From 95c10ce3c780e16cc488c8c1eeaec815d475fd77 Mon Sep 17 00:00:00 2001
From: defiantnerd <97224712+defiantnerd@users.noreply.github.com>
Date: Fri, 28 Aug 2026 11:03:00 +0200
Subject: [PATCH] lvgl host: fix platform_set_embed_parent signature

platform.h declares the embed seam as

  void platform_set_embed_parent(Session*, uint32_t, void* native_parent);

but platform_lvgl.cpp defined the third parameter as `unsigned long`. That
is a different overload - and on MSVC x64 `unsigned long` is 32-bit, so it
cannot even collapse into the pointer type by accident. The `void*` version
that widgets.cpp actually calls was therefore never defined, and any
-DNEUI_WITH_LVGL=ON build failed to link with an undefined symbol.

Match the header, and record the value into wd->embed_parent the way the
null host does so the public NEUI_API_EMBED state round-trips. LVGL owns the
whole display, so nothing ever acts on it: there is no foreign native parent
to embed into, event_fd stays -1 and pump_and_tick stays a no-op. Documented
as such in the host's stubbed-or-absent list.

Audited every other platform_* seam in platform.h against all six platform
layers (return type + parameter types); this was the only mismatch.
---
 docs/host-lvgl.md                     |  3 +++
 hosts/crossplatform/platform_lvgl.cpp | 16 +++++++++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/docs/host-lvgl.md b/docs/host-lvgl.md
index 82ac44f..01a3f2a 100644
--- a/docs/host-lvgl.md
+++ b/docs/host-lvgl.md
@@ -57,6 +57,9 @@ scope):
   own display driver, which an embedded target does anyway.
 - Dialogs are resizable; overlay changes (combo drop, popup menu, toast) still invalidate the whole
   frame.
+- DAW embedding (`NEUI_API_EMBED`): the seams are present so the host links and the API round-trips,
+  but LVGL owns the whole display - there is no foreign native parent, so `set_parent` is recorded
+  and ignored, `event_fd` is -1, and `pump_and_tick` is a no-op.
 
 **Known cost to be aware of on 565 targets**: LVGL's software vector path renders ThorVG only into
 ARGB8888/XRGB8888, so on RGB565 every vector task round-trips through a temporary full-framebuffer
diff --git a/hosts/crossplatform/platform_lvgl.cpp b/hosts/crossplatform/platform_lvgl.cpp
index ee42de2..1def87a 100644
--- a/hosts/crossplatform/platform_lvgl.cpp
+++ b/hosts/crossplatform/platform_lvgl.cpp
@@ -1437,9 +1437,19 @@ namespace xpl_host
     g_retired_windows.push_back(w);
   }
 
-  void platform_set_embed_parent(Session*, uint32_t, unsigned long) {}
-  int  platform_embed_event_fd(void*) { return -1; }
-  void platform_embed_pump_and_tick(void*) {}
+  // DAW-embedding seams - LVGL owns the whole display, so there is no foreign
+  // native parent to embed into. The setter still records the value (as the
+  // null host does) so the public NEUI_API_EMBED state round-trips; nothing
+  // ever acts on it, and platform_create_plugwindow ignores wd.embed_parent.
+  void platform_set_embed_parent(Session* session, uint32_t widget_index,
+                                 void* native_parent)
+  {
+    if (!session) return;
+    auto* wd = session->get_widget(widget_index);
+    if (wd) wd->embed_parent = reinterpret_cast<uintptr_t>(native_parent);
+  }
+  int  platform_embed_event_fd(void* /*native_handle*/) { return -1; }
+  void platform_embed_pump_and_tick(void* /*native_handle*/) {}
 
   void platform_destroy_window(WidgetData& wd)
   {