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tesseract/textord/colpartitionset.cpp

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///////////////////////////////////////////////////////////////////////
// File: colpartitionset.cpp
// Description: Class to hold a list of ColPartitions of the page that
// correspond roughly to columns.
// Author: Ray Smith
// Created: Thu Aug 14 10:54:01 PDT 2008
//
// (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.
//
///////////////////////////////////////////////////////////////////////
#include "colpartitionset.h"
#include "ndminx.h"
#include "workingpartset.h"
#include "tablefind.h"
namespace tesseract {
// Minimum width of a column to be interesting as a multiple of resolution.
const double kMinColumnWidth = 2.0 / 3;
ELISTIZE(ColPartitionSet)
ColPartitionSet::ColPartitionSet(ColPartition_LIST* partitions) {
ColPartition_IT it(&parts_);
it.add_list_after(partitions);
ComputeCoverage();
}
ColPartitionSet::ColPartitionSet(ColPartition* part) {
ColPartition_IT it(&parts_);
it.add_after_then_move(part);
ComputeCoverage();
}
ColPartitionSet::~ColPartitionSet() {
}
// Return an element of the parts_ list from its index.
ColPartition* ColPartitionSet::GetColumnByIndex(int index) {
ColPartition_IT it(&parts_);
it.mark_cycle_pt();
for (int i = 0; i < index && !it.cycled_list(); ++i, it.forward());
if (it.cycled_list())
return NULL;
return it.data();
}
// Return the ColPartition that contains the given coords, if any, else NULL.
ColPartition* ColPartitionSet::ColumnContaining(int x, int y) {
ColPartition_IT it(&parts_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
if (part->ColumnContains(x, y))
return part;
}
return NULL;
}
// Insert the ColPartitions in our list into the given grid.
void ColPartitionSet::ReturnParts(ColPartition_LIST* parts) {
ColPartition_IT it(parts);
it.add_list_before(&parts_);
}
// Merge any significantly overlapping partitions within the this and other,
// and unique the boxes so that no two partitions use the same box.
// Return true if any changes were made to either set.
bool ColPartitionSet::MergeOverlaps(ColPartitionSet* other, WidthCallback* cb) {
bool debug = TabFind::WithinTestRegion(2, bounding_box_.left(),
bounding_box_.bottom()) ||
TabFind::WithinTestRegion(2, other->bounding_box_.left(),
other->bounding_box_.bottom());
if (debug) {
tprintf("Considering merge on:\n");
Print();
other->Print();
}
ColPartition_IT it1(&parts_);
ColPartition_IT it2(&other->parts_);
bool any_merged = false;
it1.mark_cycle_pt();
it2.mark_cycle_pt();
// Iterate the two lists in parallel, using the fact that they are
// sorted by x-coord to keep the iterators in sync.
while (!it1.cycled_list() && !it2.cycled_list()) {
any_merged = false;
ColPartition* part1 = it1.data();
ColPartition* part2 = it2.data();
if (debug) {
tprintf("Vover=%d, HOver=%d, Hcompatible=%d, typesmatch=%d\n",
part1->VOverlaps(*part2), part1->HOverlaps(*part2),
part1->HCompatible(*part2), part1->TypesMatch(*part2));
}
if (part1->VOverlaps(*part2) &&
part1->HCompatible(*part2) && part1->TypesMatch(*part2)) {
// Partitions seem to be mergeable, so absorb part1 into part2.
part1->Absorb(it2.extract(), cb);
any_merged = true;
it1.forward();
it2.forward();
} else if (part1->HOverlaps(*part2) && part1->TypesMatch(*part2) &&
part1->Unique(part2, cb)) {
// Unique moved some boxes, so check to see in either partition was
// left empty. If not, any_merged is not set true.
if (part1->IsEmpty()) {
any_merged = true;
delete it1.extract();
it1.forward();
continue;
}
if (part2->IsEmpty()) {
any_merged = true;
delete it2.extract();
it2.forward();
continue;
}
}
if (!any_merged) {
// Move on the iterator that point to the leftmost partition.
if (part1->IsLeftOf(*part2)) {
it1.forward();
} else {
it2.forward();
}
}
}
if (any_merged) {
ComputeCoverage();
other->ComputeCoverage();
}
return any_merged;
}
// Attempt to improve this by adding partitions or expanding partitions.
void ColPartitionSet::ImproveColumnCandidate(WidthCallback* cb,
PartSetVector* src_sets) {
int set_size = src_sets->size();
// Iterate over the provided column sets, as each one may have something
// to improve this.
for (int i = 0; i < set_size; ++i) {
ColPartitionSet* column_set = src_sets->get(i);
if (column_set == NULL)
continue;
// Iterate over the parts in this and column_set, adding bigger or
// new parts in column_set to this.
ColPartition_IT part_it(&parts_);
ASSERT_HOST(!part_it.empty());
int prev_right = MIN_INT32;
part_it.mark_cycle_pt();
ColPartition_IT col_it(&column_set->parts_);
for (col_it.mark_cycle_pt(); !col_it.cycled_list(); col_it.forward()) {
ColPartition* col_part = col_it.data();
if (col_part->blob_type() < BRT_UNKNOWN)
continue; // Ignore image partitions.
int col_left = col_part->left_key();
int col_right = col_part->right_key();
// Sync-up part_it (in this) so it matches the col_part in column_set.
ColPartition* part = part_it.data();
while (!part_it.at_last() && part->right_key() < col_left) {
prev_right = part->right_key();
part_it.forward();
part = part_it.data();
}
int part_left = part->left_key();
int part_right = part->right_key();
if (part_right < col_left || col_right < part_left) {
// There is no overlap so this is a new partition.
AddPartition(col_part->ShallowCopy(), &part_it);
continue;
}
// Check the edges of col_part to see if they can improve part.
bool part_width_ok = cb->Run(part->KeyWidth(part_left, part_right));
if (col_left < part_left && col_left > prev_right) {
// The left edge of the column is better and it doesn't overlap,
// so we can potentially expand it.
int col_box_left = col_part->BoxLeftKey();
bool tab_width_ok = cb->Run(part->KeyWidth(col_left, part_right));
bool box_width_ok = cb->Run(part->KeyWidth(col_box_left, part_right));
if (tab_width_ok || (!part_width_ok )) {
// The tab is leaving the good column metric at least as good as
// it was before, so use the tab.
part->CopyLeftTab(*col_part, false);
part->SetColumnGoodness(cb);
} else if (col_box_left < part_left &&
(box_width_ok || !part_width_ok)) {
// The box is leaving the good column metric at least as good as
// it was before, so use the box.
part->CopyLeftTab(*col_part, true);
part->SetColumnGoodness(cb);
}
part_left = part->left_key();
}
if (col_right > part_right &&
(part_it.at_last() ||
part_it.data_relative(1)->left_key() > col_right)) {
// The right edge is better, so we can possibly expand it.
int col_box_right = col_part->BoxRightKey();
bool tab_width_ok = cb->Run(part->KeyWidth(part_left, col_right));
bool box_width_ok = cb->Run(part->KeyWidth(part_left, col_box_right));
if (tab_width_ok || (!part_width_ok )) {
// The tab is leaving the good column metric at least as good as
// it was before, so use the tab.
part->CopyRightTab(*col_part, false);
part->SetColumnGoodness(cb);
} else if (col_box_right > part_right &&
(box_width_ok || !part_width_ok)) {
// The box is leaving the good column metric at least as good as
// it was before, so use the box.
part->CopyRightTab(*col_part, true);
part->SetColumnGoodness(cb);
}
}
}
}
ComputeCoverage();
}
// If this set is good enough to represent a new partitioning into columns,
// add it to the vector of sets, otherwise delete it.
void ColPartitionSet::AddToColumnSetsIfUnique(PartSetVector* column_sets,
WidthCallback* cb) {
bool debug = TabFind::WithinTestRegion(2, bounding_box_.left(),
bounding_box_.bottom());
if (debug) {
tprintf("Considering new column candidate:\n");
Print();
}
if (!LegalColumnCandidate()) {
if (debug) {
tprintf("Not a legal column candidate:\n");
Print();
}
delete this;
return;
}
for (int i = 0; i < column_sets->size(); ++i) {
ColPartitionSet* columns = column_sets->get(i);
// In ordering the column set candidates, total_coverage_ is king,
// followed by good_column_count_ and then total column_count.
bool better = total_coverage_ > columns->total_coverage_;
if (total_coverage_ == columns->total_coverage_) {
better = good_column_count_ > columns->good_column_count_;
if (good_column_count_ == columns->good_column_count_) {
better = parts_.length() > columns->parts_.length();
}
}
if (better) {
// The new one is better so add it.
if (debug)
tprintf("Good one\n");
column_sets->insert(this, i);
return;
}
if (columns->CompatibleColumns(false, this, cb)) {
if (debug)
tprintf("Duplicate\n");
delete this;
return; // It is not unique.
}
}
if (debug)
tprintf("Added to end\n");
column_sets->push_back(this);
}
// Return true if the partitions in other are all compatible with the columns
// in this.
bool ColPartitionSet::CompatibleColumns(bool debug, ColPartitionSet* other,
WidthCallback* cb) {
if (debug) {
tprintf("CompatibleColumns testing compability\n");
Print();
other->Print();
}
if (other->parts_.empty()) {
if (debug)
tprintf("CompatibleColumns true due to empty other\n");
return true;
}
ColPartition_IT it(&other->parts_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
if (part->blob_type() < BRT_UNKNOWN) {
if (debug) {
tprintf("CompatibleColumns ignoring image partition\n");
part->Print();
}
continue; // Image partitions are irrelevant to column compability.
}
int y = part->MidY();
int left = part->bounding_box().left();
int right = part->bounding_box().right();
ColPartition* left_col = ColumnContaining(left, y);
ColPartition* right_col = ColumnContaining(right, y);
if (right_col == NULL || left_col == NULL) {
if (debug) {
tprintf("CompatibleColumns false due to partition edge outside\n");
part->Print();
}
return false; // A partition edge lies outside of all columns
}
if (right_col != left_col && cb->Run(right - left)) {
if (debug) {
tprintf("CompatibleColumns false due to good width in multiple cols\n");
part->Print();
}
return false; // Partition with a good width must be in a single column.
}
ColPartition_IT it2= it;
while (!it2.at_last()) {
it2.forward();
ColPartition* next_part = it2.data();
if (!BLOBNBOX::IsTextType(next_part->blob_type()))
continue; // Non-text partitions are irrelevant.
int next_left = next_part->bounding_box().left();
if (next_left == right) {
break; // They share the same edge, so one must be a pull-out.
}
// Search to see if right and next_left fall within a single column.
ColPartition* next_left_col = ColumnContaining(next_left, y);
if (right_col == next_left_col) {
// There is a column break in this column.
// Check for the difference between different column layout and
// a pull-out block.
int part_box_width = part->bounding_box().width();
int part_margin_width = part->right_margin() - part->left_margin();
int next_box_width = next_part->bounding_box().width();
int next_margin_width = next_part->right_margin() -
next_part->left_margin();
int next_right = next_part->bounding_box().right();
if (part_box_width < next_margin_width &&
next_box_width < part_margin_width) {
if (debug) {
tprintf("CompatibleColumns false due to equal sized columns\n");
tprintf("part1 %d-%d = %d, part2 %d-%d = %d\n",
left, right, part->ColumnWidth(),
next_left, next_right, next_part->ColumnWidth());
right_col->Print();
}
return false; // Must be a new column layout as they are equal size.
}
ColPartition* next_right_col = ColumnContaining(next_right, y);
if (left_col == right_col && next_right_col == next_left_col) {
// Column completely contains both. Not allowed.
if (debug) {
tprintf("CompatibleColumns false due to containing 2 partitions\n");
tprintf("part1 %d-%d, part2 %d-%d\n",
left, right, next_left, next_right);
right_col->Print();
}
return false;
}
}
break;
}
}
if (debug)
tprintf("CompatibleColumns true!\n");
return true;
}
// Returns the total width of all blobs in the part_set that do not lie
// within an approved column. Used as a cost measure for using this
// column set over another that might be compatible.
int ColPartitionSet::UnmatchedWidth(ColPartitionSet* part_set) {
int total_width = 0;
ColPartition_IT it(&part_set->parts_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
if (!BLOBNBOX::IsTextType(part->blob_type())) {
continue; // Non-text partitions are irrelevant to column compatibility.
}
int y = part->MidY();
BLOBNBOX_C_IT box_it(part->boxes());
for (box_it.mark_cycle_pt(); !box_it.cycled_list(); box_it.forward()) {
const TBOX& box = it.data()->bounding_box();
// Assume that the whole blob is outside any column iff its x-middle
// is outside.
int x = (box.left() + box.right()) / 2;
ColPartition* col = ColumnContaining(x, y);
if (col == NULL)
total_width += box.width();
}
}
return total_width;
}
// Return true if this ColPartitionSet makes a legal column candidate by
// having legal individual partitions and non-overlapping adjacent pairs.
bool ColPartitionSet::LegalColumnCandidate() {
ColPartition_IT it(&parts_);
if (it.empty())
return false;
bool any_text_parts = false;
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
if (BLOBNBOX::IsTextType(part->blob_type())) {
if (!part->IsLegal())
return false; // Individual partition is illegal.
any_text_parts = true;
}
if (!it.at_last()) {
ColPartition* next_part = it.data_relative(1);
if (next_part->left_key() < part->right_key()) {
return false;
}
}
}
return any_text_parts;
}
// Return a copy of this. If good_only will only copy the Good ColPartitions.
ColPartitionSet* ColPartitionSet::Copy(bool good_only) {
ColPartition_LIST copy_parts;
ColPartition_IT src_it(&parts_);
ColPartition_IT dest_it(&copy_parts);
for (src_it.mark_cycle_pt(); !src_it.cycled_list(); src_it.forward()) {
ColPartition* part = src_it.data();
if (BLOBNBOX::IsTextType(part->blob_type()) &&
(!good_only || part->good_width() || part->good_column()))
dest_it.add_after_then_move(part->ShallowCopy());
}
if (dest_it.empty())
return NULL;
return new ColPartitionSet(&copy_parts);
}
// Return the bounding boxes of columns at the given y-range
void ColPartitionSet::GetColumnBoxes(int y_bottom, int y_top,
ColSegment_LIST *segments) {
ColPartition_IT it(&parts_);
ColSegment_IT col_it(segments);
col_it.move_to_last();
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
ICOORD bot_left(part->LeftAtY(y_top), y_bottom);
ICOORD top_right(part->RightAtY(y_bottom), y_top);
ColSegment *col_seg = new ColSegment();
col_seg->InsertBox(TBOX(bot_left, top_right));
col_it.add_after_then_move(col_seg);
}
}
// Display the edges of the columns at the given y coords.
void ColPartitionSet::DisplayColumnEdges(int y_bottom, int y_top,
ScrollView* win) {
ColPartition_IT it(&parts_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
win->Line(part->LeftAtY(y_top), y_top, part->LeftAtY(y_bottom), y_bottom);
win->Line(part->RightAtY(y_top), y_top, part->RightAtY(y_bottom), y_bottom);
}
}
// Return the ColumnSpanningType that best explains the columns overlapped
// by the given coords(left,right,y), with the given margins.
// Also return the first and last column index touched by the coords and
// the leftmost spanned column.
// Column indices are 2n + 1 for real columns (0 based) and even values
// represent the gaps in between columns, with 0 being left of the leftmost.
// resolution refers to the ppi resolution of the image.
ColumnSpanningType ColPartitionSet::SpanningType(int resolution,
int left, int right, int y,
int left_margin,
int right_margin,
int* first_col,
int* last_col,
int* first_spanned_col) {
*first_col = -1;
*last_col = -1;
*first_spanned_col = -1;
int margin_columns = 0;
ColPartition_IT it(&parts_);
int col_index = 1;
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward(), col_index += 2) {
ColPartition* part = it.data();
if (part->ColumnContains(left, y)) {
// In the default case, first_col is set, but columns_spanned remains
// zero, so first_col will get reset in the first column genuinely
// spanned, but we can tell the difference from a noise partition
// that touches no column.
*first_col = col_index;
if (part->ColumnContains(right, y)) {
// Both within a single column.
*last_col = col_index;
return CST_FLOWING;
}
if (left_margin <= part->LeftAtY(y)) {
// It completely spans this column.
*first_spanned_col = col_index;
margin_columns = 1;
}
} else if (part->ColumnContains(right, y)) {
if (*first_col < 0) {
// It started in-between.
*first_col = col_index - 1;
}
if (right_margin >= part->RightAtY(y)) {
// It completely spans this column.
if (margin_columns == 0)
*first_spanned_col = col_index;
++margin_columns;
}
*last_col = col_index;
break;
} else if (left < part->LeftAtY(y) && right > part->RightAtY(y)) {
// Neither left nor right are contained within, so it spans this
// column.
if (*first_col < 0) {
// It started in between the previous column and the current column.
*first_col = col_index - 1;
}
if (margin_columns == 0)
*first_spanned_col = col_index;
*last_col = col_index;
} else if (right < part->LeftAtY(y)) {
// We have gone past the end.
*last_col = col_index - 1;
if (*first_col < 0) {
// It must lie completely between columns =>noise.
*first_col = col_index - 1;
}
break;
}
}
if (*first_col < 0)
*first_col = col_index - 1; // The last in-between.
if (*last_col < 0)
*last_col = col_index - 1; // The last in-between.
ASSERT_HOST(*first_col >= 0 && *last_col >= 0);
ASSERT_HOST(*first_col <= *last_col);
if (*first_col == *last_col && right - left < kMinColumnWidth * resolution) {
// Neither end was in a column, and it didn't span any, so it lies
// entirely between columns, therefore noise.
return CST_NOISE;
} else if (margin_columns <= 1) {
// An exception for headings that stick outside of single-column text.
if (margin_columns == 1 && parts_.singleton()) {
return CST_HEADING;
}
// It is a pullout, as left and right were not in the same column, but
// it doesn't go to the edge of its start and end.
return CST_PULLOUT;
}
// Its margins went to the edges of first and last columns => heading.
return CST_HEADING;
}
// The column_set has changed. Close down all in-progress WorkingPartSets in
// columns that do not match and start new ones for the new columns in this.
// As ColPartitions are turned into BLOCKs, the used ones are put in
// used_parts, as they still need to be referenced in the grid.
void ColPartitionSet::ChangeWorkColumns(const ICOORD& bleft,
const ICOORD& tright,
int resolution,
ColPartition_LIST* used_parts,
WorkingPartSet_LIST* working_set_list) {
// Move the input list to a temporary location so we can delete its elements
// as we add them to the output working_set.
WorkingPartSet_LIST work_src;
WorkingPartSet_IT src_it(&work_src);
src_it.add_list_after(working_set_list);
src_it.move_to_first();
WorkingPartSet_IT dest_it(working_set_list);
// Completed blocks and to_blocks are accumulated and given to the first new
// one whenever we keep a column, or at the end.
BLOCK_LIST completed_blocks;
TO_BLOCK_LIST to_blocks;
WorkingPartSet* first_new_set = NULL;
WorkingPartSet* working_set = NULL;
ColPartition_IT col_it(&parts_);
for (col_it.mark_cycle_pt(); !col_it.cycled_list(); col_it.forward()) {
ColPartition* column = col_it.data();
// Any existing column to the left of column is completed.
while (!src_it.empty() &&
((working_set = src_it.data())->column() == NULL ||
working_set->column()->right_key() <= column->left_key())) {
src_it.extract();
working_set->ExtractCompletedBlocks(bleft, tright, resolution,
used_parts, &completed_blocks,
&to_blocks);
delete working_set;
src_it.forward();
}
// Make a new between-column WorkingSet for before the current column.
working_set = new WorkingPartSet(NULL);
dest_it.add_after_then_move(working_set);
if (first_new_set == NULL)
first_new_set = working_set;
// A matching column gets to stay, and first_new_set gets all the
// completed_sets.
working_set = src_it.empty() ? NULL : src_it.data();
if (working_set != NULL &&
working_set->column()->MatchingColumns(*column)) {
working_set->set_column(column);
dest_it.add_after_then_move(src_it.extract());
src_it.forward();
first_new_set->InsertCompletedBlocks(&completed_blocks, &to_blocks);
first_new_set = NULL;
} else {
// Just make a new working set for the current column.
working_set = new WorkingPartSet(column);
dest_it.add_after_then_move(working_set);
}
}
// Complete any remaining src working sets.
while (!src_it.empty()) {
working_set = src_it.extract();
working_set->ExtractCompletedBlocks(bleft, tright, resolution,
used_parts, &completed_blocks,
&to_blocks);
delete working_set;
src_it.forward();
}
// Make a new between-column WorkingSet for after the last column.
working_set = new WorkingPartSet(NULL);
dest_it.add_after_then_move(working_set);
if (first_new_set == NULL)
first_new_set = working_set;
// The first_new_set now gets any accumulated completed_parts/blocks.
first_new_set->InsertCompletedBlocks(&completed_blocks, &to_blocks);
}
// Accumulate the widths and gaps into the given variables.
void ColPartitionSet::AccumulateColumnWidthsAndGaps(int* total_width,
int* width_samples,
int* total_gap,
int* gap_samples) {
ColPartition_IT it(&parts_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
*total_width += part->ColumnWidth();
++*width_samples;
if (!it.at_last()) {
ColPartition* next_part = it.data_relative(1);
int gap = part->KeyWidth(part->right_key(), next_part->left_key());
*total_gap += gap;
++*gap_samples;
}
}
}
// Provide debug output for this ColPartitionSet and all the ColPartitions.
void ColPartitionSet::Print() {
ColPartition_IT it(&parts_);
tprintf("Partition set of %d parts, %d good, coverage=%d (%d,%d)->(%d,%d)\n",
it.length(), good_column_count_, total_coverage_,
bounding_box_.left(), bounding_box_.bottom(),
bounding_box_.right(), bounding_box_.top());
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
part->Print();
}
}
// PRIVATE CODE.
// Add the given partition to the list in the appropriate place.
void ColPartitionSet::AddPartition(ColPartition* new_part,
ColPartition_IT* it) {
bounding_box_ += new_part->bounding_box();
if (new_part->good_column() || new_part->good_width()) {
total_coverage_ += new_part->ColumnWidth();
++good_column_count_;
if (new_part->good_width())
++good_column_count_;
}
int new_right = new_part->right_key();
if (it->data()->left_key() >= new_right)
it->add_before_stay_put(new_part);
else
it->add_after_stay_put(new_part);
}
// Compute the coverage and good column count.
void ColPartitionSet::ComputeCoverage() {
// Count the number of good columns and sum their width.
ColPartition_IT it(&parts_);
good_column_count_ = 0;
total_coverage_ = 0;
bounding_box_ = TBOX();
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
bounding_box_ += part->bounding_box();
if (part->good_column() || part->good_width()) {
total_coverage_ += part->ColumnWidth();
++good_column_count_;
if (part->good_width())
++good_column_count_;
}
}
}
} // namespace tesseract.
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