lstmboxrenderer.cpp

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/**********************************************************************
 * File:        lstmboxrenderer.cpp
 * Description: Renderer for creating box file for LSTM training.
 *              based on the tsv renderer.
 *
 * (C) Copyright 2019, Google Inc.
 ** 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 <tesseract/baseapi.h> // for TessBaseAPI
#include <tesseract/renderer.h>
#include "tesseractclass.h" // for Tesseract
 
namespace tesseract {
 
static void AddBoxToLSTM(int right, int bottom, int top, int image_height, int page_num,
                         std::string &text) {
  text += " " + std::to_string(image_height - bottom);
  text += " " + std::to_string(right + 5);
  text += " " + std::to_string(image_height - top);
  text += " " + std::to_string(page_num);
}
 
char *TessBaseAPI::GetLSTMBoxText(int page_number = 0) {
  if (tesseract_ == nullptr || (page_res_ == nullptr && Recognize(nullptr) < 0)) {
    return nullptr;
  }
 
  std::string lstm_box_str;
  bool first_word = true;
  int left = 0, top = 0, right = 0, bottom = 0;
 
  LTRResultIterator *res_it = GetLTRIterator();
  while (!res_it->Empty(RIL_BLOCK)) {
    if (res_it->Empty(RIL_SYMBOL)) {
      res_it->Next(RIL_SYMBOL);
      continue;
    }
    if (!first_word) {
      if (!(res_it->IsAtBeginningOf(RIL_TEXTLINE))) {
        if (res_it->IsAtBeginningOf(RIL_WORD)) {
          lstm_box_str += "  " + std::to_string(left);
          AddBoxToLSTM(right, bottom, top, image_height_, page_number, lstm_box_str);
          lstm_box_str += "\n"; // end of row for word
        }                       // word
      } else {
        if (res_it->IsAtBeginningOf(RIL_TEXTLINE)) {
          lstm_box_str += "\t " + std::to_string(left);
          AddBoxToLSTM(right, bottom, top, image_height_, page_number, lstm_box_str);
          lstm_box_str += "\n"; // end of row for line
        }                       // line
      }
    } // not first word
    first_word = false;
    // Use bounding box for whole line for everything
    res_it->BoundingBox(RIL_TEXTLINE, &left, &top, &right, &bottom);
    do {
      lstm_box_str += std::unique_ptr<const char[]>(res_it->GetUTF8Text(RIL_SYMBOL)).get();
      res_it->Next(RIL_SYMBOL);
    } while (!res_it->Empty(RIL_BLOCK) && !res_it->IsAtBeginningOf(RIL_SYMBOL));
    lstm_box_str += " " + std::to_string(left);
    AddBoxToLSTM(right, bottom, top, image_height_, page_number, lstm_box_str);
    lstm_box_str += "\n"; // end of row for symbol
  }
  if (!first_word) { // if first_word is true  => empty page
    lstm_box_str += "\t " + std::to_string(left);
    AddBoxToLSTM(right, bottom, top, image_height_, page_number, lstm_box_str);
    lstm_box_str += "\n"; // end of PAGE
  }
  char *ret = new char[lstm_box_str.length() + 1];
  strcpy(ret, lstm_box_str.c_str());
  delete res_it;
  return ret;
}
 
/**********************************************************************
 * LSTMBox Renderer interface implementation
 **********************************************************************/
TessLSTMBoxRenderer::TessLSTMBoxRenderer(const char *outputbase)
    : TessResultRenderer(outputbase, "box") {}
 
bool TessLSTMBoxRenderer::AddImageHandler(TessBaseAPI *api) {
  const std::unique_ptr<const char[]> lstmbox(api->GetLSTMBoxText(imagenum()));
  if (lstmbox == nullptr) {
    return false;
  }
 
  AppendString(lstmbox.get());
 
  return true;
}
 
} // namespace tesseract.