sdl_v2.cpp

static void DrawSurfaceToScreen()
 {
     int n = _num_dirty_rects;
     if (n == 0) return;

     _num_dirty_rects = 0;

     if (n > MAX_DIRTY_RECTS) {
         SDL_CALL SDL_UpdateTexture(
             _sdl_texture, NULL, _sdl_surface->pixels, _sdl_surface->pitch);
         SDL_CALL SDL_RenderClear(_sdl_renderer);
         SDL_CALL SDL_RenderCopy(_sdl_renderer, _sdl_texture, NULL, NULL);
     } else {
         void *pixels;
         int pitch;

         SDL_CALL SDL_LockTexture(_sdl_texture, NULL, &pixels, &pitch);
         memcpy(
             pixels, _sdl_surface->pixels,
             pitch * _sdl_surface->h);
         SDL_CALL SDL_UnlockTexture(_sdl_texture);

         for (int i = 0; i < n; i++) {
             SDL_CALL SDL_RenderCopy(
                 _sdl_renderer, _sdl_texture, &_dirty_rects[i], &_dirty_rects[i]);
         }
     }

     SDL_CALL SDL_RenderPresent(_sdl_renderer);
 }