CameraX的使用

最新推荐文章于 2025-04-01 11:14:42 发布

Decrue

最新推荐文章于 2025-04-01 11:14:42 发布

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本文链接：https://blog.youkuaiyun.com/Decrue/article/details/118515087

本文详细介绍了如何在Android应用中使用CameraX库进行相机预览、拍照、图片存储、闪光灯控制以及亮度调节。通过步骤演示了设置布局、请求权限、启动相机、拍照保存、切换闪光灯以及使用SeekBar调节屏幕亮度的过程。

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1.导入CameraX依赖到build.grade(Module:app)

2.CameraX需要Java8中的方法，确定build.grade(Module:app)中是否有以下两个方法

3.在清单中设置相机权限

4.这里使用网上demo，设置layout布局文件

设置一个button和一个Camera.view.PreviewView预览画面

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

5.在MainActivity.kt中设置请求权限和实现CameraX预览画面，可成功调用设备权限并展示预览

//初始化定义
private var preview: Preview? = null
private var imageCapture: ImageCapture? = null
private var imageAnalyzer: ImageAnalysis? = null
private var camera: Camera? = null

//权限判断
if (allPermissionsGranted()) {
    startCamera()
} else {
    ActivityCompat.requestPermissions(
        this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)}

//定义图片输出文件位置
outputDirectory = createPhotoAlbum()

//预览
    private fun startCamera() {
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
        cameraProviderFuture.addListener(Runnable {
            // Used to bind the lifecycle of cameras to the lifecycle owner
            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
            // Preview
            preview = Preview.Builder()
                .build()
            imageCapture = ImageCapture.Builder()
                .setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
                .build()
            // Select back camera
            val cameraSelector = CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build()
            try {
                // Unbind use cases before rebinding
                cameraProvider.unbindAll()
                // Bind use cases to camera
                camera = cameraProvider.bindToLifecycle(
                    this, cameraSelector, preview, imageCapture)
                preview?.setSurfaceProvider(viewFinder.surfaceProvider)
            } catch(exc: Exception) {
                Timber.d("Use case binding failed==$exc")
            }
        }, ContextCompat.getMainExecutor(this))
    }

//权限设置
private fun allPermissionsGranted() = REQUIRED_PERMISSIONS.all {
    ContextCompat.checkSelfPermission(
        baseContext, it) == PackageManager.PERMISSION_GRANTED
}

//权限返回结果
override fun onRequestPermissionsResult(
    requestCode: Int, permissions: Array<String>, grantResults:
    IntArray) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults)
    if (requestCode == REQUEST_CODE_PERMISSIONS) {
        if (allPermissionsGranted()) {
            startCamera()
        } else {
            Toast.makeText(this,
                "未获得权限",
                Toast.LENGTH_SHORT).show()
            finish()
        }
    }
}

6.拍照与图片存储，页面布局设置一个按钮

<Button
    android:id="@+id/camera_capture_button"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:layout_marginBottom="25dp"
    android:text="拍照" />

7.在MainActivity.kt中实现拍照和图片存储，可成功实现

//初始化定义输出文件位置
private lateinit var outputDirectory: File

outputDirectory = createPhotoAlbum()

//按钮点击监听事件
camera_capture_button.setOnClickListener { takePhoto() }

private fun takePhoto() {
        val imageCapture = imageCapture ?: return
        // Create timestamped output file to hold the image
        val photoFile = File(
            outputDirectory,
            SimpleDateFormat(FILENAME_FORMAT, Locale.US
            ).format(System.currentTimeMillis()) + ".jpg")
        Timber.d("photoFile==$photoFile")
        // Create output options object which contains file + metadata
        val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile).build()
        // Setup image capture listener which is triggered after photo has
        // been taken
        imageCapture.takePicture(
            outputOptions, ContextCompat.getMainExecutor(this), object : ImageCapture.OnImageSavedCallback {
                override fun onError(exc: ImageCaptureException) {
                    Log.e(TAG, "拍照失败: ${exc.message}", exc)
                }
                override fun onImageSaved(output: ImageCapture.OutputFileResults) {
                    val savedUri = Uri.fromFile(photoFile)
                    val msg = "拍照成功，图片存放地址: $savedUri"
                    Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
                    Log.d(TAG, msg)
                }
            })
    }

//自定义图片存储位置
fun createPhotoAlbum(): File {
    val name = "loupeAlbum"
    val albumDir = File(Environment.getExternalStorageDirectory(),name)
    if (!albumDir.exists()){
        albumDir.mkdirs()
    }
    return albumDir
}

8.实现闪光灯开关，同布局设置按钮，在MainActivity.kt实现

//activity_main.xml
<Button
    android:id="@+id/camera_light_button"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:layout_alignParentBottom="true"
    android:layout_marginLeft="25dp"
    android:layout_marginBottom="25dp"
    android:text="打开" />
//MainActivity.kt
//初始化定义判断开关参数
private var isOpenFlash = true
//按钮监听事件
camera_light_button.setOnClickListener{ toggleTorch() }
//闪光灯开关方法
private fun toggleTorch() {
    if (isOpenFlash){
        camera_light_button.text = "close"
    }else{
        camera_light_button.text = "open"
    }
    camera?.cameraControl?.enableTorch(isOpenFlash)
    isOpenFlash = !isOpenFlash
}

9.实现进度条SeekBar调节设备亮度，同布局设置控件，在MainActivity.kt实现

//activity_main.xml
<TextView
    android:layout_above="@+id/camera_capture_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="10dp"
    android:text="亮度"
    android:textSize="20dp" />
<SeekBar
    android:layout_above="@+id/camera_capture_button"
    android:id="@+id/camera_seekbar_light"
    android:layout_width="300dp"
    android:layout_height="wrap_content"
    android:layout_marginBottom="10dp"
    android:layout_centerHorizontal="true"
    android:max="255"/>
//MainActivity.kt
//获取设备当前亮度值
camera_seekbar_light.progress = Settings.System.getInt(
    contentResolver,
    Settings.System.SCREEN_BRIGHTNESS)
//亮度进度条监听事件
camera_seekbar_light.setOnSeekBarChangeListener(object : OnSeekBarChangeListener {
    override fun onProgressChanged(seekBar: SeekBar, progress: Int, fromUser: Boolean) { changeP(progress.toFloat() / 255)}
    override fun onStartTrackingTouch(seekBar: SeekBar) {}
    override fun onStopTrackingTouch(seekBar: SeekBar) {}
})
//调节亮度方法
private fun changeP(f: Float) {
    val param = window.attributes
    param.screenBrightness = f
    window.attributes = param
}