今天给老铁们介绍Camera2相机开发流程详解;
Android 5.0对拍照API进行了全新的机开解设计,新增了全新设计的发流Camera 2 API,这些API不仅大幅提高了Android系统拍照的程详功能,还能支持RAW照片输出,自定甚至允许程序调整相机的义相对焦模式、曝光模式、机开解快门等;
Camera2引用了管道的程详概念将安卓设备和摄像头之间联通起来,系统向摄像头发送 Capture 请求,而摄像头会返回 CameraMetadata。这一切建立在一个叫作 CameraCaptureSession 的会话中;
架构在核心参与类角色有:CameraManager、CameraDevice、CameraCharacteristics、CameraRequest与CameraRequest.Builder、CameraCaptureSession以及CaptureResult;
位于android.hardware.camera2.CameraManager下,也是Android 21(5.0)添加的,和其他系统服务一样通过 Context.getSystemService(CameraManager.class ) 或者Context.getSystemService(Context.CAMERA_SERVICE) 来完成初始化,主要用于管理系统摄像头:
描述Cameradevice属性的对象,可以使用CameraManager通过getCameraCharacteristics(String cameraId)进行查询;
CameraRequest代表了一次捕获请求,而CameraRequest.Builder用于描述捕获图片的各种参数设置,包含捕获硬件(传感器,镜头,闪存),对焦模式、曝光模式,处理流水线,控制算法和输出缓冲区的配置,然后传递到对应的会话中进行设置,CameraRequest.Builder则负责生成CameraRequest对象。当程序调用setRepeatingRequest()方法进行预览时,或调用capture()方法进行拍照时,都需要传入CameraRequest参数。CameraRequest可以通过CameraRequest.Builder来进行初始化,通过调用createCaptureRequest来获得;
CaptureRequest描述是从图像传感器捕获单个图像的结果的子集的对象,当CaptureRequest被处理之后由CameraDevice生成;
CameraManager处于顶层管理位置负责检测获取所有摄像头及其特性和传入指定的CameraDevice.StateCallback回调打开指定摄像头,CameraDevice是负责管理抽象对象,包括监听Camera 的状态回调CameraDevice.StateCallback、创建CameraCaptureSession和CameraRequest;
- <uses-permission android:name="android.permission.CAMERA" />
- <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
- <TextureView
- android:id="@+id/textureView"
- android:layout_width="match_parent"
- android:layout_height="match_parent" />
- class Camera2Helper(val mActivity: Activity, private val mTextureView: TextureView) {
- companion object {
- const val PREVIEW_WIDTH = 720 //预览的宽度
- const val PREVIEW_HEIGHT = 1280 //预览的高度
- const val SAVE_WIDTH = 720 //保存图片的宽度
- const val SAVE_HEIGHT = 1280 //保存图片的高度
- }
- private lateinit var mCameraManager: CameraManager
- private var mImageReader: ImageReader? = null
- private var mCameraDevice: CameraDevice? = null
- private var mCameraCaptureSession: CameraCaptureSession? = null
- private var mCameraId = "0"
- private lateinit var mCameraCharacteristics: CameraCharacteristics
- private var mCameraSensorOrientation = 0 //摄像头方向
- private var mCameraFacing = CameraCharacteristics.LENS_FACING_BACK //默认使用后置摄像头
- private val mDisplayRotation = mActivity.windowManager.defaultDisplay.rotation //手机方向
- private var canTakePic = true //是否可以拍照
- private var canExchangeCamera = false //是否可以切换摄像头
- private var mCameraHandler: Handler
- private val handlerThread = HandlerThread("CameraThread")
- private var mPreviewSize = Size(PREVIEW_WIDTH, PREVIEW_HEIGHT) //预览大小
- private var mSavePicSize = Size(SAVE_WIDTH, SAVE_HEIGHT) //保存图片大小
- init {
- handlerThread.start()
- mCameraHandler = Handler(handlerThread.looper)
- mTextureView.surfaceTextureListener = object : TextureView.SurfaceTextureListener {
- override fun onSurfaceTextureSizeChanged(surface: SurfaceTexture?, width: Int, height: Int) {
- }
- override fun onSurfaceTextureUpdated(surface: SurfaceTexture?) {
- }
- override fun onSurfaceTextureDestroyed(surface: SurfaceTexture?): Boolean {
- releaseCamera()
- return true
- }
- override fun onSurfaceTextureAvailable(surface: SurfaceTexture?, width: Int, height: Int) {
- initCameraInfo()
- }
- }
- }
- }
- /**
- * 初始化
- */
- private fun initCameraInfo() {
- mCameraManager = mActivity.getSystemService(Context.CAMERA_SERVICE) as CameraManager
- val cameraIdList = mCameraManager.cameraIdList
- if (cameraIdList.isEmpty()) {
- mActivity.toast("没有可用相机")
- return
- }
- for (id in cameraIdList) {
- val cameraCharacteristics = mCameraManager.getCameraCharacteristics(id)
- val facing = cameraCharacteristics.get(CameraCharacteristics.LENS_FACING)
- if (facing == mCameraFacing) {
- mCameraId = id
- mCameraCharacteristics = cameraCharacteristics
- }
- log("设备中的摄像头 $id")
- }
- val supportLevel = mCameraCharacteristics.get(CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL)
- if (supportLevel == CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY) {
- mActivity.toast("相机硬件不支持新特性")
- }
- //获取摄像头方向
- mCameraSensorOrientation = mCameraCharacteristics.get(CameraCharacteristics.SENSOR_ORIENTATION)
- //获取StreamConfigurationMap,它是管理摄像头支持的所有输出格式和尺寸
- val configurationMap = mCameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP)
- val savePicSize = configurationMap.getOutputSizes(ImageFormat.JPEG) //保存照片尺寸
- val previewSize = configurationMap.getOutputSizes(SurfaceTexture::class.java) //预览尺寸
- val exchange = exchangeWidthAndHeight(mDisplayRotation, mCameraSensorOrientation)
- mSavePicSize = getBestSize(
- if (exchange) mSavePicSize.height else mSavePicSize.width,
- if (exchange) mSavePicSize.width else mSavePicSize.height,
- if (exchange) mSavePicSize.height else mSavePicSize.width,
- if (exchange) mSavePicSize.width else mSavePicSize.height,
- savePicSize.toList())
- mPreviewSize = getBestSize(
- if (exchange) mPreviewSize.height else mPreviewSize.width,
- if (exchange) mPreviewSize.width else mPreviewSize.height,
- if (exchange) mTextureView.height else mTextureView.width,
- if (exchange) mTextureView.width else mTextureView.height,
- previewSize.toList())
- mTextureView.surfaceTexture.setDefaultBufferSize(mPreviewSize.width, mPreviewSize.height)
- log("预览最优尺寸 :${ mPreviewSize.width} * ${ mPreviewSize.height}, 比例 ${ mPreviewSize.width.toFloat() / mPreviewSize.height}")
- log("保存图片最优尺寸 :${ mSavePicSize.width} * ${ mSavePicSize.height}, 比例 ${ mSavePicSize.width.toFloat() / mSavePicSize.height}")
- //根据预览的尺寸大小调整TextureView的大小,保证画面不被拉伸
- val orientation = mActivity.resources.configuration.orientation
- if (orientation == Configuration.ORIENTATION_LANDSCAPE)
- mTextureView.setAspectRatio(mPreviewSize.width, mPreviewSize.height)
- else
- mTextureView.setAspectRatio(mPreviewSize.height, mPreviewSize.width)
- mImageReader = ImageReader.newInstance(mPreviewSize.width, mPreviewSize.height, ImageFormat.JPEG, 1)
- mImageReader?.setOnImageAvailableListener(onImageAvailableListener, mCameraHandler)
- if (openFaceDetect)
- initFaceDetect()
- openCamera()
- }
- /**
- * 根据提供的屏幕方向 [displayRotation] 和相机方向 [sensorOrientation] 返回是否需要交换宽高
- */
- private fun exchangeWidthAndHeight(displayRotation: Int, sensorOrientation: Int): Boolean {
- var exchange = false
- when (displayRotation) {
- Surface.ROTATION_0, Surface.ROTATION_180 ->
- if (sensorOrientation == 90 || sensorOrientation == 270) {
- exchange = true
- }
- Surface.ROTATION_90, Surface.ROTATION_270 ->
- if (sensorOrientation == 0 || sensorOrientation == 180) {
- exchange = true
- }
- else -> log("Display rotation is invalid: $displayRotation")
- }
- log("屏幕方向 $displayRotation")
- log("相机方向 $sensorOrientation")
- return exchange
- }
- /**
- *
- * 根据提供的参数值返回与指定宽高相等或最接近的尺寸
- *
- * @param targetWidth 目标宽度
- * @param targetHeight 目标高度
- * @param maxWidth 最大宽度(即TextureView的宽度)
- * @param maxHeight 最大高度(即TextureView的高度)
- * @param sizeList 支持的Size列表
- *
- * @return 返回与指定宽高相等或最接近的尺寸
- *
- */
- private fun getBestSize(targetWidth: Int, targetHeight: Int, maxWidth: Int, maxHeight: Int, sizeList: List<Size>): Size {
- val bigEnough = ArrayList<Size>() //比指定宽高大的Size列表
- val notBigEnough = ArrayList<Size>() //比指定宽高小的Size列表
- for (size in sizeList) {
- //宽<=最大宽度 && 高<=最大高度 && 宽高比 == 目标值宽高比
- if (size.width <= maxWidth && size.height <= maxHeight
- && size.width == size.height * targetWidth / targetHeight) {
- if (size.width >= targetWidth && size.height >= targetHeight)
- bigEnough.add(size)
- else
- notBigEnough.add(size)
- }
- log("系统支持的尺寸: ${ size.width} * ${ size.height} , 比例 :${ size.width.toFloat() / size.height}")
- }
- log("最大尺寸 :$maxWidth * $maxHeight, 比例 :${ targetWidth.toFloat() / targetHeight}")
- log("目标尺寸 :$targetWidth * $targetHeight, 比例 :${ targetWidth.toFloat() / targetHeight}")
- //选择bigEnough中最小的值 或 notBigEnough中最大的值
- return when {
- bigEnough.size > 0 -> Collections.min(bigEnough, CompareSizesByArea())
- notBigEnough.size > 0 -> Collections.max(notBigEnough, CompareSizesByArea())
- else -> sizeList[0]
- }
- }
- /**
- * 打开相机
- */
- private fun openCamera() {
- if (ContextCompat.checkSelfPermission(mActivity, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
- mActivity.toast("没有相机权限!")
- return
- }
- mCameraManager.openCamera(mCameraId, object : CameraDevice.StateCallback() {
- override fun onOpened(camera: CameraDevice) {
- log("onOpened")
- mCameraDevice = camera
- createCaptureSession(camera)
- }
- override fun onDisconnected(camera: CameraDevice) {
- log("onDisconnected")
- }
- override fun onError(camera: CameraDevice, error: Int) {
- log("onError $error")
- mActivity.toast("打开相机失败!$error")
- }
- }, mCameraHandler)
- }
- /**
- * 创建预览会话
- */
- private fun createCaptureSession(cameraDevice: CameraDevice) {
- val captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW)
- val surface = Surface(mTextureView.surfaceTexture)
- captureRequestBuilder.addTarget(surface) // 将CaptureRequest的构建器与Surface对象绑定在一起
- captureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH) // 闪光灯
- captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE) // 自动对焦
- // 为相机预览,创建一个CameraCaptureSession对象
- cameraDevice.createCaptureSession(arrayListOf(surface, mImageReader?.surface), object : CameraCaptureSession.StateCallback() {
- override fun onConfigureFailed(session: CameraCaptureSession?) {
- mActivity.toast("开启预览会话失败!")
- }
- override fun onConfigured(session: CameraCaptureSession) {
- mCameraCaptureSession = session
- session.setRepeatingRequest(captureRequestBuilder.build(), mCaptureCallBack, mCameraHandler)
- }
- }, mCameraHandler)
- }
- private val mCaptureCallBack = object : CameraCaptureSession.CaptureCallback() {
- override fun onCaptureCompleted(session: CameraCaptureSession, request: CaptureRequest?, result: TotalCaptureResult) {
- super.onCaptureCompleted(session, request, result)
- canExchangeCamera = true
- canTakePic = true
- }
- override fun onCaptureFailed(session: CameraCaptureSession?, request: CaptureRequest?, failure: CaptureFailure?) {
- super.onCaptureFailed(session, request, failure)
- log("onCaptureFailed")
- mActivity.toast("开启预览失败!")
- }
- }
- /**
- * 拍照
- */
- fun takePic() {
- if (mCameraDevice == null || !mTextureView.isAvailable || !canTakePic) return
- mCameraDevice?.apply {
- val captureRequestBuilder = createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE)
- captureRequestBuilder.addTarget(mImageReader?.surface)
- captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE) // 自动对焦
- captureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH) // 闪光灯
- captureRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION, mCameraSensorOrientation) //根据摄像头方向对保存的照片进行旋转,使其为"自然方向"
- mCameraCaptureSession?.capture(captureRequestBuilder.build(), null, mCameraHandler)
- ?: mActivity.toast("拍照异常!")
- }
- }
- private val onImageAvailableListener = OnImageAvailableListener {
- val image = it.acquireNextImage()
- val byteBuffer = image.planes[0].buffer
- val byteArray = ByteArray(byteBuffer.remaining())
- byteBuffer.get(byteArray)
- it.close()
- BitmapUtils.savePic(byteArray, mCameraSensorOrientation == 270, { savedPath, time ->
- mActivity.runOnUiThread {
- mActivity.toast("图片保存成功!保存路径:$savedPath 耗时:$time")
- }
- }, { msg ->
- mActivity.runOnUiThread {
- mActivity.toast("图片保存失败!$msg")
- }
- })
- }
- fun releaseCamera() {
- mCameraCaptureSession?.close()
- mCameraCaptureSession = null
- mCameraDevice?.close()
- mCameraDevice = null
- mImageReader?.close()
- mImageReader = null
- canExchangeCamera = false
- }
- fun releaseThread() {
- handlerThread.quitSafely()
- }
Camera2 API和旧的Camera API区别很大, 刚开始用可能会很不习惯, 但Camera2有很多优势, 提供了非常多的参数供我们控制;
一起学习加油老铁们;
责任编辑:武晓燕 来源: Android开发编程 Camera2 相机开发
(责任编辑:娱乐)
力合微(688589.SH)2020年归母净利2782.05万元 基本每股收益0.33元