Added support for desktop full screen with pillarboxing and letterboxing

and started adding some comments to the code

src/ObjectStore.c

@@ -41,9 +41,22 @@ ObjectStore *create_object_store() {
   return os;
 }
 
+bool object_exists(ObjectStore *os, void *object) {
+  // This is a crude implementation for checking that an object has already
+  // been added.
+  // TODO (Abdelrahman): Figure out if there is a better way of doing this
+  for (size_t i = 0; i < MAX_OBJ_COUNT; ++i) {
+    if (object == os->object_ptrs[i]) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 ObjectID add_object_to_store(ObjectStore *os, void *object, EventHandlerPtr eh,
                              UpdateFuncPtr uf, RenderFuncPtr rf) {
-  if (!os || !object ||
+  if (!os || !object || object_exists(os, object) ||
       (os->count + 1 == MAX_OBJ_COUNT && os->deleted_count == 0)) {
 #ifdef DEBUG_ENGINE
     printf("Failed to add object\n");
@@ -52,14 +65,6 @@ ObjectID add_object_to_store(ObjectStore *os, void *object, EventHandlerPtr eh,
     return INVALID_ID;
   }
 
-  // TODO (Abdelrahman): Need to figure out a way to check that the object
-  // hasn't already been added to the store. If it has been added before, the
-  // function should return -1 indicating an error to ensure that there aren't
-  // two references to the same object without the user being aware that they
-  // refer to the same thing. If the user intentionally copies the ID of one
-  // object, then it would be their responsibility to make sure they don't
-  // delete the object using one of the IDs, then try to use it with the other.
-
   ObjectID id;
 
   if (os->deleted_count > 0) {
@@ -141,7 +146,10 @@ void destroy_object_store(ObjectStore **os) {
     return;
   }
 
-  for (size_t i = 0; i < (*os)->count; ++i) {
+  // TODO (Abdelrahman): Figure out if there is a better way to remove all of
+  // the existing objects without having to loop for the maximum number of
+  // objects allowed.
+  for (size_t i = 0; i < MAX_OBJ_COUNT; ++i) {
     (*os)->object_ptrs[i] = NULL;
     (*os)->event_handlers[i] = NULL;
     (*os)->update_funcs[i] = NULL;