CameraX 无法拍摄照片

Question

我添加了来自

的代码

https://developer.android.com/training/camerax

link .预览、权限和其他一切工作正常，但我无法通过按钮捕获照片。我声明了按钮有一个监听器并连接了函数takePhoto()，但它似乎不起作用，以前它工作正常，我不知道是不是因为新版本的CameraX功能正在使用，我不知道，但它似乎没有正确响应。我打开了 Logcat，当我按下按钮时，它显示了按下的消息：

D/ViewRootImpl@70b5dc2[MainActivity]: ViewPostIme pointer 0
D/ViewRootImpl@70b5dc2[MainActivity]: ViewPostIme pointer 1

但就是这样，没有别的，但这是我目前的问题，这是一个小问题，但我相信我错过了一些东西来解决这个简单的问题，我不知道是什么原因导致的.这是我将在下面提供的代码：

Gradle:

plugins {
    id 'com.android.application'
    id 'kotlin-android'
}

android {
    compileSdk 30

    defaultConfig {
        applicationId "com.example.camerax1"
        minSdk 21
        targetSdk 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
}

dependencies {
    implementation 'androidx.core:core-ktx:1.6.0'
    implementation 'androidx.appcompat:appcompat:1.3.1'
    implementation 'com.google.android.material:material:1.4.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.0'
    implementation 'androidx.camera:camera-camera2:1.1.0-alpha08'
    implementation 'androidx.camera:camera-lifecycle:1.1.0-alpha08'
    implementation 'androidx.camera:camera-view:1.0.0-alpha28'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
}

activity_main.xml

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context=".MainActivity">

    <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="85dp"
        android:layout_height="85dp"
        android:layout_marginBottom="25dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        android:importantForAccessibility="no" />

</androidx.constraintlayout.widget.ConstraintLayout>

一次完整代码classMainActivity.kt

class MainActivity : AppCompatActivity() {
    private var imageCapture: ImageCapture? = null

    private lateinit var outputDirectory: File
    private lateinit var cameraExecutor: ExecutorService

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

        //Request camera permissions
        if (allPermissions()) {
            startCamera()
        } else {
            ActivityCompat.requestPermissions(this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)
        }

        val captureBtn = findViewById<Button>(R.id.captureButton)
        captureBtn.setOnClickListener {
            takePhoto()
        }

        outputDirectory = getOutputDirectory()
        cameraExecutor = Executors.newSingleThreadExecutor()
    }



    private fun takePhoto() {
        Toast.makeText(baseContext, "Processing..", Toast.LENGTH_SHORT).show()
        //Get a stable reference of the modifiable image capture use case
        val imageCapture = imageCapture ?: return

        //Create time-stamped output file to hold the image
        val photoFile = File(
            outputDirectory,
            SimpleDateFormat(FILENAME_FORMAT, Locale.ENGLISH).format(System.currentTimeMillis()) + ".jpg")

        //Create output options object which contains file + metadata
        val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile).build()

        //Set up image capture listener, which is triggered after photo has been taken
        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)
                }
            }
        )
    }

    private fun startCamera() {
        val viewFiner = findViewById<PreviewView>(R.id.previewView)
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)

        cameraProviderFuture.addListener({
            //Used to bind the lifecycle of camera to the lifecycle owner
            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

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

            //Select back camera as a default
            val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

            try {
                //Unbind use cases before rebinding
                cameraProvider.unbindAll()

                //Bind use cases to camera
                cameraProvider.bindToLifecycle(
                    this,
                    cameraSelector,
                    preview
                )
            } catch (exc: Exception) {
                Log.e(TAG, "Use case binding failed", exc)
                Toast.makeText(this, "Use case binding failed: $exc", Toast.LENGTH_SHORT).show()
            }
        }, ContextCompat.getMainExecutor(this))
    }

    private fun allPermissions() = REQUIRED_PERMISSIONS.all {
        ContextCompat.checkSelfPermission(baseContext, it) == PackageManager.PERMISSION_GRANTED
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        if (requestCode == REQUEST_CODE_PERMISSIONS) {
            if (allPermissions()) {
                startCamera()
            } else {
                Toast.makeText(this, "Permissions not granted by the user.", Toast.LENGTH_SHORT).show()
                finish()
            }
        }
    }

    private fun getOutputDirectory(): File {
        val mediaDir = externalMediaDirs.firstOrNull().let {
            File(it, resources.getString(R.string.app_name)).apply { mkdirs() }
        }
        return if (mediaDir.exists())
            mediaDir else filesDir
    }

    override fun onDestroy() {
        super.onDestroy()
        cameraExecutor.shutdown()
    }

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

Answer 1

您的代码没有将 ImageCapture.Builder() 绑定到相机提供程序，这是它不捕获图像的主要原因。您需要绑定imageCapture builder，可以通过以下方式完成。在您的 startCamera() 函数中，您需要按以下方式绑定 imageCapture :

    private fun startCamera() {
        val viewFiner = findViewById<PreviewView>(R.id.previewView)
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)

        cameraProviderFuture.addListener({
            //Used to bind the lifecycle of camera to the lifecycle owner
            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

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

            //set Image Capture Builder
            imageCapture = ImageCapture.Builder()
            .setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
            .build()

            //Select back camera as a default
            val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

            try {
                //Unbind use cases before rebinding
                cameraProvider.unbindAll()

                //Bind use cases to camera
               //Add imageCapture to lifecycle 
                cameraProvider.bindToLifecycle(
                    this,
                    cameraSelector,
                    preview,
                    imageCapture
                )
            } catch (exc: Exception) {
                Log.e(TAG, "Use case binding failed", exc)
                Toast.makeText(this, "Use case binding failed: $exc", Toast.LENGTH_SHORT).show()
            }
        }, ContextCompat.getMainExecutor(this))
    }

CameraX 无法拍摄照片

CameraX not able to capture a photo

android

kotlin

android-camerax