Make MultiSplitter::rectForDrop() receive WindowBeingDragged

Instead of FloatingWindow, which won't exist on wayland while a
drag is in progress.

src/private/MultiSplitter.cpp

@@ -31,6 +31,7 @@
 #include "FrameworkWidgetFactory.h"
 #include "multisplitter/Widget_qwidget.h"
 #include "DropArea_p.h"
+#include "WindowBeingDragged_p.h"
 
 #include <QScopedValueRollback>
 
@@ -436,10 +437,11 @@ Layouting::ItemContainer *MultiSplitter::rootItem() const
     return m_rootItem;
 }
 
-QRect MultiSplitter::rectForDrop(const FloatingWindow *fw, Location location,
+QRect MultiSplitter::rectForDrop(const WindowBeingDragged *wbd, Location location,
                                  const Layouting::Item *relativeTo) const
 {
     Layouting::Item item(nullptr);
+    FloatingWindow *fw = wbd ? wbd->floatingWindow() : nullptr;
     if (!fw)
         return {};
 

src/private/MultiSplitter_p.h

@@ -40,7 +40,7 @@ namespace KDDockWidgets {
 class MainWindowBase;
 class FloatingWindow;
 class Frame;
-
+class WindowBeingDragged;
 
 /**
  * MultiSplitter is simply a wrapper around Layouting::Item in which the hosted widgets are
@@ -131,7 +131,7 @@ public:
      * Excludes the Separator thickness, result is actually smaller than what needed. In other words,
      * the result will be exactly the same as the geometry the widget will get.
      */
-    QRect rectForDrop(const FloatingWindow *, KDDockWidgets::Location location,
+    QRect rectForDrop(const WindowBeingDragged *wbd, KDDockWidgets::Location location,
                       const Layouting::Item *relativeTo) const;
 
     bool deserialize(const LayoutSaver::MultiSplitter &);

src/private/WindowBeingDragged.cpp

@@ -18,6 +18,9 @@ using namespace KDDockWidgets;
 
 static Draggable* bestDraggable(Draggable *draggable)
 {
+    if (!draggable)
+        return nullptr;
+
     // When de detach a title bar it will get hidden and we only the title bar of the FloatingWindow is visible
     /// Apparently that causes problems with grabbing the mouse, so instead use a visible draggable.
     // grabbing mouse on an hidden window works usually, it's some edge case on Windows with MFC.
@@ -54,6 +57,17 @@ WindowBeingDragged::WindowBeingDragged(FloatingWindow *fw, Draggable *draggable)
     if (!qIsNaN(opacity) && !qFuzzyCompare(1.0, opacity))
         fw->setWindowOpacity(opacity);
 }
+#if DOCKS_DEVELOPER_MODE
+
+// Just used by tests
+WindowBeingDragged::WindowBeingDragged(FloatingWindow *fw)
+    : m_floatingWindow(fw)
+    , m_draggable(nullptr)
+    , m_affinities(fw->affinities())
+{
+}
+
+#endif
 
 WindowBeingDragged::~WindowBeingDragged()
 {

src/private/WindowBeingDragged_p.h

@@ -26,6 +26,11 @@ struct DOCKS_EXPORT_FOR_UNIT_TESTS WindowBeingDragged
 {
 public:
     explicit WindowBeingDragged(FloatingWindow *fw, Draggable *draggable);
+#if DOCKS_DEVELOPER_MODE
+    // For tests.
+    explicit WindowBeingDragged(FloatingWindow *fw);
+#endif
+
     ~WindowBeingDragged();
     void init();
 

src/private/indicators/ClassicIndicators.cpp

@@ -181,7 +181,7 @@ void ClassicIndicators::setDropLocation(ClassicIndicators::DropLocation location
 
     auto windowBeingDragged = DragController::instance()->windowBeingDragged();
 
-    QRect rect = m_dropArea->rectForDrop(windowBeingDragged->floatingWindow(), multisplitterLocation,
+    QRect rect = m_dropArea->rectForDrop(windowBeingDragged, multisplitterLocation,
                                          m_dropArea->itemForFrame(relativeToFrame));
 
     m_rubberBand->setGeometry(rect);

tests/tst_common.cpp

@@ -20,6 +20,7 @@
 #include "TitleBar_p.h"
 #include "Position_p.h"
 #include "DropAreaWithCentralFrame_p.h"
+#include "WindowBeingDragged_p.h"
 
 #include <QtTest/QtTest>
 #include <QObject>
@@ -352,8 +353,11 @@ void TestCommon::tst_sizeAfterRedock()
     DropArea *dropArea = fw1->dropArea();
 
     MultiSplitter *ms1 = fw1->multiSplitter();
-    const QRect suggestedDropRect = ms1->rectForDrop(oldFw2, Location_OnBottom, nullptr);
-    QCOMPARE(suggestedDropRect.height(), height2);
+    {
+        WindowBeingDragged wbd2(oldFw2);
+        const QRect suggestedDropRect = ms1->rectForDrop(&wbd2, Location_OnBottom, nullptr);
+        QCOMPARE(suggestedDropRect.height(), height2);
+    }
 
     dropArea->drop(dw2->floatingWindow(), Location_OnBottom, nullptr);
 

tests/tst_docks.cpp

@@ -2930,7 +2930,7 @@ void TestDocks::tst_negativeAnchorPosition6()
     layout->checkSanity();
 
     Item *centralItem = m->dropArea()->centralFrame();
-    layout->rectForDrop(d2->floatingWindow(), Location_OnTop, centralItem);
+    layout->rectForDrop(nullptr, Location_OnTop, centralItem);
     layout->checkSanity();
 
     delete m->window();
@@ -3443,7 +3443,10 @@ void TestDocks::tst_rectForDropCrash()
 
     m->addDockWidget(d1, Location_OnTop);
     Item *centralItem = m->dropArea()->centralFrame();
-    layout->rectForDrop(d2->floatingWindow(), Location_OnTop, centralItem);
+    {
+        WindowBeingDragged wbd2(d2->floatingWindow());
+        layout->rectForDrop(&wbd2, Location_OnTop, centralItem);
+    }
     layout->checkSanity();
 
     delete m->window();
@@ -5095,8 +5098,11 @@ void TestDocks::tst_maximumSizePolicy()
     // Make the floating window big, and see if the suggested highlight is still small
     dock1->window()->resize(QSize(dock1->width(), 800));
 
-    const QRect highlightRect = m1->multiSplitter()->rectForDrop(dock1->floatingWindow(), Location_OnBottom, nullptr);
-    QVERIFY(highlightRect.height() <= maxHeight + tollerance);
+    {
+        WindowBeingDragged wbd1(dock1->floatingWindow());
+        const QRect highlightRect = m1->multiSplitter()->rectForDrop(&wbd1, Location_OnBottom, nullptr);
+        QVERIFY(highlightRect.height() <= maxHeight + tollerance);
+    }
 
     // Now drop it, and check too
     m1->addDockWidget(dock1, Location_OnBottom);