Android開發 CameraX開發

前言

　　google推出Camera后,發現Camera功能簡單,難以滿足需求調用Camera各種效果,所以又推出了Camera2. Camera2功能強大但是使用十分麻煩,回調與冗余代碼太多,而且特別容易在釋放Camera上犯錯導致activty的內存泄露. 所以google推出了更簡單易用,但是功能也強大的CameraX.

　　因為CameraX的簡單可以幫助我們高效率開發,所以也是有學習的必要性.(Camera2了解就行,沒必要死磕浪費太多時間),CameraX有以下優勢:

1. CameraX與Liftcycle結合,與Activity或者Fragment的生命周期捆綁,不要考慮攝像頭的釋放問題,減少了代碼的復雜度.
2. CameraX兼容至 Android L (API 21)
3. 依然支持Camera2的豐富攝像頭功能

添加依賴

    // CameraX 核心庫使用 camera2 實現
    implementation "androidx.camera:camera-camera2:1.0.0-beta03"
    // 可以使用CameraView
    implementation "androidx.camera:camera-view:1.0.0-alpha10"
    // 可以使用供應商擴展
    implementation "androidx.camera:camera-extensions:1.0.0-alpha10"
    //camerax的生命周期庫
    implementation "androidx.camera:camera-lifecycle:1.0.0-beta03"

獲取權限

跟以前一樣,需要動態授權一些必要權限

 <!-- 相機相關 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

預覽攝像頭畫面

從最簡單的預覽攝像頭圖像開始,我們逐步了解使用方式,代碼如下:

布局要求使用PreviewView,作為SurfaceProvider

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

代碼:

class CameraXActivity : AppCompatActivity() {
    private val TAG = CameraXActivity::class.java.simpleName
private lateinit var mPreviewView: PreviewView

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_camera_x2)
        mPreviewView = findViewById(R.id.previewView)
        startCameraPreview()
    }

    /**
     * 開始相機預覽
     */
    private fun startCameraPreview() {
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
        cameraProviderFuture.addListener(Runnable {
            //用於將相機的生命周期綁定到生命周期所有者
            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
            //創建預覽
            val preview = Preview.Builder().build()
            //選擇后置攝像頭
            val cameraSelector = CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build()
            try {
                //在重新綁定之前取消綁定
                cameraProvider.unbindAll()
                //將生命周期,選擇攝像頭,預覽,綁定到相機
                val camera = cameraProvider.bindToLifecycle(this, cameraSelector, preview)
                //設置預覽的View
                preview.setSurfaceProvider(mPreviewView.createSurfaceProvider(camera.cameraInfo))
            } catch (exc: Exception) {
                Log.e(TAG, "Use case binding failed", exc)
            }
        }, ContextCompat.getMainExecutor(this))
    }
}

特別簡單就完成了,而且無需考慮攝像頭的釋放

實現拍照

class CameraXActivity : AppCompatActivity() {
    private val TAG = CameraXActivity::class.java.simpleName
    private lateinit var mImageCapture: ImageCapture
    private lateinit var mImageAnalysis: ImageAnalysis
    private lateinit var mPreviewView: PreviewView
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_camera_x2)
        mPreviewView = findViewById(R.id.previewView)
        startCameraPreview()
        takePhoto.setOnClickListener {
            //點擊后拍照
            takePhoto()
        }
    }

    /**
     * 開始相機預覽
     */
    private fun startCameraPreview() {
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
        cameraProviderFuture.addListener(Runnable {
            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
            val preview = Preview.Builder().build()
            //創建圖像捕捉
            mImageCapture = ImageCapture.Builder().build()
            val cameraSelector = CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build()
            try {
                cameraProvider.unbindAll()
                //請注意,這里新增了一個ImageCapture
                val camera = cameraProvider.bindToLifecycle(this, cameraSelector, preview, mImageCapture)
                preview.setSurfaceProvider(mPreviewView.createSurfaceProvider(camera.cameraInfo))
            } catch (exc: Exception) {
                Log.e(TAG, "Use case binding failed", exc)
            }
        }, ContextCompat.getMainExecutor(this))
    }

    /**
     * 拍照
     */
    private fun takePhoto() {
        //圖像的保存路徑與名稱
        val photoFile = File(applicationContext.externalCacheDir?.path
                , SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.getDefault()).format(System.currentTimeMillis()) + ".jpg")

        // 創建圖像文件輸出選項
        val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile).build()

        //拍照,並且注冊拍照后的結果監聽
        mImageCapture.takePicture(outputOptions, ContextCompat.getMainExecutor(this), object : ImageCapture.OnImageSavedCallback {
            override fun onError(exc: ImageCaptureException) {
                Log.e(TAG, "Photo capture failed: ${exc.message}", exc)
            }

            override fun onImageSaved(output: 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)
            }
        })
    }
}

拍照圖像旋轉

代碼的其他部分與上面的示例代碼一致, 我們只需要關注ImageCapture的創建與添加setTargetRotation

    private fun createImageCapture():ImageCapture{
        //創建圖像捕捉
        mImageCapture = ImageCapture.Builder()
                .setTargetRotation(Surface.ROTATION_90)//設置旋轉角度,並且只能有4個旋轉方向屬性ROTATION_0/ROTATION_90/ROTATION_180/ROTATION_270
                .build()
        return mImageCapture
    }

設置執行IO線程

    private fun createImageCapture():ImageCapture{
        //創建圖像捕捉
        mImageCapture = ImageCapture.Builder()
                .setIoExecutor(Executors.newSingleThreadExecutor())//設置執行IO線程
                .build()
        return mImageCapture
    }

設置捕捉模式

    private fun createImageCapture():ImageCapture{
        //創建圖像捕捉
        mImageCapture = ImageCapture.Builder()
                //CAPTURE_MODE_MAXIMIZE_QUALITY 高畫質
                //CAPTURE_MODE_MINIMIZE_LATENCY 低延遲
                .setCaptureMode(ImageCapture.CAPTURE_MODE_MAXIMIZE_QUALITY)
                .build()
        return mImageCapture
    }

設置閃光燈

    private fun createImageCapture():ImageCapture{
        //創建圖像捕捉
        mImageCapture = ImageCapture.Builder()
                //FLASH_MODE_ON 閃光燈開啟
                //FLASH_MODE_OFF 閃光燈關閉
                //FLASH_MODE_AUTO 閃光燈自動
                .setFlashMode(ImageCapture.FLASH_MODE_ON)
                .build()
        return mImageCapture
    }

設置寬高比

    private fun createImageCapture():ImageCapture{
        mImageCapture = ImageCapture.Builder()
                //RATIO_4_3   4比3
                //RATIO_16_9  16比9
                .setTargetAspectRatio(AspectRatio.RATIO_16_9)
                .build()
        return mImageCapture
    }

設置分辨率

下面還帖了一些注釋,這注釋的意思是,你可以隨便設置分辨率大小,但是真正的分辨率並不一定是你設置的數值,而是在攝像頭里獲取的分辨率列表中去取最近似值.

為什么會有這種說明? 我這里給沒有接觸過攝像頭開發的朋友說明一下:

手機的攝像頭的分辨率並不是可以隨便設置的,這需要取決於你開發的設備的攝像頭驅動的分辨率列表. 在以往開發Camera1和Camera2的時候我們需要自己獲取這份列表,從中選擇我們需要的分辨率. 在使用CameraX的時候他們幫我們簡化了這個篩選過程,你只需要設置目標分辨率,代碼會自動選擇近似分辨率

    private fun createImageCapture(): ImageCapture {
        mImageCapture = ImageCapture.Builder()
                /*
                目標分辨率嘗試建立圖像分辨率的最小界限。實際圖像分辨率將是尺寸上最接近的可用分辨率，該分辨率不小於由相機實現確定的目標分辨率。
                但是，如果不存在等於或大於目標分辨率的分辨率，則將選擇最接近的小於目標分辨率的可用分辨率。
                與提供的 {@link Size} 具有相同縱橫比的分辨率將在不同縱橫比的分辨率之前優先考慮。
                 */
                .setTargetResolution(Size(1280, 720))
                .build()
        return mImageCapture
    }

控制對焦

val factory = SurfaceOrientedMeteringPointFactory(width, height)
val point = factory.createPoint(x, y)
val action = FocusMeteringAction.Builder(point, FocusMeteringAction.FLAG_AF)
    .addPoint(point2, FocusMeteringAction.FLAG_AE) // could have many
    // auto calling cancelFocusAndMetering in 5 seconds
    .setAutoCancelDuration(5, TimeUnit.SECONDS)
    .build()

val future = cameraControl.startFocusAndMetering(action)
future.addListener( Runnable {
    val result = future.get()
    // process the result
} , executor)

實現錄像

   private void takeVideo() {
        VideoCapture videoCapture = new VideoCaptureConfig.Builder()
                //設置寬高
                .setTargetAspectRatio(aspectRatio(width, height))
                //設置旋轉角度
                .setTargetRotation(previewView.getDisplay().getRotation())
                .build();
        //錄像前必須解綁
        cameraProvider.unbindAll();
        //開啟相機預覽
        preview.setSurfaceProvider(previewView.createSurfaceProvider());
        //綁定生命周期，這里如果沒有參數preview，則只錄像，不顯示畫面
        cameraProvider.bindToLifecycle(this, cameraSelector,preview, videoCapture);
        //視頻路徑
        File file = getFile(".mp4");
        //開始錄像
        videoCapture.startRecording(file, ContextCompat.getMainExecutor(MainActivity.this), new VideoCapture.OnVideoSavedCallback() {
            @Override
            public void onVideoSaved(@NonNull File file) {
                Toast.makeText(MainActivity.this, file.getAbsolutePath(), Toast.LENGTH_SHORT).show();
            }
 
            @Override
            public void onError(int videoCaptureError, @NonNull String message, @Nullable Throwable cause) {
                Log.d(TAG, "onError: " + message);
            }
        });
        //停止錄像，並且回調OnVideoSavedCallback
        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                videoCapture.stopRecording();
                preview.clear();
            }
        });
    

分析圖像

 

val imageAnalysis = ImageAnalysis.Builder()
    .setTargetResolution(Size(1280, 720))
    .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
    .build()

imageAnalysis.setAnalyzer(Executors.newSingleThreadExecutor(), ImageAnalysis.Analyzer { image ->
    val rotationDegrees = image.imageInfo.rotationDegrees //旋轉角度
    val format = image.format //格式
    val width = image.width //寬
    val height = image.height //高
    val plane = image.planes[0] //PlaneProxy數據
    val buffer = plane.buffer
    Log.e("ytzn", "rotationDegrees = $rotationDegrees")
    Log.e("ytzn", "format = $format")
    Log.e("ytzn", "width = $width")
    Log.e("ytzn", "height = $height")

    // insert your code here.
})
cameraProvider.bindToLifecycle(this as LifecycleOwner, cameraSelector, imageAnalysis, preview)

CameraX 會生成 YUV_420_888 格式的圖片 在ImageFormat類里可以看到此格式

拓展功能

    private fun setPreviewExtender(builder: Preview.Builder, cameraSelector: CameraSelector) {
        val extender = AutoPreviewExtender.create(builder)
        //自動模式
        if (extender.isExtensionAvailable(cameraSelector)) {
            extender.enableExtension(cameraSelector)
        }
        //散景擴展
        val bokehPreviewExtender = BokehPreviewExtender.create(builder)
        if (bokehPreviewExtender.isExtensionAvailable(cameraSelector)) {
            bokehPreviewExtender.enableExtension(cameraSelector)
        }
        //hdr擴展
        val hdrPreviewExtender = HdrPreviewExtender.create(builder)
        if (hdrPreviewExtender.isExtensionAvailable(cameraSelector)) {
            hdrPreviewExtender.enableExtension(cameraSelector)
        }
        //美顏模式
        val beautyPreviewExtender = BeautyPreviewExtender.create(builder)
        if (beautyPreviewExtender.isExtensionAvailable(cameraSelector)) {
            beautyPreviewExtender.enableExtension(cameraSelector)
        }
        //夜晚模式
        val nightPreviewExtender = NightPreviewExtender.create(builder)
        if (nightPreviewExtender.isExtensionAvailable(cameraSelector)) {
            nightPreviewExtender.enableExtension(cameraSelector)
        }

    }

CameraX的一些問題

個人在開發過程中發現了一些問題,如下:

1.CameraX不支持外置攝像頭

2.一直沒找到跟Camera2一樣配置攝像頭拍照參數的方式

 

End