From d2468507875486faa03bbf95f56171047b65b6a7 Mon Sep 17 00:00:00 2001
From: ocornut <omar@miracleworld.net>
Date: Thu, 13 Nov 2025 15:42:19 +0100
Subject: [PATCH] Fonts: added comment about the classic AddFontFromMemoryTTF()
 issue. (#9067, #6916, #6781, #5330, #4307, #2042, #2029, #1734, #1259, #220)

---
 imgui_draw.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/imgui_draw.cpp b/imgui_draw.cpp
index 54d72f410..21ae9e258 100644
--- a/imgui_draw.cpp
+++ b/imgui_draw.cpp
@@ -3633,6 +3633,11 @@ void ImFontAtlasFontSourceAddToFont(ImFontAtlas* atlas, ImFont* font, ImFontConf
 void ImFontAtlasFontDestroySourceData(ImFontAtlas* atlas, ImFontConfig* src)
 {
     IM_UNUSED(atlas);
+    // IF YOU GET A CRASH IN THE IM_FREE() CALL HERE AND USED AddFontFromMemoryTTF():
+    // - DUE TO LEGACY REASON AddFontFromMemoryTTF() TRANSFERS MEMORY OWNERSHIP BY DEFAULT.
+    // - IT WILL THEREFORE CRASH WHEN PASSED DATA WHICH MAY NOT BE FREEED BY IMGUI.
+    // - USE `ImFontConfig font_cfg; font_cfg.FontDataOwnedByAtlas = false; io.Fonts->AddFontFromMemoryTTF(....., &cfg);` to disable passing ownership/
+    // WE WILL ADDRESS THIS IN A FUTURE REWORK OF THE API.
     if (src->FontDataOwnedByAtlas)
         IM_FREE(src->FontData);
     src->FontData = NULL;