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Use std::stringstream to generate ALTO output and add <SP> element
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Using std::stringstream simplifies the code.
The <SP> element is needed between two >String> elements.
Remove also some unneeded spaces in the ALTO output.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
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@stweil
stweil committed Dec 12, 2018
1 parent 5307b2c commit fbbbdb4
Showing 1 changed file with 53 additions and 78 deletions.
131 changes: 53 additions & 78 deletions src/api/altorenderer.cpp
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Expand Up @@ -14,17 +14,17 @@
// limitations under the License.

#include <memory>
#include <sstream> // for std::stringstream
#include "baseapi.h"
#include "renderer.h"

namespace tesseract {

///
/// Add coordinates to specified TextBlock, TextLine, or String bounding box
/// Add word confidence if adding to a String bounding box
/// Add coordinates to specified TextBlock, TextLine or String bounding box.
/// Add word confidence if adding to a String bounding box.
///
static void AddBoxToAlto(const ResultIterator* it, PageIteratorLevel level,
STRING* alto_str) {
std::stringstream& alto_str) {
int left, top, right, bottom;
it->BoundingBox(level, &left, &top, &right, &bottom);

Expand All @@ -33,43 +33,19 @@ static void AddBoxToAlto(const ResultIterator* it, PageIteratorLevel level,
int height = bottom - top;
int width = right - left;

*alto_str += " HPOS=\"";
alto_str->add_str_int("", hpos);
*alto_str += "\"";
*alto_str += " VPOS=\"";
alto_str->add_str_int("", vpos);
*alto_str += "\"";
*alto_str += " WIDTH=\"";
alto_str->add_str_int("", width);
*alto_str += "\"";
*alto_str += " HEIGHT=\"";
alto_str->add_str_int("", height);
*alto_str += "\"";
alto_str << " HPOS=\"" << hpos << "\"";
alto_str << " VPOS=\"" << vpos << "\"";
alto_str << " WIDTH=\"" << width << "\"";
alto_str << " HEIGHT=\"" << height << "\"";

if (level == RIL_WORD) {
int wc = it->Confidence(RIL_WORD);
*alto_str += " WC=\"0.";
alto_str->add_str_int("", wc);
*alto_str += "\"";
}
if (level != RIL_WORD) {
*alto_str += ">";
alto_str << " WC=\"0." << wc << "\"";
} else {
alto_str << ">";
}
}

///
/// Add a unique ID to an ALTO element
///
static void AddIdToAlto(STRING* alto_str, const std::string base, int num1) {
const size_t BUFSIZE = 64;
char id_buffer[BUFSIZE];
snprintf(id_buffer, BUFSIZE - 1, "%s_%d", base.c_str(), num1);
id_buffer[BUFSIZE - 1] = '\0';
*alto_str += " ID=\"";
*alto_str += id_buffer;
*alto_str += "\"";
}

///
/// Append the ALTO XML for the beginning of the document
///
Expand Down Expand Up @@ -111,10 +87,10 @@ bool TessAltoRenderer::BeginDocumentHandler() {
/// Append the ALTO XML for the layout of the image
///
bool TessAltoRenderer::AddImageHandler(TessBaseAPI* api) {
const std::unique_ptr<const char[]> hocr(api->GetAltoText(imagenum()));
if (hocr == nullptr) return false;
const std::unique_ptr<const char[]> text(api->GetAltoText(imagenum()));
if (text == nullptr) return false;

AppendString(hocr.get());
AppendString(text.get());

return true;
}
Expand Down Expand Up @@ -150,8 +126,6 @@ char* TessBaseAPI::GetAltoText(ETEXT_DESC* monitor, int page_number) {
int lcnt = 0, bcnt = 0, wcnt = 0;
int page_id = page_number;

STRING alto_str("");

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

#ifdef _WIN32
Expand All @@ -171,23 +145,16 @@ char* TessBaseAPI::GetAltoText(ETEXT_DESC* monitor, int page_number) {
delete[] utf8_str;
#endif

alto_str += "\t\t<Page WIDTH=\"";
alto_str.add_str_int("", rect_width_);
alto_str += "\" HEIGHT=\"";
alto_str.add_str_int("", rect_height_);
alto_str += "\" PHYSICAL_IMG_NR=\"";
alto_str.add_str_int("", rect_height_);
alto_str += "\"";
AddIdToAlto(&alto_str, "page", page_id);
alto_str += ">\n";
alto_str +=
("\t\t\t<PrintSpace HPOS=\"0\" "
"VPOS=\"0\""
" WIDTH=\"");
alto_str.add_str_int("", rect_width_);
alto_str += "\" HEIGHT=\"";
alto_str.add_str_int("", rect_height_);
alto_str += "\">\n";
std::stringstream alto_str;
alto_str
<< "\t\t<Page WIDTH=\"" << rect_width_ << "\" HEIGHT=\""
<< rect_height_
// TODO: next line is buggy because rect_height is not an image number.
<< "\" PHYSICAL_IMG_NR=\"" << rect_height_ << "\""
<< " ID=\"page_" << page_id << "\">\n"
<< "\t\t\t<PrintSpace HPOS=\"0\" VPOS=\"0\""
<< " WIDTH=\"" << rect_width_ << "\""
<< " HEIGHT=\"" << rect_height_ << "\">\n";

ResultIterator* res_it = GetIterator();
while (!res_it->Empty(RIL_BLOCK)) {
Expand All @@ -197,58 +164,66 @@ char* TessBaseAPI::GetAltoText(ETEXT_DESC* monitor, int page_number) {
}

if (res_it->IsAtBeginningOf(RIL_BLOCK)) {
alto_str += "\t\t\t\t<TextBlock ";
AddIdToAlto(&alto_str, "block", bcnt);
AddBoxToAlto(res_it, RIL_BLOCK, &alto_str);
alto_str += "\n";
alto_str << "\t\t\t\t<TextBlock ID=\"block_" << bcnt << "\"";
AddBoxToAlto(res_it, RIL_BLOCK, alto_str);
alto_str << "\n";
}

if (res_it->IsAtBeginningOf(RIL_TEXTLINE)) {
alto_str += "\t\t\t\t\t<TextLine ";
AddIdToAlto(&alto_str, "line", lcnt);
AddBoxToAlto(res_it, RIL_TEXTLINE, &alto_str);
alto_str += "\n";
alto_str << "\t\t\t\t\t<TextLine ID=\"line_" << lcnt << "\"";
AddBoxToAlto(res_it, RIL_TEXTLINE, alto_str);
alto_str << "\n";
}

alto_str += "\t\t\t\t\t\t<String ";
AddIdToAlto(&alto_str, "string", wcnt);
AddBoxToAlto(res_it, RIL_WORD, &alto_str);
alto_str += " CONTENT=\"";
alto_str << "\t\t\t\t\t\t<String ID=\"string_" << wcnt << "\"";
AddBoxToAlto(res_it, RIL_WORD, alto_str);
alto_str << " CONTENT=\"";

bool last_word_in_line = res_it->IsAtFinalElement(RIL_TEXTLINE, RIL_WORD);
bool last_word_in_block = res_it->IsAtFinalElement(RIL_BLOCK, RIL_WORD);

int left, top, right, bottom;
res_it->BoundingBox(RIL_WORD, &left, &top, &right, &bottom);

do {
const std::unique_ptr<const char[]> grapheme(
res_it->GetUTF8Text(RIL_SYMBOL));
if (grapheme && grapheme[0] != 0) {
alto_str += HOcrEscape(grapheme.get());
alto_str << HOcrEscape(grapheme.get()).c_str();
}
res_it->Next(RIL_SYMBOL);
} while (!res_it->Empty(RIL_BLOCK) && !res_it->IsAtBeginningOf(RIL_WORD));

alto_str += "\"/>\n";
alto_str << "\"/>";

wcnt++;

if (last_word_in_line) {
alto_str += "\t\t\t\t\t</TextLine>\n";
alto_str << "\n\t\t\t\t\t</TextLine>\n";
lcnt++;
} else {
int hpos = right;
int vpos = top;
res_it->BoundingBox(RIL_WORD, &left, &top, &right, &bottom);
int width = left - hpos;
alto_str << "<SP WIDTH=\"" << width << "\" VPOS=\"" << vpos
<< "\" HPOS=\"" << hpos << "\"/>\n";
}

if (last_word_in_block) {
alto_str += "\t\t\t\t</TextBlock>\n";
alto_str << "\t\t\t\t</TextBlock>\n";
bcnt++;
}
}

alto_str += "\t\t\t</PrintSpace>\n";
alto_str += "\t\t</Page>\n";
alto_str << "\t\t\t</PrintSpace>\n"
<< "\t\t</Page>\n";
const std::string& text = alto_str.str();

char* ret = new char[alto_str.length() + 1];
strcpy(ret, alto_str.string());
char* result = new char[text.length() + 1];
strcpy(result, text.c_str());
delete res_it;
return ret;
return result;
}

} // namespace tesseract

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