Android CameraX-獲取相機信息（視角，預覽圖像尺寸）

Question

我正在嘗試從舊的Android相機API切換到新的CameraX API。 我正在為增強現實應用程序使用預覽模式，我需要在預覽所使用的相機上獲取一些信息，例如視角和尺寸。

到目前為止，這是我的代碼：

PreviewConfig config = new PreviewConfig.Builder()
                .setLensFacing(CameraX.LensFacing.BACK)
                .setTargetResolution(new Size(dsiWidth, dsiHeight))
                .build();
Preview preview = new Preview(config);
preview.setOnPreviewOutputUpdateListener(new Preview.OnPreviewOutputUpdateListener() {
            @Override
            public void onUpdated(Preview.PreviewOutput output) {
                tvCameraView.setSurfaceTexture(output.getSurfaceTexture());
            }
        });
CameraX.bindToLifecycle(this, preview);

到目前為止，該方法有效。 但是，如何獲得有關預覽所用相機的信息？ 在此先多謝！

Answer 1

使用"androidx.camera:camera-camera2:1.0.0-alpha02"依賴項時，可以查看Camera2CameraFactory類。 在那里您可以看到如何確定前后攝像頭。

    @Override
    public Set<String> getAvailableCameraIds() throws CameraInfoUnavailableException {
        List<String> camerasList = null;
        try {
            camerasList = Arrays.asList(mCameraManager.getCameraIdList());
        } catch (CameraAccessException e) {
            throw new CameraInfoUnavailableException(
                    "Unable to retrieve list of cameras on device.", e);
        }
        // Use a LinkedHashSet to preserve order
        return new LinkedHashSet<>(camerasList);
    }

    @Nullable
    @Override
    public String cameraIdForLensFacing(LensFacing lensFacing)
            throws CameraInfoUnavailableException {
        Set<String> cameraIds = getAvailableCameraIds();

        // Convert to from CameraX enum to Camera2 CameraMetadata
        Integer lensFacingInteger = -1;
        switch (lensFacing) {
            case BACK:
                lensFacingInteger = CameraMetadata.LENS_FACING_BACK;
                break;
            case FRONT:
                lensFacingInteger = CameraMetadata.LENS_FACING_FRONT;
                break;
        }

        for (String cameraId : cameraIds) {
            CameraCharacteristics characteristics = null;
            try {
                characteristics = mCameraManager.getCameraCharacteristics(cameraId);
            } catch (CameraAccessException e) {
                throw new CameraInfoUnavailableException(
                        "Unable to retrieve info for camera with id " + cameraId + ".", e);
            }
            Integer cameraLensFacing = characteristics.get(CameraCharacteristics.LENS_FACING);
            if (cameraLensFacing == null) {
                continue;
            }
            if (cameraLensFacing.equals(lensFacingInteger)) {
                return cameraId;
            }
        }

        return null;
    }

歸結為從攝像頭服務中選擇與方向匹配的第一個攝像頭。 我假設他們將在未來的camerax版本中擴展這些api。