text: # Copyright The PyTorch Lightning team.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  from typing import Any
  
  from flash.core.data.io.input import DataKeys
  from flash.core.data.io.output_transform import OutputTransform
  from flash.core.utilities.imports import _FASTFACE_AVAILABLE
  
  if _FASTFACE_AVAILABLE:
      import fastface as ff
  
  
  class FaceDetectionOutputTransform(OutputTransform):
      """Generates preds from model output."""
  
      @staticmethod
      def per_batch_transform(batch: Any) -> Any:
          scales = batch["scales"]
          paddings = batch["paddings"]
  
          batch.pop("scales", None)
          batch.pop("paddings", None)
  
          preds = batch[DataKeys.PREDS]
  
          # preds: list of torch.Tensor(N, 5) as x1, y1, x2, y2, score
          preds = [preds[preds[:, 5] == batch_idx, :5] for batch_idx in range(len(preds))]
          preds = ff.utils.preprocess.adjust_results(preds, scales, paddings)
  
          return preds
  