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Use std::stringstream to generate hOCR output
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Using std::stringstream simplifies the code and allows conversion of
double to string independant of the current locale setting.

Signed-off-by: Stefan Weil <[email protected]>
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@stweil
stweil committed Dec 16, 2018
1 parent 72d8df5 commit db9c7e0
Showing 1 changed file with 93 additions and 127 deletions.
220 changes: 93 additions & 127 deletions src/api/hocrrenderer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,9 @@
*
**********************************************************************/

#include <locale> // for std::locale::classic
#include <memory> // for std::unique_ptr
#include <sstream> // for std::stringstream
#include "baseapi.h" // for TessBaseAPI
#include "renderer.h"
#include "tesseractclass.h" // for Tesseract
Expand Down Expand Up @@ -46,10 +48,11 @@ static tesseract::Orientation GetBlockTextOrientation(const PageIterator* it) {
* direction and does not add any baseline information to the hocr string.
*/
static void AddBaselineCoordsTohOCR(const PageIterator* it,
PageIteratorLevel level, STRING* hocr_str) {
PageIteratorLevel level,
std::stringstream& hocr_str) {
tesseract::Orientation orientation = GetBlockTextOrientation(it);
if (orientation != ORIENTATION_PAGE_UP) {
hocr_str->add_str_int("; textangle ", 360 - orientation * 90);
hocr_str << "; textangle " << 360 - orientation * 90;
return;
}

Expand All @@ -69,68 +72,36 @@ static void AddBaselineCoordsTohOCR(const PageIterator* it,

// Now fit a line through the points so we can extract coefficients for the
// equation: y = p1 x + p0
double p1 = 0;
double p0 = 0;
if (x1 == x2) {
// Problem computing the polynomial coefficients.
return;
}
p1 = (y2 - y1) / static_cast<double>(x2 - x1);
p0 = y1 - static_cast<double>(p1 * x1);
double p1 = (y2 - y1) / static_cast<double>(x2 - x1);
double p0 = y1 - p1 * x1;

hocr_str->add_str_double("; baseline ", round(p1 * 1000.0) / 1000.0);
hocr_str->add_str_double(" ", round(p0 * 1000.0) / 1000.0);
}

static void AddIdTohOCR(STRING* hocr_str, const std::string base, int num1,
int num2) {
const size_t BUFSIZE = 64;
char id_buffer[BUFSIZE];
if (num2 >= 0) {
snprintf(id_buffer, BUFSIZE - 1, "%s_%d_%d", base.c_str(), num1, num2);
} else {
snprintf(id_buffer, BUFSIZE - 1, "%s_%d", base.c_str(), num1);
}
id_buffer[BUFSIZE - 1] = '\0';
*hocr_str += " id='";
*hocr_str += id_buffer;
*hocr_str += "'";
}

static void AddIdTohOCR(STRING* hocr_str, const std::string base, int num1,
int num2, int num3) {
const size_t BUFSIZE = 64;
char id_buffer[BUFSIZE];
snprintf(id_buffer, BUFSIZE - 1, "%s_%d_%d_%d", base.c_str(), num1, num2,
num3);
id_buffer[BUFSIZE - 1] = '\0';
*hocr_str += " id='";
*hocr_str += id_buffer;
*hocr_str += "'";
hocr_str << "; baseline " << round(p1 * 1000.0) / 1000.0 << " "
<< round(p0 * 1000.0) / 1000.0;
}

static void AddBoxTohOCR(const ResultIterator* it, PageIteratorLevel level,
STRING* hocr_str) {
std::stringstream& hocr_str) {
int left, top, right, bottom;
it->BoundingBox(level, &left, &top, &right, &bottom);
// This is the only place we use double quotes instead of single quotes,
// but it may too late to change for consistency
hocr_str->add_str_int(" title=\"bbox ", left);
hocr_str->add_str_int(" ", top);
hocr_str->add_str_int(" ", right);
hocr_str->add_str_int(" ", bottom);
hocr_str << " title=\"bbox " << left << " " << top << " " << right << " "
<< bottom;
// Add baseline coordinates & heights for textlines only.
if (level == RIL_TEXTLINE) {
AddBaselineCoordsTohOCR(it, level, hocr_str);
// add custom height measures
float row_height, descenders, ascenders; // row attributes
it->RowAttributes(&row_height, &descenders, &ascenders);
// TODO(rays): Do we want to limit these to a single decimal place?
hocr_str->add_str_double("; x_size ", row_height);
hocr_str->add_str_double("; x_descenders ", descenders * -1);
hocr_str->add_str_double("; x_ascenders ", ascenders);
hocr_str << "; x_size " << row_height << "; x_descenders " << -descenders
<< "; x_ascenders " << ascenders;
}
*hocr_str += "\">";
hocr_str << "\">";
}

/**
Expand Down Expand Up @@ -166,8 +137,6 @@ char* TessBaseAPI::GetHOCRText(ETEXT_DESC* monitor, int page_number) {
bool font_info = false;
GetBoolVariable("hocr_font_info", &font_info);

STRING hocr_str("");

if (input_file_ == nullptr) SetInputName(nullptr);

#ifdef _WIN32
Expand All @@ -187,22 +156,25 @@ char* TessBaseAPI::GetHOCRText(ETEXT_DESC* monitor, int page_number) {
delete[] utf8_str;
#endif

hocr_str += " <div class='ocr_page'";
AddIdTohOCR(&hocr_str, "page", page_id, -1);
hocr_str += " title='image \"";
std::stringstream hocr_str;
// Use "C" locale (needed for double values x_size and x_descenders).
hocr_str.imbue(std::locale::classic());
// Use 8 digits for double values.
hocr_str.precision(8);
hocr_str << " <div class='ocr_page'";
hocr_str << " id='"
<< "page_" << page_id << "'";
hocr_str << " title='image \"";
if (input_file_) {
hocr_str += HOcrEscape(input_file_->string());
hocr_str << HOcrEscape(input_file_->string()).c_str();
} else {
hocr_str += "unknown";
hocr_str << "unknown";
}
hocr_str.add_str_int("\"; bbox ", rect_left_);
hocr_str.add_str_int(" ", rect_top_);
hocr_str.add_str_int(" ", rect_width_);
hocr_str.add_str_int(" ", rect_height_);
hocr_str.add_str_int("; ppageno ", page_number);
hocr_str += "'>\n";
hocr_str << "\"; bbox " << rect_left_ << " " << rect_top_ << " "
<< rect_width_ << " " << rect_height_ << "; ppageno " << page_number
<< "'>\n";

ResultIterator* res_it = GetIterator();
std::unique_ptr<ResultIterator> res_it(GetIterator());
while (!res_it->Empty(RIL_BLOCK)) {
if (res_it->Empty(RIL_WORD)) {
res_it->Next(RIL_WORD);
Expand All @@ -212,29 +184,30 @@ char* TessBaseAPI::GetHOCRText(ETEXT_DESC* monitor, int page_number) {
// Open any new block/paragraph/textline.
if (res_it->IsAtBeginningOf(RIL_BLOCK)) {
para_is_ltr = true; // reset to default direction
hocr_str += " <div class='ocr_carea'";
AddIdTohOCR(&hocr_str, "block", page_id, bcnt);
AddBoxTohOCR(res_it, RIL_BLOCK, &hocr_str);
hocr_str << " <div class='ocr_carea'"
<< " id='"
<< "block_" << page_id << "_" << bcnt << "'";
AddBoxTohOCR(res_it.get(), RIL_BLOCK, hocr_str);
}
if (res_it->IsAtBeginningOf(RIL_PARA)) {
hocr_str += "\n <p class='ocr_par'";
hocr_str << "\n <p class='ocr_par'";
para_is_ltr = res_it->ParagraphIsLtr();
if (!para_is_ltr) {
hocr_str += " dir='rtl'";
hocr_str << " dir='rtl'";
}
AddIdTohOCR(&hocr_str, "par", page_id, pcnt);
hocr_str << " id='"
<< "par_" << page_id << "_" << pcnt << "'";
paragraph_lang = res_it->WordRecognitionLanguage();
if (paragraph_lang) {
hocr_str += " lang='";
hocr_str += paragraph_lang;
hocr_str += "'";
hocr_str << " lang='" << paragraph_lang << "'";
}
AddBoxTohOCR(res_it, RIL_PARA, &hocr_str);
AddBoxTohOCR(res_it.get(), RIL_PARA, hocr_str);
}
if (res_it->IsAtBeginningOf(RIL_TEXTLINE)) {
hocr_str += "\n <span class='ocr_line'";
AddIdTohOCR(&hocr_str, "line", page_id, lcnt);
AddBoxTohOCR(res_it, RIL_TEXTLINE, &hocr_str);
hocr_str << "\n <span class='ocr_line'"
<< " id='"
<< "line_" << page_id << "_" << lcnt << "'";
AddBoxTohOCR(res_it.get(), RIL_TEXTLINE, hocr_str);
}

// Now, process the word...
Expand All @@ -243,8 +216,9 @@ char* TessBaseAPI::GetHOCRText(ETEXT_DESC* monitor, int page_number) {
if (tesseract_->lstm_choice_mode) {
confidencemap = res_it->GetBestLSTMSymbolChoices();
}
hocr_str += "\n <span class='ocrx_word'";
AddIdTohOCR(&hocr_str, "word", page_id, wcnt);
hocr_str << "\n <span class='ocrx_word'"
<< " id='"
<< "word_" << page_id << "_" << wcnt << "'";
int left, top, right, bottom;
bool bold, italic, underlined, monospace, serif, smallcaps;
int pointsize, font_id;
Expand All @@ -253,126 +227,118 @@ char* TessBaseAPI::GetHOCRText(ETEXT_DESC* monitor, int page_number) {
font_name =
res_it->WordFontAttributes(&bold, &italic, &underlined, &monospace,
&serif, &smallcaps, &pointsize, &font_id);
hocr_str.add_str_int(" title='bbox ", left);
hocr_str.add_str_int(" ", top);
hocr_str.add_str_int(" ", right);
hocr_str.add_str_int(" ", bottom);
hocr_str.add_str_int("; x_wconf ", res_it->Confidence(RIL_WORD));
hocr_str << " title='bbox " << left << " " << top << " " << right << " "
<< bottom << "; x_wconf "
<< static_cast<int>(res_it->Confidence(RIL_WORD));
if (font_info) {
if (font_name) {
hocr_str += "; x_font ";
hocr_str += HOcrEscape(font_name);
hocr_str << "; x_font " << HOcrEscape(font_name).c_str();
}
hocr_str.add_str_int("; x_fsize ", pointsize);
hocr_str << "; x_fsize " << pointsize;
}
hocr_str += "'";
hocr_str << "'";
const char* lang = res_it->WordRecognitionLanguage();
if (lang && (!paragraph_lang || strcmp(lang, paragraph_lang))) {
hocr_str += " lang='";
hocr_str += lang;
hocr_str += "'";
hocr_str << " lang='" << lang << "'";
}
switch (res_it->WordDirection()) {
// Only emit direction if different from current paragraph direction
case DIR_LEFT_TO_RIGHT:
if (!para_is_ltr) hocr_str += " dir='ltr'";
if (!para_is_ltr) hocr_str << " dir='ltr'";
break;
case DIR_RIGHT_TO_LEFT:
if (para_is_ltr) hocr_str += " dir='rtl'";
if (para_is_ltr) hocr_str << " dir='rtl'";
break;
case DIR_MIX:
case DIR_NEUTRAL:
default: // Do nothing.
break;
}
hocr_str += ">";
hocr_str << ">";
bool last_word_in_line = res_it->IsAtFinalElement(RIL_TEXTLINE, RIL_WORD);
bool last_word_in_para = res_it->IsAtFinalElement(RIL_PARA, RIL_WORD);
bool last_word_in_block = res_it->IsAtFinalElement(RIL_BLOCK, RIL_WORD);
if (bold) hocr_str += "<strong>";
if (italic) hocr_str += "<em>";
if (bold) hocr_str << "<strong>";
if (italic) hocr_str << "<em>";
do {
const std::unique_ptr<const char[]> grapheme(
res_it->GetUTF8Text(RIL_SYMBOL));
if (grapheme && grapheme[0] != 0) {
hocr_str += HOcrEscape(grapheme.get());
hocr_str << HOcrEscape(grapheme.get()).c_str();
}
res_it->Next(RIL_SYMBOL);
} while (!res_it->Empty(RIL_BLOCK) && !res_it->IsAtBeginningOf(RIL_WORD));
if (italic) hocr_str += "</em>";
if (bold) hocr_str += "</strong>";
if (italic) hocr_str << "</em>";
if (bold) hocr_str << "</strong>";
// If the lstm choice mode is required it is added here
if (tesseract_->lstm_choice_mode == 1 && confidencemap != nullptr) {
for (size_t i = 0; i < confidencemap->size(); i++) {
hocr_str += "\n <span class='ocrx_cinfo'";
AddIdTohOCR(&hocr_str, "timestep", page_id, wcnt, tcnt);
hocr_str += ">";
hocr_str << "\n <span class='ocrx_cinfo'"
<< " id='"
<< "timestep_" << page_id << "_" << wcnt << "_" << tcnt << "'"
<< ">";
std::vector<std::pair<const char*, float>> timestep =
(*confidencemap)[i];
for (std::pair<const char*, float> conf : timestep) {
hocr_str += "<span class='ocr_glyph'";
AddIdTohOCR(&hocr_str, "choice", page_id, wcnt, gcnt);
hocr_str.add_str_int(" title='x_confs ", int(conf.second * 100));
hocr_str += "'";
hocr_str += ">";
hocr_str += conf.first;
hocr_str += "</span>";
hocr_str << "<span class='ocr_glyph'"
<< " id='"
<< "choice_" << page_id << "_" << wcnt << "_" << gcnt << "'"
<< " title='x_confs " << int(conf.second * 100) << "'>"
<< conf.first << "</span>";
gcnt++;
}
hocr_str += "</span>";
hocr_str << "</span>";
tcnt++;
}
} else if (tesseract_->lstm_choice_mode == 2 && confidencemap != nullptr) {
for (size_t i = 0; i < confidencemap->size(); i++) {
std::vector<std::pair<const char*, float>> timestep =
(*confidencemap)[i];
if (timestep.size() > 0) {
hocr_str += "\n <span class='ocrx_cinfo'";
AddIdTohOCR(&hocr_str, "lstm_choices", page_id, wcnt, tcnt);
hocr_str += " chosen='";
hocr_str += timestep[0].first;
hocr_str += "'>";
hocr_str << "\n <span class='ocrx_cinfo'"
<< " id='"
<< "lstm_choices_" << page_id << "_" << wcnt << "_" << tcnt
<< "'"
<< " chosen='" << timestep[0].first << "'>";
for (size_t j = 1; j < timestep.size(); j++) {
hocr_str += "<span class='ocr_glyph'";
AddIdTohOCR(&hocr_str, "choice", page_id, wcnt, gcnt);
hocr_str.add_str_int(" title='x_confs ",
int(timestep[j].second * 100));
hocr_str += "'";
hocr_str += ">";
hocr_str += timestep[j].first;
hocr_str += "</span>";
hocr_str << "<span class='ocr_glyph'"
<< " id='"
<< "choice_" << page_id << "_" << wcnt << "_" << gcnt
<< "'"
<< " title='x_confs " << int(timestep[j].second * 100)
<< "'>" << timestep[j].first << "</span>";
gcnt++;
}
hocr_str += "</span>";
hocr_str << "</span>";
tcnt++;
}
}
}
hocr_str += "</span>";
hocr_str << "</span>";
tcnt = 1;
gcnt = 1;
wcnt++;
// Close any ending block/paragraph/textline.
if (last_word_in_line) {
hocr_str += "\n </span>";
hocr_str << "\n </span>";
lcnt++;
}
if (last_word_in_para) {
hocr_str += "\n </p>\n";
hocr_str << "\n </p>\n";
pcnt++;
para_is_ltr = true; // back to default direction
}
if (last_word_in_block) {
hocr_str += " </div>\n";
hocr_str << " </div>\n";
bcnt++;
}
}
hocr_str += " </div>\n";
hocr_str << " </div>\n";

char* ret = new char[hocr_str.length() + 1];
strcpy(ret, hocr_str.string());
delete res_it;
return ret;
const std::string& text = hocr_str.str();
char* result = new char[text.length() + 1];
strcpy(result, text.c_str());
return result;
}

/**********************************************************************
Expand Down

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