tesseract/textord/bbgrid.cpp

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///////////////////////////////////////////////////////////////////////
// File: bbgrid.cpp
// Description: Class to hold BLOBNBOXs in a grid for fast access
// to neighbours.
// Author: Ray Smith
// Created: Wed Jun 06 17:22:01 PDT 2007
//
// (C) Copyright 2007, 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 "bbgrid.h"
#include "helpers.h"
#include "ocrblock.h"
namespace tesseract {
///////////////////////////////////////////////////////////////////////
// BBGrid IMPLEMENTATION.
///////////////////////////////////////////////////////////////////////
GridBase::GridBase() {
}
GridBase::GridBase(int gridsize, const ICOORD& bleft, const ICOORD& tright) {
Init(gridsize, bleft, tright);
}
GridBase::~GridBase() {
}
// (Re)Initialize the grid. The gridsize is the size in pixels of each cell,
// and bleft, tright are the bounding box of everything to go in it.
void GridBase::Init(int gridsize, const ICOORD& bleft, const ICOORD& tright) {
gridsize_ = gridsize;
bleft_ = bleft;
tright_ = tright;
if (gridsize_ == 0)
gridsize_ = 1;
gridwidth_ = (tright.x() - bleft.x() + gridsize_ - 1) / gridsize_;
gridheight_ = (tright.y() - bleft.y() + gridsize_ - 1) / gridsize_;
gridbuckets_ = gridwidth_ * gridheight_;
}
// Compute the given grid coordinates from image coords.
void GridBase::GridCoords(int x, int y, int* grid_x, int* grid_y) const {
*grid_x = (x - bleft_.x()) / gridsize_;
*grid_y = (y - bleft_.y()) / gridsize_;
ClipGridCoords(grid_x, grid_y);
}
// Clip the given grid coordinates to fit within the grid.
void GridBase::ClipGridCoords(int* x, int* y) const {
*x = ClipToRange(*x, 0, gridwidth_ - 1);
*y = ClipToRange(*y, 0, gridheight_ - 1);
}
IntGrid::IntGrid() {
grid_ = nullptr;
}
IntGrid::IntGrid(int gridsize, const ICOORD& bleft, const ICOORD& tright)
: grid_(nullptr) {
Init(gridsize, bleft, tright);
}
IntGrid::~IntGrid() {
delete [] grid_;
}
// (Re)Initialize the grid. The gridsize is the size in pixels of each cell,
// and bleft, tright are the bounding box of everything to go in it.
void IntGrid::Init(int gridsize, const ICOORD& bleft, const ICOORD& tright) {
GridBase::Init(gridsize, bleft, tright);
delete [] grid_;
grid_ = new int[gridbuckets_];
Clear();
}
// Clear all the ints in the grid to zero.
void IntGrid::Clear() {
for (int i = 0; i < gridbuckets_; ++i) {
grid_[i] = 0;
}
}
// Rotate the grid by rotation, keeping cell contents.
// rotation must be a multiple of 90 degrees.
// NOTE: due to partial cells, cell coverage in the rotated grid will be
// inexact. This is why there is no Rotate for the generic BBGrid.
// TODO(rays) investigate fixing this inaccuracy by moving the origin after
// rotation.
void IntGrid::Rotate(const FCOORD& rotation) {
ASSERT_HOST(rotation.x() == 0.0f || rotation.y() == 0.0f);
ICOORD old_bleft(bleft());
ICOORD old_tright(tright());
int old_width = gridwidth();
int old_height = gridheight();
TBOX box(bleft(), tright());
box.rotate(rotation);
int* old_grid = grid_;
grid_ = nullptr;
Init(gridsize(), box.botleft(), box.topright());
// Iterate over the old grid, copying data to the rotated position in the new.
int oldi = 0;
FCOORD x_step(rotation);
x_step *= gridsize();
for (int oldy = 0; oldy < old_height; ++oldy) {
FCOORD line_pos(old_bleft.x(), old_bleft.y() + gridsize() * oldy);
line_pos.rotate(rotation);
for (int oldx = 0; oldx < old_width; ++oldx, line_pos += x_step, ++oldi) {
int grid_x, grid_y;
GridCoords(static_cast<int>(line_pos.x() + 0.5),
static_cast<int>(line_pos.y() + 0.5),
&grid_x, &grid_y);
grid_[grid_y * gridwidth() + grid_x] = old_grid[oldi];
}
}
delete [] old_grid;
}
// Returns a new IntGrid containing values equal to the sum of all the
// neighbouring cells. The returned grid must be deleted after use.
// For ease of implementation, edge cells are double counted, to make them
// have the same range as the non-edge cells.
IntGrid* IntGrid::NeighbourhoodSum() const {
IntGrid* sumgrid = new IntGrid(gridsize(), bleft(), tright());
for (int y = 0; y < gridheight(); ++y) {
for (int x = 0; x < gridwidth(); ++x) {
int cell_count = 0;
for (int yoffset = -1; yoffset <= 1; ++yoffset) {
for (int xoffset = -1; xoffset <= 1; ++xoffset) {
int grid_x = x + xoffset;
int grid_y = y + yoffset;
ClipGridCoords(&grid_x, &grid_y);
cell_count += GridCellValue(grid_x, grid_y);
}
}
if (GridCellValue(x, y) > 1)
sumgrid->SetGridCell(x, y, cell_count);
}
}
return sumgrid;
}
// Returns true if more than half the area of the rect is covered by grid
// cells that are over the threshold.
bool IntGrid::RectMostlyOverThreshold(const TBOX& rect, int threshold) const {
int min_x, min_y, max_x, max_y;
GridCoords(rect.left(), rect.bottom(), &min_x, &min_y);
GridCoords(rect.right(), rect.top(), &max_x, &max_y);
int total_area = 0;
for (int y = min_y; y <= max_y; ++y) {
for (int x = min_x; x <= max_x; ++x) {
int value = GridCellValue(x, y);
if (value > threshold) {
TBOX cell_box(x * gridsize_, y * gridsize_,
(x + 1) * gridsize_, (y + 1) * gridsize_);
cell_box &= rect; // This is in-place box intersection.
total_area += cell_box.area();
}
}
}
return total_area * 2 > rect.area();
}
// Returns true if any cell value in the given rectangle is zero.
bool IntGrid::AnyZeroInRect(const TBOX& rect) const {
int min_x, min_y, max_x, max_y;
GridCoords(rect.left(), rect.bottom(), &min_x, &min_y);
GridCoords(rect.right(), rect.top(), &max_x, &max_y);
for (int y = min_y; y <= max_y; ++y) {
for (int x = min_x; x <= max_x; ++x) {
if (GridCellValue(x, y) == 0)
return true;
}
}
return false;
}
// Returns a full-resolution binary pix in which each cell over the given
// threshold is filled as a black square. pixDestroy after use.
// Edge cells, which have a zero 4-neighbour, are not marked.
Pix* IntGrid::ThresholdToPix(int threshold) const {
Pix* pix = pixCreate(tright().x() - bleft().x(),
tright().y() - bleft().y(), 1);
int cellsize = gridsize();
for (int y = 0; y < gridheight(); ++y) {
for (int x = 0; x < gridwidth(); ++x) {
if (GridCellValue(x, y) > threshold &&
GridCellValue(x - 1, y) > 0 && GridCellValue(x + 1, y) > 0 &&
GridCellValue(x, y - 1) > 0 && GridCellValue(x, y + 1) > 0) {
pixRasterop(pix, x * cellsize, tright().y() - ((y + 1) * cellsize),
cellsize, cellsize, PIX_SET, nullptr, 0, 0);
}
}
}
return pix;
}
// Make a Pix of the correct scaled size for the TraceOutline functions.
Pix* GridReducedPix(const TBOX& box, int gridsize,
ICOORD bleft, int* left, int* bottom) {
// Compute grid bounds of the outline and pad all round by 1.
int grid_left = (box.left() - bleft.x()) / gridsize - 1;
int grid_bottom = (box.bottom() - bleft.y()) / gridsize - 1;
int grid_right = (box.right() - bleft.x()) / gridsize + 1;
int grid_top = (box.top() - bleft.y()) / gridsize + 1;
*left = grid_left;
*bottom = grid_bottom;
return pixCreate(grid_right - grid_left + 1,
grid_top - grid_bottom + 1,
1);
}
// Helper function to return a scaled Pix with one pixel per grid cell,
// set (black) where the given outline enters the corresponding grid cell,
// and clear where the outline does not touch the grid cell.
// Also returns the grid coords of the bottom-left of the Pix, in *left
// and *bottom, which corresponds to (0, 0) on the Pix.
// Note that the Pix is used upside-down, with (0, 0) being the bottom-left.
Pix* TraceOutlineOnReducedPix(C_OUTLINE* outline, int gridsize,
ICOORD bleft, int* left, int* bottom) {
2016-11-08 02:46:33 +08:00
const TBOX& box = outline->bounding_box();
Pix* pix = GridReducedPix(box, gridsize, bleft, left, bottom);
int wpl = pixGetWpl(pix);
l_uint32* data = pixGetData(pix);
int length = outline->pathlength();
ICOORD pos = outline->start_pos();
for (int i = 0; i < length; ++i) {
int grid_x = (pos.x() - bleft.x()) / gridsize - *left;
int grid_y = (pos.y() - bleft.y()) / gridsize - *bottom;
SET_DATA_BIT(data + grid_y * wpl, grid_x);
pos += outline->step(i);
}
return pix;
}
#if 0 // Example code shows how to use TraceOutlineOnReducedPix.
C_OUTLINE_IT ol_it(blob->cblob()->out_list());
int grid_left, grid_bottom;
Pix* pix = TraceOutlineOnReducedPix(ol_it.data(), gridsize_, bleft_,
&grid_left, &grid_bottom);
grid->InsertPixPtBBox(grid_left, grid_bottom, pix, blob);
pixDestroy(&pix);
#endif
// As TraceOutlineOnReducedPix above, but on a BLOCK instead of a C_OUTLINE.
Pix* TraceBlockOnReducedPix(BLOCK* block, int gridsize,
ICOORD bleft, int* left, int* bottom) {
const TBOX& box = block->pdblk.bounding_box();
Pix* pix = GridReducedPix(box, gridsize, bleft, left, bottom);
int wpl = pixGetWpl(pix);
l_uint32* data = pixGetData(pix);
ICOORDELT_IT it(block->pdblk.poly_block()->points());
for (it.mark_cycle_pt(); !it.cycled_list();) {
ICOORD pos = *it.data();
it.forward();
ICOORD next_pos = *it.data();
ICOORD line_vector = next_pos - pos;
int major, minor;
ICOORD major_step, minor_step;
line_vector.setup_render(&major_step, &minor_step, &major, &minor);
int accumulator = major / 2;
while (pos != next_pos) {
int grid_x = (pos.x() - bleft.x()) / gridsize - *left;
int grid_y = (pos.y() - bleft.y()) / gridsize - *bottom;
SET_DATA_BIT(data + grid_y * wpl, grid_x);
pos += major_step;
accumulator += minor;
if (accumulator >= major) {
accumulator -= major;
pos += minor_step;
}
}
}
return pix;
}
} // namespace tesseract.