// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil; c-brace-offset: 0; -*-
// TeXFont_TFM.cpp
//
// Part of KDVI - A DVI previewer for the KDE desktop environment
//
// (C) 2003 Stefan Kebekus
// Distributed under the GPL

#include <config.h>

#include "TeXFont_TFM.h"
#include "kvs_debug.h"

#include <QDataStream>
#include <QFile>

//#define DEBUG_TFM


TeXFont_TFM::TeXFont_TFM(TeXFontDefinition *parent)
  : TeXFont(parent)
{
#ifdef DEBUG_TFM
  kDebug(kvs::dvi) << "TeXFont_TFM::TeXFont_TFM( parent=" << parent << " )";
#endif

  QFile file( parent->filename );
  if ( !file.open( QIODevice::ReadOnly ) ) {
    kError(kvs::dvi) << "TeXFont_TFM::TeXFont_TFM(): Could not read TFM file" << endl;
    return;
  }
  QDataStream stream( &file );

  // Data from the very beginning of the TFM file, as specified in
  // "The DVI Driver Standard, Level 0", section D.2.1
  quint16 lf, lh, bc, ec, nw, nh, nd;
  stream >> lf >> lh >> bc >> ec >> nw >> nh >> nd;
#ifdef DEBUG_TFM
  kDebug(kvs::dvi) << "lf= " << lf
                << "lh= " << lh << endl
                << "bc= " << bc << endl
                << "ec= " << ec << endl
                << "nw= " << nw << endl
                << "nh= " << nh << endl
                << "nd= " << nd << endl;
#endif
  if ((bc > ec) || (ec >= TeXFontDefinition::max_num_of_chars_in_font)) {
    kError(kvs::dvi) << "TeXFont_TFM::TeXFont_TFM( filename=" << parent->filename << " ): The font has an invalid bc and ec entries." << endl;
    file.close();
    return;
  }

  // Data from the HEADER section of the TFM data.
  file.seek(24);
  stream >> checksum >> design_size_in_TeX_points.value;
#ifdef DEBUG_TFM
  kDebug(kvs::dvi) << "checksum    = " << checksum
                << "design_size = " << design_size_in_TeX_points.toDouble() << " TeX Points" << endl
                << "            = " << design_size_in_TeX_points.toDouble()*254.0/7227.0 << " cm" << endl;
#endif

  // Width table
  fix_word widthTable_in_units_of_design_size[TeXFontDefinition::max_num_of_chars_in_font];
  for(unsigned int i=0; i<TeXFontDefinition::max_num_of_chars_in_font; i++)
    widthTable_in_units_of_design_size[i].value = 0;

  file.seek( 24 + 4*lh + 4*(ec-bc) );
  for(unsigned int i=0; i<nw; i++) {

    stream >> widthTable_in_units_of_design_size[i].value;
    // Some characters, which are used as parts of glyphs, have width
    // 0 --the real width is caculated in a lig_kern program and
    // depends on the preceding character. We cannot calculate the
    // real width here and take 0.4 times the design size as an
    // approximation.
    if (widthTable_in_units_of_design_size[i].value == 0)
      widthTable_in_units_of_design_size[i].fromDouble(0.4);
  }

  // Height table
  fix_word heightTable_in_units_of_design_size[16];
  for(unsigned int i=0; i<16; i++)
    heightTable_in_units_of_design_size[i].value = 0;
  for(unsigned int i=0; i<nh; i++) {
    stream >> heightTable_in_units_of_design_size[i].value;
  }

  // Char-Info table
  file.seek( 24 + 4*lh );
  for(unsigned int characterCode=bc; characterCode<ec; characterCode++) {
    glyph *g = glyphtable+characterCode;

    quint8 byte;
    stream >> byte;
    if (byte >= nw)
      kError(kvs::dvi) << "TeXFont_TFM::TeXFont_TFM( filename=" << parent->filename << " ): The font has an invalid Char-Info table." << endl;
    else {
      characterWidth_in_units_of_design_size[characterCode] = widthTable_in_units_of_design_size[byte];
      g->dvi_advance_in_units_of_design_size_by_2e20 = widthTable_in_units_of_design_size[byte].value;
    }

    stream >> byte;
    byte = byte >> 4;
    if (byte >= nh)
      kError(kvs::dvi) << "TeXFont_TFM::TeXFont_TFM( filename=" << parent->filename << " ): The font has an invalid Char-Info table." << endl;
    else
      characterHeight_in_units_of_design_size[characterCode] = heightTable_in_units_of_design_size[byte];

    stream >> byte;
    stream >> byte;
  }
  file.close();
}


TeXFont_TFM::~TeXFont_TFM()
{
}


glyph* TeXFont_TFM::getGlyph(quint16 characterCode, bool generateCharacterPixmap, const QColor& color)
{
#ifdef DEBUG_TFM
  kDebug(kvs::dvi) << "TeXFont_TFM::getGlyph( ch=" << ch << ", generateCharacterPixmap=" << generateCharacterPixmap << " )";
#endif

  // Paranoia checks
  if (characterCode >= TeXFontDefinition::max_num_of_chars_in_font) {
    kError(kvs::dvi) << "TeXFont_TFM::getGlyph(): Argument is too big." << endl;
    return glyphtable;
  }

  // This is the address of the glyph that will be returned.
  class glyph *g = glyphtable+characterCode;

  if ((generateCharacterPixmap == true) && ((g->shrunkenCharacter.isNull()) || (color != g->color)) ) {
    g->color = color;
    quint16 pixelWidth = (quint16)(parent->displayResolution_in_dpi *
                                     design_size_in_TeX_points.toDouble() *
                                     characterWidth_in_units_of_design_size[characterCode].toDouble() * 100.0/7227.0 + 0.5);
    quint16 pixelHeight = (quint16)(parent->displayResolution_in_dpi *
                                      design_size_in_TeX_points.toDouble() *
                                      characterHeight_in_units_of_design_size[characterCode].toDouble() * 100.0/7227.0 + 0.5);

    // Just make sure that weired TFM files never lead to giant
    // pixmaps that eat all system memory...
    if (pixelWidth > 50)
      pixelWidth = 50;
    if (pixelHeight > 50)
      pixelHeight = 50;

    g->shrunkenCharacter = QImage(pixelWidth, pixelHeight, QImage::Format_RGB32);
    g->shrunkenCharacter.fill(color.rgba());
    g->x2 = 0;
    g->y2 = pixelHeight;
  }

  return g;
}