UI: Add context menu support for tree-view items

Tree-view items can now easily define their own context menu. This works
by overriding the `ui::AbstractTreeViewItem::build_context_menu()`
function. See the documentation:
https://wiki.blender.org/wiki/Source/Interface/Views#Context_Menus

Consistently with the Outliner and File Browser, the right-clicked item
also gets activated. This makes sure the correct context is set for the
operators and makes it clear to the user which item is operated on.

An operator to rename the active item is also added, which is something
you'd typically want to put in the context menu as well.

1 files changed, 13 insertions, 0 deletions

diff --git a/source/blender/editors/interface/tree_view.cc b/source/blender/editors/interface/tree_view.cc
index 3f66810b7f6..3f3a8c5bce5 100644
--- a/source/blender/editors/interface/tree_view.cc
+++ b/source/blender/editors/interface/tree_view.cc
@@ -369,6 +369,11 @@ bool AbstractTreeViewItem::rename(StringRefNull new_name)
   return true;
 }
 
+void AbstractTreeViewItem::build_context_menu(bContext & /*C*/, uiLayout & /*column*/) const
+{
+  /* No context menu by default. */
+}
+
 void AbstractTreeViewItem::update_from_old(const AbstractTreeViewItem &old)
 {
   is_open_ = old.is_open_;
@@ -707,3 +712,11 @@ void UI_tree_view_item_begin_rename(uiTreeViewItemHandle *item_handle)
   AbstractTreeViewItem &item = reinterpret_cast<AbstractTreeViewItem &>(*item_handle);
   item.begin_renaming();
 }
+
+void UI_tree_view_item_context_menu_build(bContext *C,
+                                          const uiTreeViewItemHandle *item_handle,
+                                          uiLayout *column)
+{
+  const AbstractTreeViewItem &item = reinterpret_cast<const AbstractTreeViewItem &>(*item_handle);
+  item.build_context_menu(*C, *column);
+}