Outliner: Refactor element warning and mode column querying

Uses a inheritance based approach for querying warning of tree elements
and the mode column support of display modes.

For the warnings, tree elements can override the
`AbstractTreeElement::getWarning()` method and return a warning string.
The UI will draw the warning column with warning icons. This makes the
warning column more generalized and easier to extend to more use-cases.
E.g. library override elements will use this after a followup commit.

To support mode toggles a display mode can now just return true in the
`AbstractTreeDisplay::supportsModeColumn()` method. This makes it
trivial to add mode columns to other display modes, and less error prone
because there's no need to hunt down a bunch of display mode checks in
different places.

9 files changed, 58 insertions, 53 deletions

diff --git a/source/blender/editors/space_outliner/tree/tree_display.cc b/source/blender/editors/space_outliner/tree/tree_display.cc
index 141c68594e8..6ab497b3fbb 100644
--- a/source/blender/editors/space_outliner/tree/tree_display.cc
+++ b/source/blender/editors/space_outliner/tree/tree_display.cc
@@ -45,9 +45,9 @@ std::unique_ptr<AbstractTreeDisplay> AbstractTreeDisplay::createFromDisplayMode(
   return nullptr;
 }
 
-bool AbstractTreeDisplay::hasWarnings() const
+bool AbstractTreeDisplay::supportsModeColumn() const
 {
-  return has_warnings;
+  return false;
 }
 
 }  // namespace blender::ed::outliner
diff --git a/source/blender/editors/space_outliner/tree/tree_display.hh b/source/blender/editors/space_outliner/tree/tree_display.hh
index 327f29aa15e..190e35c81d6 100644
--- a/source/blender/editors/space_outliner/tree/tree_display.hh
+++ b/source/blender/editors/space_outliner/tree/tree_display.hh
@@ -75,12 +75,16 @@ class AbstractTreeDisplay {
    */
   virtual ListBase buildTree(const TreeSourceData &source_data) = 0;
 
-  /** Accessor to whether given tree has some warnings to display. */
-  bool hasWarnings() const;
+  /**
+   * Define if the display mode should be allowed to show a mode column on the left. This column
+   * adds an icon to indicate which objects are in the current mode (edit mode, pose mode, etc.)
+   * and allows adding other objects to the mode by clicking the icon.
+   *
+   * Returns false by default.
+   */
+  virtual bool supportsModeColumn() const;
 
  protected:
-  bool has_warnings = false;
-
   /** All derived classes will need a handle to this, so storing it in the base for convenience. */
   SpaceOutliner &space_outliner_;
 };
@@ -100,6 +104,8 @@ class TreeDisplayViewLayer final : public AbstractTreeDisplay {
 
   ListBase buildTree(const TreeSourceData &source_data) override;
 
+  bool supportsModeColumn() const override;
+
  private:
   void add_view_layer(Scene &, ListBase &, TreeElement *);
   void add_layer_collections_recursive(ListBase &, ListBase &, TreeElement &);
@@ -212,6 +218,8 @@ class TreeDisplayScenes final : public AbstractTreeDisplay {
   TreeDisplayScenes(SpaceOutliner &space_outliner);
 
   ListBase buildTree(const TreeSourceData &source_data) override;
+
+  bool supportsModeColumn() const override;
 };
 
 /* -------------------------------------------------------------------- */
diff --git a/source/blender/editors/space_outliner/tree/tree_display_libraries.cc b/source/blender/editors/space_outliner/tree/tree_display_libraries.cc
index 476bbdb63ae..46a89f17687 100644
--- a/source/blender/editors/space_outliner/tree/tree_display_libraries.cc
+++ b/source/blender/editors/space_outliner/tree/tree_display_libraries.cc
@@ -136,9 +136,6 @@ TreeElement *TreeDisplayLibraries::add_library_contents(Main &mainvar, ListBase
           tenlib = outliner_add_element(&space_outliner_, &lb, &mainvar, nullptr, TSE_ID_BASE, 0);
           tenlib->name = IFACE_("Current File");
         }
-        if (tenlib->flag & TE_HAS_WARNING) {
-          has_warnings = true;
-        }
       }
 
       /* Create data-block list parent element on demand. */
diff --git a/source/blender/editors/space_outliner/tree/tree_display_scenes.cc b/source/blender/editors/space_outliner/tree/tree_display_scenes.cc
index 9e00a425a5a..6b1de7f8b95 100644
--- a/source/blender/editors/space_outliner/tree/tree_display_scenes.cc
+++ b/source/blender/editors/space_outliner/tree/tree_display_scenes.cc
@@ -26,6 +26,11 @@ TreeDisplayScenes::TreeDisplayScenes(SpaceOutliner &space_outliner)
 {
 }
 
+bool TreeDisplayScenes::supportsModeColumn() const
+{
+  return true;
+}
+
 ListBase TreeDisplayScenes::buildTree(const TreeSourceData &source_data)
 {
   /* On first view we open scenes. */
diff --git a/source/blender/editors/space_outliner/tree/tree_display_view_layer.cc b/source/blender/editors/space_outliner/tree/tree_display_view_layer.cc
index 19811e45b90..80b3365766a 100644
--- a/source/blender/editors/space_outliner/tree/tree_display_view_layer.cc
+++ b/source/blender/editors/space_outliner/tree/tree_display_view_layer.cc
@@ -55,6 +55,11 @@ TreeDisplayViewLayer::TreeDisplayViewLayer(SpaceOutliner &space_outliner)
 {
 }
 
+bool TreeDisplayViewLayer::supportsModeColumn() const
+{
+  return true;
+}
+
 ListBase TreeDisplayViewLayer::buildTree(const TreeSourceData &source_data)
 {
   ListBase tree = {nullptr};
diff --git a/source/blender/editors/space_outliner/tree/tree_element.cc b/source/blender/editors/space_outliner/tree/tree_element.cc
index 1e3fd2df7c2..94d55b70e3c 100644
--- a/source/blender/editors/space_outliner/tree/tree_element.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element.cc
@@ -100,6 +100,11 @@ std::unique_ptr<AbstractTreeElement> AbstractTreeElement::createFromType(const i
   return nullptr;
 }
 
+StringRefNull AbstractTreeElement::getWarning() const
+{
+  return "";
+}
+
 void AbstractTreeElement::uncollapse_by_default(TreeElement *legacy_te)
 {
   if (!TREESTORE(legacy_te)->used) {
@@ -118,39 +123,4 @@ void tree_element_expand(const AbstractTreeElement &tree_element, SpaceOutliner
   tree_element.expand(space_outliner);
 }
 
-bool tree_element_warnings_get(TreeElement *te, int *r_icon, const char **r_message)
-{
-  TreeStoreElem *tselem = te->store_elem;
-
-  if (tselem->type != TSE_SOME_ID) {
-    return false;
-  }
-  if (te->idcode != ID_LI) {
-    return false;
-  }
-
-  Library *library = (Library *)tselem->id;
-  if (library->tag & LIBRARY_TAG_RESYNC_REQUIRED) {
-    if (r_icon) {
-      *r_icon = ICON_ERROR;
-    }
-    if (r_message) {
-      *r_message = TIP_(
-          "Contains linked library overrides that need to be resynced, updating the library is "
-          "recommended");
-    }
-    return true;
-  }
-  if (library->id.tag & LIB_TAG_MISSING) {
-    if (r_icon) {
-      *r_icon = ICON_ERROR;
-    }
-    if (r_message) {
-      *r_message = TIP_("Missing library");
-    }
-    return true;
-  }
-  return false;
-}
-
 }  // namespace blender::ed::outliner
diff --git a/source/blender/editors/space_outliner/tree/tree_element.hh b/source/blender/editors/space_outliner/tree/tree_element.hh
index c6593a517dd..d665ff49f53 100644
--- a/source/blender/editors/space_outliner/tree/tree_element.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element.hh
@@ -8,6 +8,8 @@
 
 #include <memory>
 
+#include "BLI_string_ref.hh"
+
 struct ListBase;
 struct SpaceOutliner;
 struct TreeElement;
@@ -56,6 +58,12 @@ class AbstractTreeElement {
   }
 
   /**
+   * By letting this return a warning message, the tree element will display a warning icon with
+   * the message in the tooltip.
+   */
+  virtual blender::StringRefNull getWarning() const;
+
+  /**
    * Expand this tree element if it is displayed for the first time (as identified by its
    * tree-store element).
    *
@@ -96,13 +104,4 @@ struct TreeElement *outliner_add_element(SpaceOutliner *space_outliner,
 
 void tree_element_expand(const AbstractTreeElement &tree_element, SpaceOutliner &space_outliner);
 
-/**
- * Get actual warning data of a tree element, if any.
- *
- * \param r_icon: The icon to display as warning.
- * \param r_message: The message to display as warning.
- * \return true if there is a warning, false otherwise.
- */
-bool tree_element_warnings_get(struct TreeElement *te, int *r_icon, const char **r_message);
-
 }  // namespace blender::ed::outliner
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_library.cc b/source/blender/editors/space_outliner/tree/tree_element_id_library.cc
index 0dcaec0385a..4f1b951ccaf 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_library.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_library.cc
@@ -4,6 +4,8 @@
  * \ingroup spoutliner
  */
 
+#include "BLT_translation.h"
+
 #include "DNA_ID.h"
 #include "DNA_listBase.h"
 
@@ -24,4 +26,21 @@ bool TreeElementIDLibrary::isExpandValid() const
   return true;
 }
 
+StringRefNull TreeElementIDLibrary::getWarning() const
+{
+  Library &library = reinterpret_cast<Library &>(id_);
+
+  if (library.tag & LIBRARY_TAG_RESYNC_REQUIRED) {
+    return TIP_(
+        "Contains linked library overrides that need to be resynced, updating the library is "
+        "recommended");
+  }
+
+  if (library.id.tag & LIB_TAG_MISSING) {
+    return TIP_("Missing library");
+  }
+
+  return {};
+}
+
 }  // namespace blender::ed::outliner
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_library.hh b/source/blender/editors/space_outliner/tree/tree_element_id_library.hh
index ed599cf04da..2d89b55813f 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_library.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_library.hh
@@ -17,6 +17,8 @@ class TreeElementIDLibrary final : public TreeElementID {
   TreeElementIDLibrary(TreeElement &legacy_te, Library &library);
 
   bool isExpandValid() const override;
+
+  blender::StringRefNull getWarning() const override;
 };
 
 }  // namespace blender::ed::outliner