Fix T78688: Crash changing workspace with specific fullscreen setup

When switching workspaces we need to have an unused screen layout that
we can activate. The other window now showed the only available screen
layout in fullscreen though.
Usually when there's no unused screen layout we duplicate an existing
one, but that code didn't respect the fullscreen case properly.

This also tries to clean up the logic a bit, but things are still rather
complicated to follow.

Changes in this code are always risky. Of course things worked fine in
my tests, but I wouldn't be surprised if something breaks.

1 files changed, 5 insertions, 26 deletions

diff --git a/source/blender/editors/screen/workspace_edit.c b/source/blender/editors/screen/workspace_edit.c
index 478a0adfd9a..b20dc80d158 100644
--- a/source/blender/editors/screen/workspace_edit.c
+++ b/source/blender/editors/screen/workspace_edit.c
@@ -88,22 +88,15 @@ static void workspace_change_update(WorkSpace *workspace_new,
 #endif
 }
 
-static bool workspace_change_find_new_layout_cb(const WorkSpaceLayout *layout, void *UNUSED(arg))
-{
-  /* return false to stop the iterator if we've found a layout that can be activated */
-  return workspace_layout_set_poll(layout) ? false : true;
-}
-
 static WorkSpaceLayout *workspace_change_get_new_layout(Main *bmain,
                                                         WorkSpace *workspace_new,
                                                         wmWindow *win)
 {
-  /* ED_workspace_duplicate may have stored a layout to activate
-   * once the workspace gets activated. */
   WorkSpaceLayout *layout_old = WM_window_get_active_layout(win);
   WorkSpaceLayout *layout_new;
-  bScreen *screen_new;
 
+  /* ED_workspace_duplicate may have stored a layout to activate
+   * once the workspace gets activated. */
   if (win->workspace_hook->temp_workspace_store) {
     layout_new = win->workspace_hook->temp_layout_store;
   }
@@ -113,20 +106,9 @@ static WorkSpaceLayout *workspace_change_get_new_layout(Main *bmain,
       layout_new = workspace_new->layouts.first;
     }
   }
-  screen_new = BKE_workspace_layout_screen_get(layout_new);
-
-  if (screen_new->winid) {
-    /* screen is already used, try to find a free one */
-    WorkSpaceLayout *layout_temp = BKE_workspace_layout_iter_circular(
-        workspace_new, layout_new, workspace_change_find_new_layout_cb, NULL, false);
-    if (!layout_temp) {
-      /* fallback solution: duplicate layout from old workspace */
-      layout_temp = ED_workspace_layout_duplicate(bmain, workspace_new, layout_old, win);
-    }
-    layout_new = layout_temp;
-  }
 
-  return layout_new;
+  return ED_workspace_screen_change_ensure_unused_layout(
+      bmain, workspace_new, layout_new, layout_old, win);
 }
 
 /**
@@ -153,10 +135,7 @@ bool ED_workspace_change(WorkSpace *workspace_new, bContext *C, wmWindowManager
     return false;
   }
 
-  screen_new = screen_change_prepare(screen_old, screen_new, bmain, C, win);
-  if (BKE_workspace_layout_screen_get(layout_new) != screen_new) {
-    layout_new = BKE_workspace_layout_find(workspace_new, screen_new);
-  }
+  screen_change_prepare(screen_old, screen_new, bmain, C, win);
 
   if (screen_new == NULL) {
     return false;