UI: show the windowing environment in the "About" splash

Show the windowing environment on non MS-Windows/Apple systems,
since X11/WAYLAND are selected startup there was no convenient way
for users to know which back-end was being used.

Include the windowing environment in the About splash & system-info.txt
since it will be useful for handling bug reports.

This commit adds a private API call not intended for general use
as I would like to be able to remove this later and it's only needed
in the specific case of testing if Blender is using WAYLAND or X11
(which maybe be used via XWayland).

Python scripts can already inspect the system to check which windowing
environment used, the API call is mainly useful for troubleshooting.

2 files changed, 25 insertions, 0 deletions

diff --git a/source/blender/windowmanager/WM_api.h b/source/blender/windowmanager/WM_api.h
index 5b6f7939ab9..1f9de8040f6 100644
--- a/source/blender/windowmanager/WM_api.h
+++ b/source/blender/windowmanager/WM_api.h
@@ -119,6 +119,13 @@ void WM_init_splash(struct bContext *C);
 
 void WM_init_opengl(void);
 
+/**
+ * Return an identifier for the underlying GHOST implementation.
+ * \warning Use of this function should be limited & never for compatibility checks.
+ * see: #GHOST_ISystem::getSystemBackend for details.
+ */
+const char *WM_ghost_backend(void);
+
 void WM_check(struct bContext *C);
 void WM_reinit_gizmomap_all(struct Main *bmain);
 
diff --git a/source/blender/windowmanager/intern/wm_window.c b/source/blender/windowmanager/intern/wm_window.c
index a4f92da2774..b1b13390932 100644
--- a/source/blender/windowmanager/intern/wm_window.c
+++ b/source/blender/windowmanager/intern/wm_window.c
@@ -91,6 +91,9 @@
 
 /* the global to talk to ghost */
 static GHOST_SystemHandle g_system = NULL;
+#if !(defined(WIN32) || defined(__APPLE__))
+static const char *g_system_backend_id = NULL;
+#endif
 
 typedef enum eWinOverrideFlag {
   WIN_OVERRIDE_GEOM = (1 << 0),
@@ -1552,6 +1555,9 @@ void wm_ghost_init(bContext *C)
     /* This will leak memory, it's preferable to crashing. */
     exit(1);
   }
+#if !(defined(WIN32) || defined(__APPLE__))
+  g_system_backend_id = GHOST_SystemBackend();
+#endif
 
   GHOST_Debug debug = {0};
   if (G.debug & G_DEBUG_GHOST) {
@@ -1597,6 +1603,18 @@ void wm_ghost_exit(void)
   g_system = NULL;
 }
 
+const char *WM_ghost_backend(void)
+{
+#if !(defined(WIN32) || defined(__APPLE__))
+  return g_system_backend_id ? g_system_backend_id : "NONE";
+#else
+  /* While this could be supported, at the moment it's only needed with GHOST X11/WAYLAND
+   * to check which was selected and the API call may be removed after that's no longer needed.
+   * Use dummy values to prevent this being used on other systems. */
+  return g_system ? "DEFAULT" : "NONE";
+#endif
+}
+
 /** \} */
 
 /* -------------------------------------------------------------------- */