LVGL fix potential memory leak

lib/libesp32/berry_mapping/src/be_cb_module.c

@@ -12,6 +12,10 @@
 #include "be_vm.h"
 #include "be_mem.h"
 
+// Tasmota Logging
+extern void tasmota_log_C(uint32_t loglevel, const char * berry_buf, ...);
+enum LoggingLevels {LOG_LEVEL_NONE, LOG_LEVEL_ERROR, LOG_LEVEL_INFO, LOG_LEVEL_DEBUG, LOG_LEVEL_DEBUG_MORE};
+
 /*********************************************************************************************\
  * Callback structures
  * 
@@ -185,6 +189,7 @@ static int32_t be_cb_make_cb(bvm *vm) {
 \*********************************************************************************************/
 static int32_t be_cb_gen_cb(bvm *vm) {
   int32_t top = be_top(vm);
+  // tasmota_log_C(LOG_LEVEL_DEBUG, "BRY: gen_cb() called");
   if (top >= 1 && be_isfunction(vm, 1)) {
     // find first available slot
     int32_t slot;

lib/libesp32_lvgl/lv_binding_berry/src/embedded/lvgl_glob.be

@@ -32,9 +32,16 @@ class LVGL_glob
   end
 
   #- register an lv.lv_* object in the mapping -#
+  #
+  # returns `true` if it was already present, false instead
   def register_obj(obj)
     if self.cb_obj == nil    self.cb_obj = {} end
+    if self.cb_obj.contains(obj._p)
+      return true
+    else
       self.cb_obj[obj._p] = obj
+      return false
+    end
   end
 
   # get event callback by rank number, expand the list if needed
@@ -115,13 +122,32 @@ class LVGL_glob
     end
   end
 
+  # remove all references to an object when `lv.EVENT_DELETE` is triggered
+  def remove_cb(obj)
+    import introspect
+    var obj_ptr = obj._p
+    # print(">>> DELETE",obj,obj_ptr)
+    self.deregister_obj(obj_ptr)
+    # print(self.cb_event_closure)
+  end
+
+  #
+  # Warning: `make_cb` is called by `cb.gen_cb()` as a cb handler.
+  # Calling back `cb.gen_cb()` should be done with caution to avoid infinite loops.
+  #
   def make_cb(f, obj, name)
+    # fast exit if not for us
+    if name == nil return nil end
+
     import cb
     # print('>> make_cb', f, name, obj)
     # record the object, whatever the callback
     
     if name  == "lv_event_cb"
-      self.register_obj(obj)                # keep a record of the object to prevent from being gc'ed
+      var first_cb = !self.register_obj(obj)                # keep a record of the object to prevent from being gc'ed
+      if first_cb                                           # first time we register a CB for this object, register also a DELETE event
+        obj.add_event_cb(/ o -> self.remove_cb(o), lv.EVENT_DELETE, 0)
+      end
       var rank = self.add_cb_event_closure(obj._p, f)
       # if self.cb_event_closure.contains(obj._p)
       #   tasmota.log("LVG: object:" + str(obj) + "has already an event callback", 2)