Fix item highlighting through DBus

Before this commit, even items that are distant children of
currently open views were considered selectable. This lead to the
bug that items meant to be highlighted through DBus would not be
highlighted if any ancestor of the item was open in any view.

This was fixed by only considering items in view if they can be
seen by scrolling. Main difficulty here was to make this also work
for the details view mode which allows expanding.

To implement this cleanly, some refactoring seemed necessary
because the logic to determine if an item is already in view
was previously intertwined with the logic to identify already open
directories.

This commit also contains the following refactorings aiming to
make the code more readable:
- A magic value (-1) is replaced using std::optional.
- A boolean trap is removed.
- A QPair is replaced by a struct with named variables.
- More and improved documentation

2 files changed, 17 insertions, 0 deletions

diff --git a/src/views/dolphinview.cpp b/src/views/dolphinview.cpp
index 6372266d4..590fe336b 100644
--- a/src/views/dolphinview.cpp
+++ b/src/views/dolphinview.cpp
@@ -1490,6 +1490,16 @@ bool DolphinView::itemsExpandable() const
     return m_mode == DetailsView;
 }
 
+bool DolphinView::isExpanded(const KFileItem& item) const
+{
+    Q_ASSERT(item.isDir());
+    Q_ASSERT(items().contains(item));
+    if (!itemsExpandable()) {
+        return false;
+    }
+    return m_model->isExpanded(m_model->index(item));
+}
+
 void DolphinView::restoreState(QDataStream& stream)
 {
     // Read the version number of the view state and check if the version is supported.
diff --git a/src/views/dolphinview.h b/src/views/dolphinview.h
index 2ecd75957..aff4c51a8 100644
--- a/src/views/dolphinview.h
+++ b/src/views/dolphinview.h
@@ -292,6 +292,13 @@ public:
     bool itemsExpandable() const;
 
     /**
+     * @returns true if the @p item is one of the items() of this view and
+     * is currently expanded. false otherwise.
+     * Only directories in view modes that allow expanding can ever be expanded.
+     */
+    bool isExpanded(const KFileItem &item) const;
+
+    /**
      * Restores the view state (current item, contents position, details view expansion state)
      */
     void restoreState(QDataStream& stream);