githubmirror/tesseract

src/ccstruct/ocrblock.cpp
515 строк18 KB
Stefan Weil
Prepare support for image width and height larger than 32767
27 окт 2021, 09:45
27 окт 2021, 09:4559fbad0
/**********************************************************************
 * File:        ocrblock.cpp  (Formerly block.c)
 * Description: BLOCK member functions and iterator functions.
 * Author:      Ray Smith
 *
 * (C) Copyright 1991, Hewlett-Packard Ltd.
 ** 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 "ocrblock.h"

#include "stepblob.h"
#include "tprintf.h"

#include <cstdlib>
#include <memory> // std::unique_ptr

namespace tesseract {

/**
 * BLOCK::BLOCK
 *
 * Constructor for a simple rectangular block.
 */
BLOCK::BLOCK(const char *name, ///< filename
             bool prop,        ///< proportional
             int16_t kern,     ///< kerning
             int16_t space,    ///< spacing
             TDimension xmin,  ///< bottom left
             TDimension ymin,
             TDimension xmax,  ///< top right
             TDimension ymax)
    : pdblk(xmin, ymin, xmax, ymax)
    , filename(name)
    , re_rotation_(1.0f, 0.0f)
    , classify_rotation_(1.0f, 0.0f)
    , skew_(1.0f, 0.0f) {
  ICOORDELT_IT left_it = &pdblk.leftside;
  ICOORDELT_IT right_it = &pdblk.rightside;

  proportional = prop;
  kerning = kern;
  spacing = space;
  font_class = -1; // not assigned
  cell_over_xheight_ = 2.0f;
  pdblk.hand_poly = nullptr;
  left_it.set_to_list(&pdblk.leftside);
  right_it.set_to_list(&pdblk.rightside);
  // make default box
  left_it.add_to_end(new ICOORDELT(xmin, ymin));
  left_it.add_to_end(new ICOORDELT(xmin, ymax));
  right_it.add_to_end(new ICOORDELT(xmax, ymin));
  right_it.add_to_end(new ICOORDELT(xmax, ymax));
}

/**
 * decreasing_top_order
 *
 * Sort Comparator: Return <0 if row1 top < row2 top
 */

static int decreasing_top_order(const void *row1, const void *row2) {
  return (*reinterpret_cast<ROW *const *>(row2))->bounding_box().top() -
         (*reinterpret_cast<ROW *const *>(row1))->bounding_box().top();
}

/**
 * BLOCK::rotate
 *
 * Rotate the polygon by the given rotation and recompute the bounding_box.
 */
void BLOCK::rotate(const FCOORD &rotation) {
  pdblk.poly_block()->rotate(rotation);
  pdblk.box = *pdblk.poly_block()->bounding_box();
}

// Returns the bounding box including the desired combination of upper and
// lower noise/diacritic elements.
TBOX BLOCK::restricted_bounding_box(bool upper_dots, bool lower_dots) const {
  TBOX box;
  // This is a read-only iteration of the rows in the block.
  ROW_IT it(const_cast<ROW_LIST *>(&rows));
  for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
    box += it.data()->restricted_bounding_box(upper_dots, lower_dots);
  }
  return box;
}

/**
 * BLOCK::reflect_polygon_in_y_axis
 *
 * Reflects the polygon in the y-axis and recompute the bounding_box.
 * Does nothing to any contained rows/words/blobs etc.
 */
void BLOCK::reflect_polygon_in_y_axis() {
  pdblk.poly_block()->reflect_in_y_axis();
  pdblk.box = *pdblk.poly_block()->bounding_box();
}

/**
 * BLOCK::sort_rows
 *
 * Order rows so that they are in order of decreasing Y coordinate
 */

void BLOCK::sort_rows() { // order on "top"
  ROW_IT row_it(&rows);

  row_it.sort(decreasing_top_order);
}

/**
 * BLOCK::compress
 *
 * Delete space between the rows. (And maybe one day, compress the rows)
 * Fill space of block from top down, left aligning rows.
 */

void BLOCK::compress() { // squash it up
#define ROW_SPACING 5

  ROW_IT row_it(&rows);
  ROW *row;
  ICOORD row_spacing(0, ROW_SPACING);

  ICOORDELT_IT icoordelt_it;

  sort_rows();

  pdblk.box = TBOX(pdblk.box.topleft(), pdblk.box.topleft());
  pdblk.box.move_bottom_edge(ROW_SPACING);
  for (row_it.mark_cycle_pt(); !row_it.cycled_list(); row_it.forward()) {
    row = row_it.data();
    row->move(pdblk.box.botleft() - row_spacing - row->bounding_box().topleft());
    pdblk.box += row->bounding_box();
  }

  pdblk.leftside.clear();
  icoordelt_it.set_to_list(&pdblk.leftside);
  icoordelt_it.add_to_end(new ICOORDELT(pdblk.box.left(), pdblk.box.bottom()));
  icoordelt_it.add_to_end(new ICOORDELT(pdblk.box.left(), pdblk.box.top()));
  pdblk.rightside.clear();
  icoordelt_it.set_to_list(&pdblk.rightside);
  icoordelt_it.add_to_end(new ICOORDELT(pdblk.box.right(), pdblk.box.bottom()));
  icoordelt_it.add_to_end(new ICOORDELT(pdblk.box.right(), pdblk.box.top()));
}

/**
 * BLOCK::check_pitch
 *
 * Check whether the block is fixed or prop, set the flag, and set
 * the pitch if it is fixed.
 */

void BLOCK::check_pitch() { // check prop
  //      tprintf("Missing FFT fixed pitch stuff!\n");
  pitch = -1;
}

/**
 * BLOCK::compress
 *
 * Compress and move in a single operation.
 */

void BLOCK::compress( // squash it up
    const ICOORD vec  // and move
) {
  pdblk.box.move(vec);
  compress();
}

/**
 * BLOCK::print
 *
 * Print the info on a block
 */

void BLOCK::print( // print list of sides
    FILE *,        ///< file to print on
    bool dump      ///< print full detail
) {
  ICOORDELT_IT it = &pdblk.leftside; // iterator

  pdblk.box.print();
  tprintf("Proportional= %s\n", proportional ? "TRUE" : "FALSE");
  tprintf("Kerning= %d\n", kerning);
  tprintf("Spacing= %d\n", spacing);
  tprintf("Fixed_pitch=%d\n", pitch);
  tprintf("Filename= %s\n", filename.c_str());

  if (dump) {
    tprintf("Left side coords are:\n");
    for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
      tprintf("(%d,%d) ", it.data()->x(), it.data()->y());
    }
    tprintf("\n");
    tprintf("Right side coords are:\n");
    it.set_to_list(&pdblk.rightside);
    for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
      tprintf("(%d,%d) ", it.data()->x(), it.data()->y());
    }
    tprintf("\n");
  }
}

/**
 * BLOCK::operator=
 *
 * Assignment - duplicate the block structure, but with an EMPTY row list.
 */

BLOCK &BLOCK::operator=( // assignment
    const BLOCK &source  // from this
) {
  this->ELIST_LINK::operator=(source);
  pdblk = source.pdblk;
  proportional = source.proportional;
  kerning = source.kerning;
  spacing = source.spacing;
  filename = source.filename; // STRINGs assign ok
  if (!rows.empty()) {
    rows.clear();
  }
  re_rotation_ = source.re_rotation_;
  classify_rotation_ = source.classify_rotation_;
  skew_ = source.skew_;
  return *this;
}

// This function is for finding the approximate (horizontal) distance from
// the x-coordinate of the left edge of a symbol to the left edge of the
// text block which contains it.  We are passed:
//   segments - output of PB_LINE_IT::get_line() which contains x-coordinate
//       intervals for the scan line going through the symbol's y-coordinate.
//       Each element of segments is of the form (x()=start_x, y()=length).
//   x - the x coordinate of the symbol we're interested in.
//   margin - return value, the distance from x,y to the left margin of the
//       block containing it.
// If all segments were to the right of x, we return false and 0.
static bool LeftMargin(ICOORDELT_LIST *segments, int x, int *margin) {
  bool found = false;
  *margin = 0;
  if (segments->empty()) {
    return found;
  }
  ICOORDELT_IT seg_it(segments);
  for (seg_it.mark_cycle_pt(); !seg_it.cycled_list(); seg_it.forward()) {
    int cur_margin = x - seg_it.data()->x();
    if (cur_margin >= 0) {
      if (!found) {
        *margin = cur_margin;
      } else if (cur_margin < *margin) {
        *margin = cur_margin;
      }
      found = true;
    }
  }
  return found;
}

// This function is for finding the approximate (horizontal) distance from
// the x-coordinate of the right edge of a symbol to the right edge of the
// text block which contains it.  We are passed:
//   segments - output of PB_LINE_IT::get_line() which contains x-coordinate
//       intervals for the scan line going through the symbol's y-coordinate.
//       Each element of segments is of the form (x()=start_x, y()=length).
//   x - the x coordinate of the symbol we're interested in.
//   margin - return value, the distance from x,y to the right margin of the
//       block containing it.
// If all segments were to the left of x, we return false and 0.
static bool RightMargin(ICOORDELT_LIST *segments, int x, int *margin) {
  bool found = false;
  *margin = 0;
  if (segments->empty()) {
    return found;
  }
  ICOORDELT_IT seg_it(segments);
  for (seg_it.mark_cycle_pt(); !seg_it.cycled_list(); seg_it.forward()) {
    int cur_margin = seg_it.data()->x() + seg_it.data()->y() - x;
    if (cur_margin >= 0) {
      if (!found) {
        *margin = cur_margin;
      } else if (cur_margin < *margin) {
        *margin = cur_margin;
      }
      found = true;
    }
  }
  return found;
}

// Compute the distance from the left and right ends of each row to the
// left and right edges of the block's polyblock.  Illustration:
//  ____________________________   _______________________
//  |  Howdy neighbor!         |  |rectangular blocks look|
//  |  This text is  written to|  |more like stacked pizza|
//  |illustrate how useful poly-  |boxes.                 |
//  |blobs  are   in -----------  ------   The    polyblob|
//  |dealing    with|     _________     |for a BLOCK  rec-|
//  |harder   layout|   /===========\   |ords the possibly|
//  |issues.        |    |  _    _  |   |skewed    pseudo-|
//  |  You  see this|    | |_| \|_| |   |rectangular      |
//  |text is  flowed|    |      }   |   |boundary     that|
//  |around  a  mid-|     \   ____  |   |forms the  ideal-|
//  |cloumn portrait._____ \       /  __|ized  text margin|
//  |  Polyblobs     exist| \    /   |from which we should|
//  |to account for insets|  |   |   |measure    paragraph|
//  |which make  otherwise|  -----   |indentation.        |
//  -----------------------          ----------------------
//
// If we identify a drop-cap, we measure the left margin for the lines
// below the first line relative to one space past the drop cap.  The
// first line's margin and those past the drop cap area are measured
// relative to the enclosing polyblock.
//
// TODO(rays): Before this will work well, we'll need to adjust the
//             polyblob tighter around the text near images, as in:
//             UNLV_AUTO:mag.3G0  page 2
//             UNLV_AUTO:mag.3G4  page 16
void BLOCK::compute_row_margins() {
  if (row_list()->empty() || row_list()->singleton()) {
    return;
  }

  // If Layout analysis was not called, default to this.
  POLY_BLOCK rect_block(pdblk.bounding_box(), PT_FLOWING_TEXT);
  POLY_BLOCK *pblock = &rect_block;
  if (pdblk.poly_block() != nullptr) {
    pblock = pdblk.poly_block();
  }

  // Step One: Determine if there is a drop-cap.
  //           TODO(eger): Fix up drop cap code for RTL languages.
  ROW_IT r_it(row_list());
  ROW *first_row = r_it.data();
  ROW *second_row = r_it.data_relative(1);

  // initialize the bottom of a fictitious drop cap far above the first line.
  int drop_cap_bottom = first_row->bounding_box().top() + first_row->bounding_box().height();
  int drop_cap_right = first_row->bounding_box().left();
  int mid_second_line = second_row->bounding_box().top() - second_row->bounding_box().height() / 2;
  WERD_IT werd_it(r_it.data()->word_list()); // words of line one
  if (!werd_it.empty()) {
    C_BLOB_IT cblob_it(werd_it.data()->cblob_list());
    for (cblob_it.mark_cycle_pt(); !cblob_it.cycled_list(); cblob_it.forward()) {
      TBOX bbox = cblob_it.data()->bounding_box();
      if (bbox.bottom() <= mid_second_line) {
        // we found a real drop cap
        first_row->set_has_drop_cap(true);
        if (drop_cap_bottom > bbox.bottom()) {
          drop_cap_bottom = bbox.bottom();
        }
        if (drop_cap_right < bbox.right()) {
          drop_cap_right = bbox.right();
        }
      }
    }
  }

  // Step Two: Calculate the margin from the text of each row to the block
  //           (or drop-cap) boundaries.
  PB_LINE_IT lines(pblock);
  r_it.set_to_list(row_list());
  for (r_it.mark_cycle_pt(); !r_it.cycled_list(); r_it.forward()) {
    ROW *row = r_it.data();
    TBOX row_box = row->bounding_box();
    int left_y = row->base_line(row_box.left()) + row->x_height();
    int left_margin;
    const std::unique_ptr</*non-const*/ ICOORDELT_LIST> segments_left(lines.get_line(left_y));
    LeftMargin(segments_left.get(), row_box.left(), &left_margin);

    if (row_box.top() >= drop_cap_bottom) {
      int drop_cap_distance = row_box.left() - row->space() - drop_cap_right;
      if (drop_cap_distance < 0) {
        drop_cap_distance = 0;
      }
      if (drop_cap_distance < left_margin) {
        left_margin = drop_cap_distance;
      }
    }

    int right_y = row->base_line(row_box.right()) + row->x_height();
    int right_margin;
    const std::unique_ptr</*non-const*/ ICOORDELT_LIST> segments_right(lines.get_line(right_y));
    RightMargin(segments_right.get(), row_box.right(), &right_margin);
    row->set_lmargin(left_margin);
    row->set_rmargin(right_margin);
  }
}

/**********************************************************************
 * PrintSegmentationStats
 *
 * Prints segmentation stats for the given block list.
 **********************************************************************/

void PrintSegmentationStats(BLOCK_LIST *block_list) {
  int num_blocks = 0;
  int num_rows = 0;
  int num_words = 0;
  int num_blobs = 0;
  BLOCK_IT block_it(block_list);
  for (block_it.mark_cycle_pt(); !block_it.cycled_list(); block_it.forward()) {
    BLOCK *block = block_it.data();
    ++num_blocks;
    ROW_IT row_it(block->row_list());
    for (row_it.mark_cycle_pt(); !row_it.cycled_list(); row_it.forward()) {
      ++num_rows;
      ROW *row = row_it.data();
      // Iterate over all werds in the row.
      WERD_IT werd_it(row->word_list());
      for (werd_it.mark_cycle_pt(); !werd_it.cycled_list(); werd_it.forward()) {
        WERD *werd = werd_it.data();
        ++num_words;
        num_blobs += werd->cblob_list()->length();
      }
    }
  }
  tprintf("Block list stats:\nBlocks = %d\nRows = %d\nWords = %d\nBlobs = %d\n", num_blocks,
          num_rows, num_words, num_blobs);
}

/**********************************************************************
 * ExtractBlobsFromSegmentation
 *
 * Extracts blobs from the given block list and adds them to the output list.
 * The block list must have been created by performing a page segmentation.
 **********************************************************************/

void ExtractBlobsFromSegmentation(BLOCK_LIST *blocks, C_BLOB_LIST *output_blob_list) {
  C_BLOB_IT return_list_it(output_blob_list);
  BLOCK_IT block_it(blocks);
  for (block_it.mark_cycle_pt(); !block_it.cycled_list(); block_it.forward()) {
    BLOCK *block = block_it.data();
    ROW_IT row_it(block->row_list());
    for (row_it.mark_cycle_pt(); !row_it.cycled_list(); row_it.forward()) {
      ROW *row = row_it.data();
      // Iterate over all werds in the row.
      WERD_IT werd_it(row->word_list());
      for (werd_it.mark_cycle_pt(); !werd_it.cycled_list(); werd_it.forward()) {
        WERD *werd = werd_it.data();
        return_list_it.move_to_last();
        return_list_it.add_list_after(werd->cblob_list());
        return_list_it.move_to_last();
        return_list_it.add_list_after(werd->rej_cblob_list());
      }
    }
  }
}

/**********************************************************************
 * RefreshWordBlobsFromNewBlobs()
 *
 * Refreshes the words in the block_list by using blobs in the
 * new_blobs list.
 * Block list must have word segmentation in it.
 * It consumes the blobs provided in the new_blobs list. The blobs leftover in
 * the new_blobs list after the call weren't matched to any blobs of the words
 * in block list.
 * The output not_found_blobs is a list of blobs from the original segmentation
 * in the block_list for which no corresponding new blobs were found.
 **********************************************************************/

void RefreshWordBlobsFromNewBlobs(BLOCK_LIST *block_list, C_BLOB_LIST *new_blobs,
                                  C_BLOB_LIST *not_found_blobs) {
  // Now iterate over all the blobs in the segmentation_block_list_, and just
  // replace the corresponding c-blobs inside the werds.
  BLOCK_IT block_it(block_list);
  for (block_it.mark_cycle_pt(); !block_it.cycled_list(); block_it.forward()) {
    BLOCK *block = block_it.data();
    if (block->pdblk.poly_block() != nullptr && !block->pdblk.poly_block()->IsText()) {
      continue; // Don't touch non-text blocks.
    }
    // Iterate over all rows in the block.
    ROW_IT row_it(block->row_list());
    for (row_it.mark_cycle_pt(); !row_it.cycled_list(); row_it.forward()) {
      ROW *row = row_it.data();
      // Iterate over all werds in the row.
      WERD_IT werd_it(row->word_list());
      WERD_LIST new_words;
      WERD_IT new_words_it(&new_words);
      for (werd_it.mark_cycle_pt(); !werd_it.cycled_list(); werd_it.forward()) {
        WERD *werd = werd_it.extract();
        WERD *new_werd = werd->ConstructWerdWithNewBlobs(new_blobs, not_found_blobs);
        if (new_werd) {
          // Insert this new werd into the actual row's werd-list. Remove the
          // existing one.
          new_words_it.add_after_then_move(new_werd);
          delete werd;
        } else {
          // Reinsert the older word back, for lack of better options.
          // This is critical since dropping the words messes up segmentation:
          // eg. 1st word in the row might otherwise have W_FUZZY_NON turned on.
          new_words_it.add_after_then_move(werd);
        }
      }
      // Get rid of the old word list & replace it with the new one.
      row->word_list()->clear();
      werd_it.move_to_first();
      werd_it.add_list_after(&new_words);
    }
  }
}

} // namespace tesseract