Cleanup/refactor: Workspace API, boilerplate code, early exit

* Simplify workspace API a bit
* Comment on behavior of workspace-layout relations where exposed in API
* Remove annoying getters/setters
* Avoid lookups if we can early exit
* A NULL check is removed in `direct_link_workspace()` that I don't see
  a need for. Am not 100% sure though, fingers crossed.

In general these changes should improve readability and make things
easier to reason about.

1 files changed, 43 insertions, 35 deletions

diff --git a/source/blender/blenkernel/intern/workspace.c b/source/blender/blenkernel/intern/workspace.c
index 3a69b95c114..4625fd76293 100644
--- a/source/blender/blenkernel/intern/workspace.c
+++ b/source/blender/blenkernel/intern/workspace.c
@@ -69,17 +69,9 @@ static void workspace_free_data(ID *id)
 static void workspace_foreach_id(ID *id, LibraryForeachIDData *data)
 {
   WorkSpace *workspace = (WorkSpace *)id;
-  ListBase *layouts = BKE_workspace_layouts_get(workspace);
 
-  LISTBASE_FOREACH (WorkSpaceLayout *, layout, layouts) {
-    bScreen *screen = BKE_workspace_layout_screen_get(layout);
-
-    /* CALLBACK_INVOKE expects an actual pointer, not a variable holding the pointer.
-     * However we can't access layout->screen here
-     * since we are outside the workspace project. */
-    BKE_LIB_FOREACHID_PROCESS(data, screen, IDWALK_CB_USER);
-    /* allow callback to set a different screen */
-    BKE_workspace_layout_screen_set(layout, screen);
+  LISTBASE_FOREACH (WorkSpaceLayout *, layout, &workspace->layouts) {
+    BKE_LIB_FOREACHID_PROCESS(data, layout->screen, IDWALK_CB_USER);
   }
 }
 
@@ -228,7 +220,7 @@ WorkSpaceInstanceHook *BKE_workspace_instance_hook_create(const Main *bmain)
 
   /* set an active screen-layout for each possible window/workspace combination */
   for (WorkSpace *workspace = bmain->workspaces.first; workspace; workspace = workspace->id.next) {
-    BKE_workspace_hook_layout_for_workspace_set(hook, workspace, workspace->layouts.first);
+    BKE_workspace_active_layout_set(hook, workspace, workspace->layouts.first);
   }
 
   return hook;
@@ -433,6 +425,10 @@ WorkSpace *BKE_workspace_active_get(WorkSpaceInstanceHook *hook)
 }
 void BKE_workspace_active_set(WorkSpaceInstanceHook *hook, WorkSpace *workspace)
 {
+  if (hook->active == workspace) {
+    return;
+  }
+
   hook->active = workspace;
   if (workspace) {
     WorkSpaceLayout *layout = workspace_relation_get_data_matching_parent(
@@ -443,13 +439,47 @@ void BKE_workspace_active_set(WorkSpaceInstanceHook *hook, WorkSpace *workspace)
   }
 }
 
+/**
+ * Get the layout that is active for \a hook (which is the visible layout for the active workspace
+ * in \a hook).
+ */
 WorkSpaceLayout *BKE_workspace_active_layout_get(const WorkSpaceInstanceHook *hook)
 {
   return hook->act_layout;
 }
-void BKE_workspace_active_layout_set(WorkSpaceInstanceHook *hook, WorkSpaceLayout *layout)
+
+/**
+ * Get the layout to be activated should \a workspace become or be the active workspace in \a hook.
+ */
+WorkSpaceLayout *BKE_workspace_active_layout_for_workspace_get(const WorkSpaceInstanceHook *hook,
+                                                               const WorkSpace *workspace)
+{
+  /* If the workspace is active, the active layout can be returned, no need for a lookup. */
+  if (hook->active == workspace) {
+    return hook->act_layout;
+  }
+
+  /* Inactive workspace */
+  return workspace_relation_get_data_matching_parent(&workspace->hook_layout_relations, hook);
+}
+
+/**
+ * \brief Activate a layout
+ *
+ * Sets \a layout as active for \a workspace when activated through or already active in \a hook.
+ * So when the active workspace of \a hook is \a workspace, \a layout becomes the active layout of
+ * \a hook too. See #BKE_workspace_active_set().
+ *
+ * \a workspace does not need to be active for this.
+ *
+ * WorkSpaceInstanceHook.act_layout should only be modified directly to update the layout pointer.
+ */
+void BKE_workspace_active_layout_set(WorkSpaceInstanceHook *hook,
+                                     WorkSpace *workspace,
+                                     WorkSpaceLayout *layout)
 {
   hook->act_layout = layout;
+  workspace_relation_ensure_updated(&workspace->hook_layout_relations, hook, layout);
 }
 
 bScreen *BKE_workspace_active_screen_get(const WorkSpaceInstanceHook *hook)
@@ -462,12 +492,7 @@ void BKE_workspace_active_screen_set(WorkSpaceInstanceHook *hook,
 {
   /* we need to find the WorkspaceLayout that wraps this screen */
   WorkSpaceLayout *layout = BKE_workspace_layout_find(hook->active, screen);
-  BKE_workspace_hook_layout_for_workspace_set(hook, workspace, layout);
-}
-
-ListBase *BKE_workspace_layouts_get(WorkSpace *workspace)
-{
-  return &workspace->layouts;
+  BKE_workspace_active_layout_set(hook, workspace, layout);
 }
 
 const char *BKE_workspace_layout_name_get(const WorkSpaceLayout *layout)
@@ -485,22 +510,5 @@ bScreen *BKE_workspace_layout_screen_get(const WorkSpaceLayout *layout)
 {
   return layout->screen;
 }
-void BKE_workspace_layout_screen_set(WorkSpaceLayout *layout, bScreen *screen)
-{
-  layout->screen = screen;
-}
-
-WorkSpaceLayout *BKE_workspace_hook_layout_for_workspace_get(const WorkSpaceInstanceHook *hook,
-                                                             const WorkSpace *workspace)
-{
-  return workspace_relation_get_data_matching_parent(&workspace->hook_layout_relations, hook);
-}
-void BKE_workspace_hook_layout_for_workspace_set(WorkSpaceInstanceHook *hook,
-                                                 WorkSpace *workspace,
-                                                 WorkSpaceLayout *layout)
-{
-  hook->act_layout = layout;
-  workspace_relation_ensure_updated(&workspace->hook_layout_relations, hook, layout);
-}
 
 /** \} */