C++ BLOBNBOX::ClearNeighbours方法代码示例

// Computes the noise_density_ by summing the number of elements in a
// neighbourhood of each grid cell.
void StrokeWidth::ComputeNoiseDensity(TO_BLOCK* block, TabFind* line_grid) {
  // Run a preliminary strokewidth neighbour detection on the medium blobs.
  line_grid->InsertBlobList(true, true, false, &block->blobs, false, this);
  BLOBNBOX_IT blob_it(&block->blobs);
  for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
    SetNeighbours(false, blob_it.data());
  }
  // Remove blobs with a good strokewidth neighbour from the grid.
  for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
    BLOBNBOX* blob = blob_it.data();
    if (blob->GoodTextBlob() > 0)
      RemoveBBox(blob);
    blob->ClearNeighbours();
  }
  // Insert the smaller blobs into the grid.
  line_grid->InsertBlobList(true, true, false, &block->small_blobs,
                            false, this);
  line_grid->InsertBlobList(true, true, false, &block->noise_blobs,
                            false, this);
  if (noise_density_ != NULL)
    delete noise_density_;
  IntGrid* cell_counts = CountCellElements();
  noise_density_ = cell_counts->NeighbourhoodSum();
  delete cell_counts;
  // Clear the grid as we don't want the small stuff hanging around in it.
  Clear();
}

// Tests each blob in the list to see if it is certain non-text using 2
// conditions:
// 1. blob overlaps a cell with high value in noise_density_ (previously set
// by ComputeNoiseDensity).
// OR 2. The blob overlaps more than max_blob_overlaps in *this grid. This
// condition is disabled with max_blob_overlaps == -1.
// If it does, the blob is declared non-text, and is used to mark up the
// nontext_mask. Such blobs are fully deleted, and non-noise blobs have their
// neighbours reset, as they may now point to deleted data.
// WARNING: The blobs list blobs may be in the *this grid, but they are
// not removed. If any deleted blobs might be in *this, then this must be
// Clear()ed immediately after MarkAndDeleteNonTextBlobs is called.
// If the win is not NULL, deleted blobs are drawn on it in red, and kept
// blobs are drawn on it in ok_color.
void CCNonTextDetect::MarkAndDeleteNonTextBlobs(BLOBNBOX_LIST* blobs,
        int max_blob_overlaps,
        ScrollView* win,
        ScrollView::Color ok_color,
        Pix* nontext_mask) {
    int imageheight = tright().y() - bleft().x();
    BLOBNBOX_IT blob_it(blobs);
    BLOBNBOX_LIST dead_blobs;
    BLOBNBOX_IT dead_it(&dead_blobs);
    for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
        BLOBNBOX* blob = blob_it.data();
        TBOX box = blob->bounding_box();
        if (!noise_density_->RectMostlyOverThreshold(box, max_noise_count_) &&
                (max_blob_overlaps < 0 ||
                 !BlobOverlapsTooMuch(blob, max_blob_overlaps))) {
            blob->ClearNeighbours();
#ifndef GRAPHICS_DISABLED
            if (win != NULL)
                blob->plot(win, ok_color, ok_color);
#endif  // GRAPHICS_DISABLED
        } else {
            if (noise_density_->AnyZeroInRect(box)) {
                // There is a danger that the bounding box may overlap real text, so
                // we need to render the outline.
                Pix* blob_pix = blob->cblob()->render_outline();
                pixRasterop(nontext_mask, box.left(), imageheight - box.top(),
                            box.width(), box.height(), PIX_SRC | PIX_DST,
                            blob_pix, 0, 0);
                pixDestroy(&blob_pix);
            } else {
                if (box.area() < gridsize() * gridsize()) {
                    // It is a really bad idea to make lots of small components in the
                    // photo mask, so try to join it to a bigger area by expanding the
                    // box in a way that does not touch any zero noise density cell.
                    box = AttemptBoxExpansion(box, *noise_density_, gridsize());
                }
                // All overlapped cells are non-zero, so just mark the rectangle.
                pixRasterop(nontext_mask, box.left(), imageheight - box.top(),
                            box.width(), box.height(), PIX_SET, NULL, 0, 0);
            }
#ifndef GRAPHICS_DISABLED
            if (win != NULL)
                blob->plot(win, ScrollView::RED, ScrollView::RED);
#endif  // GRAPHICS_DISABLED
            // It is safe to delete the cblob now, as it isn't used by the grid
            // or BlobOverlapsTooMuch, and the BLOBNBOXes will go away with the
            // dead_blobs list.
            // TODO(rays) delete the delete when the BLOBNBOX destructor deletes
            // the cblob.
            delete blob->cblob();
            dead_it.add_to_end(blob_it.extract());
        }
    }
}

// Moves blobs that look like they don't sit well on a textline from the
// input blobs list to the output small_blobs list.
// This gets them away from initial textline finding to stop diacritics
// from forming incorrect textlines. (Introduced mainly to fix Thai.)
void TextlineProjection::MoveNonTextlineBlobs(
    BLOBNBOX_LIST* blobs, BLOBNBOX_LIST* small_blobs) const {
  BLOBNBOX_IT it(blobs);
  BLOBNBOX_IT small_it(small_blobs);
  for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
    BLOBNBOX* blob = it.data();
    const TBOX& box = blob->bounding_box();
    bool debug = AlignedBlob::WithinTestRegion(2, box.left(),
                                               box.bottom());
    if (BoxOutOfHTextline(box, NULL, debug) && !blob->UniquelyVertical()) {
      blob->ClearNeighbours();
      small_it.add_to_end(it.extract());
    }
  }
}