From b1c084790fbbe44820d6805a5da4bc6c1ecac5c4 Mon Sep 17 00:00:00 2001
From: mattias <mattias@idefix.freepascal.org>
Date: Mon, 21 Oct 2019 16:36:27 +0000
Subject: [PATCH] rtl: SetMethodProp: reuse callback if possible

---
 packages/rtl/typinfo.pas | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/packages/rtl/typinfo.pas b/packages/rtl/typinfo.pas
index 20d5376..9f004d7 100644
--- a/packages/rtl/typinfo.pas
+++ b/packages/rtl/typinfo.pas
@@ -1418,7 +1418,19 @@ procedure SetMethodProp(Instance: TObject; PropInfo: TTypeMemberProperty;
 var
   cb: TJSFunction;
 begin
-  cb:=createCallback(Value.Data,Value.Code);
+  // Note: Value.Data=nil is allowed and can be used by designer code
+  if Value.Code=nil then
+    cb:=nil
+  else if isFunction(Value.Code)
+      and (TJSObject(Value.Code)['scope']=Value.Data)
+      and (isFunction(TJSObject(Value.Code)['fn']) or isString(TJSObject(Value.Code)['fn']))
+      then
+    begin
+    // Value.Code is already a callback
+    cb:=TJSFunction(Value.Code);
+    end
+  else
+    cb:=createCallback(Value.Data,Value.Code);
   SetJSValueProp(Instance,PropInfo,cb);
 end;