Android Camera2 拍照入门学习
dingyou110
8年前
<p>Android 5.0(21)之后， android.hardware.Camera 被废弃(下面称为 Camera1 )，还有一个 android.graphics.Camera ，这个 android.graphics.Camera 不是用来照相的，是用来处理图像的，可以做出 3D 的图像效果之类的，之前的 Camera1 则由 android.hardware.Camera2 来代替</p> <p>Camera2 支持 RAW 输出，可以调节曝光，对焦模式，快门等，功能比原先 Camera 强大</p> <h2>1.Camera1使用</h2> <p>使用步骤：</p> <ol> <li>调用 Camera.open() ，打开相机，默认为后置，可以根据摄像头 ID 来指定打开前置还是后置</li> <li>调用 Camera.getParameters() 得到一个 Camera.Parameters 对象</li> <li>使用 步骤2 得到的 Camera.Parameters 对象，对拍照参数进行设置</li> <li>调用 Camera.setPreviewDispaly(SurfaceHolder holder) ，指定使用哪个 SurfaceView 来显示预览图片</li> <li>调用 Camera.startPreview() 方法开始预览取景</li> <li>调用 Camera.takePicture() 方法进行拍照</li> <li>拍照结束后，调用 Camera.stopPreview() 结束取景预览，之后再 replease() 方法释放资源</li> </ol> <p>这几个步骤从 疯狂Android讲义 中学到</p> <h2>1.1简单使用</h2> <p>使用 SurfaceView 进行取景的预览，点击屏幕进行拍照，用 ImageView 来展示拍的照片</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/37a3e9f75ca1c72de47b6e6bd86a33e8.png"></p> <p style="text-align:center">取景</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/7433aa58d9c04c2981d31806f92e80e9.png"></p> <p style="text-align:center">拍照预览</p> <p>想买关于操作系统和C的书看，知乎很多人推荐这两本，就买了，感觉确实不错。然而，深入理解操作系统买早了，啃不动</p> <p>布局文件：</p> <pre> <code class="language-java"><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <SurfaceView android:id="@+id/surface_view_camera2_activity" android:layout_width="match_parent" android:layout_height="match_parent" /> <ImageView android:id="@+id/iv_show_camera2_activity" android:layout_width="180dp" android:layout_height="320dp" android:visibility="gone" android:layout_centerInParent="true" android:scaleType="centerCrop" /> </RelativeLayout></code></pre> <p>Activity 代码：</p> <pre> <code class="language-java">public class CameraActivity extends AppCompatActivity implements View.OnClickListener { private SurfaceView mSurfaceView; private SurfaceHolder mSurfaceHolder; private Camera mCamera; private ImageView iv_show; private int viewWidth, viewHeight;//mSurfaceView的宽和高 @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_camera2); initView(); } /** * 初始化控件 */ private void initView() { iv_show = (ImageView) findViewById(R.id.iv_show_camera2_activity); //mSurfaceView mSurfaceView = (SurfaceView) findViewById(R.id.surface_view_camera2_activity); mSurfaceHolder = mSurfaceView.getHolder(); // mSurfaceView 不需要自己的缓冲区 mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); // mSurfaceView添加回调 mSurfaceHolder.addCallback(new SurfaceHolder.Callback() { @Override public void surfaceCreated(SurfaceHolder holder) { //SurfaceView创建 // 初始化Camera initCamera(); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { } @Override public void surfaceDestroyed(SurfaceHolder holder) { //SurfaceView销毁 // 释放Camera资源 if (mCamera != null) { mCamera.stopPreview(); mCamera.release(); } } }); //设置点击监听 mSurfaceView.setOnClickListener(this); } @Override public void onWindowFocusChanged(boolean hasFocus) { super.onWindowFocusChanged(hasFocus); if (mSurfaceView != null) { viewWidth = mSurfaceView.getWidth(); viewHeight = mSurfaceView.getHeight(); } } /** * SurfaceHolder 回调接口方法 */ private void initCamera() { mCamera = Camera.open();//默认开启后置 mCamera.setDisplayOrientation(90);//摄像头进行旋转90° if (mCamera != null) { try { Camera.Parameters parameters = mCamera.getParameters(); //设置预览照片的大小 parameters.setPreviewFpsRange(viewWidth, viewHeight); //设置相机预览照片帧数 parameters.setPreviewFpsRange(4, 10); //设置图片格式 parameters.setPictureFormat(ImageFormat.JPEG); //设置图片的质量 parameters.set("jpeg-quality", 90); //设置照片的大小 parameters.setPictureSize(viewWidth, viewHeight); //通过SurfaceView显示预览 mCamera.setPreviewDisplay(mSurfaceHolder); //开始预览 mCamera.startPreview(); } catch (IOException e) { e.printStackTrace(); } } } /** * 点击回调方法 */ @Override public void onClick(View v) { if (mCamera == null) return; //自动对焦后拍照 mCamera.autoFocus(autoFocusCallback); } /** * 自动对焦 对焦成功后 就进行拍照 */ Camera.AutoFocusCallback autoFocusCallback = new Camera.AutoFocusCallback() { @Override public void onAutoFocus(boolean success, Camera camera) { if (success) {//对焦成功 camera.takePicture(new Camera.ShutterCallback() {//按下快门 @Override public void onShutter() { //按下快门瞬间的操作 } }, new Camera.PictureCallback() { @Override public void onPictureTaken(byte[] data, Camera camera) {//是否保存原始图片的信息 } }, pictureCallback); } } }; /** * 获取图片 */ Camera.PictureCallback pictureCallback = new Camera.PictureCallback() { @Override public void onPictureTaken(byte[] data, Camera camera) { final Bitmap resource = BitmapFactory.decodeByteArray(data, 0, data.length); if (resource == null) { Toast.makeText(CameraActivity.this, "拍照失败", Toast.LENGTH_SHORT).show(); } final Matrix matrix = new Matrix(); matrix.setRotate(90); final Bitmap bitmap = Bitmap.createBitmap(resource, 0, 0, resource.getWidth(), resource.getHeight(), matrix, true); if (bitmap != null && iv_show != null && iv_show.getVisibility() == View.GONE) { mCamera.stopPreview(); iv_show.setVisibility(View.VISIBLE); mSurfaceView.setVisibility(View.GONE); Toast.makeText(CameraActivity.this, "拍照", Toast.LENGTH_SHORT).show(); iv_show.setImageBitmap(bitmap); } } }; }</code></pre> <p>权限：</p> <pre> <code class="language-java"><uses-permission android:name="android.permission.CAMERA" /></code></pre> <p>在获得图片后，想要显示的效果是照片是竖直显示， resource 显示的却是逆时针旋转了 90° ，照片是横着的，就使用 matrix.setRotate(90) 进行旋转</p> <h2>2.Camera2</h2> <p style="text-align:center"><img src="https://simg.open-open.com/show/58e60406b9c26cec09eb1b42d87c9a08.png"></p> <p style="text-align:center">Camera2拍照示意图</p> <p>这里引用了管道的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。</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/307f3aeb93c6f241f27b47fd493dd7fe.png"></p> <p style="text-align:center">camera2中主要的类</p> <ul> <li>CameraManaer 摄像头管理器，用于检测摄像头，打开系统摄像头，调用 CameraManager.getCameraCharacteristics(String) 可以获取指定摄像头的相关特性</li> <li>CameraCharacteristics 摄像头的特性</li> <li>CameraDevice 摄像头，类似 android.hardware.Camera 也就是 Camera1 的 Camera</li> <li>CameraCaptureSession 这个对象控制摄像头的预览或者拍照， setRepeatingRequest() 开启预览， capture() 拍照， CameraCaptureSession 提供了StateCallback、CaptureCallback两个接口来监听 CameraCaptureSession 的创建和拍照过程。</li> <li>CameraRequest和CameraRequest.Builder，预览或者拍照时，都需要一个 CameraRequest 对象。CameraRequest表示一次捕获请求，用来对z照片的各种参数设置，比如对焦模式、曝光模式等。CameraRequest.Builder用来生成CameraRequest对象。</li> </ul> <h2>2.1 简单使用</h2> <p>使用的依然是 SurfaceView 来进行展示预览</p> <p>主要思路：</p> <ol> <li>获得摄像头管理器 CameraManager mCameraManager ， mCameraManager.openCamera() 来打开摄像头</li> <li>指定要打开的摄像头，并创建 openCamera() 所需要的 CameraDevice.StateCallback stateCallback</li> <li>在 CameraDevice.StateCallback stateCallback 中调用 takePreview() ，这个方法中，使用 CaptureRequest.Builder 创建预览需要的 CameraRequest ，并初始化了 CameraCaptureSession ，最后调用了 setRepeatingRequest(previewRequest, null, childHandler) 进行了预览</li> <li>点击屏幕，调用 takePicture() ，这个方法内，最终调用了 capture(mCaptureRequest, null, childHandler)</li> <li>在 new ImageReader.OnImageAvailableListener(){} 回调方法中，将拍照拿到的图片进行展示</li> </ol> <p>代码：</p> <pre> <code class="language-java">public class Camera2Activity extends AppCompatActivity implements View.OnClickListener { private static final SparseIntArray ORIENTATIONS = new SparseIntArray(); ///为了使照片竖直显示 static { ORIENTATIONS.append(Surface.ROTATION_0, 90); ORIENTATIONS.append(Surface.ROTATION_90, 0); ORIENTATIONS.append(Surface.ROTATION_180, 270); ORIENTATIONS.append(Surface.ROTATION_270, 180); } private SurfaceView mSurfaceView; private SurfaceHolder mSurfaceHolder; private ImageView iv_show; private CameraManager mCameraManager;//摄像头管理器 private Handler childHandler, mainHandler; private String mCameraID;//摄像头Id 0 为后 1 为前 private ImageReader mImageReader; private CameraCaptureSession mCameraCaptureSession; private CameraDevice mCameraDevice; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_camera2); initVIew(); } /** * 初始化 */ private void initVIew() { iv_show = (ImageView) findViewById(R.id.iv_show_camera2_activity); //mSurfaceView mSurfaceView = (SurfaceView) findViewById(R.id.surface_view_camera2_activity); mSurfaceView.setOnClickListener(this); mSurfaceHolder = mSurfaceView.getHolder(); mSurfaceHolder.setKeepScreenOn(true); // mSurfaceView添加回调 mSurfaceHolder.addCallback(new SurfaceHolder.Callback() { @Override public void surfaceCreated(SurfaceHolder holder) { //SurfaceView创建 // 初始化Camera initCamera2(); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { } @Override public void surfaceDestroyed(SurfaceHolder holder) { //SurfaceView销毁 // 释放Camera资源 if (null != mCameraDevice) { mCameraDevice.close(); Camera2Activity.this.mCameraDevice = null; } } }); } /** * 初始化Camera2 */ @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) private void initCamera2() { HandlerThread handlerThread = new HandlerThread("Camera2"); handlerThread.start(); childHandler = new Handler(handlerThread.getLooper()); mainHandler = new Handler(getMainLooper()); mCameraID = "" + CameraCharacteristics.LENS_FACING_FRONT;//后摄像头 mImageReader = ImageReader.newInstance(1080, 1920, ImageFormat.JPEG,1); mImageReader.setOnImageAvailableListener(new ImageReader.OnImageAvailableListener() { //可以在这里处理拍照得到的临时照片 例如，写入本地 @Override public void onImageAvailable(ImageReader reader) { mCameraDevice.close(); mSurfaceView.setVisibility(View.GONE); iv_show.setVisibility(View.VISIBLE); // 拿到拍照照片数据 Image image = reader.acquireNextImage(); ByteBuffer buffer = image.getPlanes()[0].getBuffer(); byte[] bytes = new byte[buffer.remaining()]; buffer.get(bytes);//由缓冲区存入字节数组 final Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length); if (bitmap != null) { iv_show.setImageBitmap(bitmap); } } }, mainHandler); //获取摄像头管理 mCameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE); try { if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { return; } //打开摄像头 mCameraManager.openCamera(mCameraID, stateCallback, mainHandler); } catch (CameraAccessException e) { e.printStackTrace(); } } /** * 摄像头创建监听 */ private CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() { @Override public void onOpened(CameraDevice camera) {//打开摄像头 mCameraDevice = camera; //开启预览 takePreview(); } @Override public void onDisconnected(CameraDevice camera) {//关闭摄像头 if (null != mCameraDevice) { mCameraDevice.close(); Camera2Activity.this.mCameraDevice = null; } } @Override public void onError(CameraDevice camera, int error) {//发生错误 Toast.makeText(Camera2Activity.this, "摄像头开启失败", Toast.LENGTH_SHORT).show(); } }; /** * 开始预览 */ private void takePreview() { try { // 创建预览需要的CaptureRequest.Builder final CaptureRequest.Builder previewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW); // 将SurfaceView的surface作为CaptureRequest.Builder的目标 previewRequestBuilder.addTarget(mSurfaceHolder.getSurface()); // 创建CameraCaptureSession，该对象负责管理处理预览请求和拍照请求 mCameraDevice.createCaptureSession(Arrays.asList(mSurfaceHolder.getSurface(), mImageReader.getSurface()), new CameraCaptureSession.StateCallback() // ③ { @Override public void onConfigured(CameraCaptureSession cameraCaptureSession) { if (null == mCameraDevice) return; // 当摄像头已经准备好时，开始显示预览 mCameraCaptureSession = cameraCaptureSession; try { // 自动对焦 previewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE); // 打开闪光灯 previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH); // 显示预览 CaptureRequest previewRequest = previewRequestBuilder.build(); mCameraCaptureSession.setRepeatingRequest(previewRequest, null, childHandler); } catch (CameraAccessException e) { e.printStackTrace(); } } @Override public void onConfigureFailed(CameraCaptureSession cameraCaptureSession) { Toast.makeText(Camera2Activity.this, "配置失败", Toast.LENGTH_SHORT).show(); } }, childHandler); } catch (CameraAccessException e) { e.printStackTrace(); } } /** * 点击事件 */ @Override public void onClick(View v) { takePicture(); } /** * 拍照 */ private void takePicture() { if (mCameraDevice == null) return; // 创建拍照需要的CaptureRequest.Builder final CaptureRequest.Builder captureRequestBuilder; try { captureRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE); // 将imageReader的surface作为CaptureRequest.Builder的目标 captureRequestBuilder.addTarget(mImageReader.getSurface()); // 自动对焦 captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE); // 自动曝光 captureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH); // 获取手机方向 int rotation = getWindowManager().getDefaultDisplay().getRotation(); // 根据设备方向计算设置照片的方向 captureRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation)); //拍照 CaptureRequest mCaptureRequest = captureRequestBuilder.build(); mCameraCaptureSession.capture(mCaptureRequest, null, childHandler); } catch (CameraAccessException e) { e.printStackTrace(); } } }</code></pre> <p>布局代码以及权限与 Camera1 中一样，效果一样</p> <p>预览时，是将 mSurfaceHolder.getSurface() 作为目标</p> <p>显示拍照结果时，是将 mImageReader.getSurface() 作为目标</p> <h2>3.最后</h2> <p>Camera2 的功能很强大，暂时也只是学习了最基本的思路</p> <p> </p> <p> </p> <p> </p> <p>来自：http://www.jianshu.com/p/7f766eb2f4e7</p> <p> </p>