Method drawText

lib/GfxRenderer/GfxRenderer.cpp:388–469

}

void GfxRenderer::drawText(const int fontId, const int x, const int y, const char* text, const bool black,
                           const EpdFontFamily::Style style, const BidiUtils::BidiBaseDir baseDir) const {
  // cannot draw a NULL / empty string
  if (text == nullptr || *text == '\0') {
    return;
  }

  std::string visual;
  const char* renderedText = resolveVisualText(text, visual, baseDir);

  const int yPos = y + getFontAscenderSize(fontId);
  int lastBaseX = x;
  int lastBaseLeft = 0;
  int lastBaseWidth = 0;
  int lastBaseTop = 0;
  int32_t prevAdvanceFP = 0;  // 12.4 fixed-point: prev glyph's advance + next kern for snap

  if (fontCacheManager_ && fontCacheManager_->isScanning()) {
    fontCacheManager_->recordText(renderedText, fontId, style);
    return;
  }

  const auto fontIt = fontMap.find(fontId);
  if (fontIt == fontMap.end()) {
    LOG_ERR("GFX", "Font %d not found", fontId);
    return;
  }
  const auto& font = fontIt->second;

  const char* textCursor = renderedText;
  uint32_t cp;
  uint32_t prevCp = 0;
  while ((cp = utf8NextCodepoint(reinterpret_cast<const uint8_t**>(&textCursor)))) {
    // Skip Hebrew Niqqud (vowel marks)
    // Temporary: avoid adding Niqqud to built-in fonts. Remove when custom fonts are supported.
    if (cp >= 0x0591 && cp <= 0x05C7) {
      continue;
    }

    if (utf8IsCombiningMark(cp)) {
      const EpdGlyph* combiningGlyph = font.getGlyph(cp, style);
      if (!combiningGlyph) continue;
      const int raiseBy = combiningMark::raiseAboveBase(combiningGlyph->top, combiningGlyph->height, lastBaseTop);
      const int combiningX = combiningMark::centerOver(lastBaseX, lastBaseLeft, lastBaseWidth, combiningGlyph->left,
                                                       combiningGlyph->width);
      renderCharImpl<TextRotation::None>(*this, renderMode, font, cp, combiningX, yPos - raiseBy, black, style);
      continue;
    }

    cp = font.applyLigatures(cp, textCursor, style);

    // Differential rounding: snap (previous advance + current kern) as one unit so
    // identical character pairs always produce the same pixel step regardless of
    // where they fall on the line.
    if (prevCp != 0) {
      const auto kernFP = font.getKerning(prevCp, cp, style);  // 4.4 fixed-point kern
      lastBaseX += fp4::toPixel(prevAdvanceFP + kernFP);       // snap 12.4 fixed-point to nearest pixel
    }