Camera：相机这些实用技巧，赶紧学起来吧！
Carson带你学习Android
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·
2023-08-20 17:33
特别说明
本文仅涉及到 Android API 的使用以及封装，还没有涉及到专业音视频领域
正文部分
使用到相机大家都不陌生，很多应用都会使用到 Camera 硬件，一般是用于拍照或者录制视频，这都是很常见的功能。
一般来大家都是怎么使用的呢？说如果没有 UI 的限制或逻辑的限制，只是单纯的拍照或录制视频，我们其实可以通过 intent 的方式直接启动系统的拍照或录制 Activity 就能完成，这是最方便的方式。也就不需要此文了。
但是总有那么一些应用，那么一些需求，要么是需要自定义的 相机UI页面，要么是业务逻辑需要 ，一般我们就需要自己实现 Camera 的逻辑，比如显示预览页面，对回调的数据帧进行人脸判断？ 进行图片识别？ 或者需要自定义拍照与录制逻辑单击拍照长按录制？ 或者是对特效/滤镜视频的录制？
既然离不开 Camera API 的使用，那么本文就从应用的角度出发如何使用 Camera API 实现想要的效果。
那么需要具体到使用哪一种 Camera 呢？这个大家也能听说过，我们目前有三种 API 可以使用，分别是 Camera , Camera2 , CameraX ??? 谷歌是不是傻，为什么要增加我们开发者的工作量，搞这么复杂我怎么用嘛！
一、Camera的前世今生
其实主要是为了兼容性与安全性考虑，这里简单的总结一下：
Camera API 是允许应用程序直接与相机硬件交互的旧版 android.hardware.Camera 类在底层通过驱动程序直接访问相机硬件。
它提供了基本的控制与图片捕捉能力，但是这种方式具有一定的限制和设备兼容性问题。所以 Android 团队决定在 Android 5.0 引入全新的相机 API ，即Camera2 API。
Camera2 API引入了一种新的架构，应用程序通过 CameraManager 与系统 「相机服务」 进行通信，并使用CameraDevice、CameraCaptureSession等对象来控制相机功能。这种方式提供了更精细的控制和更高的性能，并解决了旧版API存在的一些限制。
其实这样很好，直接操作变为通过服务通信，并且它提供更精细的控制和更高的性能。到此的话应该没什么问题，为什么还要推出 CameraX 呢？
尽管 Camera2 API 提供了很多优势，但使用它仍然需要编写大量的代码来处理各种情况和设备兼容性。为了简化相机开发流程并提高跨设备兼容性，Google 推出了 CameraX 库
而 CameraX 库则是在 Camera2 API 的基础上进行封装和简化，以提供更一致和易用的相机接口。它抽象了底层的相机相关逻辑和设备差异，使开发者能够以统一的方式编写相机代码，而无需关心特定设备兼容性的细节。它提供了更高级别的API，使开发者能够更轻松地实现相机功能，同时保持跨设备兼容性。
所以其实我们用 Camera2 能实现的效果都能通过 CameraX 更简单的与方便的实现，所以个人也是比较推荐使用 CameraX 。
下面就把三种 Camera API 的如何使用与如何封装都写一遍。
二、Camera1 的使用与封装
一般来说我们使用 Camera1 的时候，我们都是使用 SurfaceView 或 TextureView 来承载预览画面。他们在此场景下的区别就是 TextureView 可以用一些动画实现自适应，裁剪布局等效果。
这里我们简单的 SurfaceView 来演示如何使用：
先创建 SurfaceView 并设置监听，然后添加到我们指定的容器中：
public View initCamera(Context context) {
mSurfaceView = new SurfaceView(context);
mContext = context;
mSurfaceView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
mSurfaceHolder = mSurfaceView.getHolder();
mSurfaceHolder.addCallback(new CustomCallBack());
mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
return mSurfaceView;
}
在 SurfaceView 的回调中，我们初始化 Camera
private class CustomCallBack implements SurfaceHolder.Callback {
@Override
public void surfaceCreated(SurfaceHolder holder) {
initCamera();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
releaseAllCamera();
}
}
private void initCamera() {
if (mCamera != null) {
releaseAllCamera();
}
//打开摄像头
try {
mCamera = Camera.open();
} catch (Exception e) {
e.printStackTrace();
releaseAllCamera();
}
if (mCamera == null)
return;
//设置摄像头参数
setCameraParams();
try {
mCamera.setDisplayOrientation(90); //设置拍摄方向为90度（竖屏）
mCamera.setPreviewDisplay(mSurfaceHolder);
mCamera.startPreview();
mCamera.unlock();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (RuntimeException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
这里需要额外处理预览的方向与预览尺寸,代码太多了，在下面的工具类中放出。
上面的代码只是最简单的使用，关于切换前后镜头，镜像展示，预览方向，旋转角度，回调处理等等一系列的操作使用起来很是麻烦，所以这里贴一个自用的工具类统一管理他们。
先定义一个接口回调：
public interface CameraListener {
/**
* 当打开时执行
*
* @param camera 相机实例
* @param cameraId 相机ID
* @param displayOrientation 相机预览旋转角度
* @param isMirror 是否镜像显示
*/
void onCameraOpened(Camera camera, int cameraId, int displayOrientation, boolean isMirror);
/**
* 预览数据回调
*
* @param data 预览数据
* @param camera 相机实例
*/
void onPreview(byte[] data, Camera camera);
/**
* 当相机关闭时执行
*/
void onCameraClosed();
/**
* 当出现异常时执行
*
* @param e 相机相关异常
*/
void onCameraError(Exception e);
/**
* 属性变化时调用
*
* @param cameraID 相机ID
* @param displayOrientation 相机旋转方向
*/
void onCameraConfigurationChanged(int cameraID, int displayOrientation);
}
然后就是我们的工具类，这里直接贴出：
public class CameraHelper implements Camera.PreviewCallback {
private Camera mCamera;
private int mCameraId;
private Point previewViewSize;
private View previewDisplayView;
private Camera.Size previewSize;
private Point specificPreviewSize;
private int displayOrientation = 0;
private int rotation;
private int additionalRotation;
private boolean isMirror = false;
private Integer specificCameraId = null;
private CameraListener cameraListener; //自定义监听回调
private CameraHelper(Builder builder) {
previewDisplayView = builder.previewDisplayView;
specificCameraId = builder.specificCameraId;
cameraListener = builder.cameraListener;
rotation = builder.rotation;
additionalRotation = builder.additionalRotation;
previewViewSize = builder.previewViewSize;
specificPreviewSize = builder.previewSize;
if (builder.previewDisplayView instanceof TextureView) {
isMirror = builder.isMirror;
} else if (isMirror) {
throw new RuntimeException("mirror is effective only when the preview is on a textureView");
}
}
public void init() {
if (previewDisplayView instanceof TextureView) {
((TextureView) this.previewDisplayView).setSurfaceTextureListener(textureListener);
} else if (previewDisplayView instanceof SurfaceView) {
((SurfaceView) previewDisplayView).getHolder().addCallback(surfaceCallback);
}
if (isMirror) {
previewDisplayView.setScaleX(-1);
}
}
public String start() {
String firstSize = null;
String finalSize = null;
synchronized (this) {
if (mCamera != null) {
return null;
}
//相机数量为2则打开1,1则打开0,相机ID 1为前置，0为后置
mCameraId = Camera.getNumberOfCameras() - 1;
//若指定了相机ID且该相机存在，则打开指定的相机
if (specificCameraId != null && specificCameraId <= mCameraId) {
mCameraId = specificCameraId;
}
//没有相机
if (mCameraId == -1) {
if (cameraListener != null) {
cameraListener.onCameraError(new Exception("camera not found"));
}
return null;
}
//开启相机
if (mCamera == null) {
mCamera = Camera.open(mCameraId);
}
//获取预览方向
displayOrientation = getCameraOri(rotation);
mCamera.setDisplayOrientation(displayOrientation);
try {
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewFormat(ImageFormat.NV21);
//预览大小设置
previewSize = parameters.getPreviewSize();
firstSize = previewSize.width + " - " + previewSize.height;
List<Camera.Size> supportedPreviewSizes = parameters.getSupportedPreviewSizes();
if (supportedPreviewSizes != null && supportedPreviewSizes.size() > 0) {
previewSize = getBestSupportedSize(supportedPreviewSizes, previewViewSize);
finalSize = previewSize.width + " - " + previewSize.height;
}
YYLogUtils.w("Base Preview Size ,Width:" + previewSize.width + " height:" + previewSize.height);
parameters.setPreviewSize(previewSize.width, previewSize.height);
//对焦模式设置
List<String> supportedFocusModes = parameters.getSupportedFocusModes();
if (supportedFocusModes != null && supportedFocusModes.size() > 0) {
if (supportedFocusModes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)) {
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
} else if (supportedFocusModes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO)) {
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);
} else if (supportedFocusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
}
}
//Camera 配置完成，设置回去
mCamera.setParameters(parameters);
//绑定到 TextureView 或 SurfaceView
if (previewDisplayView instanceof TextureView) {
mCamera.setPreviewTexture(((TextureView) previewDisplayView).getSurfaceTexture());
} else {
mCamera.setPreviewDisplay(((SurfaceView) previewDisplayView).getHolder());
}
//启动预览并设置预览回调
mCamera.setPreviewCallback(this);
mCamera.startPreview();
if (cameraListener != null) {
cameraListener.onCameraOpened(mCamera, mCameraId, displayOrientation, isMirror);
}
} catch (Exception e) {
if (cameraListener != null) {
cameraListener.onCameraError(e);
}
}
}
return "firstSize :" + firstSize + " finalSize:" + finalSize;
}
private int getCameraOri(int rotation) {
int degrees = rotation * 90;
switch (rotation) {
case Surface.ROTATION_0:
degrees = 0;
break;
case Surface.ROTATION_90:
degrees = 90;
break;
case Surface.ROTATION_180:
degrees = 180;
break;
case Surface.ROTATION_270:
degrees = 270;
break;
default:
break;
}
additionalRotation /= 90;
additionalRotation *= 90;
degrees += additionalRotation;
int result;
Camera.CameraInfo info = new Camera.CameraInfo();
Camera.getCameraInfo(mCameraId, info);
if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
result = (info.orientation + degrees) % 360;
result = (360 - result) % 360;
} else {
result = (info.orientation - degrees + 360) % 360;
}
return result;
}
public void stop() {
synchronized (this) {
if (mCamera == null) {
return;
}
mCamera.setPreviewCallback(null);
mCamera.stopPreview();
mCamera.release();
mCamera = null;
if (cameraListener != null) {
cameraListener.onCameraClosed();
}
}
}
public boolean isStopped() {
synchronized (this) {
return mCamera == null;
}
}
public void release() {
synchronized (this) {
stop();
previewDisplayView = null;
specificCameraId = null;
cameraListener = null;
previewViewSize = null;
specificPreviewSize = null;
previewSize = null;
}
}
/**
* 根据 Camera 获取支持的宽高，获取到最适合的预览宽高
*/
private Camera.Size getBestSupportedSize(List<Camera.Size> sizes, Point previewViewSize) {
if (sizes == null || sizes.size() == 0) {
return mCamera.getParameters().getPreviewSize();
}
Camera.Size[] tempSizes = sizes.toArray(new Camera.Size[0]);
Arrays.sort(tempSizes, new Comparator<Camera.Size>() {
@Override
public int compare(Camera.Size o1, Camera.Size o2) {
if (o1.width > o2.width) {
return -1;
} else if (o1.width == o2.width) {
return o1.height > o2.height ? -1 : 1;
} else {
return 1;
}
}
});
sizes = Arrays.asList(tempSizes);
Camera.Size bestSize = sizes.get(0);
float previewViewRatio;
if (previewViewSize != null) {
previewViewRatio = (float) previewViewSize.x / (float) previewViewSize.y;
} else {
previewViewRatio = (float) bestSize.width / (float) bestSize.height;
}
if (previewViewRatio > 1) {
previewViewRatio = 1 / previewViewRatio;
}
boolean isNormalRotate = (additionalRotation % 180 == 0);
for (Camera.Size s : sizes) {
if (specificPreviewSize != null && specificPreviewSize.x == s.width && specificPreviewSize.y == s.height) {
return s;
}
if (isNormalRotate) {
if (Math.abs((s.height / (float) s.width) - previewViewRatio) < Math.abs(bestSize.height / (float) bestSize.width - previewViewRatio)) {
bestSize = s;
}
} else {
if (Math.abs((s.width / (float) s.height) - previewViewRatio) < Math.abs(bestSize.width / (float) bestSize.height - previewViewRatio)) {
bestSize = s;
}
}
}
return bestSize;
}
public List<Camera.Size> getSupportedPreviewSizes() {
if (mCamera == null) {
return null;
}
return mCamera.getParameters().getSupportedPreviewSizes();
}
public List<Camera.Size> getSupportedPictureSizes() {
if (mCamera == null) {
return null;
}
return mCamera.getParameters().getSupportedPictureSizes();
}
@Override
public void onPreviewFrame(byte[] nv21, Camera camera) {
if (cameraListener != null && nv21 != null) {
cameraListener.onPreview(nv21, camera);
}
}
/**
* TextureView 的监听回调
*/
private TextureView.SurfaceTextureListener textureListener = new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int width, int height) {
// start();
if (mCamera != null) {
try {
mCamera.setPreviewTexture(surfaceTexture);
} catch (IOException e) {
e.printStackTrace();
}
}
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surfaceTexture, int width, int height) {
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surfaceTexture) {
stop();
return false;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture surfaceTexture) {
}
};
/**
* SurfaceView 的监听回调
*/
private SurfaceHolder.Callback surfaceCallback = new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder holder) {
if (mCamera != null) {
try {
mCamera.setPreviewDisplay(holder);
} catch (IOException e) {
e.printStackTrace();
}
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
stop();
}
};
/**
* 切换摄像头方向
*/
public void changeDisplayOrientation(int rotation) {
if (mCamera != null) {
this.rotation = rotation;
displayOrientation = getCameraOri(rotation);
mCamera.setDisplayOrientation(displayOrientation);
if (cameraListener != null) {
cameraListener.onCameraConfigurationChanged(mCameraId, displayOrientation);
}
}
}
/**
* 翻转前后摄像镜头
*/
public boolean switchCamera() {
if (Camera.getNumberOfCameras() < 2) {
return false;
}
// cameraId ,0为后置，1为前置
specificCameraId = 1 - mCameraId;
stop();
start();
return true;
}
/**
* 使用构建者模式创建，配置Camera
*/
public static final class Builder {
//预览显示的view，目前仅支持surfaceView和textureView
private View previewDisplayView;
//是否镜像显示，只支持textureView
private boolean isMirror;
//指定的相机ID
private Integer specificCameraId;
//事件回调
private CameraListener cameraListener;
//屏幕的长宽，在选择最佳相机比例时用到
private Point previewViewSize;
//屏幕的方向，一般传入getWindowManager().getDefaultDisplay().getRotation()的值即可
private int rotation;
//指定的预览宽高，若系统支持则会以这个预览宽高进行预览
private Point previewSize;
//额外的旋转角度（用于适配一些定制设备）
private int additionalRotation;
public Builder() {
}
//必须要绑定到SurfaceView或者TextureView上
public Builder previewOn(View view) {
if (view instanceof SurfaceView || view instanceof TextureView) {
previewDisplayView = view;
return this;
} else {
throw new RuntimeException("you must preview on a textureView or a surfaceView");
}
}
public Builder isMirror(boolean mirror) {
isMirror = mirror;
return this;
}
public Builder previewSize(Point point) {
previewSize = point;
return this;
}
public Builder previewViewSize(Point point) {
previewViewSize = point;
return this;
}
public Builder rotation(int rotation) {
rotation = rotation;
return this;
}
public Builder additionalRotation(int rotation) {
additionalRotation = rotation;
return this;
}
public Builder specificCameraId(Integer id) {
specificCameraId = id;
return this;
}
public Builder cameraListener(CameraListener listener) {
cameraListener = listener;
return this;
}
public CameraHelper build() {
if (previewViewSize == null) {
throw new RuntimeException("previewViewSize is null, now use default previewSize");
}
if (cameraListener == null) {
throw new RuntimeException("cameraListener is null, callback will not be called");
}
if (previewDisplayView == null) {
throw new RuntimeException("you must preview on a textureView or a surfaceView");
}
//build的时候顺便执行初始化
CameraHelper cameraHelper = new CameraHelper(this);
cameraHelper.init();
return cameraHelper;
}
}
}
我们使用起来就很简单了：
还是初始化 SurfaceView 并且添加到指定的布局容器中：
public View initCamera(Context context) {
mSurfaceView = new SurfaceView(context);
mContext = context;
mSurfaceView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
mSurfaceView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
mSurfaceView.post(() -> {
setupCameraHelper();
});
mSurfaceView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
});
return mSurfaceView;
}
private void setupCameraHelper() {
cameraHelper = new CameraHelper.Builder()
.previewViewSize(new Point(mSurfaceView.getMeasuredWidth(), mSurfaceView.getMeasuredHeight()))
.rotation(((Activity) mContext).getWindowManager().getDefaultDisplay().getRotation())
.specificCameraId(Camera.CameraInfo.CAMERA_FACING_BACK)
.isMirror(false)
.previewOn(mSurfaceView) //预览容器 推荐TextureView
.cameraListener(mCameraListener) //设置自定义的监听器
.build();
cameraHelper.start();
}
所有的逻辑就在回调中处理：
//自定义监听
private CameraListener mCameraListener = new CameraListener() {
@Override
public void onCameraOpened(Camera camera, int cameraId, int displayOrientation, boolean isMirror) {
YYLogUtils.w("CameraListener - onCameraOpened");
//你可以使用 MediaRecorder 去录制视频
mMediaRecorder = new MediaRecorder();
...
}
@Override
public void onPreview(byte[] data, Camera camera) {
// nv21 数据
// 你也可以用 MediaCodec 自己编码去录制视频
}
@Override
public void onCameraClosed() {
YYLogUtils.w("CameraListener - onCameraClosed");
}
@Override
public void onCameraError(Exception e) {
YYLogUtils.w("CameraListener - onCameraError");
}
@Override
public void onCameraConfigurationChanged(int cameraID, int displayOrientation) {
YYLogUtils.w("CameraListener - onCameraConfigurationChanged");
}
};
停止与释放的逻辑
@Override
public void releaseAllCamera() {
cameraHelper.stop();
cameraHelper.release();
}
效果：
细啊，真的是太细了，代码太详细了。
三、Camera2 的使用与封装
Camera2 的使用是通过服务获取的，使用起来相对步骤多一些。
这里我们使用 TextureView 来承载画面：
public View initCamera(Context context) {
mTextureView = new TextureView(context);
mContext = context;
mTextureView.setLayoutParams(new ViewGroup.LayoutParams(720, 1280));
mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);
return mTextureView;
}
同样的逻辑，我们在 TextureView 的回调中启动 Camera2 ：
private TextureView.SurfaceTextureListener mSurfaceTextureListener = new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture texture, int width, int height) {
// 当TextureView可用时，打开摄像头
YYLogUtils.w("当TextureView可用时,width:" + width + " height:" + height);
openCamera(width, height);
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture texture, int width, int height) {
// 当TextureView尺寸改变时，更新预览尺寸
configureTransform(width, height);
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture texture) {
// 当TextureView销毁时，释放资源
return true;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture texture) {
// 监听纹理更新事件
}
};
private void openCamera(int width, int height) {
// 获取相机管理器
mCameraManager = (CameraManager) mContext.getSystemService(Context.CAMERA_SERVICE);
// 设置自定义的线程处理
HandlerThread handlerThread = new HandlerThread("Camera2Manager");
handlerThread.start();
mBgHandler = new Handler(handlerThread.getLooper());
try {
//获取到相机信息并赋值
getCameraListCameraCharacteristics(width,height);
YYLogUtils.w("打开的摄像头id:" + mCurrentCameraId);
// 打开摄像头
mCameraManager.openCamera(mCurrentCameraId, new CameraDevice.StateCallback() {
@Override
public void onOpened(CameraDevice cameraDevice) {
// 当摄像头打开时，创建预览会话
mCameraDevice = cameraDevice;
createCameraPreviewSession(mBgHandler, mTextureView.getWidth(), mTextureView.getHeight());
}
@Override
public void onDisconnected(CameraDevice cameraDevice) {
if (mCameraDevice != null) {
mCameraDevice.close();
mCameraDevice = null;
}
}
@Override
public void onError(CameraDevice cameraDevice, int error) {
if (mCameraDevice != null) {
mCameraDevice.close();
mCameraDevice = null;
}
}
}, mBgHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
这里我们使用的 mBgHandler 我们使用的主线程，其实在子线程中更好，这里只用作展示而已（具体的后面工具类会给出）。
我们继续往下走，打开相机之后需要创建预览的会话，创建预览Surface，并且在预览会话回调中发起预览请求：
/**
* 创建相机预览会话
*/
private void createCameraPreviewSession(Handler handler, int width, int height) {
try {
// 获取SurfaceTexture并设置默认缓冲区大小
SurfaceTexture texture = mTextureView.getSurfaceTexture();
texture.setDefaultBufferSize(mTextureView.getWidth(), mTextureView.getHeight());
// 创建预览Surface
Surface surface = new Surface(texture);
// 创建CaptureRequest.Builder并设置预览Surface为目标
mPreviewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(surface);
// 创建ImageReader并设置回调
YYLogUtils.w("创建ImageReader并设置回调,width:" + width + " height:" + height);
// mImageReader = ImageReader.newInstance(mTextureView.getWidth(), mTextureView.getHeight(), ImageFormat.JPEG, 1);
mImageReader = ImageReader.newInstance(width, height, ImageFormat.YUV_420_888, 2);
mImageReader.setOnImageAvailableListener(mOnImageAvailableListener, handler);
// 将ImageReader的Surface添加到CaptureRequest.Builder中
Surface readerSurface = mImageReader.getSurface();
mPreviewRequestBuilder.addTarget(readerSurface);
// 创建预览会话
mCameraDevice.createCaptureSession(Arrays.asList(surface, readerSurface), mSessionCallback, handler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private CameraCaptureSession.StateCallback mSessionCallback = new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
// 预览会话已创建成功，开始预览
mPreviewSession = cameraCaptureSession;
updatePreview();
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
ToastUtils.INSTANCE.makeText(mContext, "Failed to create camera preview session");
}
};
private void updatePreview() {
try {
// 设置自动对焦模式
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// 构建预览请求
mPreviewRequest = mPreviewRequestBuilder.build();
// 发送预览请求
mPreviewSession.setRepeatingRequest(mPreviewRequest, null, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private ImageReader.OnImageAvailableListener mOnImageAvailableListener = new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
// YUV_420 格式
Image image = reader.acquireLatestImage();
saveImage(bytes);
image.close();
}
};
可以看到，Camera2 的基本使用比起 Camera1 来说复杂了不少，这里还是省略了一些旋转角度，预览方向，最佳尺寸等逻辑的代码（后面工具类会给出）。所以难怪谷歌要出 CameraX，自己都看不下去了呗。
当然，我们封装一下之后使用起来也是很简单的，看我的工具类。
这里分别不同的实例提供，一种是基本的预览，一种是AllSize的裁剪模式，一种是提供了 ImageReader 帧回调的终极模式。
这里真的不能全部贴出来，不然代码太多，大家可以看文章底部的源码查看。所以这里贴出的是关键代码：
由于 Camera2 的很多操作都推荐在子线程处理，这里先定义子线程的 Loop 与 Handler ：
public abstract class BaseMessageLoop {
private volatile MsgHandlerThread mHandlerThread;
private volatile Handler mHandler;
private String mName;
public BaseMessageLoop(Context context, String name) {
mName = name;
}
public MsgHandlerThread getHandlerThread() {
return mHandlerThread;
}
public Handler getHandler() {
return mHandler;
}
public void Run() {
Quit();
//LogUtil.v(TAG, mName + " HandlerThread Run");
synchronized (this) {
mHandlerThread = new MsgHandlerThread(mName);
mHandlerThread.start();
mHandler = new Handler(mHandlerThread.getLooper(), mHandlerThread);
}
}
public void Quit() {
//LogUtil.v(TAG, mName + " HandlerThread Quit");
synchronized (this) {
if (mHandlerThread != null) {
mHandlerThread.quit();
}
if (mHandler != null) {
mHandler.removeCallbacks(mHandlerThread);
}
mHandlerThread = null;
mHandler = null;
}
}
...
}
基本的预览提供：
public class BaseCommonCameraProvider extends BaseCameraProvider {
protected Activity mContext;
protected String mCameraId;
protected Handler mCameraHandler;
private final BaseMessageLoop mThread;
protected CameraDevice mCameraDevice;
protected CameraCaptureSession session;
protected AspectTextureView[] mTextureViews;
protected CameraManager cameraManager;
protected OnCameraInfoListener mCameraInfoListener;
public interface OnCameraInfoListener {
void getBestSize(Size outputSizes);
void onFrameCannback(Image image);
void initEncode();
void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int width, int height);
}
public void setCameraInfoListener(OnCameraInfoListener cameraInfoListener) {
this.mCameraInfoListener = cameraInfoListener;
}
protected BaseCommonCameraProvider(Activity mContext) {
this.mContext = mContext;
mThread = new BaseMessageLoop(mContext, "camera") {
@Override
protected boolean recvHandleMessage(Message msg) {
return false;
}
};
mThread.Run();
mCameraHandler = mThread.getHandler();
cameraManager = (CameraManager) mContext.getSystemService(Context.CAMERA_SERVICE);
}
protected String getCameraId(boolean useFront) {
try {
for (String cameraId : cameraManager.getCameraIdList()) {
CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
int cameraFacing = characteristics.get(CameraCharacteristics.LENS_FACING);
if (useFront) {
if (cameraFacing == CameraCharacteristics.LENS_FACING_FRONT) {
return cameraId;
}
} else {
if (cameraFacing == CameraCharacteristics.LENS_FACING_BACK) {
return cameraId;
}
}
}
} catch (CameraAccessException e) {
e.printStackTrace();
}
return null;
}
protected Size getCameraBestOutputSizes(String cameraId, Class clz) {
try {
//拿到支持的全部Size,并从大到小排序
CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
StreamConfigurationMap configs = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
List<Size> sizes = Arrays.asList(configs.getOutputSizes(clz));
Collections.sort(sizes, new Comparator<Size>() {
@Override
public int compare(Size o1, Size o2) {
return o1.getWidth() * o1.getHeight() - o2.getWidth() * o2.getHeight();
}
});
Collections.reverse(sizes);
YYLogUtils.w("all_sizes:" + sizes);
//去除一些不合适的预览尺寸
List<Size> suitableSizes = new ArrayList();
for (int i = 0; i < sizes.size(); i++) {
Size option = sizes.get(i);
if (textureViewSize.getWidth() > textureViewSize.getHeight()) {
if (option.getWidth() >= textureViewSize.getWidth() && option.getHeight() >= textureViewSize.getHeight()) {
suitableSizes.add(option);
}
} else {
if (option.getWidth() >= textureViewSize.getHeight() && option.getHeight() >= textureViewSize.getWidth()) {
suitableSizes.add(option);
}
}
}
YYLogUtils.w("suitableSizes:" + suitableSizes);
//获取最小占用的Size
if (!suitableSizes.isEmpty()) {
return suitableSizes.get(suitableSizes.size() - 1);
} else {
//异常情况下只能找默认的了
return sizes.get(0);
}
} catch (CameraAccessException e) {
e.printStackTrace();
}
return null;
}
protected List<Size> getCameraAllSizes(String cameraId, int format) {
try {
CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
StreamConfigurationMap configs = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
return Arrays.asList(configs.getOutputSizes(format));
} catch (CameraAccessException e) {
e.printStackTrace();
}
return null;
}
protected void releaseCameraDevice(CameraDevice cameraDevice) {
if (cameraDevice != null) {
cameraDevice.close();
cameraDevice = null;
}
}
protected void releaseCameraSession(CameraCaptureSession session) {
if (session != null) {
session.close();
session = null;
}
}
protected void releaseCamera() {
releaseCameraDevice(mCameraDevice);
releaseCameraSession(session);
}
}
对内部的一些监听与回调做了抽取，内部对切换镜头，支持的Size选择，等做了一些实现，这样简单的就能实现预览的操作。
我们常用的应该是可以裁切拉伸的 TextureView , 这里单独对它做一个预览的处理：
/**
* 只用于预览，没有帧回调
*/
public class Camera2AllSizeProvider extends BaseCommonCameraProvider {
private CaptureRequest.Builder mPreviewBuilder;
private Size outputSize;
public Camera2AllSizeProvider(Activity mContext) {
super(mContext);
Point displaySize = new Point();
mContext.getWindowManager().getDefaultDisplay().getSize(displaySize);
screenSize = new Size(displaySize.x, displaySize.y);
}
private void initCamera() {
mCameraId = getCameraId(false);//默认使用后置相机
//获取指定相机的输出尺寸列表，降序排序
outputSize = getCameraBestOutputSizes(mCameraId, SurfaceTexture.class);
//初始化预览尺寸
previewSize = outputSize;
YYLogUtils.w("previewSize,width:" + previewSize.getWidth() + "height:" + previewSize.getHeight());
if (mCameraInfoListener != null) {
mCameraInfoListener.getBestSize(outputSize);
}
}
int index = 0;
/**
* 关联并初始化TextTure
*/
public void initTexture(AspectTextureView... textureViews) {
mTextureViews = textureViews;
int size = textureViews.length;
for (AspectTextureView aspectTextureView : textureViews) {
aspectTextureView.setSurfaceTextureListener(new Camera2SimpleInterface.SimpleSurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
textureViewSize = new Size(width, height);
YYLogUtils.w("textureViewSize,width:" + textureViewSize.getWidth() + "height:" + textureViewSize.getHeight());
YYLogUtils.w("screenSize,width:" + screenSize.getWidth() + "height:" + screenSize.getHeight());
if (++index == size) {
initCamera();
openCamera();
}
}
});
}
}
@SuppressLint("MissingPermission")
private void openCamera() {
try {
cameraManager.openCamera(mCameraId, mStateCallback, mCameraHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private final CameraDevice.StateCallback mStateCallback = new Camera2SimpleInterface.SimpleCameraDeviceStateCallback() {
@Override
public void onOpened(CameraDevice camera) {
mCameraDevice = camera;
MediaCodecList allMediaCodecLists = new MediaCodecList(-1);
MediaCodecInfo avcCodecInfo = null;
for (MediaCodecInfo mediaCodecInfo : allMediaCodecLists.getCodecInfos()) {
if (mediaCodecInfo.isEncoder()) {
String[] supportTypes = mediaCodecInfo.getSupportedTypes();
for (String supportType : supportTypes) {
if (supportType.equals(MediaFormat.MIMETYPE_VIDEO_AVC)) {
avcCodecInfo = mediaCodecInfo;
Log.d("TAG", "编码器名称:" + mediaCodecInfo.getName() + " " + supportType);
MediaCodecInfo.CodecCapabilities codecCapabilities = avcCodecInfo.getCapabilitiesForType(MediaFormat.MIMETYPE_VIDEO_AVC);
int[] colorFormats = codecCapabilities.colorFormats;
for (int colorFormat : colorFormats) {
switch (colorFormat) {
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV411Planar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV411PackedPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedSemiPlanar:
Log.d("TAG", "支持的格式::" + colorFormat);
break;
}
}
}
}
}
}
//根据什么Size来展示PreView
startPreviewSession(previewSize);
}
};
public void startPreviewSession(Size size) {
YYLogUtils.w("startPreviewSession 真正的Size,width:" + size.getWidth() + " height:" + size.getHeight());
try {
releaseCameraSession(session);
mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
List<Surface> outputs = new ArrayList<>();
for (AspectTextureView aspectTextureView : mTextureViews) {
//设置预览大小与展示的裁剪模式
aspectTextureView.setScaleType(AspectInterface.ScaleType.FIT_CENTER);
aspectTextureView.setSize(size.getHeight(), size.getWidth());
SurfaceTexture surfaceTexture = aspectTextureView.getSurfaceTexture();
surfaceTexture.setDefaultBufferSize(size.getWidth(), size.getHeight());
Surface previewSurface = new Surface(surfaceTexture);
mPreviewBuilder.addTarget(previewSurface);
outputs.add(previewSurface);
}
mCameraDevice.createCaptureSession(outputs, mStateCallBack, mCameraHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private final CameraCaptureSession.StateCallback mStateCallBack = new Camera2SimpleInterface.SimpleStateCallback() {
@Override
public void onConfigured(CameraCaptureSession session) {
try {
Camera2AllSizeProvider.this.session = session;
//设置拍照前持续自动对焦
mPreviewBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
CaptureRequest request = mPreviewBuilder.build();
session.setRepeatingRequest(request, null, mCameraHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
};
public void closeCamera() {
releaseCamera();
if (mCameraDevice != null) {
mCameraDevice.close();
}
}
}
对于预览的回调，我们可以再做一个单独的实例提供：
/**
* 在预览的基础上加入ImageReader的帧回调，可以用于编码H264视频流等操作
*/
public class Camera2ImageReaderProvider extends BaseCommonCameraProvider {
private CaptureRequest.Builder mPreviewBuilder;
protected ImageReader mImageReader;
private Size outputSize;
public Camera2ImageReaderProvider(Activity mContext) {
super(mContext);
Point displaySize = new Point();
mContext.getWindowManager().getDefaultDisplay().getSize(displaySize);
screenSize = new Size(displaySize.x, displaySize.y);
YYLogUtils.w("screenSize,width:" + screenSize.getWidth() + "height:" + screenSize.getHeight(), "Camera2ImageReaderProvider");
}
private void initCamera() {
mCameraId = getCameraId(false);//默认使用后置相机
//获取指定相机的输出尺寸列表，降序排序
outputSize = getCameraBestOutputSizes(mCameraId, SurfaceTexture.class);
//初始化预览尺寸
previewSize = outputSize;
YYLogUtils.w("previewSize,width:" + previewSize.getWidth() + "height:" + previewSize.getHeight(), "Camera2ImageReaderProvider");
if (mCameraInfoListener != null) {
mCameraInfoListener.getBestSize(outputSize);
}
}
int index = 0;
/**
* 关联并初始化TextTure
*/
public void initTexture(AspectTextureView... textureViews) {
mTextureViews = textureViews;
int size = textureViews.length;
for (AspectTextureView aspectTextureView : textureViews) {
aspectTextureView.setSurfaceTextureListener(new Camera2SimpleInterface.SimpleSurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int width, int height) {
textureViewSize = new Size(width, height);
YYLogUtils.w("textureViewSize,width:" + textureViewSize.getWidth() + "height:" + textureViewSize.getHeight(), "Camera2ImageReaderProvider");
if (mCameraInfoListener != null) {
mCameraInfoListener.onSurfaceTextureAvailable(surfaceTexture, width, height);
}
if (++index == size) {
initCamera();
openCamera();
}
}
});
}
}
//初始化编码格式
public void initEncord() {
if (mCameraInfoListener != null) {
mCameraInfoListener.initEncode();
}
}
@SuppressLint("MissingPermission")
private void openCamera() {
try {
cameraManager.openCamera(mCameraId, mStateCallback, mCameraHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private final CameraDevice.StateCallback mStateCallback = new Camera2SimpleInterface.SimpleCameraDeviceStateCallback() {
@Override
public void onOpened(CameraDevice camera) {
mCameraDevice = camera;
initEncord();
MediaCodecList allMediaCodecLists = new MediaCodecList(-1);
MediaCodecInfo avcCodecInfo = null;
for (MediaCodecInfo mediaCodecInfo : allMediaCodecLists.getCodecInfos()) {
if (mediaCodecInfo.isEncoder()) {
String[] supportTypes = mediaCodecInfo.getSupportedTypes();
for (String supportType : supportTypes) {
if (supportType.equals(MediaFormat.MIMETYPE_VIDEO_AVC)) {
avcCodecInfo = mediaCodecInfo;
Log.d("TAG", "编码器名称:" + mediaCodecInfo.getName() + " " + supportType);
MediaCodecInfo.CodecCapabilities codecCapabilities = avcCodecInfo.getCapabilitiesForType(MediaFormat.MIMETYPE_VIDEO_AVC);
int[] colorFormats = codecCapabilities.colorFormats;
for (int colorFormat : colorFormats) {
switch (colorFormat) {
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV411Planar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV411PackedPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedSemiPlanar:
Log.d("TAG", "支持的格式::" + colorFormat);
break;
}
}
}
}
}
}
//根据什么Size来展示PreView
startPreviewSession(previewSize);
}
};
public void startPreviewSession(Size size) {
YYLogUtils.w("真正的预览Size,width:" + size.getWidth() + " height:" + size.getHeight(), "Camera2ImageReaderProvider");
try {
releaseCameraSession(session);
mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
List<Surface> outputs = new ArrayList<>();
for (AspectTextureView aspectTextureView : mTextureViews) {
//设置预览大小与展示的裁剪模式
aspectTextureView.setScaleType(AspectInterface.ScaleType.FIT_CENTER);
aspectTextureView.setSize(size.getHeight(), size.getWidth());
SurfaceTexture surfaceTexture = aspectTextureView.getSurfaceTexture();
surfaceTexture.setDefaultBufferSize(size.getWidth(), size.getHeight());
Surface previewSurface = new Surface(surfaceTexture);
mPreviewBuilder.addTarget(previewSurface);
outputs.add(previewSurface);
}
//这里的回调监听
mImageReader = ImageReader.newInstance(size.getWidth(), size.getHeight(), ImageFormat.YUV_420_888, 10);
mImageReader.setOnImageAvailableListener(mOnImageAvailableListener, mCameraHandler);
Surface readerSurface = mImageReader.getSurface();
mPreviewBuilder.addTarget(readerSurface);
outputs.add(readerSurface);
mCameraDevice.createCaptureSession(outputs, mStateCallBack, mCameraHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private ImageReader.OnImageAvailableListener mOnImageAvailableListener = new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
Image image = reader.acquireLatestImage();
if (image == null) {
return;
}
if (mCameraInfoListener != null) {
mCameraInfoListener.onFrameCannback(image);
}
image.close();
}
};
private final CameraCaptureSession.StateCallback mStateCallBack = new Camera2SimpleInterface.SimpleStateCallback() {
@Override
public void onConfigured(CameraCaptureSession session) {
try {
Camera2ImageReaderProvider.this.session = session;
//设置拍照前持续自动对焦
mPreviewBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// mPreviewBuilder.set(CaptureRequest.JPEG_ORIENTATION, 90);
CaptureRequest request = mPreviewBuilder.build();
session.setRepeatingRequest(request, null, mCameraHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
};
public void closeCamera() {
releaseCamera();
if (mImageReader != null) {
mImageReader.close();
}
if (mCameraDevice != null) {
mCameraDevice.close();
}
}
}
关于 Camera2 的尺寸，其实我们要了解的是三种尺寸，当前屏幕尺寸，当前 textureView 尺寸，以及当前预览的尺寸。
比较容易混淆的就是 textureView 尺寸和预览的尺寸，一个是显示控件的尺寸，一个是 Camera 支持的预览尺寸，他们的大小可能相同，但更多的可能是不同，宽高比例也可能不同 ，所以我们才需要居中裁剪或居中展示的方式来预览画面，上文关于这三种尺寸的定义与使用都有详细的注释。
上文的代码中还省略了一些非关键的类与回调，有兴趣可以去源码中查看。（本文结尾有链接）
「如何使用？」 定义完成之后我们就可以来一个简单的使用示例：
这里以 H264 的编码为例：
fun setupCamera(activity: Activity, container: ViewGroup) {
file = File(CommUtils.getContext().externalCacheDir, "${System.currentTimeMillis()}-record.h264")
if (!file.exists()) {
file.createNewFile()
}
if (!file.isDirectory) {
outputStream = FileOutputStream(file, true)
}
val textureView = AspectTextureView(activity)
textureView.layoutParams = ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)
mCamera2Provider = Camera2ImageReaderProvider(activity)
mCamera2Provider?.initTexture(textureView)
mCamera2Provider?.setCameraInfoListener(object :
BaseCommonCameraProvider.OnCameraInfoListener {
override fun getBestSize(outputSizes: Size?) {
mPreviewSize = outputSizes
}
override fun onFrameCannback(image: Image) {
if (isRecording) {
// 使用C库获取到I420格式，对应 COLOR_FormatYUV420Planar
val yuvFrame = yuvUtils.convertToI420(image)
// 与MediaFormat的编码格式宽高对应
val yuvFrameRotate = yuvUtils.rotate(yuvFrame, 90)
// 用于测试RGB图片的回调预览
bitmap = Bitmap.createBitmap(yuvFrameRotate.width, yuvFrameRotate.height, Bitmap.Config.ARGB_8888)
yuvUtils.yuv420ToArgb(yuvFrameRotate, bitmap!!)
mBitmapCallback?.invoke(bitmap)
// 旋转90度之后的I420格式添加到同步队列
val bytesFromImageAsType = yuvFrameRotate.asArray()
//使用Java工具类转换Image对象为NV21格式,对应 COLOR_FormatYUV420Flexible
// val bytesFromImageAsType = getBytesFromImageAsType(image, Camera2ImageUtils.YUV420SP)
originVideoDataList.offer(bytesFromImageAsType)
}
}
override fun initEncode() {
mediaCodecEncodeToH264()
}
override fun onSurfaceTextureAvailable(surfaceTexture: SurfaceTexture?, width: Int, height: Int) {
this@VideoH264RecoderUtils.surfaceTexture = surfaceTexture
}
})
container.addView(textureView)
}
由于这里返回的是 YUV420 ，所以这里我们需要转换为 I420 或 NV21 格式。这里我分别展示了 C 库转为 I420(YUV420) , Java 库转换为 NV21(YUV420SP) 格式。
然后我们就能把 I420 与 NV21 这两种我们常见的格式编码为 H264 文件，而怎么编码反倒不是今天的主题了，只能说方式太多了，这里先略过。
只需要这一个 setupCamera 方法，就能完成绑定，我们在 Activity 中使用即可一行代码设置进去就可以了。
class RecoderVideo1Activity : BaseActivity() {
override fun init() {
val flContainer = findViewById<FrameLayout>(R.id.fl_container)
val videoRecodeUtils = VideoH264RecoderUtils()
videoRecodeUtils.setupCamera(this, container)
}
}
效果：
四、CameraX 的使用与封装
相比前面两种 API 的使用，CameraX 的使用就简单多了，网上也很多 CameraX 的使用教程，这里我们就快速过一下。
我们初始化 PreviewView 对象，然后添加到我们指定的容器中。
public View initCamera(Context context) {
mPreviewView = new PreviewView(context);
mContext = context;
mPreviewView.setScaleType(PreviewView.ScaleType.FIT_CENTER);
mPreviewView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
mPreviewView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
if (mPreviewView.isShown()) {
startCamera();
}
mPreviewView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
});
return mPreviewView;
}
其次我们就可以启动相机并绑定到生命周期。
private void startCamera() {
//获取屏幕的分辨率
DisplayMetrics displayMetrics = new DisplayMetrics();
mPreviewView.getDisplay().getRealMetrics(displayMetrics);
//获取宽高比
int screenAspectRatio = aspectRatio(displayMetrics.widthPixels, displayMetrics.heightPixels);
int rotation = mPreviewView.getDisplay().getRotation();
ListenableFuture<ProcessCameraProvider> cameraProviderFuture = ProcessCameraProvider.getInstance(mContext);
cameraProviderFuture.addListener(() -> {
try {
//获取相机信息
mCameraProvider = cameraProviderFuture.get();
//镜头选择
mLensFacing = getLensFacing();
mCameraSelector = new CameraSelector.Builder().requireLensFacing(mLensFacing).build();
//预览对象
Preview.Builder previewBuilder = new Preview.Builder()
.setTargetAspectRatio(screenAspectRatio)
.setTargetRotation(rotation);
Preview preview = previewBuilder.build();
preview.setSurfaceProvider(mPreviewView.getSurfaceProvider());
//录制视频对象
mVideoCapture = new VideoCapture.Builder()
.setTargetAspectRatio(screenAspectRatio) //设置高宽比
.setAudioRecordSource(MediaRecorder.AudioSource.MIC) //设置音频源麦克风
.setTargetRotation(rotation)
//视频帧率
.setVideoFrameRate(30)
//bit率
.setBitRate(3 * 1024 * 1024)
.build();
// ImageAnalysis imageAnalysis = new ImageAnalysis.Builder()
// .setTargetAspectRatio(screenAspectRatio)
// .setTargetRotation(rotation)
// .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
// .build();
//
// // 在每一帧上应用颜色矩阵
// imageAnalysis.setAnalyzer(Executors.newSingleThreadExecutor(), new MyAnalyzer(mContext));
//开启CameraX
mCameraProvider.unbindAll();
if (mContext instanceof FragmentActivity) {
FragmentActivity fragmentActivity = (FragmentActivity) mContext;
mCameraProvider.bindToLifecycle(fragmentActivity, mCameraSelector, preview, mVideoCapture/*,imageAnalysis*/);
}
} catch (ExecutionException | InterruptedException e) {
e.printStackTrace();
}
}, ContextCompat.getMainExecutor(mContext));
}
这里我们使用了四个用例，预览，拍照，录制，分析。但是我们注释了分析用例，因为录制与分析这两个用例是不能同时使用的。
录制视频的话，我们就能直接使用录制用例的方法就能录制，这是最简单的。
public void startCameraRecord() {
if (mVideoCapture == null) return;
VideoCapture.OutputFileOptions outputFileOptions = new VideoCapture.OutputFileOptions.Builder(getOutFile()).build();
mVideoCapture.startRecording(outputFileOptions, mExecutorService, new VideoCapture.OnVideoSavedCallback() {
@Override
public void onVideoSaved(@NonNull VideoCapture.OutputFileResults outputFileResults) {
YYLogUtils.w("视频保存成功,outputFileResults:" + outputFileResults.getSavedUri());
if (mCameraCallback != null) mCameraCallback.takeSuccess();
}
@Override
public void onError(int videoCaptureError, @NonNull String message, @Nullable Throwable cause) {
YYLogUtils.e(message);
}
});
}
内部一些镜头选择，比例选择等代码省略了，在下面的工具类中会给出。
可以看到虽然 CameraX 的使用已经是够简单的了，但是由于都是一些重复的代码，我们还是可以对其做一些封装，代码如下：
class CameraXController {
private var mCameraProvider: ProcessCameraProvider? = null
private var mLensFacing = 0
private var mCameraSelector: CameraSelector? = null
private var mVideoCapture: VideoCapture? = null
private var mCameraCallback: ICameraCallback? = null
private val mExecutorService = Executors.newSingleThreadExecutor()
//初始化 CameraX 相关配置
fun setUpCamera(context: Context, surfaceProvider: Preview.SurfaceProvider) {
//获取屏幕的分辨率与宽高比
val displayMetrics = context.resources.displayMetrics
val screenAspectRatio = aspectRatio(displayMetrics.widthPixels, displayMetrics.heightPixels)
val cameraProviderFuture = ProcessCameraProvider.getInstance(context)
cameraProviderFuture.addListener({
mCameraProvider = cameraProviderFuture.get()
//镜头选择
mLensFacing = lensFacing
mCameraSelector = CameraSelector.Builder().requireLensFacing(mLensFacing).build()
//预览对象
val preview: Preview = Preview.Builder()
.setTargetAspectRatio(screenAspectRatio)
.build()
preview.setSurfaceProvider(surfaceProvider)
//录制视频对象
mVideoCapture = VideoCapture.Builder()
.setTargetAspectRatio(screenAspectRatio)
.setAudioRecordSource(MediaRecorder.AudioSource.MIC) //设置音频源麦克风
//视频帧率
.setVideoFrameRate(30)
//bit率
.setBitRate(3 * 1024 * 1024)
.build()
//绑定到页面
mCameraProvider?.unbindAll()
val camera = mCameraProvider?.bindToLifecycle(
context as LifecycleOwner,
mCameraSelector!!,
mVideoCapture,
preview
)
val cameraInfo = camera?.cameraInfo
val cameraControl = camera?.cameraControl
}, ContextCompat.getMainExecutor(context))
}
//根据屏幕宽高比设置预览比例为4:3还是16:9
private fun aspectRatio(widthPixels: Int, heightPixels: Int): Int {
val previewRatio = Math.max(widthPixels, heightPixels).toDouble() / Math.min(widthPixels, heightPixels).toDouble()
return if (Math.abs(previewRatio - 4.0 / 3.0) <= Math.abs(previewRatio - 16.0 / 9.0)) {
AspectRatio.RATIO_4_3
} else {
AspectRatio.RATIO_16_9
}
}
//优先选择哪一个摄像头镜头
private val lensFacing: Int
private get() {
if (hasBackCamera()) {
return CameraSelector.LENS_FACING_BACK
}
return if (hasFrontCamera()) {
CameraSelector.LENS_FACING_FRONT
} else -1
}
//是否有后摄像头
private fun hasBackCamera(): Boolean {
if (mCameraProvider == null) {
return false
}
try {
return mCameraProvider!!.hasCamera(CameraSelector.DEFAULT_BACK_CAMERA)
} catch (e: CameraInfoUnavailableException) {
e.printStackTrace()
}
return false
}
//是否有前摄像头
private fun hasFrontCamera(): Boolean {
if (mCameraProvider == null) {
return false
}
try {
return mCameraProvider!!.hasCamera(CameraSelector.DEFAULT_BACK_CAMERA)
} catch (e: CameraInfoUnavailableException) {
e.printStackTrace()
}
return false
}
// 开始录制
fun startCameraRecord(outFile: File) {
mVideoCapture ?: return
val outputFileOptions: VideoCapture.OutputFileOptions = VideoCapture.OutputFileOptions.Builder(outFile).build()
mVideoCapture!!.startRecording(outputFileOptions, mExecutorService, object : VideoCapture.OnVideoSavedCallback {
override fun onVideoSaved(outputFileResults: VideoCapture.OutputFileResults) {
YYLogUtils.w("视频保存成功,outputFileResults:" + outputFileResults.savedUri)
mCameraCallback?.takeSuccess()
}
override fun onError(videoCaptureError: Int, message: String, cause: Throwable?) {
YYLogUtils.e(message)
}
})
}
// 停止录制
fun stopCameraRecord(cameraCallback: ICameraCallback?) {
mCameraCallback = cameraCallback
mVideoCapture?.stopRecording()
}
// 释放资源
fun releseAll() {
mVideoCapture?.stopRecording()
mExecutorService.shutdown()
mCameraProvider?.unbindAll()
mCameraProvider?.shutdown()
mCameraProvider = null
}
}
对与封装之后的工具类来说，使用起来就更简单了：
override fun initCamera(context: Context): View {
mPreviewView = PreviewView(context)
mContext = context
mPreviewView.layoutParams = ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)
mPreviewView.viewTreeObserver.addOnGlobalLayoutListener(object : OnGlobalLayoutListener {
override fun onGlobalLayout() {
if (mPreviewView.isShown) {
startCamera()
}
mPreviewView.viewTreeObserver.removeOnGlobalLayoutListener(this)
}
})
return mPreviewView
}
private fun startCamera() {
cameraXController.setUpCamera(mContext, mPreviewView.surfaceProvider)
}
如果想开启视频录制：
override fun startCameraRecord() {
cameraXController.startCameraRecord(outFile)
}
同时 CameraX 自身就自带裁剪功能，也不需要我们自定义 TextureView 实现了。
居中显示与居中裁剪的效果如下：
太好了，使用起来真的是超级简单，爱了爱了。
总结
本文对于常见的三种 Camera API 做了示例代码及其对于分别进行封装。对于使用哪一种 Camera 实现效果，大家可以自行选择。
如果我想要回调 NV21 的数据，其实我会选择 Camera1 ,因为它本身返回就是这个格式不需要转换，如果我想要回调 I420 格式，我会选择 Camera2 或 CameraX ，反正需要转换，他们更方便，特别是配合 libyuv 库，效率会更高。
如果想实现录制视频的功能呢？如果是普通的录制我会选择 CameraX 自带的录制视频功能，更加的简单方便。如果是特效的录制，那么我会选择 Camera2 或 CameraX 配合 GLSurfaceView 实现。
我个人比较喜欢 CameraX ，因为我们不是专业做相机的，对于一些简单的预览与录制的需求来说，CameraX 封装的蛮好用的，使用还简单，兼容性还很高，用起来成本也小。（个人观点，比较主观）
投稿作者：Newki，原文链接：https://juejin.cn/post/7252597901762625596
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