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Use std::stringstream to generate PDF output

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Using std::stringstream simplifies the code and allows conversion of
double to string independent of the current locale setting.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
This commit is contained in:
Stefan Weil 2019-04-14 12:37:54 +02:00
parent 78a957b989
commit aa64a63f69
1 changed files with 33 additions and 33 deletions
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66
src/api/pdfrenderer.cpp
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@ -20,7 +20,9 @@
#include "config_auto.h"
#endif
#include <locale> // for std::locale::classic
#include <memory> // std::unique_ptr
#include <sstream> // for std::stringstream
#include "allheaders.h"
#include "baseapi.h"
#include <cmath>
@ -324,7 +326,6 @@ static bool CodepointToUtf16be(int code, char utf16[kMaxBytesPerCodepoint]) {
char* TessPDFRenderer::GetPDFTextObjects(TessBaseAPI* api,
double width, double height) {
STRING pdf_str("");
double ppi = api->GetSourceYResolution();
// These initial conditions are all arbitrary and will be overwritten
@ -339,18 +340,20 @@ char* TessPDFRenderer::GetPDFTextObjects(TessBaseAPI* api,
double c = 0;
double d = 1;
std::stringstream pdf_str;
// Use "C" locale (needed for double values prec()).
pdf_str.imbue(std::locale::classic());
// Use 8 digits for double values.
pdf_str.precision(8);
// TODO(jbreiden) This marries the text and image together.
// Slightly cleaner from an abstraction standpoint if this were to
// live inside a separate text object.
pdf_str += "q ";
pdf_str.add_str_double("", prec(width));
pdf_str += " 0 0 ";
pdf_str.add_str_double("", prec(height));
pdf_str += " 0 0 cm";
pdf_str << "q " << prec(width) << " 0 0 " << prec(height) << " 0 0 cm";
if (!textonly_) {
pdf_str += " /Im1 Do";
pdf_str << " /Im1 Do";
}
pdf_str += " Q\n";
pdf_str << " Q\n";
int line_x1 = 0;
int line_y1 = 0;
@ -360,7 +363,7 @@ char* TessPDFRenderer::GetPDFTextObjects(TessBaseAPI* api,
ResultIterator *res_it = api->GetIterator();
while (!res_it->Empty(RIL_BLOCK)) {
if (res_it->IsAtBeginningOf(RIL_BLOCK)) {
pdf_str += "BT\n3 Tr"; // Begin text object, use invisible ink
pdf_str << "BT\n3 Tr"; // Begin text object, use invisible ink
old_fontsize = 0; // Every block will declare its fontsize
new_block = true; // Every block will declare its affine matrix
}
@ -412,20 +415,20 @@ char* TessPDFRenderer::GetPDFTextObjects(TessBaseAPI* api,
if (writing_direction != old_writing_direction || new_block) {
AffineMatrix(writing_direction,
line_x1, line_y1, line_x2, line_y2, &a, &b, &c, &d);
pdf_str.add_str_double(" ", prec(a)); // . This affine matrix
pdf_str.add_str_double(" ", prec(b)); // . sets the coordinate
pdf_str.add_str_double(" ", prec(c)); // . system for all
pdf_str.add_str_double(" ", prec(d)); // . text that follows.
pdf_str.add_str_double(" ", prec(x)); // .
pdf_str.add_str_double(" ", prec(y)); // .
pdf_str += (" Tm "); // Place cursor absolutely
pdf_str << " " << prec(a) // . This affine matrix
<< " " << prec(b) // . sets the coordinate
<< " " << prec(c) // . system for all
<< " " << prec(d) // . text that follows.
<< " " << prec(x) // .
<< " " << prec(y) // .
<< (" Tm "); // Place cursor absolutely
new_block = false;
} else {
double dx = x - old_x;
double dy = y - old_y;
pdf_str.add_str_double(" ", prec(dx * a + dy * b));
pdf_str.add_str_double(" ", prec(dx * c + dy * d));
pdf_str += (" Td "); // Relative moveto
pdf_str << " " << prec(dx * a + dy * b)
<< " " << prec(dx * c + dy * d)
<< (" Td "); // Relative moveto
}
old_x = x;
old_y = y;
@ -444,16 +447,14 @@ char* TessPDFRenderer::GetPDFTextObjects(TessBaseAPI* api,
if (fontsize <= 0)
fontsize = kDefaultFontsize;
if (fontsize != old_fontsize) {
char textfont[20];
snprintf(textfont, sizeof(textfont), "/f-0-0 %d Tf ", fontsize);
pdf_str += textfont;
pdf_str << "/f-0-0 " << fontsize << " Tf ";
old_fontsize = fontsize;
}
}
bool last_word_in_line = res_it->IsAtFinalElement(RIL_TEXTLINE, RIL_WORD);
bool last_word_in_block = res_it->IsAtFinalElement(RIL_BLOCK, RIL_WORD);
STRING pdf_word("");
std::string pdf_word;
int pdf_word_len = 0;
do {
const std::unique_ptr<const char[]> grapheme(
@ -473,23 +474,22 @@ char* TessPDFRenderer::GetPDFTextObjects(TessBaseAPI* api,
if (word_length > 0 && pdf_word_len > 0) {
double h_stretch =
kCharWidth * prec(100.0 * word_length / (fontsize * pdf_word_len));
pdf_str.add_str_double("", h_stretch);
pdf_str += " Tz"; // horizontal stretch
pdf_str += " [ <";
pdf_str += pdf_word; // UTF-16BE representation
pdf_str += "> ] TJ"; // show the text
pdf_str << h_stretch << " Tz" // horizontal stretch
<< " [ <" << pdf_word // UTF-16BE representation
<< "> ] TJ"; // show the text
}
if (last_word_in_line) {
pdf_str += " \n";
pdf_str << " \n";
}
if (last_word_in_block) {
pdf_str += "ET\n"; // end the text object
pdf_str << "ET\n"; // end the text object
}
}
char *ret = new char[pdf_str.length() + 1];
strcpy(ret, pdf_str.string());
const std::string& text = pdf_str.str();
char* result = new char[text.length() + 1];
strcpy(result, text.c_str());
delete res_it;
return ret;
return result;
}
bool TessPDFRenderer::BeginDocumentHandler() {