--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/textord/colpartitiongrid.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,244 @@
+///////////////////////////////////////////////////////////////////////
+// File:        colpartitiongrid.h
+// Description: Class collecting code that acts on a BBGrid of ColPartitions.
+// Author:      Ray Smith
+//
+// (C) Copyright 2009, 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_COLPARTITIONGRID_H_
+#define TESSERACT_TEXTORD_COLPARTITIONGRID_H_
+
+#include "bbgrid.h"
+#include "colpartition.h"
+#include "colpartitionset.h"
+
+namespace tesseract {
+
+class TabFind;
+
+// ColPartitionGrid is a BBGrid of ColPartition.
+// It collects functions that work on the grid.
+class TESS_API ColPartitionGrid
+    : public BBGrid<ColPartition, ColPartition_CLIST, ColPartition_C_IT> {
+public:
+  ColPartitionGrid() = default;
+  ColPartitionGrid(int gridsize, const ICOORD &bleft, const ICOORD &tright);
+
+  ~ColPartitionGrid() override = default;
+
+  // Handles a click event in a display window.
+  void HandleClick(int x, int y) override;
+
+  // Merges ColPartitions in the grid that look like they belong in the same
+  // textline.
+  // For all partitions in the grid, calls the box_cb permanent callback
+  // to compute the search box, searches the box, and if a candidate is found,
+  // calls the confirm_cb to check any more rules. If the confirm_cb returns
+  // true, then the partitions are merged.
+  // Both callbacks are deleted before returning.
+  void Merges(const std::function<bool(ColPartition *, TBOX *)> &box_cb,
+              const std::function<bool(const ColPartition *,
+                                       const ColPartition *)> &confirm_cb);
+
+  // For the given partition, calls the box_cb permanent callback
+  // to compute the search box, searches the box, and if a candidate is found,
+  // calls the confirm_cb to check any more rules. If the confirm_cb returns
+  // true, then the partitions are merged.
+  // Returns true if the partition is consumed by one or more merges.
+  bool MergePart(const std::function<bool(ColPartition *, TBOX *)> &box_cb,
+                 const std::function<bool(const ColPartition *,
+                                          const ColPartition *)> &confirm_cb,
+                 ColPartition *part);
+
+  // Computes and returns the total overlap of all partitions in the grid.
+  // If overlap_grid is non-null, it is filled with a grid that holds empty
+  // partitions representing the union of all overlapped partitions.
+  int ComputeTotalOverlap(ColPartitionGrid **overlap_grid);
+
+  // Finds all the ColPartitions in the grid that overlap with the given
+  // box and returns them SortByBoxLeft(ed) and uniqued in the given list.
+  // Any partition equal to not_this (may be nullptr) is excluded.
+  void FindOverlappingPartitions(const TBOX &box, const ColPartition *not_this,
+                                 ColPartition_CLIST *parts);
+
+  // Finds and returns the best candidate ColPartition to merge with part,
+  // selected from the candidates list, based on the minimum increase in
+  // pairwise overlap among all the partitions overlapped by the combined box.
+  // If overlap_increase is not nullptr then it returns the increase in overlap
+  // that would result from the merge.
+  // See colpartitiongrid.cpp for a diagram.
+  ColPartition *BestMergeCandidate(
+      const ColPartition *part, ColPartition_CLIST *candidates, bool debug,
+      const std::function<bool(const ColPartition *, const ColPartition *)>
+          &confirm_cb,
+      int *overlap_increase);
+
+  // Split partitions where it reduces overlap between their bounding boxes.
+  // ColPartitions are after all supposed to be a partitioning of the blobs
+  // AND of the space on the page!
+  // Blobs that cause overlaps get removed, put in individual partitions
+  // and added to the big_parts list. They are most likely characters on
+  // 2 textlines that touch, or something big like a dropcap.
+  void SplitOverlappingPartitions(ColPartition_LIST *big_parts);
+
+  // Filters partitions of source_type by looking at local neighbours.
+  // Where a majority of neighbours have a text type, the partitions are
+  // changed to text, where the neighbours have image type, they are changed
+  // to image, and partitions that have no definite neighbourhood type are
+  // left unchanged.
+  // im_box and rerotation are used to map blob coordinates onto the
+  // nontext_map, which is used to prevent the spread of text neighbourhoods
+  // into images.
+  // Returns true if anything was changed.
+  bool GridSmoothNeighbours(BlobTextFlowType source_type, Image nontext_map,
+                            const TBOX &im_box, const FCOORD &rerotation);
+
+  // Reflects the grid and its colpartitions in the y-axis, assuming that
+  // all blob boxes have already been done.
+  void ReflectInYAxis();
+
+  // Rotates the grid and its colpartitions by the given angle, assuming that
+  // all blob boxes have already been done.
+  void Deskew(const FCOORD &deskew);
+
+  // Transforms the grid of partitions to the output blocks, putting each
+  // partition into a separate block. We don't really care about the order,
+  // as we just want to get as much text as possible without trying to organize
+  // it into proper blocks or columns.
+  void ExtractPartitionsAsBlocks(BLOCK_LIST *blocks, TO_BLOCK_LIST *to_blocks);
+
+  // Sets the left and right tabs of the partitions in the grid.
+  void SetTabStops(TabFind *tabgrid);
+
+  // Makes the ColPartSets and puts them in the PartSetVector ready
+  // for finding column bounds. Returns false if no partitions were found.
+  // Each ColPartition in the grid is placed in a single ColPartSet based
+  // on the bottom-left of its bounding box.
+  bool MakeColPartSets(PartSetVector *part_sets);
+
+  // Makes a single ColPartitionSet consisting of a single ColPartition that
+  // represents the total horizontal extent of the significant content on the
+  // page. Used for the single column setting in place of automatic detection.
+  // Returns nullptr if the page is empty of significant content.
+  ColPartitionSet *MakeSingleColumnSet(WidthCallback cb);
+
+  // Mark the BLOBNBOXes in each partition as being owned by that partition.
+  void ClaimBoxes();
+
+  // Retypes all the blobs referenced by the partitions in the grid.
+  // Image blobs are sliced on the grid boundaries to give the tab finder
+  // a better handle on the edges of the images, and the actual blobs are
+  // returned in the im_blobs list, as they are not owned by the block.
+  void ReTypeBlobs(BLOBNBOX_LIST *im_blobs);
+
+  // The boxes within the partitions have changed (by deskew) so recompute
+  // the bounds of all the partitions and reinsert them into the grid.
+  void RecomputeBounds(int gridsize, const ICOORD &bleft, const ICOORD &tright,
+                       const ICOORD &vertical);
+
+  // Improves the margins of the ColPartitions in the grid by calling
+  // FindPartitionMargins on each.
+  void GridFindMargins(ColPartitionSet **best_columns);
+
+  // Improves the margins of the ColPartitions in the list by calling
+  // FindPartitionMargins on each.
+  void ListFindMargins(ColPartitionSet **best_columns,
+                       ColPartition_LIST *parts);
+
+  // Deletes all the partitions in the grid after disowning all the blobs.
+  void DeleteParts();
+
+  // Deletes all the partitions in the grid that are of type BRT_UNKNOWN and
+  // all the blobs in them.
+  void DeleteUnknownParts(TO_BLOCK *block);
+
+  // Deletes all the partitions in the grid that are NOT of flow type
+  // BTFT_LEADER.
+  void DeleteNonLeaderParts();
+
+  // Finds and marks text partitions that represent figure captions.
+  void FindFigureCaptions();
+
+  //////// Functions that manipulate ColPartitions in the grid     ///////
+  //////// to find chains of partner partitions of the same type.  ///////
+  // For every ColPartition in the grid, finds its upper and lower neighbours.
+  void FindPartitionPartners();
+  // Finds the best partner in the given direction for the given partition.
+  // Stores the result with AddPartner.
+  void FindPartitionPartners(bool upper, ColPartition *part);
+  // Finds the best partner in the given direction for the given partition.
+  // Stores the result with AddPartner.
+  void FindVPartitionPartners(bool to_the_left, ColPartition *part);
+  // For every ColPartition with multiple partners in the grid, reduces the
+  // number of partners to 0 or 1. If get_desperate is true, goes to more
+  // desperate merge methods to merge flowing text before breaking partnerships.
+  void RefinePartitionPartners(bool get_desperate);
+
+private:
+  // Finds and returns a list of candidate ColPartitions to merge with part.
+  // The candidates must overlap search_box, and when merged must not
+  // overlap any other partitions that are not overlapped by each individually.
+  void FindMergeCandidates(const ColPartition *part, const TBOX &search_box,
+                           bool debug, ColPartition_CLIST *candidates);
+
+  // Smoothes the region type/flow type of the given part by looking at local
+  // neighbours and the given image mask. Searches a padded rectangle with the
+  // padding truncated on one size of the part's box in turn for each side,
+  // using the result (if any) that has the least distance to all neighbours
+  // that contribute to the decision. This biases in favor of rectangular
+  // regions without completely enforcing them.
+  // If a good decision cannot be reached, the part is left unchanged.
+  // im_box and rerotation are used to map blob coordinates onto the
+  // nontext_map, which is used to prevent the spread of text neighbourhoods
+  // into images.
+  // Returns true if the partition was changed.
+  bool SmoothRegionType(Image nontext_map, const TBOX &im_box,
+                        const FCOORD &rerotation, bool debug,
+                        ColPartition *part);
+  // Executes the search for SmoothRegionType in a single direction.
+  // Creates a bounding box that is padded in all directions except direction,
+  // and searches it for other partitions. Finds the nearest collection of
+  // partitions that makes a decisive result (if any) and returns the type
+  // and the distance of the collection. If there are any pixels in the
+  // nontext_map, then the decision is biased towards image.
+  BlobRegionType SmoothInOneDirection(BlobNeighbourDir direction,
+                                      Image nontext_map, const TBOX &im_box,
+                                      const FCOORD &rerotation, bool debug,
+                                      const ColPartition &part,
+                                      int *best_distance);
+  // Counts the partitions in the given search_box by appending the gap
+  // distance (scaled by dist_scaling) of the part from the base_part to the
+  // vector of the appropriate type for the partition. Prior to return, the
+  // vectors in the dists array are sorted in increasing order.
+  // dists must be an array of vectors of size NPT_COUNT.
+  void AccumulatePartDistances(const ColPartition &base_part,
+                               const ICOORD &dist_scaling,
+                               const TBOX &search_box, Image nontext_map,
+                               const TBOX &im_box, const FCOORD &rerotation,
+                               bool debug, std::vector<int> *dists);
+
+  // Improves the margins of the ColPartition by searching for
+  // neighbours that vertically overlap significantly.
+  void FindPartitionMargins(ColPartitionSet *columns, ColPartition *part);
+
+  // Starting at x, and going in the specified direction, up to x_limit, finds
+  // the margin for the given y range by searching sideways,
+  // and ignoring not_this.
+  int FindMargin(int x, bool right_to_left, int x_limit, int y_bottom,
+                 int y_top, const ColPartition *not_this);
+};
+
+} // namespace tesseract.
+
+#endif // TESSERACT_TEXTORD_COLPARTITIONGRID_H_