kotlin调用相机拍照

在Kotlin中调用相机拍照可以通过Android的Camera API或者更现代化的CameraX API来实现。下面是使用CameraX API的示例代码：

首先，确保在你的项目中添加了CameraX的依赖。在build.gradle文件中添加以下代码：

dependencies {
    def camerax_version = "1.0.0-beta13"
    implementation "androidx.camera:camera-camera2:$camerax_version"
    implementation "androidx.camera:camera-lifecycle:$camerax_version"
    implementation "androidx.camera:camera-view:1.0.0-alpha24"
}

然后，在你的Activity或Fragment中，你可以按照以下步骤来调用相机拍照：

1. 在布局文件中添加一个预览视图和一个拍照按钮：

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

<Button
    android:id="@+id/captureButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Capture"
    android:layout_gravity="center_horizontal" />

2. 在你的Activity或Fragment中，初始化CameraX并设置预览视图：

import androidx.camera.core.CameraSelector
import androidx.camera.core.ImageCapture
import androidx.camera.lifecycle.ProcessCameraProvider
import androidx.core.content.ContextCompat

class MainActivity : AppCompatActivity() {

    private lateinit var previewView: PreviewView
    private lateinit var captureButton: Button

    private var imageCapture: ImageCapture? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        previewView = findViewById(R.id.previewView)
        captureButton = findViewById(R.id.captureButton)

        // 请求相机权限
        if (allPermissionsGranted()) {
            startCamera()
        } else {
            ActivityCompat.requestPermissions(
                this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)
        }

        captureButton.setOnClickListener { takePhoto() }
    }

    private fun startCamera() {
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
        cameraProviderFuture.addListener({
            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

            val preview = Preview.Builder().build().also {
                it.setSurfaceProvider(previewView.surfaceProvider)
            }

            imageCapture = ImageCapture.Builder().build()

            val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

            try {
                cameraProvider.unbindAll()
                cameraProvider.bindToLifecycle(this, cameraSelector, preview, imageCapture)
            } catch (exc: Exception) {
                Log.e(TAG, "Use case binding failed", exc)
            }
        }, ContextCompat.getMainExecutor(this))
    }

    private fun takePhoto() {
        val imageCapture = imageCapture ?: return

        val photoFile = File(
            outputDirectory,
            SimpleDateFormat(FILENAME_FORMAT, Locale.US).format(System.currentTimeMillis()) + ".jpg"
        )

        val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile).build()

        imageCapture.takePicture(
            outputOptions, ContextCompat.getMainExecutor(this), object : ImageCapture.OnImageSavedCallback {
                override fun onImageSaved(outputFileResults: ImageCapture.OutputFileResults) {
                    val savedUri = Uri.fromFile(photoFile)
                    val msg = "Photo capture succeeded: $savedUri"
                    Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
                    Log.d(TAG, msg)
                }

                override fun onError(exception: ImageCaptureException) {
                    Log.e(TAG, "Photo capture failed: ${exception.message}", exception)
                }
            }
        )
    }

    companion object {
        private const val TAG = "CameraX"
        private const val FILENAME_FORMAT = "yyyy-MM-dd-HH-mm-ss-SSS"
        private const val REQUEST_CODE_PERMISSIONS = 10
        private val REQUIRED_PERMISSIONS = arrayOf(Manifest.permission.CAMERA)
    }
}

这样，当你点击拍照按钮时，就会调用相机拍照，并将照片保存到指定的文件中。