--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/textord/colpartition.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,923 @@
+///////////////////////////////////////////////////////////////////////
+// File:        colpartition.h
+// Description: Class to hold partitions of the page that correspond
+//              roughly to text lines.
+// Author:      Ray Smith
+//
+// (C) Copyright 2008, 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.
+//
+///////////////////////////////////////////////////////////////////////
+
+#ifndef TESSERACT_TEXTORD_COLPARTITION_H_
+#define TESSERACT_TEXTORD_COLPARTITION_H_
+
+#include "bbgrid.h"
+#include "blobbox.h" // For BlobRegionType.
+#include "ocrblock.h"
+#include "rect.h" // For TBOX.
+#include "scrollview.h"
+#include "tabfind.h"   // For WidthCallback.
+#include "tabvector.h" // For BLOBNBOX_CLIST.
+
+#include <algorithm>
+
+namespace tesseract {
+
+// Number of colors in the color1, color2 arrays.
+const int kRGBRMSColors = 4;
+
+class ColPartition;
+class ColPartitionSet;
+class ColPartitionGrid;
+class WorkingPartSet;
+class WorkingPartSet_LIST;
+
+// An enum to indicate how a partition sits on the columns.
+// The order of flowing/heading/pullout must be kept consistent with
+// PolyBlockType.
+enum ColumnSpanningType {
+  CST_NOISE,   // Strictly between columns.
+  CST_FLOWING, // Strictly within a single column.
+  CST_HEADING, // Spans multiple columns.
+  CST_PULLOUT, // Touches multiple columns, but doesn't span them.
+  CST_COUNT    // Number of entries.
+};
+
+ELIST2IZEH(ColPartition)
+CLISTIZEH(ColPartition)
+
+/**
+ * ColPartition is a partition of a horizontal slice of the page.
+ * It starts out as a collection of blobs at a particular y-coord in the grid,
+ * but ends up (after merging and uniquing) as an approximate text line.
+ * ColPartitions are also used to hold a partitioning of the page into
+ * columns, each representing one column. Although a ColPartition applies
+ * to a given y-coordinate range, eventually, a ColPartitionSet of ColPartitions
+ * emerges, which represents the columns over a wide y-coordinate range.
+ */
+class TESS_API ColPartition : public ELIST2_LINK {
+public:
+  // This empty constructor is here only so that the class can be ELISTIZED.
+  // TODO(rays) change deep_copy in elst.h line 955 to take a callback copier
+  // and eliminate CLASSNAME##_copier.
+  ColPartition() = default;
+
+  /**
+   * @param blob_type is the blob_region_type_ of the blobs in this partition.
+   * @param vertical is the direction of logical vertical on the possibly skewed
+   * image.
+   */
+  ColPartition(BlobRegionType blob_type, const ICOORD &vertical);
+  /**
+   * Constructs a fake ColPartition with no BLOBNBOXes to represent a
+   * horizontal or vertical line, given a type and a bounding box.
+   */
+  static ColPartition *MakeLinePartition(BlobRegionType blob_type,
+                                         const ICOORD &vertical, int left,
+                                         int bottom, int right, int top);
+
+  // Constructs and returns a fake ColPartition with a single fake BLOBNBOX,
+  // all made from a single TBOX.
+  // WARNING: Despite being on C_LISTs, the BLOBNBOX owns the C_BLOB and
+  // the ColPartition owns the BLOBNBOX!!!
+  // Call DeleteBoxes before deleting the ColPartition.
+  static ColPartition *FakePartition(const TBOX &box, PolyBlockType block_type,
+                                     BlobRegionType blob_type,
+                                     BlobTextFlowType flow);
+
+  // Constructs and returns a ColPartition with the given real BLOBNBOX,
+  // and sets it up to be a "big" partition (single-blob partition bigger
+  // than the surrounding text that may be a dropcap, two or more vertically
+  // touching characters, or some graphic element.
+  // If the given list is not nullptr, the partition is also added to the list.
+  static ColPartition *MakeBigPartition(BLOBNBOX *box,
+                                        ColPartition_LIST *big_part_list);
+
+  ~ColPartition();
+
+  // Simple accessors.
+  const TBOX &bounding_box() const {
+    return bounding_box_;
+  }
+  int left_margin() const {
+    return left_margin_;
+  }
+  void set_left_margin(int margin) {
+    left_margin_ = margin;
+  }
+  int right_margin() const {
+    return right_margin_;
+  }
+  void set_right_margin(int margin) {
+    right_margin_ = margin;
+  }
+  int median_top() const {
+    return median_top_;
+  }
+  int median_bottom() const {
+    return median_bottom_;
+  }
+  int median_left() const {
+    return median_left_;
+  }
+  int median_right() const {
+    return median_right_;
+  }
+  int median_height() const {
+    return median_height_;
+  }
+  void set_median_height(int height) {
+    median_height_ = height;
+  }
+  int median_width() const {
+    return median_width_;
+  }
+  void set_median_width(int width) {
+    median_width_ = width;
+  }
+  BlobRegionType blob_type() const {
+    return blob_type_;
+  }
+  void set_blob_type(BlobRegionType t) {
+    blob_type_ = t;
+  }
+  BlobTextFlowType flow() const {
+    return flow_;
+  }
+  void set_flow(BlobTextFlowType f) {
+    flow_ = f;
+  }
+  int good_blob_score() const {
+    return good_blob_score_;
+  }
+  bool good_width() const {
+    return good_width_;
+  }
+  bool good_column() const {
+    return good_column_;
+  }
+  bool left_key_tab() const {
+    return left_key_tab_;
+  }
+  int left_key() const {
+    return left_key_;
+  }
+  bool right_key_tab() const {
+    return right_key_tab_;
+  }
+  int right_key() const {
+    return right_key_;
+  }
+  PolyBlockType type() const {
+    return type_;
+  }
+  void set_type(PolyBlockType t) {
+    type_ = t;
+  }
+  BLOBNBOX_CLIST *boxes() {
+    return &boxes_;
+  }
+  int boxes_count() const {
+    return boxes_.length();
+  }
+  void set_vertical(const ICOORD &v) {
+    vertical_ = v;
+  }
+  ColPartition_CLIST *upper_partners() {
+    return &upper_partners_;
+  }
+  ColPartition_CLIST *lower_partners() {
+    return &lower_partners_;
+  }
+  void set_working_set(WorkingPartSet *working_set) {
+    working_set_ = working_set;
+  }
+  bool block_owned() const {
+    return block_owned_;
+  }
+  void set_block_owned(bool owned) {
+    block_owned_ = owned;
+  }
+  bool desperately_merged() const {
+    return desperately_merged_;
+  }
+  ColPartitionSet *column_set() const {
+    return column_set_;
+  }
+  void set_side_step(int step) {
+    side_step_ = step;
+  }
+  int bottom_spacing() const {
+    return bottom_spacing_;
+  }
+  void set_bottom_spacing(int spacing) {
+    bottom_spacing_ = spacing;
+  }
+  int top_spacing() const {
+    return top_spacing_;
+  }
+  void set_top_spacing(int spacing) {
+    top_spacing_ = spacing;
+  }
+
+  void set_table_type() {
+    if (type_ != PT_TABLE) {
+      type_before_table_ = type_;
+      type_ = PT_TABLE;
+    }
+  }
+  void clear_table_type() {
+    if (type_ == PT_TABLE) {
+      type_ = type_before_table_;
+    }
+  }
+  bool inside_table_column() {
+    return inside_table_column_;
+  }
+  void set_inside_table_column(bool val) {
+    inside_table_column_ = val;
+  }
+  ColPartition *nearest_neighbor_above() const {
+    return nearest_neighbor_above_;
+  }
+  void set_nearest_neighbor_above(ColPartition *part) {
+    nearest_neighbor_above_ = part;
+  }
+  ColPartition *nearest_neighbor_below() const {
+    return nearest_neighbor_below_;
+  }
+  void set_nearest_neighbor_below(ColPartition *part) {
+    nearest_neighbor_below_ = part;
+  }
+  int space_above() const {
+    return space_above_;
+  }
+  void set_space_above(int space) {
+    space_above_ = space;
+  }
+  int space_below() const {
+    return space_below_;
+  }
+  void set_space_below(int space) {
+    space_below_ = space;
+  }
+  int space_to_left() const {
+    return space_to_left_;
+  }
+  void set_space_to_left(int space) {
+    space_to_left_ = space;
+  }
+  int space_to_right() const {
+    return space_to_right_;
+  }
+  void set_space_to_right(int space) {
+    space_to_right_ = space;
+  }
+  uint8_t *color1() {
+    return color1_;
+  }
+  uint8_t *color2() {
+    return color2_;
+  }
+  bool owns_blobs() const {
+    return owns_blobs_;
+  }
+  void set_owns_blobs(bool owns_blobs) {
+    // Do NOT change ownership flag when there are blobs in the list.
+    // Immediately set the ownership flag when creating copies.
+    ASSERT_HOST(boxes_.empty());
+    owns_blobs_ = owns_blobs;
+  }
+
+  // Inline quasi-accessors that require some computation.
+
+  // Returns the middle y-coord of the bounding box.
+  int MidY() const {
+    return (bounding_box_.top() + bounding_box_.bottom()) / 2;
+  }
+  // Returns the middle y-coord of the median top and bottom.
+  int MedianY() const {
+    return (median_top_ + median_bottom_) / 2;
+  }
+  // Returns the middle x-coord of the bounding box.
+  int MidX() const {
+    return (bounding_box_.left() + bounding_box_.right()) / 2;
+  }
+  // Returns the sort key at any given x,y.
+  int SortKey(int x, int y) const {
+    return TabVector::SortKey(vertical_, x, y);
+  }
+  // Returns the x corresponding to the sortkey, y pair.
+  int XAtY(int sort_key, int y) const {
+    return TabVector::XAtY(vertical_, sort_key, y);
+  }
+  // Returns the x difference between the two sort keys.
+  int KeyWidth(int left_key, int right_key) const {
+    return (right_key - left_key) / vertical_.y();
+  }
+  // Returns the column width between the left and right keys.
+  int ColumnWidth() const {
+    return KeyWidth(left_key_, right_key_);
+  }
+  // Returns the sort key of the box left edge.
+  int BoxLeftKey() const {
+    return SortKey(bounding_box_.left(), MidY());
+  }
+  // Returns the sort key of the box right edge.
+  int BoxRightKey() const {
+    return SortKey(bounding_box_.right(), MidY());
+  }
+  // Returns the left edge at the given y, using the sort key.
+  int LeftAtY(int y) const {
+    return XAtY(left_key_, y);
+  }
+  // Returns the right edge at the given y, using the sort key.
+  int RightAtY(int y) const {
+    return XAtY(right_key_, y);
+  }
+  // Returns true if the right edge of this is to the left of the right
+  // edge of other.
+  bool IsLeftOf(const ColPartition &other) const {
+    return bounding_box_.right() < other.bounding_box_.right();
+  }
+  // Returns true if the partition contains the given x coordinate at the y.
+  bool ColumnContains(int x, int y) const {
+    return LeftAtY(y) - 1 <= x && x <= RightAtY(y) + 1;
+  }
+  // Returns true if there are no blobs in the list.
+  bool IsEmpty() const {
+    return boxes_.empty();
+  }
+  // Returns true if there is a single blob in the list.
+  bool IsSingleton() const {
+    return boxes_.singleton();
+  }
+  // Returns true if this and other overlap horizontally by bounding box.
+  bool HOverlaps(const ColPartition &other) const {
+    return bounding_box_.x_overlap(other.bounding_box_);
+  }
+  // Returns true if this and other's bounding boxes overlap vertically.
+  // TODO(rays) Make HOverlaps and VOverlaps truly symmetric.
+  bool VOverlaps(const ColPartition &other) const {
+    return bounding_box_.y_gap(other.bounding_box_) < 0;
+  }
+  // Returns the vertical overlap (by median) of this and other.
+  // WARNING! Only makes sense on horizontal partitions!
+  int VCoreOverlap(const ColPartition &other) const {
+    if (median_bottom_ == INT32_MAX || other.median_bottom_ == INT32_MAX) {
+      return 0;
+    }
+    return std::min(median_top_, other.median_top_) -
+           std::max(median_bottom_, other.median_bottom_);
+  }
+  // Returns the horizontal overlap (by median) of this and other.
+  // WARNING! Only makes sense on vertical partitions!
+  int HCoreOverlap(const ColPartition &other) const {
+    return std::min(median_right_, other.median_right_) -
+           std::max(median_left_, other.median_left_);
+  }
+  // Returns true if this and other overlap significantly vertically.
+  // WARNING! Only makes sense on horizontal partitions!
+  bool VSignificantCoreOverlap(const ColPartition &other) const {
+    if (median_bottom_ == INT32_MAX || other.median_bottom_ == INT32_MAX) {
+      return false;
+    }
+    int overlap = VCoreOverlap(other);
+    int height = std::min(median_top_ - median_bottom_,
+                          other.median_top_ - other.median_bottom_);
+    return overlap * 3 > height;
+  }
+  // Returns true if this and other can be combined without putting a
+  // horizontal step in either left or right edge of the resulting block.
+  bool WithinSameMargins(const ColPartition &other) const {
+    return left_margin_ <= other.bounding_box_.left() &&
+           bounding_box_.left() >= other.left_margin_ &&
+           bounding_box_.right() <= other.right_margin_ &&
+           right_margin_ >= other.bounding_box_.right();
+  }
+  // Returns true if the region types (aligned_text_) match.
+  // Lines never match anything, as they should never be merged or chained.
+  bool TypesMatch(const ColPartition &other) const {
+    return TypesMatch(blob_type_, other.blob_type_);
+  }
+  static bool TypesMatch(BlobRegionType type1, BlobRegionType type2) {
+    return (type1 == type2 || type1 == BRT_UNKNOWN || type2 == BRT_UNKNOWN) &&
+           !BLOBNBOX::IsLineType(type1) && !BLOBNBOX::IsLineType(type2);
+  }
+
+  // Returns true if the types are similar to each other.
+  static bool TypesSimilar(PolyBlockType type1, PolyBlockType type2) {
+    return (type1 == type2 ||
+            (type1 == PT_FLOWING_TEXT && type2 == PT_INLINE_EQUATION) ||
+            (type2 == PT_FLOWING_TEXT && type1 == PT_INLINE_EQUATION));
+  }
+
+  // Returns true if partitions is of horizontal line type
+  bool IsLineType() const {
+    return PTIsLineType(type_);
+  }
+  // Returns true if partitions is of image type
+  bool IsImageType() const {
+    return PTIsImageType(type_);
+  }
+  // Returns true if partitions is of text type
+  bool IsTextType() const {
+    return PTIsTextType(type_);
+  }
+  // Returns true if partitions is of pullout(inter-column) type
+  bool IsPulloutType() const {
+    return PTIsPulloutType(type_);
+  }
+  // Returns true if the partition is of an exclusively vertical type.
+  bool IsVerticalType() const {
+    return blob_type_ == BRT_VERT_TEXT || blob_type_ == BRT_VLINE;
+  }
+  // Returns true if the partition is of a definite horizontal type.
+  bool IsHorizontalType() const {
+    return blob_type_ == BRT_TEXT || blob_type_ == BRT_HLINE;
+  }
+  // Returns true is the partition is of a type that cannot be merged.
+  bool IsUnMergeableType() const {
+    return BLOBNBOX::UnMergeableType(blob_type_) || type_ == PT_NOISE;
+  }
+  // Returns true if this partition is a vertical line
+  // TODO(nbeato): Use PartitionType enum when Ray's code is submitted.
+  bool IsVerticalLine() const {
+    return IsVerticalType() && IsLineType();
+  }
+  // Returns true if this partition is a horizontal line
+  // TODO(nbeato): Use PartitionType enum when Ray's code is submitted.
+  bool IsHorizontalLine() const {
+    return IsHorizontalType() && IsLineType();
+  }
+
+  // Adds the given box to the partition, updating the partition bounds.
+  // The list of boxes in the partition is updated, ensuring that no box is
+  // recorded twice, and the boxes are kept in increasing left position.
+  void AddBox(BLOBNBOX *box);
+
+  // Removes the given box from the partition, updating the bounds.
+  void RemoveBox(BLOBNBOX *box);
+
+  // Returns the tallest box in the partition, as measured perpendicular to the
+  // presumed flow of text.
+  BLOBNBOX *BiggestBox();
+
+  // Returns the bounding box excluding the given box.
+  TBOX BoundsWithoutBox(BLOBNBOX *box);
+
+  // Claims the boxes in the boxes_list by marking them with a this owner
+  // pointer.
+  void ClaimBoxes();
+
+  // nullptr the owner of the blobs in this partition, so they can be deleted
+  // independently of the ColPartition.
+  void DisownBoxes();
+  // nullptr the owner of the blobs in this partition that are owned by this
+  // partition, so they can be deleted independently of the ColPartition.
+  // Any blobs that are not owned by this partition get to keep their owner
+  // without an assert failure.
+  void DisownBoxesNoAssert();
+  // Nulls the owner of the blobs in this partition that are owned by this
+  // partition and not leader blobs, removing them from the boxes_ list, thus
+  // turning this partition back to a leader partition if it contains a leader,
+  // or otherwise leaving it empty. Returns true if any boxes remain.
+  bool ReleaseNonLeaderBoxes();
+
+  // Delete the boxes that this partition owns.
+  void DeleteBoxes();
+
+  // Reflects the partition in the y-axis, assuming that its blobs have
+  // already been done. Corrects only a limited part of the members, since
+  // this function is assumed to be used shortly after initial creation, which
+  // is before a lot of the members are used.
+  void ReflectInYAxis();
+
+  // Returns true if this is a legal partition - meaning that the conditions
+  // left_margin <= bounding_box left
+  // left_key <= bounding box left key
+  // bounding box left <= bounding box right
+  // and likewise for right margin and key
+  // are all met.
+  bool IsLegal();
+
+  // Returns true if the left and right edges are approximately equal.
+  bool MatchingColumns(const ColPartition &other) const;
+
+  // Returns true if the colors match for two text partitions.
+  bool MatchingTextColor(const ColPartition &other) const;
+
+  // Returns true if the sizes match for two text partitions,
+  // taking orientation into account
+  bool MatchingSizes(const ColPartition &other) const;
+
+  // Returns true if there is no tabstop violation in merging this and other.
+  bool ConfirmNoTabViolation(const ColPartition &other) const;
+
+  // Returns true if other has a similar stroke width to this.
+  bool MatchingStrokeWidth(const ColPartition &other,
+                           double fractional_tolerance,
+                           double constant_tolerance) const;
+  // Returns true if candidate is an acceptable diacritic base char merge
+  // with this as the diacritic.
+  bool OKDiacriticMerge(const ColPartition &candidate, bool debug) const;
+
+  // Sets the sort key using either the tab vector, or the bounding box if
+  // the tab vector is nullptr. If the tab_vector lies inside the bounding_box,
+  // use the edge of the box as a key any way.
+  void SetLeftTab(const TabVector *tab_vector);
+  void SetRightTab(const TabVector *tab_vector);
+
+  // Copies the left/right tab from the src partition, but if take_box is
+  // true, copies the box instead and uses that as a key.
+  void CopyLeftTab(const ColPartition &src, bool take_box);
+  void CopyRightTab(const ColPartition &src, bool take_box);
+
+  // Returns the left rule line x coord of the leftmost blob.
+  int LeftBlobRule() const;
+  // Returns the right rule line x coord of the rightmost blob.
+  int RightBlobRule() const;
+
+  // Returns the density value for a particular BlobSpecialTextType.
+  float SpecialBlobsDensity(const BlobSpecialTextType type) const;
+  // Returns the number of blobs for a  particular BlobSpecialTextType.
+  int SpecialBlobsCount(const BlobSpecialTextType type);
+  // Set the density value for a particular BlobSpecialTextType, should ONLY be
+  // used for debugging or testing. In production code, use
+  // ComputeSpecialBlobsDensity instead.
+  void SetSpecialBlobsDensity(const BlobSpecialTextType type,
+                              const float density);
+  // Compute the SpecialTextType density of blobs, where we assume
+  // that the SpecialTextType in the boxes_ has been set.
+  void ComputeSpecialBlobsDensity();
+
+  // Add a partner above if upper, otherwise below.
+  // Add them uniquely and keep the list sorted by box left.
+  // Partnerships are added symmetrically to partner and this.
+  void AddPartner(bool upper, ColPartition *partner);
+  // Removes the partner from this, but does not remove this from partner.
+  // This asymmetric removal is so as not to mess up the iterator that is
+  // working on partner's partner list.
+  void RemovePartner(bool upper, ColPartition *partner);
+  // Returns the partner if the given partner is a singleton, otherwise nullptr.
+  ColPartition *SingletonPartner(bool upper);
+
+  // Merge with the other partition and delete it.
+  void Absorb(ColPartition *other, const WidthCallback &cb);
+
+  // Returns true if the overlap between this and the merged pair of
+  // merge candidates is sufficiently trivial to be allowed.
+  // The merged box can graze the edge of this by the ok_box_overlap
+  // if that exceeds the margin to the median top and bottom.
+  bool OKMergeOverlap(const ColPartition &merge1, const ColPartition &merge2,
+                      int ok_box_overlap, bool debug);
+
+  // Find the blob at which to split this to minimize the overlap with the
+  // given box. Returns the first blob to go in the second partition.
+  BLOBNBOX *OverlapSplitBlob(const TBOX &box);
+
+  // Split this partition keeping the first half in this and returning
+  // the second half.
+  // Splits by putting the split_blob and the blobs that follow
+  // in the second half, and the rest in the first half.
+  ColPartition *SplitAtBlob(BLOBNBOX *split_blob);
+
+  // Splits this partition at the given x coordinate, returning the right
+  // half and keeping the left half in this.
+  ColPartition *SplitAt(int split_x);
+
+  // Recalculates all the coordinate limits of the partition.
+  void ComputeLimits();
+
+  // Returns the number of boxes that overlap the given box.
+  int CountOverlappingBoxes(const TBOX &box);
+
+  // Computes and sets the type_, first_column_, last_column_ and column_set_.
+  // resolution refers to the ppi resolution of the image.
+  void SetPartitionType(int resolution, ColPartitionSet *columns);
+
+  // Returns the PartitionType from the current BlobRegionType and a column
+  // flow spanning type ColumnSpanningType, generated by
+  // ColPartitionSet::SpanningType, that indicates how the partition sits
+  // in the columns.
+  PolyBlockType PartitionType(ColumnSpanningType flow) const;
+
+  // Returns the first and last column touched by this partition.
+  // resolution refers to the ppi resolution of the image.
+  void ColumnRange(int resolution, ColPartitionSet *columns, int *first_col,
+                   int *last_col);
+
+  // Sets the internal flags good_width_ and good_column_.
+  void SetColumnGoodness(const WidthCallback &cb);
+
+  // Determines whether the blobs in this partition mostly represent
+  // a leader (fixed pitch sequence) and sets the member blobs accordingly.
+  // Note that height is assumed to have been tested elsewhere, and that this
+  // function will find most fixed-pitch text as leader without a height filter.
+  // Leader detection is limited to sequences of identical width objects,
+  // such as .... or ----, so patterns, such as .-.-.-.-. will not be found.
+  bool MarkAsLeaderIfMonospaced();
+  // Given the result of TextlineProjection::EvaluateColPartition, (positive for
+  // horizontal text, negative for vertical text, and near zero for non-text),
+  // sets the blob_type_ and flow_ for this partition to indicate whether it
+  // is strongly or weakly vertical or horizontal text, or non-text.
+  void SetRegionAndFlowTypesFromProjectionValue(int value);
+
+  // Sets all blobs with the partition blob type and flow, but never overwrite
+  // leader blobs, as we need to be able to identify them later.
+  void SetBlobTypes();
+
+  // Returns true if a decent baseline can be fitted through the blobs.
+  // Works for both horizontal and vertical text.
+  bool HasGoodBaseline();
+
+  // Adds this ColPartition to a matching WorkingPartSet if one can be found,
+  // otherwise starts a new one in the appropriate column, ending the previous.
+  void AddToWorkingSet(const ICOORD &bleft, const ICOORD &tright,
+                       int resolution, ColPartition_LIST *used_parts,
+                       WorkingPartSet_LIST *working_set);
+
+  // From the given block_parts list, builds one or more BLOCKs and
+  // corresponding TO_BLOCKs, such that the line spacing is uniform in each.
+  // Created blocks are appended to the end of completed_blocks and to_blocks.
+  // The used partitions are put onto used_parts, as they may still be referred
+  // to in the partition grid. bleft, tright and resolution are the bounds
+  // and resolution of the original image.
+  static void LineSpacingBlocks(const ICOORD &bleft, const ICOORD &tright,
+                                int resolution, ColPartition_LIST *block_parts,
+                                ColPartition_LIST *used_parts,
+                                BLOCK_LIST *completed_blocks,
+                                TO_BLOCK_LIST *to_blocks);
+  // Constructs a block from the given list of partitions.
+  // Arguments are as LineSpacingBlocks above.
+  static TO_BLOCK *MakeBlock(const ICOORD &bleft, const ICOORD &tright,
+                             ColPartition_LIST *block_parts,
+                             ColPartition_LIST *used_parts);
+
+  // Constructs a block from the given list of vertical text partitions.
+  // Currently only creates rectangular blocks.
+  static TO_BLOCK *MakeVerticalTextBlock(const ICOORD &bleft,
+                                         const ICOORD &tright,
+                                         ColPartition_LIST *block_parts,
+                                         ColPartition_LIST *used_parts);
+
+  // Makes a TO_ROW matching this and moves all the blobs to it, transferring
+  // ownership to returned TO_ROW.
+  TO_ROW *MakeToRow();
+
+  // Returns a copy of everything except the list of boxes. The resulting
+  // ColPartition is only suitable for keeping in a column candidate list.
+  ColPartition *ShallowCopy() const;
+  // Returns a copy of everything with a shallow copy of the blobs.
+  // The blobs are still owned by their original parent, so they are
+  // treated as read-only.
+  ColPartition *CopyButDontOwnBlobs();
+
+#ifndef GRAPHICS_DISABLED
+  // Provides a color for BBGrid to draw the rectangle.
+  ScrollView::Color BoxColor() const;
+#endif // !GRAPHICS_DISABLED
+
+  // Prints debug information on this.
+  void Print() const;
+  // Prints debug information on the colors.
+  void PrintColors();
+
+  // Sets the types of all partitions in the run to be the max of the types.
+  void SmoothPartnerRun(int working_set_count);
+
+  // Cleans up the partners of the given type so that there is at most
+  // one partner. This makes block creation simpler.
+  // If get_desperate is true, goes to more desperate merge methods
+  // to merge flowing text before breaking partnerships.
+  void RefinePartners(PolyBlockType type, bool get_desperate,
+                      ColPartitionGrid *grid);
+
+  // Returns true if this column partition is in the same column as
+  // part. This function will only work after the SetPartitionType function
+  // has been called on both column partitions. This is useful for
+  // doing a SideSearch when you want things in the same page column.
+  bool IsInSameColumnAs(const ColPartition &part) const;
+
+  // Sort function to sort by bounding box.
+  static int SortByBBox(const void *p1, const void *p2) {
+    const ColPartition *part1 = *static_cast<const ColPartition *const *>(p1);
+    const ColPartition *part2 = *static_cast<const ColPartition *const *>(p2);
+    int mid_y1 = part1->bounding_box_.y_middle();
+    int mid_y2 = part2->bounding_box_.y_middle();
+    if ((part2->bounding_box_.bottom() <= mid_y1 &&
+         mid_y1 <= part2->bounding_box_.top()) ||
+        (part1->bounding_box_.bottom() <= mid_y2 &&
+         mid_y2 <= part1->bounding_box_.top())) {
+      // Sort by increasing x.
+      return part1->bounding_box_.x_middle() - part2->bounding_box_.x_middle();
+    }
+    // Sort by decreasing y.
+    return mid_y2 - mid_y1;
+  }
+
+  // Sets the column bounds. Primarily used in testing.
+  void set_first_column(int column) {
+    first_column_ = column;
+  }
+  void set_last_column(int column) {
+    last_column_ = column;
+  }
+
+private:
+  // Cleans up the partners above if upper is true, else below.
+  // If get_desperate is true, goes to more desperate merge methods
+  // to merge flowing text before breaking partnerships.
+  void RefinePartnersInternal(bool upper, bool get_desperate,
+                              ColPartitionGrid *grid);
+  // Restricts the partners to only desirable types. For text and BRT_HLINE this
+  // means the same type_ , and for image types it means any image type.
+  void RefinePartnersByType(bool upper, ColPartition_CLIST *partners);
+  // Remove transitive partnerships: this<->a, and a<->b and this<->b.
+  // Gets rid of this<->b, leaving a clean chain.
+  // Also if we have this<->a and a<->this, then gets rid of this<->a, as
+  // this has multiple partners.
+  void RefinePartnerShortcuts(bool upper, ColPartition_CLIST *partners);
+  // If multiple text partners can be merged, then do so.
+  // If desperate is true, then an increase in overlap with the merge is
+  // allowed. If the overlap increases, then the desperately_merged_ flag
+  // is set, indicating that the textlines probably need to be regenerated
+  // by aggressive line fitting/splitting, as there are probably vertically
+  // joined blobs that cross textlines.
+  void RefineTextPartnersByMerge(bool upper, bool desperate,
+                                 ColPartition_CLIST *partners,
+                                 ColPartitionGrid *grid);
+  // Keep the partner with the biggest overlap.
+  void RefinePartnersByOverlap(bool upper, ColPartition_CLIST *partners);
+
+  // Return true if bbox belongs better in this than other.
+  bool ThisPartitionBetter(BLOBNBOX *bbox, const ColPartition &other);
+
+  // Smoothes the spacings in the list into groups of equal linespacing.
+  // resolution is the resolution of the original image, used as a basis
+  // for thresholds in change of spacing. page_height is in pixels.
+  static void SmoothSpacings(int resolution, int page_height,
+                             ColPartition_LIST *parts);
+
+  // Returns true if the parts array of pointers to partitions matches the
+  // condition for a spacing blip. See SmoothSpacings for what this means
+  // and how it is used.
+  static bool OKSpacingBlip(int resolution, int median_spacing,
+                            ColPartition **parts, int offset);
+
+  // Returns true if both the top and bottom spacings of this match the given
+  // spacing to within suitable margins dictated by the image resolution.
+  bool SpacingEqual(int spacing, int resolution) const;
+
+  // Returns true if both the top and bottom spacings of this and other
+  // match to within suitable margins dictated by the image resolution.
+  bool SpacingsEqual(const ColPartition &other, int resolution) const;
+
+  // Returns true if the sum spacing of this and other match the given
+  // spacing (or twice the given spacing) to within a suitable margin dictated
+  // by the image resolution.
+  bool SummedSpacingOK(const ColPartition &other, int spacing,
+                       int resolution) const;
+
+  // Returns a suitable spacing margin that can be applied to bottoms of
+  // text lines, based on the resolution and the stored side_step_.
+  int BottomSpacingMargin(int resolution) const;
+
+  // Returns a suitable spacing margin that can be applied to tops of
+  // text lines, based on the resolution and the stored side_step_.
+  int TopSpacingMargin(int resolution) const;
+
+  // Returns true if the median text sizes of this and other agree to within
+  // a reasonable multiplicative factor.
+  bool SizesSimilar(const ColPartition &other) const;
+
+  // Computes and returns in start, end a line segment formed from a
+  // forwards-iterated group of left edges of partitions that satisfy the
+  // condition that the rightmost left margin is to the left of the
+  // leftmost left bounding box edge.
+  // TODO(rays) Not good enough. Needs improving to tightly wrap text in both
+  // directions, and to loosely wrap images.
+  static void LeftEdgeRun(ColPartition_IT *part_it, ICOORD *start, ICOORD *end);
+  // Computes and returns in start, end a line segment formed from a
+  // backwards-iterated group of right edges of partitions that satisfy the
+  // condition that the leftmost right margin is to the right of the
+  // rightmost right bounding box edge.
+  // TODO(rays) Not good enough. Needs improving to tightly wrap text in both
+  // directions, and to loosely wrap images.
+  static void RightEdgeRun(ColPartition_IT *part_it, ICOORD *start,
+                           ICOORD *end);
+
+  // The margins are determined by the position of the nearest vertically
+  // overlapping neighbour to the side. They indicate the maximum extent
+  // that the block/column may be extended without touching something else.
+  // Leftmost coordinate that the region may occupy over the y limits.
+  int left_margin_ = 0;
+  // Rightmost coordinate that the region may occupy over the y limits.
+  int right_margin_ = 0;
+  // Bounding box of all blobs in the partition.
+  TBOX bounding_box_;
+  // Median top and bottom of blobs in this partition.
+  int median_bottom_ = 0;
+  int median_top_ = 0;
+  // Median height of blobs in this partition.
+  int median_height_ = 0;
+  // Median left and right of blobs in this partition.
+  int median_left_ = 0;
+  int median_right_ = 0;
+  // Median width of blobs in this partition.
+  int median_width_ = 0;
+  // blob_region_type_ for the blobs in this partition.
+  BlobRegionType blob_type_ = BRT_UNKNOWN;
+  BlobTextFlowType flow_ = BTFT_NONE; // Quality of text flow.
+  // Total of GoodTextBlob results for all blobs in the partition.
+  int good_blob_score_ = 0;
+  // True if this partition has a common width.
+  bool good_width_ = false;
+  // True if this is a good column candidate.
+  bool good_column_ = false;
+  // True if the left_key_ is from a tab vector.
+  bool left_key_tab_ = false;
+  // True if the right_key_ is from a tab vector.
+  bool right_key_tab_ = false;
+  // Left and right sort keys for the edges of the partition.
+  // If the respective *_key_tab_ is true then this key came from a tab vector.
+  // If not, then the class promises to keep the key equal to the sort key
+  // for the respective edge of the bounding box at the MidY, so that
+  // LeftAtY and RightAtY always returns an x coordinate on the line parallel
+  // to vertical_ through the bounding box edge at MidY.
+  int left_key_ = 0;
+  int right_key_ = 0;
+  // Type of this partition after looking at its relation to the columns.
+  PolyBlockType type_ = PT_UNKNOWN;
+  // The global vertical skew direction.
+  ICOORD vertical_;
+  // All boxes in the partition stored in increasing left edge coordinate.
+  BLOBNBOX_CLIST boxes_;
+  // The partitions above that matched this.
+  ColPartition_CLIST upper_partners_;
+  // The partitions below that matched this.
+  ColPartition_CLIST lower_partners_;
+  // The WorkingPartSet it lives in while blocks are being made.
+  WorkingPartSet *working_set_ = nullptr;
+  // Column_set_ is the column layout applicable to this ColPartition.
+  ColPartitionSet *column_set_ = nullptr;
+  // Flag is true when AddBox is sorting vertically, false otherwise.
+  bool last_add_was_vertical_ = false;
+  // True when the partition's ownership has been taken from the grid and
+  // placed in a working set, or, after that, in the good_parts_ list.
+  bool block_owned_ = false;
+  // Flag to indicate that this partition was subjected to a desperate merge,
+  // and therefore the textlines need rebuilding.
+  bool desperately_merged_ = false;
+  bool owns_blobs_ = true; // Does the partition own its blobs?
+  // The first and last column that this partition applies to.
+  // Flowing partitions (see type_) will have an equal first and last value
+  // of the form 2n + 1, where n is the zero-based index into the partitions
+  // in column_set_. (See ColPartitionSet::GetColumnByIndex).
+  // Heading partitions will have unequal values of the same form.
+  // Pullout partitions will have equal values, but may have even values,
+  // indicating placement between columns.
+  int first_column_ = -1;
+  int last_column_ = -1;
+  // Linespacing data.
+  int side_step_ = 0;      // Median y-shift to next blob on same line.
+  int top_spacing_ = 0;    // Line spacing from median_top_.
+  int bottom_spacing_ = 0; // Line spacing from median_bottom_.
+
+  // Nearest neighbor above with major x-overlap
+  ColPartition *nearest_neighbor_above_ = nullptr;
+  // Nearest neighbor below with major x-overlap
+  ColPartition *nearest_neighbor_below_ = nullptr;
+  int space_above_ = 0;    // Distance from nearest_neighbor_above
+  int space_below_ = 0;    // Distance from nearest_neighbor_below
+  int space_to_left_ = 0;  // Distance from the left edge of the column
+  int space_to_right_ = 0; // Distance from the right edge of the column
+  // Color foreground/background data.
+  uint8_t color1_[kRGBRMSColors];
+  uint8_t color2_[kRGBRMSColors];
+  // The density of special blobs.
+  float special_blobs_densities_[BSTT_COUNT];
+  // Type of this partition before considering it as a table cell. This is
+  // used to revert the type if a partition is first marked as a table cell but
+  // later filtering steps decide it does not belong to a table
+  PolyBlockType type_before_table_ = PT_UNKNOWN;
+  // Check whether the current partition has been assigned to a table column.
+  bool inside_table_column_ = false;
+};
+
+// Typedef it now in case it becomes a class later.
+using ColPartitionGridSearch =
+    GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>;
+
+} // namespace tesseract.
+
+#endif // TESSERACT_TEXTORD_COLPARTITION_H_