在Camera2上的捕获会话期间启用预览

Question

我正在构建一个基于Camera2的相机应用程序，但我保存的图片与我在surface View上看到的最新一张不匹配。预览会话似乎可以工作，但当我请求捕获时，新请求停止预览并捕获图像。surface view冻结在最新的pic上，并且在我按下快门按钮（预览运行和请求捕获）和捕获请求的onCaptureCompleted之间创建了一个间隙。

这是预览会话

private void createCameraPreviewSession() {

    try {

        SurfaceTexture texture = mTextureView.getSurfaceTexture();
        assert texture != null;

        texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());

        Log.d(TAG, "here is the width of texture" + mPreviewSize.getWidth());
        Log.d(TAG, "here is the height of texture" +mPreviewSize.getHeight());

        Surface surface = new Surface(texture);

        mPreviewRequestBuilder
                = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        mPreviewRequestBuilder.addTarget(surface);

        mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
                new CameraCaptureSession.StateCallback() {

                    @Override
                    public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
                        if (null == mCameraDevice) {
                            return;
                        }

                        mCaptureSession = cameraCaptureSession;
                        try {
                            mPreviewRequest = mPreviewRequestBuilder.build();
                            mCaptureSession.setRepeatingRequest(mPreviewRequest,
                                    mCaptureCallback, mBackgroundHandler);
                        } catch (CameraAccessException e) {
                            e.printStackTrace();
                        }
                    }

                    @Override
                    public void onConfigureFailed(
                            @NonNull CameraCaptureSession cameraCaptureSession) {
                        showToast("Failed");
                    }
                }, null
        );
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

    private void process(CaptureResult result) {
        switch (mState) {
            case STATE_PREVIEW:
                break;

            case STATE_CAPTURE:
                mState = STATE_PREVIEW;
                capturePicture();
                break;
        }
    }

    @Override
    public void onCaptureProgressed(@NonNull CameraCaptureSession session,
                                    @NonNull CaptureRequest request,
                                    @NonNull CaptureResult partialResult) {

        process(partialResult);
    }


    @Override
    public void onCaptureCompleted(@NonNull CameraCaptureSession session,
                                   @NonNull CaptureRequest request,
                                   @NonNull TotalCaptureResult result) {
        TotalCaptureResult iResult = result;
        Log.d(TAG, "Frame on Completed: "+result.getFrameNumber());
        process(result);
    }
}

现在的情况是，我重复预览，它起作用了。这个进程只是用来保持它的运行，在mState设置为capture之前什么都没有发生。

它被设置为当我们点击快门按钮时捕捉。当我点击按钮时，我调用：

private void takePicture(){
        try {
            mFile = ImageSaver.generateNewFileImage();
            mState = STATE_CAPTURE;
            mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
                    mBackgroundHandler);
        } catch (CameraAccessException e) {
            Log.e(TAG,"Camera exception",e);
        }
    }

然后调用CapturePicture,因为mState在mCaptureCallback中定义的捕获中

private void capturePicture() {
    mTakePictureRunnable = new Runnable() {
        @Override
        public void run() {
            takePictureNow();
        }
    };
    mBackgroundHandler.post(mTakePictureRunnable);
}

private void takePictureNow() {

    Log.d(TAG, "Running captureStillPicture");

    try {
        if (null == mCameraDevice) {
            return;
        }
        // This is the CaptureRequest.Builder that we use to take a picture.
        final CaptureRequest.Builder captureBuilder =
                mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);

        captureBuilder.addTarget(mImageReader.getSurface());

        SurfaceTexture texture = mTextureView.getSurfaceTexture();
        assert texture != null;

        texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());

        Log.d(TAG, "here is the width of texture" + mPreviewSize.getWidth());
        Log.d(TAG, "here is the height of texture" + mPreviewSize.getHeight());

        Surface surface = new Surface(texture);
        captureBuilder.addTarget(surface);


        // Orientation
        int rotation = getWindowManager().getDefaultDisplay().getRotation();
        captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));

        //Location if needed
        boolean Location_Saved = CameraSettings.Instance().getBoolean(CameraSettings.SAVE_LOCATION,
                getResources().getBoolean(R.bool.action_camera_settings_dflt_location));

        if(Location_Saved == true) {
            captureBuilder.set(CaptureRequest.JPEG_GPS_LOCATION, mLocationManager.getCurrentLocation());
        } else {
            captureBuilder.set(CaptureRequest.JPEG_GPS_LOCATION, null);
        }


        CameraCaptureSession.CaptureCallback CaptureCallback
                = new CameraCaptureSession.CaptureCallback() {

            @Override
            public void onCaptureStarted(@NonNull CameraCaptureSession session,
                                         @NonNull CaptureRequest request,
                                         @NonNull long timestamp,
                                         @NonNull long framenumber) {
                playShutterSound();
                showShutterAnimation();

            }

            @Override
            public void onCaptureCompleted(@NonNull CameraCaptureSession session,
                                           @NonNull CaptureRequest request,
                                           @NonNull TotalCaptureResult result) {
                Log.d(TAG, mFile.toString());
                mState = STATE_PREVIEW;
            }
        };

        mCaptureSession.capture(captureBuilder.build(), CaptureCallback, null);
        mCaptureSession.stopRepeating();

    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

似乎捕获没有更新表面和表面只显示时，我们在预览

想看看我存了什么吗？谢谢

Answer 1

当你拍摄一张图像时，表面会冻结，这张图像可能不是被保存的图像。如果你还想在屏幕上显示相机预览，你只需要通过调用你在第一时间用来创建预览的函数来重新启动相机预览。