// Finds a vector corresponding to a set of vertically aligned blob edges
// running through the given box. The type of vector returned and the
// search parameters are determined by the AlignedBlobParams.
// vertical_x and y are updated with an estimate of the real
// vertical direction. (skew finding.)
// Returns NULL if no decent vector can be found.
TabVector* AlignedBlob::FindVerticalAlignment(AlignedBlobParams align_params,
BLOBNBOX* bbox,
int* vertical_x,
int* vertical_y) {
int ext_start_y, ext_end_y;
BLOBNBOX_CLIST good_points;
// Search up and then down from the starting bbox.
int pt_count = AlignTabs(align_params, false, bbox, &good_points, &ext_end_y);
pt_count += AlignTabs(align_params, true, bbox, &good_points, &ext_start_y);
BLOBNBOX_C_IT it(&good_points);
it.move_to_last();
int end_y = it.data()->bounding_box().top();
it.move_to_first();
int start_y = it.data()->bounding_box().bottom();
if (pt_count >= align_params.min_points &&
end_y - start_y >= align_params.min_length) {
int confirmed_points = 0;
// Count existing confirmed points to see if vector is acceptable.
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
bbox = it.data();
if (align_params.right_tab) {
if (bbox->right_tab_type() == align_params.confirmed_type)
++confirmed_points;
} else {
if (bbox->left_tab_type() == align_params.confirmed_type)
++confirmed_points;
}
}
// Ragged vectors are not allowed to use too many already used points.
if (!align_params.ragged ||
confirmed_points + confirmed_points < pt_count) {
const TBOX& box = bbox->bounding_box();
if (WithinTestRegion(2, box.left(), box.bottom())) {
tprintf("Confirming tab vector of %d pts starting at %d,%d\n",
pt_count, box.left(), box.bottom());
}
// Flag all the aligned neighbours as confirmed .
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
bbox = it.data();
if (align_params.right_tab) {
bbox->set_right_tab_type(align_params.confirmed_type);
} else {
bbox->set_left_tab_type(align_params.confirmed_type);
}
}
// Now make the vector and return it.
TabVector* result = TabVector::FitVector(align_params.alignment,
align_params.vertical,
ext_start_y, ext_end_y,
&good_points,
vertical_x, vertical_y);
if (WithinTestRegion(2, box.left(), box.bottom())) {
result->Print("After fitting");
}
return result;
}
}
return NULL;
}
// Find a set of blobs that are aligned in the given vertical
// direction with the given blob. Returns a list of aligned
// blobs and the number in the list.
// For other parameters see FindAlignedBlob below.
int AlignedBlob::AlignTabs(const AlignedBlobParams& params,
bool top_to_bottom, BLOBNBOX* bbox,
BLOBNBOX_CLIST* good_points, int* end_y) {
int ptcount = 0;
BLOBNBOX_C_IT it(good_points);
TBOX box = bbox->bounding_box();
bool debug = WithinTestRegion(2, box.left(), box.bottom());
if (debug) {
tprintf("Starting alignment run at blob:");
box.print();
}
int x_start = params.right_tab ? box.right() : box.left();
while (bbox != nullptr) {
// Add the blob to the list if the appropriate side is a tab candidate,
// or if we are working on a ragged tab.
TabType type = params.right_tab ? bbox->right_tab_type()
: bbox->left_tab_type();
if (((type != TT_NONE && type != TT_MAYBE_RAGGED) || params.ragged) &&
(it.empty() || it.data() != bbox)) {
if (top_to_bottom)
it.add_before_then_move(bbox);
else
it.add_after_then_move(bbox);
++ptcount;
}
// Find the next blob that is aligned with the current one.
// FindAlignedBlob guarantees that forward progress will be made in the
// top_to_bottom direction, and therefore eventually it will return nullptr,
// making this while (bbox != nullptr) loop safe.
bbox = FindAlignedBlob(params, top_to_bottom, bbox, x_start, end_y);
if (bbox != nullptr) {
box = bbox->bounding_box();
if (!params.ragged)
x_start = params.right_tab ? box.right() : box.left();
}
}
if (debug) {
tprintf("Alignment run ended with %d pts at blob:", ptcount);
box.print();
}
return ptcount;
}
// Search vertically for a blob that is aligned with the input bbox.
// The search parameters are determined by AlignedBlobParams.
// top_to_bottom tells whether to search down or up.
// The return value is nullptr if nothing was found in the search box
// or if a blob was found in the gutter. On a nullptr return, end_y
// is set to the edge of the search box or the leading edge of the
// gutter blob if one was found.
BLOBNBOX* AlignedBlob::FindAlignedBlob(const AlignedBlobParams& p,
bool top_to_bottom, BLOBNBOX* bbox,
int x_start, int* end_y) {
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();
// start_y is used to guarantee that forward progress is made and the
// search does not go into an infinite loop. New blobs must extend the
// line beyond start_y.
int start_y = top_to_bottom ? box.bottom() : box.top();
if (WithinTestRegion(2, x_start, start_y)) {
tprintf("Column edges for blob at (%d,%d)->(%d,%d) are [%d, %d]\n",
box.left(), box.top(), box.right(), box.bottom(),
left_column_edge, right_column_edge);
}
// Compute skew tolerance.
int skew_tolerance = p.max_v_gap / kMaxSkewFactor;
// Calculate xmin and xmax of the search box so that it contains
// all possibly relevant boxes up to p.max_v_gap above or below accoording
// to top_to_bottom.
// Start with a notion of vertical with the current estimate.
int x2 = (p.max_v_gap * p.vertical.x() + p.vertical.y()/2) / p.vertical.y();
if (top_to_bottom) {
x2 = x_start - x2;
*end_y = start_y - p.max_v_gap;
} else {
x2 = x_start + x2;
*end_y = start_y + p.max_v_gap;
}
// Expand the box by an additional skew tolerance
int xmin = std::min(x_start, x2) - skew_tolerance;
int xmax = std::max(x_start, x2) + skew_tolerance;
// Now add direction-specific tolerances.
if (p.right_tab) {
xmax += p.min_gutter;
xmin -= p.l_align_tolerance;
} else {
xmax += p.r_align_tolerance;
xmin -= p.min_gutter;
}
// Setup a vertical search for an aligned blob.
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> vsearch(this);
if (WithinTestRegion(2, x_start, start_y))
tprintf("Starting %s %s search at %d-%d,%d, search_size=%d, gutter=%d\n",
p.ragged ? "Ragged" : "Aligned", p.right_tab ? "Right" : "Left",
xmin, xmax, start_y, p.max_v_gap, p.min_gutter);
vsearch.StartVerticalSearch(xmin, xmax, start_y);
// result stores the best real return value.
BLOBNBOX* result = nullptr;
// The backup_result is not a tab candidate and can be used if no
// real tab candidate result is found.
BLOBNBOX* backup_result = nullptr;
// neighbour is the blob that is currently being investigated.
BLOBNBOX* neighbour = nullptr;
while ((neighbour = vsearch.NextVerticalSearch(top_to_bottom)) != nullptr) {
if (neighbour == bbox)
continue;
TBOX nbox = neighbour->bounding_box();
int n_y = (nbox.top() + nbox.bottom()) / 2;
if ((!top_to_bottom && n_y > start_y + p.max_v_gap) ||
(top_to_bottom && n_y < start_y - p.max_v_gap)) {
if (WithinTestRegion(2, x_start, start_y))
tprintf("Neighbour too far at (%d,%d)->(%d,%d)\n",
nbox.left(), nbox.bottom(), nbox.right(), nbox.top());
break; // Gone far enough.
}
// It is CRITICAL to ensure that forward progress is made, (strictly
// in/decreasing n_y) or the caller could loop infinitely, while
// waiting for a sequence of blobs in a line to end.
// NextVerticalSearch alone does not guarantee this, as there may be
// more than one blob in a grid cell. See comment in AlignTabs.
if ((n_y < start_y) != top_to_bottom || nbox.y_overlap(box))
continue; // Only look in the required direction.
if (result != nullptr && result->bounding_box().y_gap(nbox) > gridsize())
return result; // This result is clear.
if (backup_result != nullptr && p.ragged && result == nullptr &&
backup_result->bounding_box().y_gap(nbox) > gridsize())
return backup_result; // This result is clear.
// If the neighbouring blob is the wrong side of a separator line, then it
// "doesn't exist" as far as we are concerned.
int x_at_n_y = x_start + (n_y - start_y) * p.vertical.x() / p.vertical.y();
if (x_at_n_y < neighbour->left_crossing_rule() ||
x_at_n_y > neighbour->right_crossing_rule())
continue; // Separator line in the way.
int n_left = nbox.left();
int n_right = nbox.right();
int n_x = p.right_tab ? n_right : n_left;
if (WithinTestRegion(2, x_start, start_y))
tprintf("neighbour at (%d,%d)->(%d,%d), n_x=%d, n_y=%d, xatn=%d\n",
nbox.left(), nbox.bottom(), nbox.right(), nbox.top(),
n_x, n_y, x_at_n_y);
if (p.right_tab &&
n_left < x_at_n_y + p.min_gutter &&
n_right > x_at_n_y + p.r_align_tolerance &&
(p.ragged || n_left < x_at_n_y + p.gutter_fraction * nbox.height())) {
// In the gutter so end of line.
if (bbox->right_tab_type() >= TT_MAYBE_ALIGNED)
bbox->set_right_tab_type(TT_DELETED);
*end_y = top_to_bottom ? nbox.top() : nbox.bottom();
if (WithinTestRegion(2, x_start, start_y))
tprintf("gutter\n");
return nullptr;
}
if (!p.right_tab &&
n_left < x_at_n_y - p.l_align_tolerance &&
n_right > x_at_n_y - p.min_gutter &&
(p.ragged || n_right > x_at_n_y - p.gutter_fraction * nbox.height())) {
// In the gutter so end of line.
if (bbox->left_tab_type() >= TT_MAYBE_ALIGNED)
bbox->set_left_tab_type(TT_DELETED);
*end_y = top_to_bottom ? nbox.top() : nbox.bottom();
if (WithinTestRegion(2, x_start, start_y))
tprintf("gutter\n");
return nullptr;
}
if ((p.right_tab && neighbour->leader_on_right()) ||
(!p.right_tab && neighbour->leader_on_left()))
continue; // Neighbours of leaders are not allowed to be used.
if (n_x <= x_at_n_y + p.r_align_tolerance &&
n_x >= x_at_n_y - p.l_align_tolerance) {
// Aligned so keep it. If it is a marked tab save it as result,
// otherwise keep it as backup_result to return in case of later failure.
if (WithinTestRegion(2, x_start, start_y))
tprintf("aligned, seeking%d, l=%d, r=%d\n",
p.right_tab, neighbour->left_tab_type(),
neighbour->right_tab_type());
TabType n_type = p.right_tab ? neighbour->right_tab_type()
: neighbour->left_tab_type();
if (n_type != TT_NONE && (p.ragged || n_type != TT_MAYBE_RAGGED)) {
if (result == nullptr) {
result = neighbour;
} else {
// Keep the closest neighbour by Euclidean distance.
// This prevents it from picking a tab blob in another column.
const TBOX& old_box = result->bounding_box();
int x_diff = p.right_tab ? old_box.right() : old_box.left();
x_diff -= x_at_n_y;
int y_diff = (old_box.top() + old_box.bottom()) / 2 - start_y;
int old_dist = x_diff * x_diff + y_diff * y_diff;
x_diff = n_x - x_at_n_y;
y_diff = n_y - start_y;
int new_dist = x_diff * x_diff + y_diff * y_diff;
if (new_dist < old_dist)
result = neighbour;
}
} else if (backup_result == nullptr) {
if (WithinTestRegion(2, x_start, start_y))
tprintf("Backup\n");
backup_result = neighbour;
} else {
TBOX backup_box = backup_result->bounding_box();
if ((p.right_tab && backup_box.right() < nbox.right()) ||
(!p.right_tab && backup_box.left() > nbox.left())) {
if (WithinTestRegion(2, x_start, start_y))
tprintf("Better backup\n");
backup_result = neighbour;
}
}
}
}
return result != nullptr ? result : backup_result;
}
// Finds a vector corresponding to a set of vertically aligned blob edges
// running through the given box. The type of vector returned and the
// search parameters are determined by the AlignedBlobParams.
// vertical_x and y are updated with an estimate of the real
// vertical direction. (skew finding.)
// Returns nullptr if no decent vector can be found.
TabVector* AlignedBlob::FindVerticalAlignment(AlignedBlobParams align_params,
BLOBNBOX* bbox,
int* vertical_x,
int* vertical_y) {
int ext_start_y, ext_end_y;
BLOBNBOX_CLIST good_points;
// Search up and then down from the starting bbox.
TBOX box = bbox->bounding_box();
bool debug = WithinTestRegion(2, box.left(), box.bottom());
int pt_count = AlignTabs(align_params, false, bbox, &good_points, &ext_end_y);
pt_count += AlignTabs(align_params, true, bbox, &good_points, &ext_start_y);
BLOBNBOX_C_IT it(&good_points);
it.move_to_last();
box = it.data()->bounding_box();
int end_y = box.top();
int end_x = align_params.right_tab ? box.right() : box.left();
it.move_to_first();
box = it.data()->bounding_box();
int start_x = align_params.right_tab ? box.right() : box.left();
int start_y = box.bottom();
// Acceptable tab vectors must have a minimum number of points,
// have a minimum acceptable length, and have a minimum gradient.
// The gradient corresponds to the skew angle.
// Ragged tabs don't need to satisfy the gradient condition, as they
// will always end up parallel to the vertical direction.
bool at_least_2_crossings = AtLeast2LineCrossings(&good_points);
if ((pt_count >= align_params.min_points &&
end_y - start_y >= align_params.min_length &&
(align_params.ragged ||
end_y - start_y >= abs(end_x - start_x) * kMinTabGradient)) ||
at_least_2_crossings) {
int confirmed_points = 0;
// Count existing confirmed points to see if vector is acceptable.
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
bbox = it.data();
if (align_params.right_tab) {
if (bbox->right_tab_type() == align_params.confirmed_type)
++confirmed_points;
} else {
if (bbox->left_tab_type() == align_params.confirmed_type)
++confirmed_points;
}
}
// Ragged vectors are not allowed to use too many already used points.
if (!align_params.ragged ||
confirmed_points + confirmed_points < pt_count) {
const TBOX& box = bbox->bounding_box();
if (debug) {
tprintf("Confirming tab vector of %d pts starting at %d,%d\n",
pt_count, box.left(), box.bottom());
}
// Flag all the aligned neighbours as confirmed .
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
bbox = it.data();
if (align_params.right_tab) {
bbox->set_right_tab_type(align_params.confirmed_type);
} else {
bbox->set_left_tab_type(align_params.confirmed_type);
}
if (debug) {
bbox->bounding_box().print();
}
}
// Now make the vector and return it.
TabVector* result = TabVector::FitVector(align_params.alignment,
align_params.vertical,
ext_start_y, ext_end_y,
&good_points,
vertical_x, vertical_y);
result->set_intersects_other_lines(at_least_2_crossings);
if (debug) {
tprintf("Box was %d, %d\n", box.left(), box.bottom());
result->Print("After fitting");
}
return result;
} else if (debug) {
tprintf("Ragged tab used too many used points: %d out of %d\n",
confirmed_points, pt_count);
}
} else if (debug) {
tprintf("Tab vector failed basic tests: pt count %d vs min %d, "
"length %d vs min %d, min grad %g\n",
pt_count, align_params.min_points, end_y - start_y,
align_params.min_length, abs(end_x - start_x) * kMinTabGradient);
}
return nullptr;
}
