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tesseract/textord/tabvector.cpp

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///////////////////////////////////////////////////////////////////////
// File: tabvector.cpp
// Description: Class to hold a near-vertical vector representing a tab-stop.
// Author: Ray Smith
// Created: Thu Apr 10 16:28:01 PST 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.
//
///////////////////////////////////////////////////////////////////////
#ifdef _MSC_VER
#pragma warning(disable:4244) // Conversion warnings
#endif
#ifdef HAVE_CONFIG_H
#include "config_auto.h"
#endif
#include "tabvector.h"
#include "blobbox.h"
#include "colfind.h"
#include "colpartitionset.h"
#include "detlinefit.h"
#include "statistc.h"
namespace tesseract {
// Multiple of height used as a gutter for evaluation search.
const int kGutterMultiple = 4;
// Multiple of neighbour gap that we expect the gutter gap to be at minimum.
const int kGutterToNeighbourRatio = 3;
// Pixel distance for tab vectors to be considered the same.
const int kSimilarVectorDist = 10;
// Pixel distance for ragged tab vectors to be considered the same if there
// is nothing in the overlap box
const int kSimilarRaggedDist = 50;
// Max multiple of height to allow filling in between blobs when evaluating.
const int kMaxFillinMultiple = 11;
// Min fraction of mean gutter size to allow a gutter on a good tab blob.
const double kMinGutterFraction = 0.5;
// Multiple of 1/n lines as a minimum gutter in evaluation.
const double kLineCountReciprocal = 4.0;
// Constant add-on for minimum gutter for aligned tabs.
const double kMinAlignedGutter = 0.25;
// Constant add-on for minimum gutter for ragged tabs.
const double kMinRaggedGutter = 1.5;
double_VAR(textord_tabvector_vertical_gap_fraction, 0.5,
"max fraction of mean blob width allowed for vertical gaps in vertical text");
double_VAR(textord_tabvector_vertical_box_ratio, 0.5,
"Fraction of box matches required to declare a line vertical");
ELISTIZE(TabConstraint)
// Create a constraint for the top or bottom of this TabVector.
void TabConstraint::CreateConstraint(TabVector* vector, bool is_top) {
TabConstraint* constraint = new TabConstraint(vector, is_top);
TabConstraint_LIST* constraints = new TabConstraint_LIST;
TabConstraint_IT it(constraints);
it.add_to_end(constraint);
if (is_top)
vector->set_top_constraints(constraints);
else
vector->set_bottom_constraints(constraints);
}
// Test to see if the constraints are compatible enough to merge.
bool TabConstraint::CompatibleConstraints(TabConstraint_LIST* list1,
TabConstraint_LIST* list2) {
if (list1 == list2)
return false;
int y_min = -MAX_INT32;
int y_max = MAX_INT32;
if (textord_debug_tabfind > 3)
tprintf("Testing constraint compatibility\n");
GetConstraints(list1, &y_min, &y_max);
GetConstraints(list2, &y_min, &y_max);
if (textord_debug_tabfind > 3)
tprintf("Resulting range = [%d,%d]\n", y_min, y_max);
return y_max >= y_min;
}
// Merge the lists of constraints and update the TabVector pointers.
// The second list is deleted.
void TabConstraint::MergeConstraints(TabConstraint_LIST* list1,
TabConstraint_LIST* list2) {
if (list1 == list2)
return;
TabConstraint_IT it(list2);
if (textord_debug_tabfind > 3)
tprintf("Merging constraints\n");
// The vectors of all constraints on list2 are now going to be on list1.
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabConstraint* constraint = it.data();
if (textord_debug_tabfind> 3)
constraint->vector_->Print("Merge");
if (constraint->is_top_)
constraint->vector_->set_top_constraints(list1);
else
constraint->vector_->set_bottom_constraints(list1);
}
it = list1;
it.add_list_before(list2);
delete list2;
}
// Set all the tops and bottoms as appropriate to a mean of the
// constrained range. Delete all the constraints and list.
void TabConstraint::ApplyConstraints(TabConstraint_LIST* constraints) {
int y_min = -MAX_INT32;
int y_max = MAX_INT32;
GetConstraints(constraints, &y_min, &y_max);
int y = (y_min + y_max) / 2;
TabConstraint_IT it(constraints);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabConstraint* constraint = it.data();
TabVector* v = constraint->vector_;
if (constraint->is_top_) {
v->SetYEnd(y);
v->set_top_constraints(NULL);
} else {
v->SetYStart(y);
v->set_bottom_constraints(NULL);
}
}
delete constraints;
}
TabConstraint::TabConstraint(TabVector* vector, bool is_top)
: vector_(vector), is_top_(is_top) {
if (is_top) {
y_min_ = vector->endpt().y();
y_max_ = vector->extended_ymax();
} else {
y_max_ = vector->startpt().y();
y_min_ = vector->extended_ymin();
}
}
// Get the max of the mins and the min of the maxes.
void TabConstraint::GetConstraints(TabConstraint_LIST* constraints,
int* y_min, int* y_max) {
TabConstraint_IT it(constraints);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabConstraint* constraint = it.data();
if (textord_debug_tabfind > 3) {
tprintf("Constraint is [%d,%d]", constraint->y_min_, constraint->y_max_);
constraint->vector_->Print(" for");
}
*y_min = MAX(*y_min, constraint->y_min_);
*y_max = MIN(*y_max, constraint->y_max_);
}
}
ELIST2IZE(TabVector)
CLISTIZE(TabVector)
// The constructor is private. See the bottom of the file...
TabVector::~TabVector() {
}
// Public factory to build a TabVector from a list of boxes.
// The TabVector will be of the given alignment type.
// The input vertical vector is used in fitting, and the output
// vertical_x, vertical_y have the resulting line vector added to them
// if the alignment is not ragged.
// The extended_start_y and extended_end_y are the maximum possible
// extension to the line segment that can be used to align with others.
// The input CLIST of BLOBNBOX good_points is consumed and taken over.
TabVector* TabVector::FitVector(TabAlignment alignment, ICOORD vertical,
int extended_start_y, int extended_end_y,
BLOBNBOX_CLIST* good_points,
int* vertical_x, int* vertical_y) {
TabVector* vector = new TabVector(extended_start_y, extended_end_y,
alignment, good_points);
if (!vector->Fit(vertical, false)) {
delete vector;
return NULL;
}
if (!vector->IsRagged()) {
vertical = vector->endpt_ - vector->startpt_;
int weight = vector->BoxCount();
*vertical_x += vertical.x() * weight;
*vertical_y += vertical.y() * weight;
}
return vector;
}
// Build a ragged TabVector by copying another's direction, shifting it
// to match the given blob, and making its initial extent the height
// of the blob, but its extended bounds from the bounds of the original.
TabVector::TabVector(const TabVector& src, TabAlignment alignment,
const ICOORD& vertical_skew, BLOBNBOX* blob)
: extended_ymin_(src.extended_ymin_), extended_ymax_(src.extended_ymax_),
sort_key_(0), percent_score_(0), mean_width_(0),
needs_refit_(true), needs_evaluation_(true), intersects_other_lines_(false),
alignment_(alignment),
top_constraints_(NULL), bottom_constraints_(NULL) {
BLOBNBOX_C_IT it(&boxes_);
it.add_to_end(blob);
TBOX box = blob->bounding_box();
if (IsLeftTab()) {
startpt_ = box.botleft();
endpt_ = box.topleft();
} else {
startpt_ = box.botright();
endpt_ = box.topright();
}
sort_key_ = SortKey(vertical_skew,
(startpt_.x() + endpt_.x()) / 2,
(startpt_.y() + endpt_.y()) / 2);
if (textord_debug_tabfind > 3)
Print("Constructed a new tab vector:");
}
// Copies basic attributes of a tab vector for simple operations.
// Copies things such startpt, endpt, range.
// Does not copy things such as partners, boxes, or constraints.
// This is useful if you only need vector information for processing, such
// as in the table detection code.
TabVector* TabVector::ShallowCopy() const {
TabVector* copy = new TabVector();
copy->startpt_ = startpt_;
copy->endpt_ = endpt_;
copy->alignment_ = alignment_;
copy->extended_ymax_ = extended_ymax_;
copy->extended_ymin_ = extended_ymin_;
copy->intersects_other_lines_ = intersects_other_lines_;
return copy;
}
// Extend this vector to include the supplied blob if it doesn't
// already have it.
void TabVector::ExtendToBox(BLOBNBOX* new_blob) {
TBOX new_box = new_blob->bounding_box();
BLOBNBOX_C_IT it(&boxes_);
if (!it.empty()) {
BLOBNBOX* blob = it.data();
TBOX box = blob->bounding_box();
while (!it.at_last() && box.top() <= new_box.top()) {
if (blob == new_blob)
return; // We have it already.
it.forward();
blob = it.data();
box = blob->bounding_box();
}
if (box.top() >= new_box.top()) {
it.add_before_stay_put(new_blob);
needs_refit_ = true;
return;
}
}
needs_refit_ = true;
it.add_after_stay_put(new_blob);
}
// Set the ycoord of the start and move the xcoord to match.
void TabVector::SetYStart(int start_y) {
startpt_.set_x(XAtY(start_y));
startpt_.set_y(start_y);
}
// Set the ycoord of the end and move the xcoord to match.
void TabVector::SetYEnd(int end_y) {
endpt_.set_x(XAtY(end_y));
endpt_.set_y(end_y);
}
// Rotate the ends by the given vector. Auto flip start and end if needed.
void TabVector::Rotate(const FCOORD& rotation) {
startpt_.rotate(rotation);
endpt_.rotate(rotation);
int dx = endpt_.x() - startpt_.x();
int dy = endpt_.y() - startpt_.y();
if ((dy < 0 && abs(dy) > abs(dx)) || (dx < 0 && abs(dx) > abs(dy))) {
// Need to flip start/end.
ICOORD tmp = startpt_;
startpt_ = endpt_;
endpt_ = tmp;
}
}
// Setup the initial constraints, being the limits of
// the vector and the extended ends.
void TabVector::SetupConstraints() {
TabConstraint::CreateConstraint(this, false);
TabConstraint::CreateConstraint(this, true);
}
// Setup the constraints between the partners of this TabVector.
void TabVector::SetupPartnerConstraints() {
// With the first and last partner, we want a common bottom and top,
// respectively, and for each change of partner, we want a common
// top of first with bottom of next.
TabVector_C_IT it(&partners_);
TabVector* prev_partner = NULL;
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* partner = it.data();
if (partner->top_constraints_ == NULL ||
partner->bottom_constraints_ == NULL) {
partner->Print("Impossible: has no constraints");
Print("This vector has it as a partner");
continue;
}
if (prev_partner == NULL) {
// This is the first partner, so common bottom.
if (TabConstraint::CompatibleConstraints(bottom_constraints_,
partner->bottom_constraints_))
TabConstraint::MergeConstraints(bottom_constraints_,
partner->bottom_constraints_);
} else {
// We need prev top to be common with partner bottom.
if (TabConstraint::CompatibleConstraints(prev_partner->top_constraints_,
partner->bottom_constraints_))
TabConstraint::MergeConstraints(prev_partner->top_constraints_,
partner->bottom_constraints_);
}
prev_partner = partner;
if (it.at_last()) {
// This is the last partner, so common top.
if (TabConstraint::CompatibleConstraints(top_constraints_,
partner->top_constraints_))
TabConstraint::MergeConstraints(top_constraints_,
partner->top_constraints_);
}
}
}
// Setup the constraints between this and its partner.
void TabVector::SetupPartnerConstraints(TabVector* partner) {
if (TabConstraint::CompatibleConstraints(bottom_constraints_,
partner->bottom_constraints_))
TabConstraint::MergeConstraints(bottom_constraints_,
partner->bottom_constraints_);
if (TabConstraint::CompatibleConstraints(top_constraints_,
partner->top_constraints_))
TabConstraint::MergeConstraints(top_constraints_,
partner->top_constraints_);
}
// Use the constraints to modify the top and bottom.
void TabVector::ApplyConstraints() {
if (top_constraints_ != NULL)
TabConstraint::ApplyConstraints(top_constraints_);
if (bottom_constraints_ != NULL)
TabConstraint::ApplyConstraints(bottom_constraints_);
}
// Merge close tab vectors of the same side that overlap.
void TabVector::MergeSimilarTabVectors(const ICOORD& vertical,
TabVector_LIST* vectors,
BlobGrid* grid) {
TabVector_IT it1(vectors);
for (it1.mark_cycle_pt(); !it1.cycled_list(); it1.forward()) {
TabVector* v1 = it1.data();
TabVector_IT it2(it1);
for (it2.forward(); !it2.at_first(); it2.forward()) {
TabVector* v2 = it2.data();
if (v2->SimilarTo(vertical, *v1, grid)) {
// Merge into the forward one, in case the combined vector now
// overlaps one in between.
if (textord_debug_tabfind) {
v2->Print("Merging");
v1->Print("by deleting");
}
v2->MergeWith(vertical, it1.extract());
if (textord_debug_tabfind) {
v2->Print("Producing");
}
ICOORD merged_vector = v2->endpt();
merged_vector -= v2->startpt();
if (textord_debug_tabfind && abs(merged_vector.x()) > 100) {
v2->Print("Garbage result of merge?");
}
break;
}
}
}
}
// Return true if this vector is the same side, overlaps, and close
// enough to the other to be merged.
bool TabVector::SimilarTo(const ICOORD& vertical,
const TabVector& other, BlobGrid* grid) const {
if ((IsRightTab() && other.IsRightTab()) ||
(IsLeftTab() && other.IsLeftTab())) {
// If they don't overlap, at least in extensions, then there is no chance.
if (ExtendedOverlap(other.extended_ymax_, other.extended_ymin_) < 0)
return false;
// A fast approximation to the scale factor of the sort_key_.
int v_scale = abs(vertical.y());
if (v_scale == 0)
v_scale = 1;
// If they are close enough, then OK.
if (sort_key_ + kSimilarVectorDist * v_scale >= other.sort_key_ &&
sort_key_ - kSimilarVectorDist * v_scale <= other.sort_key_)
return true;
// Ragged tabs get a bigger threshold.
if (!IsRagged() || !other.IsRagged() ||
sort_key_ + kSimilarRaggedDist * v_scale < other.sort_key_ ||
sort_key_ - kSimilarRaggedDist * v_scale > other.sort_key_)
return false;
if (grid == NULL) {
// There is nothing else to test!
return true;
}
// If there is nothing in the rectangle between the vector that is going to
// move, and the place it is moving to, then they can be merged.
// Setup a vertical search for any blob.
const TabVector* mover = (IsRightTab() &&
sort_key_ < other.sort_key_) ? this : &other;
int top_y = mover->endpt_.y();
int bottom_y = mover->startpt_.y();
int left = MIN(mover->XAtY(top_y), mover->XAtY(bottom_y));
int right = MAX(mover->XAtY(top_y), mover->XAtY(bottom_y));
int shift = abs(sort_key_ - other.sort_key_) / v_scale;
if (IsRightTab()) {
right += shift;
} else {
left -= shift;
}
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> vsearch(grid);
vsearch.StartVerticalSearch(left, right, top_y);
BLOBNBOX* blob;
while ((blob = vsearch.NextVerticalSearch(true)) != NULL) {
TBOX box = blob->bounding_box();
if (box.top() > bottom_y)
return true; // Nothing found.
if (box.bottom() < top_y)
continue; // Doesn't overlap.
int left_at_box = XAtY(box.bottom());
int right_at_box = left_at_box;
if (IsRightTab())
right_at_box += shift;
else
left_at_box -= shift;
if (MIN(right_at_box, box.right()) > MAX(left_at_box, box.left()))
return false;
}
return true; // Nothing found.
}
return false;
}
// Eat the other TabVector into this and delete it.
void TabVector::MergeWith(const ICOORD& vertical, TabVector* other) {
extended_ymin_ = MIN(extended_ymin_, other->extended_ymin_);
extended_ymax_ = MAX(extended_ymax_, other->extended_ymax_);
if (other->IsRagged()) {
alignment_ = other->alignment_;
}
// Merge sort the two lists of boxes.
BLOBNBOX_C_IT it1(&boxes_);
BLOBNBOX_C_IT it2(&other->boxes_);
while (!it2.empty()) {
BLOBNBOX* bbox2 = it2.extract();
it2.forward();
TBOX box2 = bbox2->bounding_box();
BLOBNBOX* bbox1 = it1.data();
TBOX box1 = bbox1->bounding_box();
while (box1.bottom() < box2.bottom() && !it1.at_last()) {
it1.forward();
bbox1 = it1.data();
box1 = bbox1->bounding_box();
}
if (box1.bottom() < box2.bottom()) {
it1.add_to_end(bbox2);
} else if (bbox1 != bbox2) {
it1.add_before_stay_put(bbox2);
}
}
Fit(vertical, true);
other->Delete(this);
}
// Add a new element to the list of partner TabVectors.
// Partners must be added in order of increasing y coordinate of the text line
// that makes them partners.
// Groups of identical partners are merged into one.
void TabVector::AddPartner(TabVector* partner) {
if (IsSeparator() || partner->IsSeparator())
return;
TabVector_C_IT it(&partners_);
if (!it.empty()) {
it.move_to_last();
if (it.data() == partner)
return;
}
it.add_after_then_move(partner);
}
// Return true if other is a partner of this.
bool TabVector::IsAPartner(const TabVector* other) {
TabVector_C_IT it(&partners_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
if (it.data() == other)
return true;
}
return false;
}
// These names must be synced with the TabAlignment enum in tabvector.h.
const char* kAlignmentNames[] = {
"Left Aligned",
"Left Ragged",
"Center",
"Right Aligned",
"Right Ragged",
"Separator"
};
// Print basic information about this tab vector.
void TabVector::Print(const char* prefix) {
tprintf(
"%s %s (%d,%d)->(%d,%d) w=%d s=%d, sort key=%d, boxes=%d,"
" partners=%d\n",
prefix, kAlignmentNames[alignment_], startpt_.x(), startpt_.y(),
endpt_.x(), endpt_.y(), mean_width_, percent_score_, sort_key_,
boxes_.length(), partners_.length());
}
// Print basic information about this tab vector and every box in it.
void TabVector::Debug(const char* prefix) {
Print(prefix);
BLOBNBOX_C_IT it(&boxes_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
BLOBNBOX* bbox = it.data();
const TBOX& box = bbox->bounding_box();
tprintf("Box at (%d,%d)->(%d,%d)\n",
box.left(), box.bottom(), box.right(), box.top());
}
}
// Draw this tabvector in place in the given window.
void TabVector::Display(ScrollView* tab_win) {
#ifndef GRAPHICS_DISABLED
if (textord_debug_printable)
tab_win->Pen(ScrollView::BLUE);
else if (alignment_ == TA_LEFT_ALIGNED)
tab_win->Pen(ScrollView::LIME_GREEN);
else if (alignment_ == TA_LEFT_RAGGED)
tab_win->Pen(ScrollView::DARK_GREEN);
else if (alignment_ == TA_RIGHT_ALIGNED)
tab_win->Pen(ScrollView::PINK);
else if (alignment_ == TA_RIGHT_RAGGED)
tab_win->Pen(ScrollView::CORAL);
else
tab_win->Pen(ScrollView::WHITE);
tab_win->Line(startpt_.x(), startpt_.y(), endpt_.x(), endpt_.y());
tab_win->Pen(ScrollView::GREY);
tab_win->Line(startpt_.x(), startpt_.y(), startpt_.x(), extended_ymin_);
tab_win->Line(endpt_.x(), extended_ymax_, endpt_.x(), endpt_.y());
char score_buf[64];
snprintf(score_buf, sizeof(score_buf), "%d", percent_score_);
tab_win->TextAttributes("Times", 50, false, false, false);
tab_win->Text(startpt_.x(), startpt_.y(), score_buf);
#endif
}
// Refit the line and/or re-evaluate the vector if the dirty flags are set.
void TabVector::FitAndEvaluateIfNeeded(const ICOORD& vertical,
TabFind* finder) {
if (needs_refit_)
Fit(vertical, true);
if (needs_evaluation_)
Evaluate(vertical, finder);
}
// Evaluate the vector in terms of coverage of its length by good-looking
// box edges. A good looking box is one where its nearest neighbour on the
// inside is nearer than half the distance its nearest neighbour on the
// outside of the putative column. Bad boxes are removed from the line.
// A second pass then further filters boxes by requiring that the gutter
// width be a minimum fraction of the mean gutter along the line.
void TabVector::Evaluate(const ICOORD& vertical, TabFind* finder) {
bool debug = false;
needs_evaluation_ = false;
int length = endpt_.y() - startpt_.y();
if (length == 0 || boxes_.empty()) {
percent_score_ = 0;
Print("Zero length in evaluate");
return;
}
// Compute the mean box height.
BLOBNBOX_C_IT it(&boxes_);
int mean_height = 0;
int height_count = 0;
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
BLOBNBOX* bbox = it.data();
const TBOX& box = bbox->bounding_box();
int height = box.height();
mean_height += height;
++height_count;
}
if (height_count > 0) mean_height /= height_count;
int max_gutter = kGutterMultiple * mean_height;
if (IsRagged()) {
// Ragged edges face a tougher test in that the gap must always be within
// the height of the blob.
max_gutter = kGutterToNeighbourRatio * mean_height;
}
STATS gutters(0, max_gutter + 1);
// Evaluate the boxes for their goodness, calculating the coverage as we go.
// Remove boxes that are not good and shorten the list to the first and
// last good boxes.
int num_deleted_boxes = 0;
bool text_on_image = false;
int good_length = 0;
const TBOX* prev_good_box = NULL;
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
BLOBNBOX* bbox = it.data();
const TBOX& box = bbox->bounding_box();
int mid_y = (box.top() + box.bottom()) / 2;
if (TabFind::WithinTestRegion(2, XAtY(box.bottom()), box.bottom())) {
if (!debug) {
tprintf("After already deleting %d boxes, ", num_deleted_boxes);
Print("Starting evaluation");
}
debug = true;
}
// A good box is one where the nearest neighbour on the inside is closer
// than half the distance to the nearest neighbour on the outside
// (of the putative column).
bool left = IsLeftTab();
int tab_x = XAtY(mid_y);
int gutter_width;
int neighbour_gap;
finder->GutterWidthAndNeighbourGap(tab_x, mean_height, max_gutter, left,
bbox, &gutter_width, &neighbour_gap);
if (debug) {
tprintf("Box (%d,%d)->(%d,%d) has gutter %d, ndist %d\n",
box.left(), box.bottom(), box.right(), box.top(),
gutter_width, neighbour_gap);
}
// Now we can make the test.
if (neighbour_gap * kGutterToNeighbourRatio <= gutter_width) {
// A good box contributes its height to the good_length.
good_length += box.top() - box.bottom();
gutters.add(gutter_width, 1);
// Two good boxes together contribute the gap between them
// to the good_length as well, as long as the gap is not
// too big.
if (prev_good_box != NULL) {
int vertical_gap = box.bottom() - prev_good_box->top();
double size1 = sqrt(static_cast<double>(prev_good_box->area()));
double size2 = sqrt(static_cast<double>(box.area()));
if (vertical_gap < kMaxFillinMultiple * MIN(size1, size2))
good_length += vertical_gap;
if (debug) {
tprintf("Box and prev good, gap=%d, target %g, goodlength=%d\n",
vertical_gap, kMaxFillinMultiple * MIN(size1, size2),
good_length);
}
} else {
// Adjust the start to the first good box.
SetYStart(box.bottom());
}
prev_good_box = &box;
if (bbox->flow() == BTFT_TEXT_ON_IMAGE)
text_on_image = true;
} else {
// Get rid of boxes that are not good.
if (debug) {
tprintf("Bad Box (%d,%d)->(%d,%d) with gutter %d, ndist %d\n",
box.left(), box.bottom(), box.right(), box.top(),
gutter_width, neighbour_gap);
}
it.extract();
++num_deleted_boxes;
}
}
if (debug) {
Print("Evaluating:");
}
// If there are any good boxes, do it again, except this time get rid of
// boxes that have a gutter that is a small fraction of the mean gutter.
// This filters out ends that run into a coincidental gap in the text.
int search_top = endpt_.y();
int search_bottom = startpt_.y();
int median_gutter = IntCastRounded(gutters.median());
if (gutters.get_total() > 0) {
prev_good_box = NULL;
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
BLOBNBOX* bbox = it.data();
const TBOX& box = bbox->bounding_box();
int mid_y = (box.top() + box.bottom()) / 2;
// A good box is one where the gutter width is at least some constant
// fraction of the mean gutter width.
bool left = IsLeftTab();
int tab_x = XAtY(mid_y);
int max_gutter = kGutterMultiple * mean_height;
if (IsRagged()) {
// Ragged edges face a tougher test in that the gap must always be
// within the height of the blob.
max_gutter = kGutterToNeighbourRatio * mean_height;
}
int gutter_width;
int neighbour_gap;
finder->GutterWidthAndNeighbourGap(tab_x, mean_height, max_gutter, left,
bbox, &gutter_width, &neighbour_gap);
// Now we can make the test.
if (gutter_width >= median_gutter * kMinGutterFraction) {
if (prev_good_box == NULL) {
// Adjust the start to the first good box.
SetYStart(box.bottom());
search_bottom = box.top();
}
prev_good_box = &box;
search_top = box.bottom();
} else {
// Get rid of boxes that are not good.
if (debug) {
tprintf("Bad Box (%d,%d)->(%d,%d) with gutter %d, mean gutter %d\n",
box.left(), box.bottom(), box.right(), box.top(),
gutter_width, median_gutter);
}
it.extract();
++num_deleted_boxes;
}
}
}
// If there has been a good box, adjust the end.
if (prev_good_box != NULL) {
SetYEnd(prev_good_box->top());
// Compute the percentage of the vector that is occupied by good boxes.
int length = endpt_.y() - startpt_.y();
percent_score_ = 100 * good_length / length;
if (num_deleted_boxes > 0) {
needs_refit_ = true;
FitAndEvaluateIfNeeded(vertical, finder);
if (boxes_.empty())
return;
}
// Test the gutter over the whole vector, instead of just at the boxes.
int required_shift;
if (search_bottom > search_top) {
search_bottom = startpt_.y();
search_top = endpt_.y();
}
double min_gutter_width = kLineCountReciprocal / boxes_.length();
min_gutter_width += IsRagged() ? kMinRaggedGutter : kMinAlignedGutter;
min_gutter_width *= mean_height;
int max_gutter_width = IntCastRounded(min_gutter_width) + 1;
if (median_gutter > max_gutter_width)
max_gutter_width = median_gutter;
int gutter_width = finder->GutterWidth(search_bottom, search_top, *this,
text_on_image, max_gutter_width,
&required_shift);
if (gutter_width < min_gutter_width) {
if (debug) {
tprintf("Rejecting bad tab Vector with %d gutter vs %g min\n",
gutter_width, min_gutter_width);
}
boxes_.shallow_clear();
percent_score_ = 0;
} else if (debug) {
tprintf("Final gutter %d, vs limit of %g, required shift = %d\n",
gutter_width, min_gutter_width, required_shift);
}
} else {
// There are no good boxes left, so score is 0.
percent_score_ = 0;
}
if (debug) {
Print("Evaluation complete:");
}
}
// (Re)Fit a line to the stored points. Returns false if the line
// is degenerate. Althougth the TabVector code mostly doesn't care about the
// direction of lines, XAtY would give silly results for a horizontal line.
// The class is mostly aimed at use for vertical lines representing
// horizontal tab stops.
bool TabVector::Fit(ICOORD vertical, bool force_parallel) {
needs_refit_ = false;
if (boxes_.empty()) {
// Don't refit something with no boxes, as that only happens
// in Evaluate, and we don't want to end up with a zero vector.
if (!force_parallel)
return false;
// If we are forcing parallel, then we just need to set the sort_key_.
ICOORD midpt = startpt_;
midpt += endpt_;
midpt /= 2;
sort_key_ = SortKey(vertical, midpt.x(), midpt.y());
return startpt_.y() != endpt_.y();
}
if (!force_parallel && !IsRagged()) {
// Use a fitted line as the vertical.
DetLineFit linepoints;
BLOBNBOX_C_IT it(&boxes_);
// Fit a line to all the boxes in the list.
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
BLOBNBOX* bbox = it.data();
TBOX box = bbox->bounding_box();
int x1 = IsRightTab() ? box.right() : box.left();
ICOORD boxpt(x1, box.bottom());
linepoints.Add(boxpt);
if (it.at_last()) {
ICOORD top_pt(x1, box.top());
linepoints.Add(top_pt);
}
}
linepoints.Fit(&startpt_, &endpt_);
if (startpt_.y() != endpt_.y()) {
vertical = endpt_;
vertical -= startpt_;
}
}
int start_y = startpt_.y();
int end_y = endpt_.y();
sort_key_ = IsLeftTab() ? MAX_INT32 : -MAX_INT32;
BLOBNBOX_C_IT it(&boxes_);
// Choose a line parallel to the vertical such that all boxes are on the
// correct side of it.
mean_width_ = 0;
int width_count = 0;
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
BLOBNBOX* bbox = it.data();
TBOX box = bbox->bounding_box();
mean_width_ += box.width();
++width_count;
int x1 = IsRightTab() ? box.right() : box.left();
// Test both the bottom and the top, as one will be more extreme, depending
// on the direction of skew.
int bottom_y = box.bottom();
int top_y = box.top();
int key = SortKey(vertical, x1, bottom_y);
if (IsLeftTab() == (key < sort_key_)) {
sort_key_ = key;
startpt_ = ICOORD(x1, bottom_y);
}
key = SortKey(vertical, x1, top_y);
if (IsLeftTab() == (key < sort_key_)) {
sort_key_ = key;
startpt_ = ICOORD(x1, top_y);
}
if (it.at_first())
start_y = bottom_y;
if (it.at_last())
end_y = top_y;
}
if (width_count > 0) {
mean_width_ = (mean_width_ + width_count - 1) / width_count;
}
endpt_ = startpt_ + vertical;
needs_evaluation_ = true;
if (start_y != end_y) {
// Set the ends of the vector to fully include the first and last blobs.
startpt_.set_x(XAtY(vertical, sort_key_, start_y));
startpt_.set_y(start_y);
endpt_.set_x(XAtY(vertical, sort_key_, end_y));
endpt_.set_y(end_y);
return true;
}
return false;
}
// Returns the singleton partner if there is one, or NULL otherwise.
TabVector* TabVector::GetSinglePartner() {
if (!partners_.singleton())
return NULL;
TabVector_C_IT partner_it(&partners_);
TabVector* partner = partner_it.data();
return partner;
}
// Return the partner of this TabVector if the vector qualifies as
// being a vertical text line, otherwise NULL.
TabVector* TabVector::VerticalTextlinePartner() {
if (!partners_.singleton())
return NULL;
TabVector_C_IT partner_it(&partners_);
TabVector* partner = partner_it.data();
BLOBNBOX_C_IT box_it1(&boxes_);
BLOBNBOX_C_IT box_it2(&partner->boxes_);
// Count how many boxes are also in the other list.
// At the same time, gather the mean width and median vertical gap.
if (textord_debug_tabfind > 1) {
Print("Testing for vertical text");
partner->Print(" partner");
}
int num_matched = 0;
int num_unmatched = 0;
int total_widths = 0;
int width = startpt().x() - partner->startpt().x();
if (width < 0)
width = -width;
STATS gaps(0, width * 2);
BLOBNBOX* prev_bbox = NULL;
box_it2.mark_cycle_pt();
for (box_it1.mark_cycle_pt(); !box_it1.cycled_list(); box_it1.forward()) {
BLOBNBOX* bbox = box_it1.data();
TBOX box = bbox->bounding_box();
if (prev_bbox != NULL) {
gaps.add(box.bottom() - prev_bbox->bounding_box().top(), 1);
}
while (!box_it2.cycled_list() && box_it2.data() != bbox &&
box_it2.data()->bounding_box().bottom() < box.bottom()) {
box_it2.forward();
}
if (!box_it2.cycled_list() && box_it2.data() == bbox &&
bbox->region_type() >= BRT_UNKNOWN &&
(prev_bbox == NULL || prev_bbox->region_type() >= BRT_UNKNOWN))
++num_matched;
else
++num_unmatched;
total_widths += box.width();
prev_bbox = bbox;
}
if (num_unmatched + num_matched == 0) return NULL;
double avg_width = total_widths * 1.0 / (num_unmatched + num_matched);
double max_gap = textord_tabvector_vertical_gap_fraction * avg_width;
int min_box_match = static_cast<int>((num_matched + num_unmatched) *
textord_tabvector_vertical_box_ratio);
bool is_vertical = (gaps.get_total() > 0 &&
num_matched >= min_box_match &&
gaps.median() <= max_gap);
if (textord_debug_tabfind > 1) {
tprintf("gaps=%d, matched=%d, unmatched=%d, min_match=%d "
"median gap=%.2f, width=%.2f max_gap=%.2f Vertical=%s\n",
gaps.get_total(), num_matched, num_unmatched, min_box_match,
gaps.median(), avg_width, max_gap, is_vertical?"Yes":"No");
}
return (is_vertical) ? partner : NULL;
}
// The constructor is private.
TabVector::TabVector(int extended_ymin, int extended_ymax,
TabAlignment alignment, BLOBNBOX_CLIST* boxes)
: extended_ymin_(extended_ymin), extended_ymax_(extended_ymax),
sort_key_(0), percent_score_(0), mean_width_(0),
needs_refit_(true), needs_evaluation_(true), alignment_(alignment),
top_constraints_(NULL), bottom_constraints_(NULL) {
BLOBNBOX_C_IT it(&boxes_);
it.add_list_after(boxes);
}
// Delete this, but first, repoint all the partners to point to
// replacement. If replacement is NULL, then partner relationships
// are removed.
void TabVector::Delete(TabVector* replacement) {
TabVector_C_IT it(&partners_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* partner = it.data();
TabVector_C_IT p_it(&partner->partners_);
// If partner already has replacement in its list, then make
// replacement null, and just remove this TabVector when we find it.
TabVector* partner_replacement = replacement;
for (p_it.mark_cycle_pt(); !p_it.cycled_list(); p_it.forward()) {
TabVector* p_partner = p_it.data();
if (p_partner == partner_replacement) {
partner_replacement = NULL;
break;
}
}
// Remove all references to this, and replace with replacement if not NULL.
for (p_it.mark_cycle_pt(); !p_it.cycled_list(); p_it.forward()) {
TabVector* p_partner = p_it.data();
if (p_partner == this) {
p_it.extract();
if (partner_replacement != NULL)
p_it.add_before_stay_put(partner_replacement);
}
}
if (partner_replacement != NULL) {
partner_replacement->AddPartner(partner);
}
}
delete this;
}
} // namespace tesseract.
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