From 6cef4cea2c599b3925ee06464254acfe806e3ebf Mon Sep 17 00:00:00 2001
From: Sergio Martins <sergio.martins@kdab.com>
Date: Fri, 7 Jan 2022 14:59:33 +0000
Subject: [PATCH] Port frameParent() to firstParentOfType()

---
 src/private/DockRegistry.cpp |  2 +-
 src/private/TitleBar.cpp     |  6 ++----
 src/private/TitleBar_p.h     |  5 ++---
 src/private/Utils_p.h        | 15 ++++++++++-----
 tests/tst_docks.cpp          | 12 +++++++++++-
 5 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/src/private/DockRegistry.cpp b/src/private/DockRegistry.cpp
index c73487d1..0d94037e 100644
--- a/src/private/DockRegistry.cpp
+++ b/src/private/DockRegistry.cpp
@@ -711,7 +711,7 @@ bool DockRegistry::eventFilter(QObject *watched, QEvent *event)
         }
     } else if (event->type() == QEvent::MouseButtonPress) {
         // When clicking on a MDI Frame we raise the window
-        if (Frame *f = parentFrame(watched)) {
+        if (Frame *f = firstParentOfType<Frame>(watched)) {
             if (f->isMDI())
                 f->raise();
         }
diff --git a/src/private/TitleBar.cpp b/src/private/TitleBar.cpp
index b22e17de..1b02e3a1 100644
--- a/src/private/TitleBar.cpp
+++ b/src/private/TitleBar.cpp
@@ -18,6 +18,7 @@
 #include "FrameworkWidgetFactory.h"
 #include "Config.h"
 #include "MainWindowBase.h"
+#include "MDILayoutWidget_p.h"
 
 #include <QTimer>
 #include <QWindowStateChangeEvent>
@@ -100,10 +101,7 @@ MainWindowBase *TitleBar::mainWindow() const
 
 bool TitleBar::isMDI() const
 {
-    if (auto mw = mainWindow())
-        return mw->isMDI();
-
-    return false;
+    return firstParentOfType<MDILayoutWidget>(this) != nullptr;
 }
 
 void TitleBar::updateButtons()
diff --git a/src/private/TitleBar_p.h b/src/private/TitleBar_p.h
index 3c8a6aee..0c9820db 100644
--- a/src/private/TitleBar_p.h
+++ b/src/private/TitleBar_p.h
@@ -112,9 +112,8 @@ public:
     ///Returns nullptr otherwise
     MainWindowBase *mainWindow() const;
 
-    /// @brief Returns if this title bar is in a main window in MDI mode
-    /// By default false. Only relevant if your main window was constructed with the
-    /// MainWindowOption_MDI option
+    /// @brief Returns if this title bar belongs to a dock widget which is in MDI mode (inside a MDI area)
+    /// For example in a main window created with MainWindowOption_MDI option
     bool isMDI() const override;
 
     /// @brief updates the close button enabled state
diff --git a/src/private/Utils_p.h b/src/private/Utils_p.h
index eb455486..226d5030 100644
--- a/src/private/Utils_p.h
+++ b/src/private/Utils_p.h
@@ -362,13 +362,18 @@ inline bool scalingFactorIsSupported(qreal factor)
 #endif
 }
 
-/// @brief Returns the parent frame which the specified object is in, if any
-inline Frame *parentFrame(QObject *from)
+template <typename T>
+inline T* firstParentOfType(const QObject *child)
 {
-    auto p = from;
+    auto p = const_cast<QObject *>(child);
     while (p) {
-        if (auto frame = qobject_cast<Frame *>(p))
-            return frame;
+        if (qobject_cast<const QWindow*>(p)) {
+            // Ignore QObject hierarchies spanning though multiple windows
+            return nullptr;
+        }
+
+        if (auto candidate = qobject_cast<T *>(p))
+            return candidate;
 
         p = p->parent();
     }
diff --git a/tests/tst_docks.cpp b/tests/tst_docks.cpp
index d27c084e..f65fa7e6 100644
--- a/tests/tst_docks.cpp
+++ b/tests/tst_docks.cpp
@@ -7526,4 +7526,14 @@ void TestDocks::tst_mdi_mixed_with_docking()
 
     mdiArea->addDockWidget(mdiWidget1, QPoint(10, 10));
     mdiArea->addDockWidget(mdiWidget2, QPoint(50, 50));
-}
\ No newline at end of file
+
+    Frame *frameMDI1 = mdiWidget1->d->frame();
+    Frame *frame1 = dock1->d->frame();
+    QVERIFY(!frame1->isMDI());
+    QVERIFY(frameMDI1->isMDI());
+    QVERIFY(!frame1->mdiLayoutWidget());
+    QVERIFY(frameMDI1->mdiLayoutWidget());
+
+    QVERIFY(!dock1->titleBar()->isMDI());
+    QVERIFY(mdiWidget1->titleBar()->isMDI());
+}