Question

我正在构建基于Camera2的相机应用程序，但我保存的图片与我在表面视图中看到的最新图片不匹配。似乎预览会话有效，但当我要求捕获时，新请求会停止预览并捕获图像。表面视图冻结在最新的图片上，在我按下快门按钮（预览运行和请求捕获）和捕获请求中的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();
    }
}

mCaptureCallback的定义如下：

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

    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);
    }
}

发生的事情是我重复预览并且有效。该过程仅用于使其保持运行，并且在mState设置为CAPTURE之前没有任何反应。

我们点击快门按钮时设置为捕捉。当我点击按钮时，我打电话给：

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mC在Capture中，如mCaptureCallback中所定义

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

定义了takePicutreNow

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();
    }
}

此过程正常，但我在印刷机和图像之间存在滞后，如果我快速移动，我在预览屏幕上看到的最新图片并不完全相同。

似乎捕捉不会更新曲面，而曲面只会在我们进入预览时显示

任何想法，看看我节省了什么？感谢

Answer 1

当您拍摄图像时，表面将冻结，而该图像可能不是保存的图像。如果仍要在屏幕上显示摄像机预览，则只需通过调用第一次用于创建预览的功能来重新启动摄像机预览。

在Camera2上捕获会话期间启用预览

1 个答案: