rntviewer/src/render.cpp

internal
u32 mem_edit_bg_color_fn(const u8 *data, u64 off, const void *user_data)
{
  const App_State *app = reinterpret_cast<const App_State *>(user_data);

  #define COL(c) (ImColor((c)[0], (c)[1], (c)[2]))
  if (app->rntinfo.header.start <= off && off <= app->rntinfo.header.end()) return COL(app->vsettings.col_header);
  if (app->rntinfo.footer.start <= off && off <= app->rntinfo.footer.end()) return COL(app->vsettings.col_footer);
  #undef COL

  return IM_COL32(0, 0, 0, 0);
}

internal
MemoryEditor make_memory_editor(const App_State &app)
{
  MemoryEditor mem_edit;
  // mem_edit.ReadOnly = true;
  mem_edit.Cols = 32;
  mem_edit.OptShowDataPreview = true;
  mem_edit.BgColorFn = mem_edit_bg_color_fn;
  mem_edit.BgColorFnUserData = &app;
  return mem_edit;
}

Viewer_Settings make_viewer_settings()
{
  Viewer_Settings settings {};
#define COL(c, r, g, b) settings.c[0] = r/255.0, settings.c[1] = g/255.0, settings.c[2] = b/255.0
  COL(col_header, 150, 0, 50);
  COL(col_footer, 50, 0, 150);
#undef COL
  return settings;
}

internal
void update_and_render(Arena *arena, App_State &app, f32 delta_time)
{
  (void)delta_time;
  
  ImGui::SetNextWindowPos({ 0, 0 });
  ImGui::SetNextWindowSize({ (f32)app.win_data.width, (f32)app.win_data.height });

  Temp scratch = temp_begin(arena);
  defer { temp_end(scratch); };

  const u64 inspected_max_size = 2048;
  u64 text_buf_size = min(app.inspected_file_size * 2, inspected_max_size);
  char *text_buf = arena_push_array_no_zero<char>(scratch.arena, text_buf_size + 1);
  // Convert file content to human readable
  // @Speed: maybe do this only when the file changes
  for (u64 i = 0; i < text_buf_size / 2; ++i)
    sprintf(&text_buf[2 * i], "%02X", app.inspected_fmem[i]);
  text_buf[text_buf_size] = 0;
  
  const auto main_win_flags = ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoDecoration;
  if (ImGui::Begin("main", nullptr, main_win_flags)) {
    ImGui::Text("Inspecting RNTuple '%s' (%s)", app.ntpl_name, 
                (const char *)rntuple_description(scratch.arena, app.rntinfo.anchor));
    ImGui::Separator();

    {
      static MemoryEditor mem_edit = make_memory_editor(app);
      ImGui::BeginTable("Hex View", 2);

      ImGui::TableNextColumn();
      mem_edit.DrawContents(app.inspected_fmem, app.inspected_file_size);

      ImGui::TableNextColumn();
      ImGui::ColorEdit3("Header", app.vsettings.col_header, ImGuiColorEditFlags_NoInputs);
      ImGui::ColorEdit3("Footer", app.vsettings.col_footer, ImGuiColorEditFlags_NoInputs);

      ImGui::EndTable();
    }

    ImGui::End();
  }
}