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
double old_x = 0.0, old_y = 0.0;
int old_fontsize = 0;
tesseract::WritingDirection old_writing_direction =
WRITING_DIRECTION_LEFT_TO_RIGHT;
bool new_block = true;
int fontsize = 0;
double a = 1;
double b = 0;
double c = 0;
double d = 1;
// 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 /Im1 Do Q\n";
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
old_fontsize = 0; // Every block will declare its fontsize
new_block = true; // Every block will declare its affine matrix
}
int line_x1, line_y1, line_x2, line_y2;
if (res_it->IsAtBeginningOf(RIL_TEXTLINE)) {
int x1, y1, x2, y2;
res_it->Baseline(RIL_TEXTLINE, &x1, &y1, &x2, &y2);
ClipBaseline(ppi, x1, y1, x2, y2, &line_x1, &line_y1, &line_x2, &line_y2);
}
if (res_it->Empty(RIL_WORD)) {
res_it->Next(RIL_WORD);
continue;
}
// Writing direction changes at a per-word granularity
tesseract::WritingDirection writing_direction;
{
tesseract::Orientation orientation;
tesseract::TextlineOrder textline_order;
float deskew_angle;
res_it->Orientation(&orientation, &writing_direction,
&textline_order, &deskew_angle);
if (writing_direction != WRITING_DIRECTION_TOP_TO_BOTTOM) {
switch (res_it->WordDirection()) {
case DIR_LEFT_TO_RIGHT:
writing_direction = WRITING_DIRECTION_LEFT_TO_RIGHT;
break;
case DIR_RIGHT_TO_LEFT:
writing_direction = WRITING_DIRECTION_RIGHT_TO_LEFT;
break;
default:
writing_direction = old_writing_direction;
}
}
}
// Where is word origin and how long is it?
double x, y, word_length;
{
int word_x1, word_y1, word_x2, word_y2;
res_it->Baseline(RIL_WORD, &word_x1, &word_y1, &word_x2, &word_y2);
GetWordBaseline(writing_direction, ppi, height,
word_x1, word_y1, word_x2, word_y2,
line_x1, line_y1, line_x2, line_y2,
&x, &y, &word_length);
}
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
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
}
old_x = x;
old_y = y;
old_writing_direction = writing_direction;
// Adjust font size on a per word granularity. Pay attention to
// fontsize, old_fontsize, and pdf_str. We've found that for
// in Arabic, Tesseract will happily return a fontsize of zero,
// so we make up a default number to protect ourselves.
{
bool bold, italic, underlined, monospace, serif, smallcaps;
int font_id;
res_it->WordFontAttributes(&bold, &italic, &underlined, &monospace,
&serif, &smallcaps, &fontsize, &font_id);
const int kDefaultFontsize = 8;
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;
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("");
int pdf_word_len = 0;
do {
const char *grapheme = res_it->GetUTF8Text(RIL_SYMBOL);
if (grapheme && grapheme[0] != '\0') {
// TODO(jbreiden) Do a real UTF-16BE conversion
// http://en.wikipedia.org/wiki/UTF-16#Example_UTF-16_encoding_procedure
string_32 utf32;
CubeUtils::UTF8ToUTF32(grapheme, &utf32);
char utf16[20];
for (int i = 0; i < static_cast<int>(utf32.length()); i++) {
snprintf(utf16, sizeof(utf16), "<%04X>", utf32[i]);
pdf_word += utf16;
pdf_word_len++;
}
}
delete[]grapheme;
res_it->Next(RIL_SYMBOL);
} while (!res_it->Empty(RIL_BLOCK) && !res_it->IsAtBeginningOf(RIL_WORD));
if (word_length > 0 && pdf_word_len > 0 && fontsize > 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
}
if (last_word_in_line) {
pdf_str += " \n";
}
if (last_word_in_block) {
pdf_str += "ET\n"; // end the text object
}
}
char *ret = new char[pdf_str.length() + 1];
strcpy(ret, pdf_str.string());
delete res_it;
return ret;
}
AffineMatrix AffineMatrix::clone() const {
return AffineMatrix(a, b, c, d, tx, ty);
}