidx.camera.lifecycle)
    implementation(libs.androidx.camera.camera2)
  	implementation(libs.androidx.camera.view)
}

视图

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import android.content.ContentValues
import android.content.Context
import android.graphics.Bitmap
import android.graphics.ImageDecoder
import android.os.Build
import android.provider.MediaStore
import android.util.Log
import androidx.camera.core.CameraSelector
import androidx.camera.core.ImageCapture
import androidx.camera.core.ImageCaptureException
import androidx.camera.core.Preview
import androidx.camera.lifecycle.ProcessCameraProvider
import androidx.camera.view.PreviewView
import androidx.compose.foundation.Image
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.runtime.Composable
import androidx.compose.runtime.DisposableEffect
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.MutableState
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.asImageBitmap
import androidx.compose.ui.graphics.painter.BitmapPainter
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.unit.dp
import androidx.compose.ui.viewinterop.AndroidView
import androidx.core.content.ContextCompat
import androidx.lifecycle.LifecycleOwner
import java.text.SimpleDateFormat
import java.util.Locale
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors

@Composable
fun CameraScreen() {
    val context = LocalContext.current
    val lifecycleOwner = androidx.lifecycle.compose.LocalLifecycleOwner.current
    val previewView = remember { PreviewView(context) }
    var capturedImage by remember { mutableStateOf<Bitmap?>(null) }
    // 用于存储ImageCapture实例的变量
    val imageCaptureInstance = remember { mutableStateOf<ImageCapture?>(null) }
    // 创建相机执行器
    val cameraExecutor = remember { Executors.newSingleThreadExecutor() }

    // 初始化相机
    LaunchedEffect(Unit) {
        startCamera(previewView, context, imageCaptureInstance, lifecycleOwner, cameraExecutor)
    }
    // 释放相机资源
    DisposableEffect(Unit) {
        onDispose {
            cameraExecutor.shutdown()
        }
    }
    Box(modifier = Modifier.fillMaxSize()) {
        // 相机预览
        AndroidView(
            factory = { previewView },
            modifier = Modifier.fillMaxSize()
        )

        capturedImage?.let {
            Image(
                painter = BitmapPainter(
                    it.asImageBitmap()
                ),
                modifier = Modifier
                    .fillMaxSize()
                    .background(Color(0xaa000000)),
                contentDescription = "显示Bitmap图片"
            )
        }


        // 拍照按钮和其他控制
        Column(
            modifier = Modifier
                .align(Alignment.BottomCenter)
                .fillMaxSize(),
            verticalArrangement = Arrangement.Bottom,
            horizontalAlignment = Alignment.CenterHorizontally
        ) {
            IconButton(
                onClick = {
                    Log.i("CameraX", "onClick: ")
                    takePhoto(
                        context = context,
                        imageCapture = imageCaptureInstance.value,
                        cameraExecutor = cameraExecutor,
                        onImageCaptured = { bitmap ->
                            capturedImage = bitmap
                        }
                    )
                },
                modifier = Modifier
                    .size(72.dp)
                    .padding(24.dp)
            ) {
                Icon(
                    painter = painterResource(id = android.R.drawable.ic_menu_camera),
                    contentDescription = "Take photo",
                    modifier = Modifier.size(72.dp)
                )
            }
        }
    }


}

private fun startCamera(
    previewView: PreviewView,
    context: Context,
    imageCaptureInstance: MutableState<ImageCapture?>,
    lifecycleOwner: LifecycleOwner,
    cameraExecutor: ExecutorService
) {
    val cameraProviderFuture = ProcessCameraProvider.getInstance(context)

    cameraProviderFuture.addListener({
        val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

        // 预览用例
        val preview = Preview.Builder()
            .build()
            .also {
                it.surfaceProvider = previewView.surfaceProvider
            }

        // 图像捕获用例
        val imageCapture = ImageCapture.Builder()
            .build()

        imageCaptureInstance.value = imageCapture

        // 选择后置摄像头
        val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

        try {
            // 解绑所有先前绑定的用例
            cameraProvider.unbindAll()

            // 绑定相机和用例
            cameraProvider.bindToLifecycle(
                lifecycleOwner, cameraSelector, preview, imageCapture
            )

        } catch (exc: Exception) {
            Log.e("CameraX", "使用相机时发生错误", exc)
        }

    }, ContextCompat.getMainExecutor(context))
}

private fun takePhoto(
    context: Context,
    imageCapture: ImageCapture?,
    cameraExecutor: ExecutorService,
    onImageCaptured: (Bitmap) -> Unit
) {
    // 获取ImageCapture实例
    val imageCapture = imageCapture ?: return

    // 创建带时间戳的文件名
    val name = SimpleDateFormat("yyyy-MM-dd-HH-mm-ss-SSS", Locale.US)
        .format(System.currentTimeMillis())

    // 创建内容值
    val contentValues = ContentValues().apply {
        put(MediaStore.MediaColumns.DISPLAY_NAME, name)
        put(MediaStore.MediaColumns.MIME_TYPE, "image/jpeg")
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.P) {
            put(MediaStore.Images.Media.RELATIVE_PATH, "Pictures/CameraX-Image")
        }
    }

    // 创建输出选项对象
    val outputOptions = ImageCapture.OutputFileOptions
        .Builder(
            context.contentResolver,
            MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
            contentValues
        )
        .build()

    // 拍摄照片
    imageCapture.takePicture(
        outputOptions,
        ContextCompat.getMainExecutor(context),
        object : ImageCapture.OnImageSavedCallback {
            override fun onError(exc: ImageCaptureException) {
                Log.e("CameraX", "拍照失败: ${exc.message}", exc)
            }

            @Suppress("DEPRECATION")
            override fun onImageSaved(output: ImageCapture.OutputFileResults) {
                val savedUri = output.savedUri ?: return

                // 将保存的URI转换为Bitmap
                val bitmap = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
                    val source = ImageDecoder.createSource(context.contentResolver, savedUri)
                    ImageDecoder.decodeBitmap(source)
                } else {
                    MediaStore.Images.Media.getBitmap(context.contentResolver, savedUri)
                }
                onImageCaptured(bitmap)
                Log.d("CameraX", "照片已保存到: $savedUri")
            }
        }
    )
}

使用

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import androidx.compose.runtime.Composable
import androidx.navigation.NavHostController
import com.xhkjedu.zxs_android.componts.camera.CameraScreen

@Composable
fun ScreenCamera(navController: NavHostController) {
    CameraScreen()
}