DataTransformer.h

/* Copyright (c) 2016 Baidu, Inc. All Rights Reserve.

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. */

#include <iostream>
#include <fstream>
#include <opencv2/opencv.hpp>
#include <vector>
#include <string>
#include <algorithm>

#include "paddle/utils/Thread.h"

using namespace cv;
using namespace paddle;

/**
 * This is an image processing module with OpenCV, such as
 * resizing, scaling, mirroring, substracting the image mean...
 *
 * This class has a double BlockQueue and they shared the same memory.
 * It is used to avoid create memory each time. And it also can
 * return the data even if the data are processing in multi-threads.
 */
class DataTransformer {
public:
  DataTransformer(int threadNum,
                  int capacity,
                  bool isTest,
                  bool isColor,
                  int cropHeight,
                  int cropWidth,
                  int imgSize,
                  bool isEltMean,
                  bool isChannelMean,
                  float* meanValues);
  virtual ~DataTransformer() {
    if (meanValues_) {
      free(meanValues_);
    }
  }

  /**
   * @brief Start multi-threads to transform a list of input data.
   * The processed data will be saved in Queue of prefetchFull_.
   *
   * @param data   Data containing the image string to be transformed.
   * @param label  The label of input image.
   */
  void start(vector<char*>& data, int* datalen, int* labels);

  /**
   * @brief Applies the transformation on one image Mat.
   *
   * @param img    The input img to be transformed.
   * @param target target is used to save the transformed data.
   */
  void transform(Mat& img, float* target);

  /**
   * @brief Decode the image string, then calls transform() function.
   *
   * @param src  The input image string.
   * @param size The length of string.
   * @param trg  trg is used to save the transformed data.
   */
  void startFetching(const char* src, const int size, float* trg);

  /**
   * @brief Return the transformed data and its label.
   */
  void obtain(float* data, int* label);

private:
  int isTest_;
  int isColor_;
  int cropHeight_;
  int cropWidth_;
  int imgSize_;
  int capacity_;
  int fetchCount_;
  bool isEltMean_;
  bool isChannelMean_;
  int numThreads_;
  float scale_;
  int imgPixels_;
  float* meanValues_;

  /**
   * Initialize the mean values.
   */
  void loadMean(float* values);

  /**
   * @brief Generates a random integer from Uniform({min, min + 1, ..., max}).
   * @param min The lower bound (inclusive) value of the random number.
   * @param max The upper bound (inclusive) value of the random number.
   *
   * @return
   * A uniformly random integer value from ({min, min + 1, ..., max}).
   */
  int Rand(int min, int max);

  typedef std::pair<float*, int> DataType;
  typedef std::shared_ptr<DataType> DataTypePtr;
  std::vector<DataTypePtr> prefetch_;
  std::unique_ptr<SyncThreadPool> syncThreadPool_;
  BlockingQueue<DataTypePtr> prefetchFree_;
  BlockingQueue<DataTypePtr> prefetchFull_;

};  // class DataTransformer