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boxword.cpp
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boxword.cpp
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///////////////////////////////////////////////////////////////////////
// File: boxword.cpp
// Description: Class to represent the bounding boxes of the output.
// Author: Ray Smith
//
// (C) Copyright 2010, 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 "blobs.h"
#include "boxword.h"
#include "host.h" // for NearlyEqual
#include "normalis.h"
#include "ocrblock.h"
#include "pageres.h"
namespace tesseract {
// Clip output boxes to input blob boxes for bounds that are within this
// tolerance. Otherwise, the blob may be chopped and we have to just use
// the word bounding box.
const int kBoxClipTolerance = 2;
BoxWord::BoxWord() : length_(0) {
}
BoxWord::BoxWord(const BoxWord& src) {
CopyFrom(src);
}
BoxWord& BoxWord::operator=(const BoxWord& src) {
CopyFrom(src);
return *this;
}
void BoxWord::CopyFrom(const BoxWord& src) {
bbox_ = src.bbox_;
length_ = src.length_;
boxes_.clear();
boxes_.reserve(length_);
for (int i = 0; i < length_; ++i)
boxes_.push_back(src.boxes_[i]);
}
// Factory to build a BoxWord from a TWERD using the DENORMs on each blob to
// switch back to original image coordinates.
BoxWord* BoxWord::CopyFromNormalized(TWERD* tessword) {
auto* boxword = new BoxWord();
// Count the blobs.
boxword->length_ = tessword->NumBlobs();
// Allocate memory.
boxword->boxes_.reserve(boxword->length_);
for (int b = 0; b < boxword->length_; ++b) {
TBLOB* tblob = tessword->blobs[b];
TBOX blob_box;
for (TESSLINE* outline = tblob->outlines; outline != nullptr;
outline = outline->next) {
EDGEPT* edgept = outline->loop;
// Iterate over the edges.
do {
if (!edgept->IsHidden() || !edgept->prev->IsHidden()) {
ICOORD pos(edgept->pos.x, edgept->pos.y);
TPOINT denormed;
tblob->denorm().DenormTransform(nullptr, edgept->pos, &denormed);
pos.set_x(denormed.x);
pos.set_y(denormed.y);
TBOX pt_box(pos, pos);
blob_box += pt_box;
}
edgept = edgept->next;
} while (edgept != outline->loop);
}
boxword->boxes_.push_back(blob_box);
}
boxword->ComputeBoundingBox();
return boxword;
}
// Clean up the bounding boxes from the polygonal approximation by
// expanding slightly, then clipping to the blobs from the original_word
// that overlap. If not null, the block provides the inverse rotation.
void BoxWord::ClipToOriginalWord(const BLOCK* block, WERD* original_word) {
for (int i = 0; i < length_; ++i) {
TBOX box = boxes_[i];
// Expand by a single pixel, as the poly approximation error is 1 pixel.
box = TBOX(box.left() - 1, box.bottom() - 1,
box.right() + 1, box.top() + 1);
// Now find the original box that matches.
TBOX original_box;
C_BLOB_IT b_it(original_word->cblob_list());
for (b_it.mark_cycle_pt(); !b_it.cycled_list(); b_it.forward()) {
TBOX blob_box = b_it.data()->bounding_box();
if (block != nullptr)
blob_box.rotate(block->re_rotation());
if (blob_box.major_overlap(box)) {
original_box += blob_box;
}
}
if (!original_box.null_box()) {
if (NearlyEqual<int>(original_box.left(), box.left(), kBoxClipTolerance))
box.set_left(original_box.left());
if (NearlyEqual<int>(original_box.right(), box.right(),
kBoxClipTolerance))
box.set_right(original_box.right());
if (NearlyEqual<int>(original_box.top(), box.top(), kBoxClipTolerance))
box.set_top(original_box.top());
if (NearlyEqual<int>(original_box.bottom(), box.bottom(),
kBoxClipTolerance))
box.set_bottom(original_box.bottom());
}
original_box = original_word->bounding_box();
if (block != nullptr)
original_box.rotate(block->re_rotation());
boxes_[i] = box.intersection(original_box);
}
ComputeBoundingBox();
}
// Merges the boxes from start to end, not including end, and deletes
// the boxes between start and end.
void BoxWord::MergeBoxes(int start, int end) {
start = ClipToRange(start, 0, length_);
end = ClipToRange(end, 0, length_);
if (end <= start + 1)
return;
for (int i = start + 1; i < end; ++i) {
boxes_[start] += boxes_[i];
}
int shrinkage = end - 1 - start;
length_ -= shrinkage;
for (int i = start + 1; i < length_; ++i)
boxes_[i] = boxes_[i + shrinkage];
boxes_.truncate(length_);
}
// Inserts a new box before the given index.
// Recomputes the bounding box.
void BoxWord::InsertBox(int index, const TBOX& box) {
if (index < length_)
boxes_.insert(box, index);
else
boxes_.push_back(box);
length_ = boxes_.size();
ComputeBoundingBox();
}
// Changes the box at the given index to the new box.
// Recomputes the bounding box.
void BoxWord::ChangeBox(int index, const TBOX& box) {
boxes_[index] = box;
ComputeBoundingBox();
}
// Deletes the box with the given index, and shuffles up the rest.
// Recomputes the bounding box.
void BoxWord::DeleteBox(int index) {
ASSERT_HOST(0 <= index && index < length_);
boxes_.remove(index);
--length_;
ComputeBoundingBox();
}
// Deletes all the boxes stored in BoxWord.
void BoxWord::DeleteAllBoxes() {
length_ = 0;
boxes_.clear();
bbox_ = TBOX();
}
// Computes the bounding box of the word.
void BoxWord::ComputeBoundingBox() {
bbox_ = TBOX();
for (int i = 0; i < length_; ++i)
bbox_ += boxes_[i];
}
// This and other putatively are the same, so call the (permanent) callback
// for each blob index where the bounding boxes match.
// The callback is deleted on completion.
void BoxWord::ProcessMatchedBlobs(const TWERD& other,
TessCallback1<int>* cb) const {
for (int i = 0; i < length_ && i < other.NumBlobs(); ++i) {
TBOX blob_box = other.blobs[i]->bounding_box();
if (blob_box == boxes_[i])
cb->Run(i);
}
delete cb;
}
} // namespace tesseract.