Method renderPage

src/activities/reader/XtcReaderActivity.cpp:207–388

}

void XtcReaderActivity::renderPage() {
  const uint16_t pageWidth = xtc->getPageWidth();
  const uint16_t pageHeight = xtc->getPageHeight();
  const uint8_t bitDepth = xtc->getBitDepth();

  // Calculate buffer size for one page
  // XTG (1-bit): Row-major, ((width+7)/8) * height bytes
  // XTH (2-bit): Two bit planes, column-major, ((width * height + 7) / 8) * 2 bytes
  size_t pageBufferSize;
  if (bitDepth == 2) {
    pageBufferSize = ((static_cast<size_t>(pageWidth) * pageHeight + 7) / 8) * 2;
  } else {
    pageBufferSize = ((pageWidth + 7) / 8) * pageHeight;
  }

  // Allocate page buffer
  uint8_t* pageBuffer = static_cast<uint8_t*>(malloc(pageBufferSize));
  if (!pageBuffer) {
    LOG_ERR("XTR", "Failed to allocate page buffer (%lu bytes)", pageBufferSize);
    renderer.clearScreen();
    renderer.drawCenteredText(UI_12_FONT_ID, 300, tr(STR_MEMORY_ERROR), true, EpdFontFamily::BOLD);
    renderer.displayBuffer();
    return;
  }

  // Load page data
  size_t bytesRead = xtc->loadPage(currentPage, pageBuffer, pageBufferSize);
  if (bytesRead == 0) {
    LOG_ERR("XTR", "Failed to load page %lu: bufferSize=%lu bitDepth=%u error=%s", currentPage, pageBufferSize,
            bitDepth, xtc::errorToString(xtc->getLastError()));
    free(pageBuffer);
    renderer.clearScreen();
    renderer.drawCenteredText(UI_12_FONT_ID, 300, tr(STR_PAGE_LOAD_ERROR), true, EpdFontFamily::BOLD);
    renderer.displayBuffer();
    return;
  }

  // Clear screen first
  renderer.clearScreen();

  // Copy page bitmap using GfxRenderer's drawPixel
  // XTC/XTCH pages are pre-rendered with status bar included, so render full page
  const uint16_t maxSrcY = pageHeight;

  if (bitDepth == 2) {
    // XTH 2-bit mode: Two bit planes, column-major order
    // - Columns scanned right to left (x = width-1 down to 0)
    // - 8 vertical pixels per byte (MSB = topmost pixel in group)
    // - First plane: Bit1, Second plane: Bit2
    // - Pixel value = (bit1 << 1) | bit2
    // - Grayscale: 0=White, 1=Dark Grey, 2=Light Grey, 3=Black

    const size_t planeSize = (static_cast<size_t>(pageWidth) * pageHeight + 7) / 8;
    const uint8_t* plane1 = pageBuffer;              // Bit1 plane
    const uint8_t* plane2 = pageBuffer + planeSize;  // Bit2 plane
    const size_t colBytes = (pageHeight + 7) / 8;    // Bytes per column (100 for 800 height)

    // Lambda to get pixel value at (x, y)