use prototype inheritance for lua screens, rather than functions

this gives us a way to give each screen nice little hooks, like
'onShown' and 'onHidden'. later we can use these hooks to disable
bindings for screens that aren't in-use.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/ui/screen_lua.cpp b/src/ui/screen_lua.cpp
index 5130b4f7..d6c7a26f 100644
--- a/src/ui/screen_lua.cpp
+++ b/src/ui/screen_lua.cpp
@@ -7,8 +7,10 @@
 #include "screen_lua.hpp"
 
 #include "core/lv_obj_tree.h"
+#include "lua.h"
 #include "lua.hpp"
 
+#include "lua_thread.hpp"
 #include "luavgl.h"
 
 namespace ui {
@@ -22,6 +24,40 @@ Lua::~Lua() {
   }
 }
 
+auto Lua::onShown() -> void {
+  if (!s_ || !obj_ref_) {
+    return;
+  }
+  lua_rawgeti(s_, LUA_REGISTRYINDEX, *obj_ref_);
+  lua_pushliteral(s_, "onShown");
+
+  if (lua_gettable(s_, -2) == LUA_TFUNCTION) {
+    lua_pushvalue(s_, -2);
+    lua::CallProtected(s_, 1, 0);
+  } else {
+    lua_pop(s_, 1);
+  }
+
+  lua_pop(s_, 1);
+}
+
+auto Lua::onHidden() -> void {
+  if (!s_ || !obj_ref_) {
+    return;
+  }
+  lua_rawgeti(s_, LUA_REGISTRYINDEX, *obj_ref_);
+  lua_pushliteral(s_, "onHidden");
+
+  if (lua_gettable(s_, -2) == LUA_TFUNCTION) {
+    lua_pushvalue(s_, -2);
+    lua::CallProtected(s_, 1, 0);
+  } else {
+    lua_pop(s_, 1);
+  }
+
+  lua_pop(s_, 1);
+}
+
 auto Lua::SetObjRef(lua_State* s) -> void {
   assert(s_ == nullptr);
   s_ = s;