pageiterator.cpp

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// File:        pageiterator.cpp
// Description: Iterator for tesseract page structure that avoids using
//              tesseract internal data structures.
// Author:      Ray Smith
//
// (C) Copyright 2010, 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 <allheaders.h>
#include <tesseract/pageiterator.h>
#include "helpers.h"
#include "pageres.h"
#include "tesseractclass.h"
 
#include <algorithm>
 
namespace tesseract {
 
PageIterator::PageIterator(PAGE_RES *page_res, Tesseract *tesseract, int scale,
                           int scaled_yres, int rect_left, int rect_top,
                           int rect_width, int rect_height)
    : page_res_(page_res),
      tesseract_(tesseract),
      word_(nullptr),
      word_length_(0),
      blob_index_(0),
      cblob_it_(nullptr),
      include_upper_dots_(false),
      include_lower_dots_(false),
      scale_(scale),
      scaled_yres_(scaled_yres),
      rect_left_(rect_left),
      rect_top_(rect_top),
      rect_width_(rect_width),
      rect_height_(rect_height) {
  it_ = new PAGE_RES_IT(page_res);
  PageIterator::Begin();
}
 
PageIterator::~PageIterator() {
  delete it_;
  delete cblob_it_;
}
 
PageIterator::PageIterator(const PageIterator &src)
    : page_res_(src.page_res_),
      tesseract_(src.tesseract_),
      word_(nullptr),
      word_length_(src.word_length_),
      blob_index_(src.blob_index_),
      cblob_it_(nullptr),
      include_upper_dots_(src.include_upper_dots_),
      include_lower_dots_(src.include_lower_dots_),
      scale_(src.scale_),
      scaled_yres_(src.scaled_yres_),
      rect_left_(src.rect_left_),
      rect_top_(src.rect_top_),
      rect_width_(src.rect_width_),
      rect_height_(src.rect_height_) {
  it_ = new PAGE_RES_IT(*src.it_);
  BeginWord(src.blob_index_);
}
 
const PageIterator &PageIterator::operator=(const PageIterator &src) {
  page_res_ = src.page_res_;
  tesseract_ = src.tesseract_;
  include_upper_dots_ = src.include_upper_dots_;
  include_lower_dots_ = src.include_lower_dots_;
  scale_ = src.scale_;
  scaled_yres_ = src.scaled_yres_;
  rect_left_ = src.rect_left_;
  rect_top_ = src.rect_top_;
  rect_width_ = src.rect_width_;
  rect_height_ = src.rect_height_;
  delete it_;
  it_ = new PAGE_RES_IT(*src.it_);
  BeginWord(src.blob_index_);
  return *this;
}
 
bool PageIterator::PositionedAtSameWord(const PAGE_RES_IT *other) const {
  return (it_ == nullptr && it_ == other) ||
         ((other != nullptr) && (it_ != nullptr) && (*it_ == *other));
}
 
// ============= Moving around within the page ============.
 
void PageIterator::Begin() {
  it_->restart_page_with_empties();
  BeginWord(0);
}
 
void PageIterator::RestartParagraph() {
  if (it_->block() == nullptr) {
    return; // At end of the document.
  }
  PAGE_RES_IT para(page_res_);
  PAGE_RES_IT next_para(para);
  next_para.forward_paragraph();
  while (next_para.cmp(*it_) <= 0) {
    para = next_para;
    next_para.forward_paragraph();
  }
  *it_ = para;
  BeginWord(0);
}
 
bool PageIterator::IsWithinFirstTextlineOfParagraph() const {
  PageIterator p_start(*this);
  p_start.RestartParagraph();
  return p_start.it_->row() == it_->row();
}
 
void PageIterator::RestartRow() {
  it_->restart_row();
  BeginWord(0);
}
 
bool PageIterator::Next(PageIteratorLevel level) {
  if (it_->block() == nullptr) {
    return false; // Already at the end!
  }
  if (it_->word() == nullptr) {
    level = RIL_BLOCK;
  }
 
  switch (level) {
    case RIL_BLOCK:
      it_->forward_block();
      break;
    case RIL_PARA:
      it_->forward_paragraph();
      break;
    case RIL_TEXTLINE:
      for (it_->forward_with_empties(); it_->row() == it_->prev_row();
           it_->forward_with_empties()) {
        ;
      }
      break;
    case RIL_WORD:
      it_->forward_with_empties();
      break;
    case RIL_SYMBOL:
      if (cblob_it_ != nullptr) {
        cblob_it_->forward();
      }
      ++blob_index_;
      if (blob_index_ >= word_length_) {
        it_->forward_with_empties();
      } else {
        return true;
      }
      break;
  }
  BeginWord(0);
  return it_->block() != nullptr;
}
 
bool PageIterator::IsAtBeginningOf(PageIteratorLevel level) const {
  if (it_->block() == nullptr) {
    return false; // Already at the end!
  }
  if (it_->word() == nullptr) {
    return true; // In an image block.
  }
  switch (level) {
    case RIL_BLOCK:
      return blob_index_ == 0 && it_->block() != it_->prev_block();
    case RIL_PARA:
      return blob_index_ == 0 &&
             (it_->block() != it_->prev_block() ||
              it_->row()->row->para() != it_->prev_row()->row->para());
    case RIL_TEXTLINE:
      return blob_index_ == 0 && it_->row() != it_->prev_row();
    case RIL_WORD:
      return blob_index_ == 0;
    case RIL_SYMBOL:
      return true;
  }
  return false;
}
 
bool PageIterator::IsAtFinalElement(PageIteratorLevel level,
                                    PageIteratorLevel element) const {
  if (Empty(element)) {
    return true; // Already at the end!
  }
  // The result is true if we step forward by element and find we are
  // at the end of the page or at beginning of *all* levels in:
  // [level, element).
  // When there is more than one level difference between element and level,
  // we could for instance move forward one symbol and still be at the first
  // word on a line, so we also have to be at the first symbol in a word.
  PageIterator next(*this);
  next.Next(element);
  if (next.Empty(element)) {
    return true; // Reached the end of the page.
  }
  while (element > level) {
    element = static_cast<PageIteratorLevel>(element - 1);
    if (!next.IsAtBeginningOf(element)) {
      return false;
    }
  }
  return true;
}
 
int PageIterator::Cmp(const PageIterator &other) const {
  int word_cmp = it_->cmp(*other.it_);
  if (word_cmp != 0) {
    return word_cmp;
  }
  if (blob_index_ < other.blob_index_) {
    return -1;
  }
  if (blob_index_ == other.blob_index_) {
    return 0;
  }
  return 1;
}
 
// ============= Accessing data ==============.
// Coordinate system:
// Integer coordinates are at the cracks between the pixels.
// The top-left corner of the top-left pixel in the image is at (0,0).
// The bottom-right corner of the bottom-right pixel in the image is at
// (width, height).
// Every bounding box goes from the top-left of the top-left contained
// pixel to the bottom-right of the bottom-right contained pixel, so
// the bounding box of the single top-left pixel in the image is:
// (0,0)->(1,1).
// If an image rectangle has been set in the API, then returned coordinates
// relate to the original (full) image, rather than the rectangle.
 
bool PageIterator::BoundingBoxInternal(PageIteratorLevel level, int *left,
                                       int *top, int *right,
                                       int *bottom) const {
  if (Empty(level)) {
    return false;
  }
  TBOX box;
  PARA *para = nullptr;
  switch (level) {
    case RIL_BLOCK:
      box = it_->block()->block->restricted_bounding_box(include_upper_dots_,
                                                         include_lower_dots_);
      break;
    case RIL_PARA:
      para = it_->row()->row->para();
      // Fall through.
    case RIL_TEXTLINE:
      box = it_->row()->row->restricted_bounding_box(include_upper_dots_,
                                                     include_lower_dots_);
      break;
    case RIL_WORD:
      box = it_->word()->word->restricted_bounding_box(include_upper_dots_,
                                                       include_lower_dots_);
      break;
    case RIL_SYMBOL:
      if (cblob_it_ == nullptr) {
        box = it_->word()->box_word->BlobBox(blob_index_);
      } else {
        box = cblob_it_->data()->bounding_box();
      }
  }
  if (level == RIL_PARA) {
    PageIterator other = *this;
    other.Begin();
    do {
      if (other.it_->block() &&
          other.it_->block()->block == it_->block()->block &&
          other.it_->row() && other.it_->row()->row &&
          other.it_->row()->row->para() == para) {
        box = box.bounding_union(other.it_->row()->row->bounding_box());
      }
    } while (other.Next(RIL_TEXTLINE));
  }
  if (level != RIL_SYMBOL || cblob_it_ != nullptr) {
    box.rotate(it_->block()->block->re_rotation());
  }
  // Now we have a box in tesseract coordinates relative to the image rectangle,
  // we have to convert the coords to a top-down system.
  const int pix_height = pixGetHeight(tesseract_->pix_binary());
  const int pix_width = pixGetWidth(tesseract_->pix_binary());
  *left = ClipToRange(static_cast<int>(box.left()), 0, pix_width);
  *top = ClipToRange(pix_height - box.top(), 0, pix_height);
  *right = ClipToRange(static_cast<int>(box.right()), *left, pix_width);
  *bottom = ClipToRange(pix_height - box.bottom(), *top, pix_height);
  return true;
}
 
bool PageIterator::BoundingBox(PageIteratorLevel level, int *left, int *top,
                               int *right, int *bottom) const {
  return BoundingBox(level, 0, left, top, right, bottom);
}
 
bool PageIterator::BoundingBox(PageIteratorLevel level, const int padding,
                               int *left, int *top, int *right,
                               int *bottom) const {
  if (!BoundingBoxInternal(level, left, top, right, bottom)) {
    return false;
  }
  // Convert to the coordinate system of the original image.
  *left = ClipToRange(*left / scale_ + rect_left_ - padding, rect_left_,
                      rect_left_ + rect_width_);
  *top = ClipToRange(*top / scale_ + rect_top_ - padding, rect_top_,
                     rect_top_ + rect_height_);
  *right = ClipToRange((*right + scale_ - 1) / scale_ + rect_left_ + padding,
                       *left, rect_left_ + rect_width_);
  *bottom = ClipToRange((*bottom + scale_ - 1) / scale_ + rect_top_ + padding,
                        *top, rect_top_ + rect_height_);
  return true;
}
 
bool PageIterator::Empty(PageIteratorLevel level) const {
  if (it_->block() == nullptr) {
    return true; // Already at the end!
  }
  if (it_->word() == nullptr && level != RIL_BLOCK) {
    return true; // image block
  }
  if (level == RIL_SYMBOL && blob_index_ >= word_length_) {
    return true; // Zero length word, or already at the end of it.
  }
  return false;
}
 
PolyBlockType PageIterator::BlockType() const {
  if (it_->block() == nullptr || it_->block()->block == nullptr) {
    return PT_UNKNOWN; // Already at the end!
  }
  if (it_->block()->block->pdblk.poly_block() == nullptr) {
    return PT_FLOWING_TEXT; // No layout analysis used - assume text.
  }
  return it_->block()->block->pdblk.poly_block()->isA();
}
 
Pta *PageIterator::BlockPolygon() const {
  if (it_->block() == nullptr || it_->block()->block == nullptr) {
    return nullptr; // Already at the end!
  }
  if (it_->block()->block->pdblk.poly_block() == nullptr) {
    return nullptr; // No layout analysis used - no polygon.
  }
  // Copy polygon, so we can unrotate it to image coordinates.
  POLY_BLOCK *internal_poly = it_->block()->block->pdblk.poly_block();
  ICOORDELT_LIST vertices;
  vertices.deep_copy(internal_poly->points(), ICOORDELT::deep_copy);
  POLY_BLOCK poly(&vertices, internal_poly->isA());
  poly.rotate(it_->block()->block->re_rotation());
  ICOORDELT_IT it(poly.points());
  Pta *pta = ptaCreate(it.length());
  int num_pts = 0;
  for (it.mark_cycle_pt(); !it.cycled_list(); it.forward(), ++num_pts) {
    ICOORD *pt = it.data();
    // Convert to top-down coords within the input image.
    int x = static_cast<float>(pt->x()) / scale_ + rect_left_;
    int y = rect_top_ + rect_height_ - static_cast<float>(pt->y()) / scale_;
    x = ClipToRange(x, rect_left_, rect_left_ + rect_width_);
    y = ClipToRange(y, rect_top_, rect_top_ + rect_height_);
    ptaAddPt(pta, x, y);
  }
  return pta;
}
 
Pix *PageIterator::GetBinaryImage(PageIteratorLevel level) const {
  int left, top, right, bottom;
  if (!BoundingBoxInternal(level, &left, &top, &right, &bottom)) {
    return nullptr;
  }
  if (level == RIL_SYMBOL && cblob_it_ != nullptr &&
      cblob_it_->data()->area() != 0) {
    return cblob_it_->data()->render();
  }
  Box *box = boxCreate(left, top, right - left, bottom - top);
  Image pix = pixClipRectangle(tesseract_->pix_binary(), box, nullptr);
  boxDestroy(&box);
  if (level == RIL_BLOCK || level == RIL_PARA) {
    // Clip to the block polygon as well.
    TBOX mask_box;
    Image mask = it_->block()->block->render_mask(&mask_box);
    int mask_x = left - mask_box.left();
    int mask_y = top - (tesseract_->ImageHeight() - mask_box.top());
    // AND the mask and pix, putting the result in pix.
    pixRasterop(pix, std::max(0, -mask_x), std::max(0, -mask_y),
                pixGetWidth(pix), pixGetHeight(pix), PIX_SRC & PIX_DST, mask,
                std::max(0, mask_x), std::max(0, mask_y));
    mask.destroy();
  }
  return pix;
}
 
Pix *PageIterator::GetImage(PageIteratorLevel level, int padding,
                            Pix *original_img, int *left, int *top) const {
  int right, bottom;
  if (!BoundingBox(level, left, top, &right, &bottom)) {
    return nullptr;
  }
  if (original_img == nullptr) {
    return GetBinaryImage(level);
  }
 
  // Expand the box.
  *left = std::max(*left - padding, 0);
  *top = std::max(*top - padding, 0);
  right = std::min(right + padding, rect_width_);
  bottom = std::min(bottom + padding, rect_height_);
  Box *box = boxCreate(*left, *top, right - *left, bottom - *top);
  Image grey_pix = pixClipRectangle(original_img, box, nullptr);
  boxDestroy(&box);
  if (level == RIL_BLOCK || level == RIL_PARA) {
    // Clip to the block polygon as well.
    TBOX mask_box;
    Image mask = it_->block()->block->render_mask(&mask_box);
    // Copy the mask registered correctly into an image the size of grey_pix.
    int mask_x = *left - mask_box.left();
    int mask_y = *top - (pixGetHeight(original_img) - mask_box.top());
    int width = pixGetWidth(grey_pix);
    int height = pixGetHeight(grey_pix);
    Image resized_mask = pixCreate(width, height, 1);
    pixRasterop(resized_mask, std::max(0, -mask_x), std::max(0, -mask_y), width,
                height, PIX_SRC, mask, std::max(0, mask_x),
                std::max(0, mask_y));
    mask.destroy();
    pixDilateBrick(resized_mask, resized_mask, 2 * padding + 1,
                   2 * padding + 1);
    pixInvert(resized_mask, resized_mask);
    pixSetMasked(grey_pix, resized_mask, UINT32_MAX);
    resized_mask.destroy();
  }
  return grey_pix;
}
 
bool PageIterator::Baseline(PageIteratorLevel level, int *x1, int *y1, int *x2,
                            int *y2) const {
  if (it_->word() == nullptr) {
    return false; // Already at the end!
  }
  ROW *row = it_->row()->row;
  WERD *word = it_->word()->word;
  TBOX box = (level == RIL_WORD || level == RIL_SYMBOL) ? word->bounding_box()
                                                        : row->bounding_box();
  int left = box.left();
  ICOORD startpt(left, static_cast<int16_t>(row->base_line(left) + 0.5));
  int right = box.right();
  ICOORD endpt(right, static_cast<int16_t>(row->base_line(right) + 0.5));
  // Rotate to image coordinates and convert to global image coords.
  startpt.rotate(it_->block()->block->re_rotation());
  endpt.rotate(it_->block()->block->re_rotation());
  *x1 = startpt.x() / scale_ + rect_left_;
  *y1 = (rect_height_ - startpt.y()) / scale_ + rect_top_;
  *x2 = endpt.x() / scale_ + rect_left_;
  *y2 = (rect_height_ - endpt.y()) / scale_ + rect_top_;
  return true;
}
 
void PageIterator::RowAttributes(float *row_height, float *descenders,
                                 float *ascenders) const {
  *row_height = it_->row()->row->x_height() + it_->row()->row->ascenders() -
                it_->row()->row->descenders();
  *descenders = it_->row()->row->descenders();
  *ascenders = it_->row()->row->ascenders();
}
 
void PageIterator::Orientation(tesseract::Orientation *orientation,
                               tesseract::WritingDirection *writing_direction,
                               tesseract::TextlineOrder *textline_order,
                               float *deskew_angle) const {
  auto *block_res = it_->block();
  if (block_res == nullptr) {
    // Nothing can be done, so return default values.
    *orientation = ORIENTATION_PAGE_UP;
    *writing_direction = WRITING_DIRECTION_LEFT_TO_RIGHT;
    *textline_order = TEXTLINE_ORDER_TOP_TO_BOTTOM;
    return;
  }
  auto *block = block_res->block;
 
  // Orientation
  FCOORD up_in_image(0.0, 1.0);
  up_in_image.unrotate(block->classify_rotation());
  up_in_image.rotate(block->re_rotation());
 
  if (up_in_image.x() == 0.0F) {
    if (up_in_image.y() > 0.0F) {
      *orientation = ORIENTATION_PAGE_UP;
    } else {
      *orientation = ORIENTATION_PAGE_DOWN;
    }
  } else if (up_in_image.x() > 0.0F) {
    *orientation = ORIENTATION_PAGE_RIGHT;
  } else {
    *orientation = ORIENTATION_PAGE_LEFT;
  }
 
  // Writing direction
  bool is_vertical_text = (block->classify_rotation().x() == 0.0);
  bool right_to_left = block->right_to_left();
  *writing_direction = is_vertical_text
                           ? WRITING_DIRECTION_TOP_TO_BOTTOM
                           : (right_to_left ? WRITING_DIRECTION_RIGHT_TO_LEFT
                                            : WRITING_DIRECTION_LEFT_TO_RIGHT);
 
  // Textline Order
  const bool is_mongolian = false; // TODO(eger): fix me
  *textline_order = is_vertical_text
                        ? (is_mongolian ? TEXTLINE_ORDER_LEFT_TO_RIGHT
                                        : TEXTLINE_ORDER_RIGHT_TO_LEFT)
                        : TEXTLINE_ORDER_TOP_TO_BOTTOM;
 
  // Deskew angle
  FCOORD skew = block->skew(); // true horizontal for textlines
  *deskew_angle = -skew.angle();
}
 
void PageIterator::ParagraphInfo(tesseract::ParagraphJustification *just,
                                 bool *is_list_item, bool *is_crown,
                                 int *first_line_indent) const {
  *just = tesseract::JUSTIFICATION_UNKNOWN;
  if (!it_->row() || !it_->row()->row || !it_->row()->row->para() ||
      !it_->row()->row->para()->model) {
    return;
  }
 
  PARA *para = it_->row()->row->para();
  *is_list_item = para->is_list_item;
  *is_crown = para->is_very_first_or_continuation;
  *first_line_indent = para->model->first_indent() - para->model->body_indent();
  *just = para->model->justification();
}
 
void PageIterator::BeginWord(int offset) {
  WERD_RES *word_res = it_->word();
  if (word_res == nullptr) {
    // This is a non-text block, so there is no word.
    word_length_ = 0;
    blob_index_ = 0;
    word_ = nullptr;
    return;
  }
  if (word_res->best_choice != nullptr) {
    // Recognition has been done, so we are using the box_word, which
    // is already baseline denormalized.
    word_length_ = word_res->best_choice->length();
    if (word_res->box_word != nullptr) {
      if (word_res->box_word->length() != static_cast<unsigned>(word_length_)) {
        tprintf("Corrupted word! best_choice[len=%d] = %s, box_word[len=%d]: ",
                word_length_, word_res->best_choice->unichar_string().c_str(),
                word_res->box_word->length());
        word_res->box_word->bounding_box().print();
      }
      ASSERT_HOST(word_res->box_word->length() ==
                  static_cast<unsigned>(word_length_));
    }
    word_ = nullptr;
    // We will be iterating the box_word.
    delete cblob_it_;
    cblob_it_ = nullptr;
  } else {
    // No recognition yet, so a "symbol" is a cblob.
    word_ = word_res->word;
    ASSERT_HOST(word_->cblob_list() != nullptr);
    word_length_ = word_->cblob_list()->length();
    if (cblob_it_ == nullptr) {
      cblob_it_ = new C_BLOB_IT;
    }
    cblob_it_->set_to_list(word_->cblob_list());
  }
  for (blob_index_ = 0; blob_index_ < offset; ++blob_index_) {
    if (cblob_it_ != nullptr) {
      cblob_it_->forward();
    }
  }
}
 
bool PageIterator::SetWordBlamerBundle(BlamerBundle *blamer_bundle) {
  if (it_->word() != nullptr) {
    it_->word()->blamer_bundle = blamer_bundle;
    return true;
  } else {
    return false;
  }
}
 
} // namespace tesseract.