捕获图像时锁定预览 camera2

Question

我已经使用 camera2 Api 实现了连拍图像捕捉，它的工作正常，速度为 6 fps..bt 我的问题是当它拍照时它会触发焦点锁定，这就是为什么预览会锁定一小段时间，我想删除它预览锁定，我希望预览始终启用，这是我的静态捕获突发，我正在关注谷歌的 camera2 示例

private void captuteStillImage() {
    try {
        count = 0;
        CaptureRequest.Builder captureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);

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

        CameraCaptureSession.CaptureCallback captureCallback = new CameraCaptureSession.CaptureCallback() {
            @Override
            public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
                super.onCaptureCompleted(session, request, result);
                //unlockFocus();
                count++;
                Log.e("count",count+"");
                runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    tv_count.setText(count+"");

                }
            });

                if (count >= MAX_CAPTURE) {
                   unlockFocus();
                }
                Log.e("Image Capture", "Successfully");
            }
        };

        // mCameraCaptureSession.capture(captureBuilder.build(), captureCallback, null);

        List<CaptureRequest> captureList = new ArrayList<CaptureRequest>();
        captureBuilder.addTarget(mImageReader.getSurface());
        for (int i = 0; i < MAX_CAPTURE; i++) {
            captureList.add(captureBuilder.build());
        }
        //mCameraCaptureSession.stopRepeating();
        mCameraCaptureSession.captureBurst(captureList, captureCallback, null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

Answer 1

我在 camera2basic (https://github.com/googlesamples/android-Camera2Basic) 上对此进行了一些实验，发现如果我在获取图像之后和保存之前调用解锁，我可以更快地恢复预览 - 我还删除了对 unLockFocus 中的原始调用捕获回调。

    /**
     * This a callback object for the {@link ImageReader}. "onImageAvailable" will be called when a
     * still image is ready to be saved.
     */
    private final ImageReader.OnImageAvailableListener mOnImageAvailableListener
            = new ImageReader.OnImageAvailableListener() {

        @Override
        public void onImageAvailable(ImageReader reader) {
            Log.d(TAG,"onImageAvailable");

            //Get the image
            Image cameraImage = reader.acquireNextImage();

            //Now unlock the focus so the UI does not look locked - note that this is a much earlier point than in the
            //original Camera2Basic example from google as the original place was causing the preview to lock during any
            //image manipulation and saving.
            unlockFocus();

            //Save the image file in the background - note check you have permissions granted by user or this will cause an exception.
            mBackgroundHandler.post(new ImageSaver(getActivity().getApplicationContext(), cameraImage, outputPicFile);

        }

    };

但是，Camera2Basic 有很多回调，我发现当您开始测试 Activity 或 Fragment 暂停和恢复的场景时，特别是如果您的应用也有其他异步回调，很容易陷入竞争条件可能会导致意外行为或崩溃。

如果您只是想要一个简单的相机示例，它可以在拍照时更快地返回预览，那么基本的 FotoApparat 示例可能也值得一看：

• https://github.com/Fotoapparat/Fotoapparat