Add hello world sdl project

The idea is eventually to visualize the tree to help debugging

CMakeLists.txt

@@ -74,6 +74,15 @@ set_target_properties(versioned_map PROPERTIES LINKER_LANGUAGE C)
 
 include(CTest)
 
+option(BUILD_TREE_VIS "Build tree visualization" OFF)
+if(BUILD_TREE_VIS)
+  find_package(SDL2 REQUIRED)
+  find_package(SDL2_ttf REQUIRED)
+  add_executable(tree_vis TreeVis.cpp)
+  target_link_libraries(tree_vis PRIVATE SDL2::SDL2)
+  target_link_libraries(tree_vis PRIVATE SDL2_ttf::SDL2_ttf)
+endif()
+
 if(BUILD_TESTING)
   add_executable(rootset_test RootSet.cpp)
   target_compile_definitions(rootset_test PRIVATE ENABLE_ROOTSET_TESTS)

TreeVis.cpp

@@ -0,0 +1,53 @@
+#include <SDL.h>
+#include <SDL_ttf.h>
+
+int main(int argc, char *argv[]) {
+  SDL_Init(SDL_INIT_VIDEO);
+
+  TTF_Init();
+
+  SDL_Window *window =
+      SDL_CreateWindow("Hello World", SDL_WINDOWPOS_UNDEFINED,
+                       SDL_WINDOWPOS_UNDEFINED | SDL_WINDOW_ALLOW_HIGHDPI, 1920,
+                       1080, SDL_WINDOW_SHOWN);
+
+  SDL_Renderer *renderer =
+      SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
+
+  TTF_Font *font =
+      TTF_OpenFont("../third_party/scientifica/ttf/scientifica.ttf", 72);
+
+  bool running = true;
+  while (running) {
+    SDL_Event event;
+    while (SDL_PollEvent(&event)) {
+      if (event.type == SDL_QUIT) {
+        running = false;
+      }
+    }
+
+    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
+    SDL_RenderClear(renderer);
+
+    auto *surface = TTF_RenderUTF8_Solid(font, "Hello World", {0, 255, 0});
+    SDL_Texture *texture = SDL_CreateTextureFromSurface(renderer, surface);
+    SDL_Rect dst = {0, 0, 0, 0};
+    SDL_QueryTexture(texture, NULL, NULL, &dst.w, &dst.h);
+    SDL_RenderCopy(renderer, texture, NULL, &dst);
+
+    SDL_DestroyTexture(texture);
+    SDL_FreeSurface(surface);
+
+    SDL_RenderPresent(renderer);
+  }
+
+  TTF_CloseFont(font);
+
+  SDL_DestroyRenderer(renderer);
+  SDL_DestroyWindow(window);
+
+  TTF_Quit();
+  SDL_Quit();
+
+  return 0;
+}