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tabfind.cpp
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///////////////////////////////////////////////////////////////////////
// File: TabFind.cpp
// Description: Subclass of BBGrid to find vertically aligned blobs.
// Author: Ray Smith
// Created: Fri Mar 21 15:03:01 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 HAVE_CONFIG_H
#include "config_auto.h"
#endif
#include "tabfind.h"
#include "alignedblob.h"
#include "blobbox.h"
#include "colpartitiongrid.h"
#include "detlinefit.h"
#include "linefind.h"
#include "ndminx.h"
namespace tesseract {
// Multiple of box size to search for initial gaps.
const int kTabRadiusFactor = 5;
// Min and Max multiple of height to search vertically when extrapolating.
const int kMinVerticalSearch = 3;
const int kMaxVerticalSearch = 12;
const int kMaxRaggedSearch = 25;
// Minimum number of lines in a column width to make it interesting.
const int kMinLinesInColumn = 10;
// Minimum width of a column to be interesting.
const int kMinColumnWidth = 200;
// Minimum fraction of total column lines for a column to be interesting.
const double kMinFractionalLinesInColumn = 0.125;
// Fraction of height used as alignment tolerance for aligned tabs.
const double kAlignedFraction = 0.03125;
// Maximum gutter width (in absolute inch) that we care about
const double kMaxGutterWidthAbsolute = 2.00;
// Multiplier of gridsize for min gutter width of TT_MAYBE_RAGGED blobs.
const int kRaggedGutterMultiple = 5;
// Min aspect ratio of tall objects to be considered a separator line.
// (These will be ignored in searching the gutter for obstructions.)
const double kLineFragmentAspectRatio = 10.0;
// Min number of points to accept after evaluation.
const int kMinEvaluatedTabs = 3;
// Up to 30 degrees is allowed for rotations of diacritic blobs.
// Keep this value slightly larger than kCosSmallAngle in blobbox.cpp
// so that the assert there never fails.
const double kCosMaxSkewAngle = 0.866025;
BOOL_VAR(textord_tabfind_show_initialtabs, false, "Show tab candidates");
BOOL_VAR(textord_tabfind_show_finaltabs, false, "Show tab vectors");
TabFind::TabFind(int gridsize, const ICOORD& bleft, const ICOORD& tright,
TabVector_LIST* vlines, int vertical_x, int vertical_y,
int resolution)
: AlignedBlob(gridsize, bleft, tright),
resolution_(resolution),
image_origin_(0, tright.y() - 1) {
width_cb_ = NULL;
v_it_.set_to_list(&vectors_);
v_it_.add_list_after(vlines);
SetVerticalSkewAndParellelize(vertical_x, vertical_y);
width_cb_ = NewPermanentTessCallback(this, &TabFind::CommonWidth);
}
TabFind::~TabFind() {
if (width_cb_ != NULL)
delete width_cb_;
}
///////////////// PUBLIC functions (mostly used by TabVector). //////////////
// Insert a list of blobs into the given grid (not necessarily this).
// If take_ownership is true, then the blobs are removed from the source list.
// See InsertBlob for the other arguments.
// It would seem to make more sense to swap this and grid, but this way
// around allows grid to not be derived from TabFind, eg a ColPartitionGrid,
// while the grid that provides the tab stops(this) has to be derived from
// TabFind.
void TabFind::InsertBlobsToGrid(bool h_spread, bool v_spread,
BLOBNBOX_LIST* blobs,
BBGrid<BLOBNBOX, BLOBNBOX_CLIST,
BLOBNBOX_C_IT>* grid) {
BLOBNBOX_IT blob_it(blobs);
int b_count = 0;
int reject_count = 0;
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
// if (InsertBlob(true, true, blob, grid)) {
if (InsertBlob(h_spread, v_spread, blob, grid)) {
++b_count;
} else {
++reject_count;
}
}
if (textord_debug_tabfind) {
tprintf("Inserted %d blobs into grid, %d rejected.\n",
b_count, reject_count);
}
}
// Insert a single blob into the given grid (not necessarily this).
// If h_spread, then all cells covered horizontally by the box are
// used, otherwise, just the bottom-left. Similarly for v_spread.
// A side effect is that the left and right rule edges of the blob are
// set according to the tab vectors in this (not grid).
bool TabFind::InsertBlob(bool h_spread, bool v_spread, BLOBNBOX* blob,
BBGrid<BLOBNBOX, BLOBNBOX_CLIST,
BLOBNBOX_C_IT>* grid) {
TBOX box = blob->bounding_box();
blob->set_left_rule(LeftEdgeForBox(box, false, false));
blob->set_right_rule(RightEdgeForBox(box, false, false));
blob->set_left_crossing_rule(LeftEdgeForBox(box, true, false));
blob->set_right_crossing_rule(RightEdgeForBox(box, true, false));
if (blob->joined_to_prev())
return false;
grid->InsertBBox(h_spread, v_spread, blob);
return true;
}
// Calls SetBlobRuleEdges for all the blobs in the given block.
void TabFind::SetBlockRuleEdges(TO_BLOCK* block) {
SetBlobRuleEdges(&block->blobs);
SetBlobRuleEdges(&block->small_blobs);
SetBlobRuleEdges(&block->noise_blobs);
SetBlobRuleEdges(&block->large_blobs);
}
// Sets the left and right rule and crossing_rules for the blobs in the given
// list by fiding the next outermost tabvectors for each blob.
void TabFind::SetBlobRuleEdges(BLOBNBOX_LIST* blobs) {
BLOBNBOX_IT blob_it(blobs);
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
TBOX box = blob->bounding_box();
blob->set_left_rule(LeftEdgeForBox(box, false, false));
blob->set_right_rule(RightEdgeForBox(box, false, false));
blob->set_left_crossing_rule(LeftEdgeForBox(box, true, false));
blob->set_right_crossing_rule(RightEdgeForBox(box, true, false));
}
}
// Returns the gutter width of the given TabVector between the given y limits.
// Also returns x-shift to be added to the vector to clear any intersecting
// blobs. The shift is deducted from the returned gutter.
// If ignore_unmergeables is true, then blobs of UnMergeableType are
// ignored as if they don't exist. (Used for text on image.)
// max_gutter_width is used as the maximum width worth searching for in case
// there is nothing near the TabVector.
int TabFind::GutterWidth(int bottom_y, int top_y, const TabVector& v,
bool ignore_unmergeables, int max_gutter_width,
int* required_shift) {
bool right_to_left = v.IsLeftTab();
int bottom_x = v.XAtY(bottom_y);
int top_x = v.XAtY(top_y);
int start_x = right_to_left ? MAX(top_x, bottom_x) : MIN(top_x, bottom_x);
BlobGridSearch sidesearch(this);
sidesearch.StartSideSearch(start_x, bottom_y, top_y);
int min_gap = max_gutter_width;
*required_shift = 0;
BLOBNBOX* blob = NULL;
while ((blob = sidesearch.NextSideSearch(right_to_left)) != NULL) {
const TBOX& box = blob->bounding_box();
if (box.bottom() >= top_y || box.top() <= bottom_y)
continue; // Doesn't overlap enough.
if (box.height() >= gridsize() * 2 &&
box.height() > box.width() * kLineFragmentAspectRatio) {
// Skip likely separator line residue.
continue;
}
if (ignore_unmergeables && BLOBNBOX::UnMergeableType(blob->region_type()))
continue; // Skip non-text if required.
int mid_y = (box.bottom() + box.top()) / 2;
// We use the x at the mid-y so that the required_shift guarantees
// to clear all the blobs on the tab-stop. If we use the min/max
// of x at top/bottom of the blob, then exactness would be required,
// which is not a good thing.
int tab_x = v.XAtY(mid_y);
int gap;
if (right_to_left) {
gap = tab_x - box.right();
if (gap < 0 && box.left() - tab_x < *required_shift)
*required_shift = box.left() - tab_x;
} else {
gap = box.left() - tab_x;
if (gap < 0 && box.right() - tab_x > *required_shift)
*required_shift = box.right() - tab_x;
}
if (gap > 0 && gap < min_gap)
min_gap = gap;
}
// Result may be negative, in which case, this is a really bad tabstop.
return min_gap - abs(*required_shift);
}
// Find the gutter width and distance to inner neighbour for the given blob.
void TabFind::GutterWidthAndNeighbourGap(int tab_x, int mean_height,
int max_gutter, bool left,
BLOBNBOX* bbox, int* gutter_width,
int* neighbour_gap ) {
const TBOX& box = bbox->bounding_box();
// The gutter and internal sides of the box.
int gutter_x = left ? box.left() : box.right();
int internal_x = left ? box.right() : box.left();
// On ragged edges, the gutter side of the box is away from the tabstop.
int tab_gap = left ? gutter_x - tab_x : tab_x - gutter_x;
*gutter_width = max_gutter;
// If the box is away from the tabstop, we need to increase
// the allowed gutter width.
if (tab_gap > 0)
*gutter_width += tab_gap;
bool debug = WithinTestRegion(2, box.left(), box.bottom());
if (debug)
tprintf("Looking in gutter\n");
// Find the nearest blob on the outside of the column.
BLOBNBOX* gutter_bbox = AdjacentBlob(bbox, left,
bbox->flow() == BTFT_TEXT_ON_IMAGE, 0.0,
*gutter_width, box.top(), box.bottom());
if (gutter_bbox != NULL) {
const TBOX& gutter_box = gutter_bbox->bounding_box();
*gutter_width = left ? tab_x - gutter_box.right()
: gutter_box.left() - tab_x;
}
if (*gutter_width >= max_gutter) {
// If there is no box because a tab was in the way, get the tab coord.
TBOX gutter_box(box);
if (left) {
gutter_box.set_left(tab_x - max_gutter - 1);
gutter_box.set_right(tab_x - max_gutter);
int tab_gutter = RightEdgeForBox(gutter_box, true, false);
if (tab_gutter < tab_x - 1)
*gutter_width = tab_x - tab_gutter;
} else {
gutter_box.set_left(tab_x + max_gutter);
gutter_box.set_right(tab_x + max_gutter + 1);
int tab_gutter = LeftEdgeForBox(gutter_box, true, false);
if (tab_gutter > tab_x + 1)
*gutter_width = tab_gutter - tab_x;
}
}
if (*gutter_width > max_gutter)
*gutter_width = max_gutter;
// Now look for a neighbour on the inside.
if (debug)
tprintf("Looking for neighbour\n");
BLOBNBOX* neighbour = AdjacentBlob(bbox, !left,
bbox->flow() == BTFT_TEXT_ON_IMAGE, 0.0,
*gutter_width, box.top(), box.bottom());
int neighbour_edge = left ? RightEdgeForBox(box, true, false)
: LeftEdgeForBox(box, true, false);
if (neighbour != NULL) {
const TBOX& n_box = neighbour->bounding_box();
if (debug) {
tprintf("Found neighbour:");
n_box.print();
}
if (left && n_box.left() < neighbour_edge)
neighbour_edge = n_box.left();
else if (!left && n_box.right() > neighbour_edge)
neighbour_edge = n_box.right();
}
*neighbour_gap = left ? neighbour_edge - internal_x
: internal_x - neighbour_edge;
}
// Return the x-coord that corresponds to the right edge for the given
// box. If there is a rule line to the right that vertically overlaps it,
// then return the x-coord of the rule line, otherwise return the right
// edge of the page. For details see RightTabForBox below.
int TabFind::RightEdgeForBox(const TBOX& box, bool crossing, bool extended) {
TabVector* v = RightTabForBox(box, crossing, extended);
return v == NULL ? tright_.x() : v->XAtY((box.top() + box.bottom()) / 2);
}
// As RightEdgeForBox, but finds the left Edge instead.
int TabFind::LeftEdgeForBox(const TBOX& box, bool crossing, bool extended) {
TabVector* v = LeftTabForBox(box, crossing, extended);
return v == NULL ? bleft_.x() : v->XAtY((box.top() + box.bottom()) / 2);
}
// This comment documents how this function works.
// For its purpose and arguments, see the comment in tabfind.h.
// TabVectors are stored sorted by perpendicular distance of middle from
// the global mean vertical vector. Since the individual vectors can have
// differing directions, their XAtY for a given y is not necessarily in the
// right order. Therefore the search has to be run with a margin.
// The middle of a vector that passes through (x,y) cannot be higher than
// halfway from y to the top, or lower than halfway from y to the bottom
// of the coordinate range; therefore, the search margin is the range of
// sort keys between these halfway points. Any vector with a sort key greater
// than the upper margin must be to the right of x at y, and likewise any
// vector with a sort key less than the lower margin must pass to the left
// of x at y.
TabVector* TabFind::RightTabForBox(const TBOX& box, bool crossing,
bool extended) {
if (v_it_.empty())
return NULL;
int top_y = box.top();
int bottom_y = box.bottom();
int mid_y = (top_y + bottom_y) / 2;
int right = crossing ? (box.left() + box.right()) / 2 : box.right();
int min_key, max_key;
SetupTabSearch(right, mid_y, &min_key, &max_key);
// Position the iterator at the first TabVector with sort_key >= min_key.
while (!v_it_.at_first() && v_it_.data()->sort_key() >= min_key)
v_it_.backward();
while (!v_it_.at_last() && v_it_.data()->sort_key() < min_key)
v_it_.forward();
// Find the leftmost tab vector that overlaps and has XAtY(mid_y) >= right.
TabVector* best_v = NULL;
int best_x = -1;
int key_limit = -1;
do {
TabVector* v = v_it_.data();
int x = v->XAtY(mid_y);
if (x >= right &&
(v->VOverlap(top_y, bottom_y) > 0 ||
(extended && v->ExtendedOverlap(top_y, bottom_y) > 0))) {
if (best_v == NULL || x < best_x) {
best_v = v;
best_x = x;
// We can guarantee that no better vector can be found if the
// sort key exceeds that of the best by max_key - min_key.
key_limit = v->sort_key() + max_key - min_key;
}
}
// Break when the search is done to avoid wrapping the iterator and
// thereby potentially slowing the next search.
if (v_it_.at_last() ||
(best_v != NULL && v->sort_key() > key_limit))
break; // Prevent restarting list for next call.
v_it_.forward();
} while (!v_it_.at_first());
return best_v;
}
// As RightTabForBox, but finds the left TabVector instead.
TabVector* TabFind::LeftTabForBox(const TBOX& box, bool crossing,
bool extended) {
if (v_it_.empty())
return NULL;
int top_y = box.top();
int bottom_y = box.bottom();
int mid_y = (top_y + bottom_y) / 2;
int left = crossing ? (box.left() + box.right()) / 2 : box.left();
int min_key, max_key;
SetupTabSearch(left, mid_y, &min_key, &max_key);
// Position the iterator at the last TabVector with sort_key <= max_key.
while (!v_it_.at_last() && v_it_.data()->sort_key() <= max_key)
v_it_.forward();
while (!v_it_.at_first() && v_it_.data()->sort_key() > max_key) {
v_it_.backward();
}
// Find the rightmost tab vector that overlaps and has XAtY(mid_y) <= left.
TabVector* best_v = NULL;
int best_x = -1;
int key_limit = -1;
do {
TabVector* v = v_it_.data();
int x = v->XAtY(mid_y);
if (x <= left &&
(v->VOverlap(top_y, bottom_y) > 0 ||
(extended && v->ExtendedOverlap(top_y, bottom_y) > 0))) {
if (best_v == NULL || x > best_x) {
best_v = v;
best_x = x;
// We can guarantee that no better vector can be found if the
// sort key is less than that of the best by max_key - min_key.
key_limit = v->sort_key() - (max_key - min_key);
}
}
// Break when the search is done to avoid wrapping the iterator and
// thereby potentially slowing the next search.
if (v_it_.at_first() ||
(best_v != NULL && v->sort_key() < key_limit))
break; // Prevent restarting list for next call.
v_it_.backward();
} while (!v_it_.at_last());
return best_v;
}
// Return true if the given width is close to one of the common
// widths in column_widths_.
bool TabFind::CommonWidth(int width) {
width /= kColumnWidthFactor;
ICOORDELT_IT it(&column_widths_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ICOORDELT* w = it.data();
if (w->x() - 1 <= width && width <= w->y() + 1)
return true;
}
return false;
}
// Return true if the sizes are more than a
// factor of 2 different.
bool TabFind::DifferentSizes(int size1, int size2) {
return size1 > size2 * 2 || size2 > size1 * 2;
}
// Return true if the sizes are more than a
// factor of 5 different.
bool TabFind::VeryDifferentSizes(int size1, int size2) {
return size1 > size2 * 5 || size2 > size1 * 5;
}
///////////////// PROTECTED functions (used by ColumnFinder). //////////////
// Top-level function to find TabVectors in an input page block.
// Returns false if the detected skew angle is impossible.
// Applies the detected skew angle to deskew the tabs, blobs and part_grid.
bool TabFind::FindTabVectors(TabVector_LIST* hlines,
BLOBNBOX_LIST* image_blobs, TO_BLOCK* block,
int min_gutter_width,
double tabfind_aligned_gap_fraction,
ColPartitionGrid* part_grid,
FCOORD* deskew, FCOORD* reskew) {
ScrollView* tab_win = FindInitialTabVectors(image_blobs, min_gutter_width,
tabfind_aligned_gap_fraction,
block);
ComputeColumnWidths(tab_win, part_grid);
TabVector::MergeSimilarTabVectors(vertical_skew_, &vectors_, this);
SortVectors();
CleanupTabs();
if (!Deskew(hlines, image_blobs, block, deskew, reskew))
return false; // Skew angle is too large.
part_grid->Deskew(*deskew);
ApplyTabConstraints();
#ifndef GRAPHICS_DISABLED
if (textord_tabfind_show_finaltabs) {
tab_win = MakeWindow(640, 50, "FinalTabs");
DisplayBoxes(tab_win);
DisplayTabs("FinalTabs", tab_win);
tab_win = DisplayTabVectors(tab_win);
}
#endif // GRAPHICS_DISABLED
return true;
}
// Top-level function to not find TabVectors in an input page block,
// but setup for single column mode.
void TabFind::DontFindTabVectors(BLOBNBOX_LIST* image_blobs, TO_BLOCK* block,
FCOORD* deskew, FCOORD* reskew) {
InsertBlobsToGrid(false, false, image_blobs, this);
InsertBlobsToGrid(true, false, &block->blobs, this);
deskew->set_x(1.0f);
deskew->set_y(0.0f);
reskew->set_x(1.0f);
reskew->set_y(0.0f);
}
// Cleans up the lists of blobs in the block ready for use by TabFind.
// Large blobs that look like text are moved to the main blobs list.
// Main blobs that are superseded by the image blobs are deleted.
void TabFind::TidyBlobs(TO_BLOCK* block) {
BLOBNBOX_IT large_it = &block->large_blobs;
BLOBNBOX_IT blob_it = &block->blobs;
int b_count = 0;
for (large_it.mark_cycle_pt(); !large_it.cycled_list(); large_it.forward()) {
BLOBNBOX* large_blob = large_it.data();
if (large_blob->owner() != NULL) {
blob_it.add_to_end(large_it.extract());
++b_count;
}
}
if (textord_debug_tabfind) {
tprintf("Moved %d large blobs to normal list\n",
b_count);
#ifndef GRAPHICS_DISABLED
ScrollView* rej_win = MakeWindow(500, 300, "Image blobs");
block->plot_graded_blobs(rej_win);
block->plot_noise_blobs(rej_win);
rej_win->Update();
#endif // GRAPHICS_DISABLED
}
block->DeleteUnownedNoise();
}
// Helper function to setup search limits for *TabForBox.
void TabFind::SetupTabSearch(int x, int y, int* min_key, int* max_key) {
int key1 = TabVector::SortKey(vertical_skew_, x, (y + tright_.y()) / 2);
int key2 = TabVector::SortKey(vertical_skew_, x, (y + bleft_.y()) / 2);
*min_key = MIN(key1, key2);
*max_key = MAX(key1, key2);
}
ScrollView* TabFind::DisplayTabVectors(ScrollView* tab_win) {
#ifndef GRAPHICS_DISABLED
// For every vector, display it.
TabVector_IT it(&vectors_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* vector = it.data();
vector->Display(tab_win);
}
tab_win->Update();
#endif
return tab_win;
}
// PRIVATE CODE.
//
// First part of FindTabVectors, which may be used twice if the text
// is mostly of vertical alignment.
ScrollView* TabFind::FindInitialTabVectors(BLOBNBOX_LIST* image_blobs,
int min_gutter_width,
double tabfind_aligned_gap_fraction,
TO_BLOCK* block) {
if (textord_tabfind_show_initialtabs) {
ScrollView* line_win = MakeWindow(0, 0, "VerticalLines");
line_win = DisplayTabVectors(line_win);
}
// Prepare the grid.
if (image_blobs != NULL)
InsertBlobsToGrid(true, false, image_blobs, this);
InsertBlobsToGrid(true, false, &block->blobs, this);
ScrollView* initial_win = FindTabBoxes(min_gutter_width,
tabfind_aligned_gap_fraction);
FindAllTabVectors(min_gutter_width);
TabVector::MergeSimilarTabVectors(vertical_skew_, &vectors_, this);
SortVectors();
EvaluateTabs();
if (textord_tabfind_show_initialtabs && initial_win != NULL)
initial_win = DisplayTabVectors(initial_win);
MarkVerticalText();
return initial_win;
}
// Helper displays all the boxes in the given vector on the given window.
static void DisplayBoxVector(const GenericVector<BLOBNBOX*>& boxes,
ScrollView* win) {
#ifndef GRAPHICS_DISABLED
for (int i = 0; i < boxes.size(); ++i) {
TBOX box = boxes[i]->bounding_box();
int left_x = box.left();
int right_x = box.right();
int top_y = box.top();
int bottom_y = box.bottom();
ScrollView::Color box_color = boxes[i]->BoxColor();
win->Pen(box_color);
win->Rectangle(left_x, bottom_y, right_x, top_y);
}
win->Update();
#endif // GRAPHICS_DISABLED
}
// For each box in the grid, decide whether it is a candidate tab-stop,
// and if so add it to the left/right tab boxes.
ScrollView* TabFind::FindTabBoxes(int min_gutter_width,
double tabfind_aligned_gap_fraction) {
left_tab_boxes_.clear();
right_tab_boxes_.clear();
// For every bbox in the grid, determine whether it uses a tab on an edge.
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> gsearch(this);
gsearch.StartFullSearch();
BLOBNBOX* bbox;
while ((bbox = gsearch.NextFullSearch()) != NULL) {
if (TestBoxForTabs(bbox, min_gutter_width, tabfind_aligned_gap_fraction)) {
// If it is any kind of tab, insert it into the vectors.
if (bbox->left_tab_type() != TT_NONE)
left_tab_boxes_.push_back(bbox);
if (bbox->right_tab_type() != TT_NONE)
right_tab_boxes_.push_back(bbox);
}
}
// Sort left tabs by left and right by right to see the outermost one first
// on a ragged tab.
left_tab_boxes_.sort(SortByBoxLeft<BLOBNBOX>);
right_tab_boxes_.sort(SortRightToLeft<BLOBNBOX>);
ScrollView* tab_win = NULL;
#ifndef GRAPHICS_DISABLED
if (textord_tabfind_show_initialtabs) {
tab_win = MakeWindow(0, 100, "InitialTabs");
tab_win->Pen(ScrollView::BLUE);
tab_win->Brush(ScrollView::NONE);
// Display the left and right tab boxes.
DisplayBoxVector(left_tab_boxes_, tab_win);
DisplayBoxVector(right_tab_boxes_, tab_win);
tab_win = DisplayTabs("Tabs", tab_win);
}
#endif // GRAPHICS_DISABLED
return tab_win;
}
bool TabFind::TestBoxForTabs(BLOBNBOX* bbox, int min_gutter_width,
double tabfind_aligned_gap_fraction) {
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> radsearch(this);
TBOX box = bbox->bounding_box();
// If there are separator lines, get the column edges.
int left_column_edge = bbox->left_rule();
int right_column_edge = bbox->right_rule();
// The edges of the bounding box of the blob being processed.
int left_x = box.left();
int right_x = box.right();
int top_y = box.top();
int bottom_y = box.bottom();
int height = box.height();
bool debug = WithinTestRegion(3, left_x, top_y);
if (debug) {
tprintf("Column edges for blob at (%d,%d)->(%d,%d) are [%d, %d]\n",
left_x, top_y, right_x, bottom_y,
left_column_edge, right_column_edge);
}
// Compute a search radius based on a multiple of the height.
int radius = (height * kTabRadiusFactor + gridsize_ - 1) / gridsize_;
radsearch.StartRadSearch((left_x + right_x)/2, (top_y + bottom_y)/2, radius);
// In Vertical Page mode, once we have an estimate of the vertical line
// spacing, the minimum amount of gutter space before a possible tab is
// increased under the assumption that column partition is always larger
// than line spacing.
int min_spacing =
static_cast<int>(height * tabfind_aligned_gap_fraction);
if (min_gutter_width > min_spacing)
min_spacing = min_gutter_width;
int min_ragged_gutter = kRaggedGutterMultiple * gridsize();
if (min_gutter_width > min_ragged_gutter)
min_ragged_gutter = min_gutter_width;
int target_right = left_x - min_spacing;
int target_left = right_x + min_spacing;
// We will be evaluating whether the left edge could be a left tab, and
// whether the right edge could be a right tab.
// A box can be a tab if its bool is_(left/right)_tab remains true, meaning
// that no blobs have been found in the gutter during the radial search.
// A box can also be a tab if there are objects in the gutter only above
// or only below, and there are aligned objects on the opposite side, but
// not too many unaligned objects. The maybe_(left/right)_tab_up counts
// aligned objects above and negatively counts unaligned objects above,
// and is set to -MAX_INT32 if a gutter object is found above.
// The other 3 maybe ints work similarly for the other sides.
// These conditions are very strict, to minimize false positives, and really
// only aligned tabs and outermost ragged tab blobs will qualify, so we
// also have maybe_ragged_left/right with less stringent rules.
// A blob that is maybe_ragged_left/right will be further qualified later,
// using the min_ragged_gutter.
bool is_left_tab = true;
bool is_right_tab = true;
bool maybe_ragged_left = true;
bool maybe_ragged_right = true;
int maybe_left_tab_up = 0;
int maybe_right_tab_up = 0;
int maybe_left_tab_down = 0;
int maybe_right_tab_down = 0;
if (bbox->leader_on_left()) {
is_left_tab = false;
maybe_ragged_left = false;
maybe_left_tab_up = -MAX_INT32;
maybe_left_tab_down = -MAX_INT32;
}
if (bbox->leader_on_right()) {
is_right_tab = false;
maybe_ragged_right = false;
maybe_right_tab_up = -MAX_INT32;
maybe_right_tab_down = -MAX_INT32;
}
int alignment_tolerance = static_cast<int>(resolution_ * kAlignedFraction);
BLOBNBOX* neighbour = NULL;
while ((neighbour = radsearch.NextRadSearch()) != NULL) {
if (neighbour == bbox)
continue;
TBOX nbox = neighbour->bounding_box();
int n_left = nbox.left();
int n_right = nbox.right();
if (debug)
tprintf("Neighbour at (%d,%d)->(%d,%d)\n",
n_left, nbox.bottom(), n_right, nbox.top());
// If the neighbouring blob is the wrong side of a separator line, then it
// "doesn't exist" as far as we are concerned.
if (n_right > right_column_edge || n_left < left_column_edge ||
left_x < neighbour->left_rule() || right_x > neighbour->right_rule())
continue; // Separator line in the way.
int n_mid_x = (n_left + n_right) / 2;
int n_mid_y = (nbox.top() + nbox.bottom()) / 2;
if (n_mid_x <= left_x && n_right >= target_right) {
if (debug)
tprintf("Not a left tab\n");
is_left_tab = false;
if (n_mid_y < top_y)
maybe_left_tab_down = -MAX_INT32;
if (n_mid_y > bottom_y)
maybe_left_tab_up = -MAX_INT32;
} else if (NearlyEqual(left_x, n_left, alignment_tolerance)) {
if (debug)
tprintf("Maybe a left tab\n");
if (n_mid_y > top_y && maybe_left_tab_up > -MAX_INT32)
++maybe_left_tab_up;
if (n_mid_y < bottom_y && maybe_left_tab_down > -MAX_INT32)
++maybe_left_tab_down;
} else if (n_left < left_x && n_right >= left_x) {
// Overlaps but not aligned so negative points on a maybe.
if (debug)
tprintf("Maybe Not a left tab\n");
if (n_mid_y > top_y && maybe_left_tab_up > -MAX_INT32)
--maybe_left_tab_up;
if (n_mid_y < bottom_y && maybe_left_tab_down > -MAX_INT32)
--maybe_left_tab_down;
}
if (n_left < left_x && nbox.y_overlap(box) && n_right >= target_right) {
maybe_ragged_left = false;
if (debug)
tprintf("Not a ragged left\n");
}
if (n_mid_x >= right_x && n_left <= target_left) {
if (debug)
tprintf("Not a right tab\n");
is_right_tab = false;
if (n_mid_y < top_y)
maybe_right_tab_down = -MAX_INT32;
if (n_mid_y > bottom_y)
maybe_right_tab_up = -MAX_INT32;
} else if (NearlyEqual(right_x, n_right, alignment_tolerance)) {
if (debug)
tprintf("Maybe a right tab\n");
if (n_mid_y > top_y && maybe_right_tab_up > -MAX_INT32)
++maybe_right_tab_up;
if (n_mid_y < bottom_y && maybe_right_tab_down > -MAX_INT32)
++maybe_right_tab_down;
} else if (n_right > right_x && n_left <= right_x) {
// Overlaps but not aligned so negative points on a maybe.
if (debug)
tprintf("Maybe Not a right tab\n");
if (n_mid_y > top_y && maybe_right_tab_up > -MAX_INT32)
--maybe_right_tab_up;
if (n_mid_y < bottom_y && maybe_right_tab_down > -MAX_INT32)
--maybe_right_tab_down;
}
if (n_right > right_x && nbox.y_overlap(box) && n_left <= target_left) {
maybe_ragged_right = false;
if (debug)
tprintf("Not a ragged right\n");
}
if (maybe_left_tab_down == -MAX_INT32 && maybe_left_tab_up == -MAX_INT32 &&
maybe_right_tab_down == -MAX_INT32 && maybe_right_tab_up == -MAX_INT32)
break;
}
if (is_left_tab || maybe_left_tab_up > 1 || maybe_left_tab_down > 1) {
bbox->set_left_tab_type(TT_MAYBE_ALIGNED);
} else if (maybe_ragged_left && ConfirmRaggedLeft(bbox, min_ragged_gutter)) {
bbox->set_left_tab_type(TT_MAYBE_RAGGED);
} else {
bbox->set_left_tab_type(TT_NONE);
}
if (is_right_tab || maybe_right_tab_up > 1 || maybe_right_tab_down > 1) {
bbox->set_right_tab_type(TT_MAYBE_ALIGNED);
} else if (maybe_ragged_right &&
ConfirmRaggedRight(bbox, min_ragged_gutter)) {
bbox->set_right_tab_type(TT_MAYBE_RAGGED);
} else {
bbox->set_right_tab_type(TT_NONE);
}
if (debug) {
tprintf("Left result = %s, Right result=%s\n",
bbox->left_tab_type() == TT_MAYBE_ALIGNED ? "Aligned" :
(bbox->left_tab_type() == TT_MAYBE_RAGGED ? "Ragged" : "None"),
bbox->right_tab_type() == TT_MAYBE_ALIGNED ? "Aligned" :
(bbox->right_tab_type() == TT_MAYBE_RAGGED ? "Ragged" : "None"));
}
return bbox->left_tab_type() != TT_NONE || bbox->right_tab_type() != TT_NONE;
}
// Returns true if there is nothing in the rectangle of width min_gutter to
// the left of bbox.
bool TabFind::ConfirmRaggedLeft(BLOBNBOX* bbox, int min_gutter) {
TBOX search_box(bbox->bounding_box());
search_box.set_right(search_box.left());
search_box.set_left(search_box.left() - min_gutter);
return NothingYOverlapsInBox(search_box, bbox->bounding_box());
}
// Returns true if there is nothing in the rectangle of width min_gutter to
// the right of bbox.
bool TabFind::ConfirmRaggedRight(BLOBNBOX* bbox, int min_gutter) {
TBOX search_box(bbox->bounding_box());
search_box.set_left(search_box.right());
search_box.set_right(search_box.right() + min_gutter);
return NothingYOverlapsInBox(search_box, bbox->bounding_box());
}
// Returns true if there is nothing in the given search_box that vertically
// overlaps target_box other than target_box itself.
bool TabFind::NothingYOverlapsInBox(const TBOX& search_box,
const TBOX& target_box) {
BlobGridSearch rsearch(this);
rsearch.StartRectSearch(search_box);
BLOBNBOX* blob;
while ((blob = rsearch.NextRectSearch()) != NULL) {
const TBOX& box = blob->bounding_box();
if (box.y_overlap(target_box) && !(box == target_box))
return false;
}
return true;
}
void TabFind::FindAllTabVectors(int min_gutter_width) {
// A list of vectors that will be created in estimating the skew.
TabVector_LIST dummy_vectors;
// An estimate of the vertical direction, revised as more lines are added.
int vertical_x = 0;
int vertical_y = 1;
// Find an estimate of the vertical direction by finding some tab vectors.
// Slowly up the search size until we get some vectors.
for (int search_size = kMinVerticalSearch; search_size < kMaxVerticalSearch;
search_size += kMinVerticalSearch) {
int vector_count = FindTabVectors(search_size, TA_LEFT_ALIGNED,
min_gutter_width,
&dummy_vectors,
&vertical_x, &vertical_y);
vector_count += FindTabVectors(search_size, TA_RIGHT_ALIGNED,
min_gutter_width,
&dummy_vectors,
&vertical_x, &vertical_y);
if (vector_count > 0)
break;
}
// Get rid of the test vectors and reset the types of the tabs.
dummy_vectors.clear();
for (int i = 0; i < left_tab_boxes_.size(); ++i) {
BLOBNBOX* bbox = left_tab_boxes_[i];
if (bbox->left_tab_type() == TT_CONFIRMED)
bbox->set_left_tab_type(TT_MAYBE_ALIGNED);
}
for (int i = 0; i < right_tab_boxes_.size(); ++i) {
BLOBNBOX* bbox = right_tab_boxes_[i];
if (bbox->right_tab_type() == TT_CONFIRMED)
bbox->set_right_tab_type(TT_MAYBE_ALIGNED);
}
if (textord_debug_tabfind) {
tprintf("Beginning real tab search with vertical = %d,%d...\n",
vertical_x, vertical_y);
}
// Now do the real thing ,but keep the vectors in the dummy_vectors list
// until they are all done, so we don't get the tab vectors confused with
// the rule line vectors.
FindTabVectors(kMaxVerticalSearch, TA_LEFT_ALIGNED, min_gutter_width,
&dummy_vectors, &vertical_x, &vertical_y);
FindTabVectors(kMaxVerticalSearch, TA_RIGHT_ALIGNED, min_gutter_width,
&dummy_vectors, &vertical_x, &vertical_y);
FindTabVectors(kMaxRaggedSearch, TA_LEFT_RAGGED, min_gutter_width,
&dummy_vectors, &vertical_x, &vertical_y);
FindTabVectors(kMaxRaggedSearch, TA_RIGHT_RAGGED, min_gutter_width,
&dummy_vectors, &vertical_x, &vertical_y);
// Now add the vectors to the vectors_ list.
TabVector_IT v_it(&vectors_);
v_it.add_list_after(&dummy_vectors);
// Now use the summed (mean) vertical vector as the direction for everything.
SetVerticalSkewAndParellelize(vertical_x, vertical_y);
}
// Helper for FindAllTabVectors finds the vectors of a particular type.
int TabFind::FindTabVectors(int search_size_multiple, TabAlignment alignment,
int min_gutter_width, TabVector_LIST* vectors,
int* vertical_x, int* vertical_y) {
TabVector_IT vector_it(vectors);
int vector_count = 0;
// Search the right or left tab boxes, looking for tab vectors.
bool right = alignment == TA_RIGHT_ALIGNED || alignment == TA_RIGHT_RAGGED;
const GenericVector<BLOBNBOX*>& boxes = right ? right_tab_boxes_
: left_tab_boxes_;
for (int i = 0; i < boxes.size(); ++i) {
BLOBNBOX* bbox = boxes[i];
if ((!right && bbox->left_tab_type() == TT_MAYBE_ALIGNED) ||
(right && bbox->right_tab_type() == TT_MAYBE_ALIGNED)) {
TabVector* vector = FindTabVector(search_size_multiple, min_gutter_width,
alignment,
bbox, vertical_x, vertical_y);
if (vector != NULL) {
++vector_count;
vector_it.add_to_end(vector);
}
}
}
return vector_count;
}
// Finds a vector corresponding to a tabstop running through the
// given box of the given alignment type.
// search_size_multiple is a multiple of height used to control
// the size of the search.
// vertical_x and y are updated with an estimate of the real
// vertical direction. (skew finding.)
// Returns NULL if no decent tabstop can be found.
TabVector* TabFind::FindTabVector(int search_size_multiple,
int min_gutter_width,
TabAlignment alignment,
BLOBNBOX* bbox,
int* vertical_x, int* vertical_y) {
int height = MAX(bbox->bounding_box().height(), gridsize());
AlignedBlobParams align_params(*vertical_x, *vertical_y,
height,
search_size_multiple, min_gutter_width,
resolution_, alignment);
// FindVerticalAlignment is in the parent (AlignedBlob) class.
return FindVerticalAlignment(align_params, bbox, vertical_x, vertical_y);
}
// Set the vertical_skew_ member from the given vector and refit
// all vectors parallel to the skew vector.
void TabFind::SetVerticalSkewAndParellelize(int vertical_x, int vertical_y) {
// Fit the vertical vector into an ICOORD, which is 16 bit.
vertical_skew_.set_with_shrink(vertical_x, vertical_y);
if (textord_debug_tabfind)
tprintf("Vertical skew vector=(%d,%d)\n",
vertical_skew_.x(), vertical_skew_.y());
v_it_.set_to_list(&vectors_);
for (v_it_.mark_cycle_pt(); !v_it_.cycled_list(); v_it_.forward()) {
TabVector* v = v_it_.data();
v->Fit(vertical_skew_, true);
}
// Now sort the vectors as their direction has potentially changed.
SortVectors();
}
// Sort all the current vectors using the given vertical direction vector.
void TabFind::SortVectors() {
vectors_.sort(TabVector::SortVectorsByKey);
v_it_.set_to_list(&vectors_);
}
// Evaluate all the current tab vectors.
void TabFind::EvaluateTabs() {
TabVector_IT rule_it(&vectors_);
for (rule_it.mark_cycle_pt(); !rule_it.cycled_list(); rule_it.forward()) {
TabVector* tab = rule_it.data();
if (!tab->IsSeparator()) {
tab->Evaluate(vertical_skew_, this);
if (tab->BoxCount() < kMinEvaluatedTabs) {
if (textord_debug_tabfind > 2)
tab->Print("Too few boxes");
delete rule_it.extract();
v_it_.set_to_list(&vectors_);
} else if (WithinTestRegion(3, tab->startpt().x(), tab->startpt().y())) {
tab->Print("Evaluated tab");
}
}
}
}
// Trace textlines from one side to the other of each tab vector, saving
// the most frequent column widths found in a list so that a given width
// can be tested for being a common width with a simple callback function.
void TabFind::ComputeColumnWidths(ScrollView* tab_win,
ColPartitionGrid* part_grid) {
#ifndef GRAPHICS_DISABLED
if (tab_win != NULL)
tab_win->Pen(ScrollView::WHITE);
#endif // GRAPHICS_DISABLED
// Accumulate column sections into a STATS
int col_widths_size = (tright_.x() - bleft_.x()) / kColumnWidthFactor;
STATS col_widths(0, col_widths_size + 1);
ApplyPartitionsToColumnWidths(part_grid, &col_widths);
#ifndef GRAPHICS_DISABLED
if (tab_win != NULL) {
tab_win->Update();
}
#endif // GRAPHICS_DISABLED
if (textord_debug_tabfind > 1)
col_widths.print();
// Now make a list of column widths.
MakeColumnWidths(col_widths_size, &col_widths);
// Turn the column width into a range.
ApplyPartitionsToColumnWidths(part_grid, NULL);
}
// Finds column width and:
// if col_widths is not null (pass1):
// pair-up tab vectors with existing ColPartitions and accumulate widths.
// else (pass2):
// find the largest real partition width for each recorded column width,
// to be used as the minimum acceptable width.
void TabFind::ApplyPartitionsToColumnWidths(ColPartitionGrid* part_grid,
STATS* col_widths) {
// For every ColPartition in the part_grid, add partners to the tabvectors
// and accumulate the column widths.
ColPartitionGridSearch gsearch(part_grid);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
BLOBNBOX_C_IT blob_it(part->boxes());
if (blob_it.empty())
continue;
BLOBNBOX* left_blob = blob_it.data();
blob_it.move_to_last();
BLOBNBOX* right_blob = blob_it.data();
TabVector* left_vector = LeftTabForBox(left_blob->bounding_box(),
true, false);
if (left_vector == NULL || left_vector->IsRightTab())
continue;
TabVector* right_vector = RightTabForBox(right_blob->bounding_box(),
true, false);
if (right_vector == NULL || right_vector->IsLeftTab())