Add Anchor::findAnchor()

src/multisplitter/Anchor.cpp

@@ -454,6 +454,23 @@ Anchor *Anchor::endFolowee() const
     return nullptr;
 }
 
+bool Anchor::findAnchor(Anchor *anchor, Anchor::Side side) const
+{
+    Q_ASSERT(anchor != this);
+    Q_ASSERT(anchor->orientation() == orientation());
+
+    for (Item *item : items(side)) {
+        Anchor *a = item->anchorAtSide(side, orientation());
+        if (anchor == a)
+            return true;
+
+        if (a->findAnchor(anchor, side))
+            return true;
+    }
+
+    return false;
+}
+
 void Anchor::onFolloweePositionChanged(int pos)
 {
     Q_ASSERT(isFollowing());

src/multisplitter/Anchor_p.h

@@ -226,6 +226,14 @@ public:
      */
     Anchor *endFolowee() const;
 
+    /**
+     * @brief Recursively looks for an anchor in the whole layout but only looking at side @p side
+     *
+     * This allows us to know if there's an anchor on the top or left of us (side1) or right or bottom
+     * (side2), in the whole layout.
+     */
+    bool findAnchor(Anchor *anchor, Side side) const;
+
     static int thickness(bool staticAnchor);
     static Anchor::Side oppositeSide(Side side);
     void onFolloweePositionChanged(int pos);

src/multisplitter/Item.cpp

@@ -235,6 +235,16 @@ int Item::minLength(Qt::Orientation orientation) const
     return KDDockWidgets::widgetMinLength(this, orientation);
 }
 
+Anchor *Item::anchorAtSide(Anchor::Side side, Qt::Orientation orientation) const
+{
+    if (!d->m_anchorGroup.isValid())
+        qWarning() << Q_FUNC_INFO << "Invalid anchor group" << &d->m_anchorGroup
+                   << "in" << this << "; window=" << parentWidget()->window();
+
+    return d->m_anchorGroup.anchorAtSide(side, orientation);
+}
+
+
 Anchor *Item::anchorAtDirection(Anchor::Side side, Qt::Orientation orientation) const
 {
     if (!d->m_anchorGroup.isValid())

src/multisplitter/Item_p.h

@@ -123,6 +123,7 @@ public:
     int length(Qt::Orientation) const;
     int minLength(Qt::Orientation orientation) const;
 
+    Anchor *anchorAtSide(Anchor::Side side, Qt::Orientation orientation) const;
     Anchor *anchorAtDirection(Anchor::Side side, Qt::Orientation orientation) const;
     Anchor *anchor(const GeometryDiff &) const;
     AnchorGroup& anchorGroup();