Windows QPA: Generate proper event when dragging item outside window

When an item was dragged outside the window, the mouse release event was not
being properly delivered and the item would stick to mouse cursor after
moving it back into the window.

Fixes: QTBUG-72994
Change-Id: Ibce990390c866e16d58f7d969673dd05e862d97e
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 18 insertions, 7 deletions

diff --git a/src/plugins/platforms/windows/qwindowsdrag.cpp b/src/plugins/platforms/windows/qwindowsdrag.cpp
index 95d1fc8b7d..322865b0f3 100644
--- a/src/plugins/platforms/windows/qwindowsdrag.cpp
+++ b/src/plugins/platforms/windows/qwindowsdrag.cpp
@@ -49,6 +49,7 @@
 #include "qwindowswindow.h"
 #include "qwindowsmousehandler.h"
 #include "qwindowscursor.h"
+#include "qwindowskeymapper.h"
 
 #include <QtGui/qevent.h>
 #include <QtGui/qpixmap.h>
@@ -205,6 +206,9 @@ static inline Qt::MouseButtons toQtMouseButtons(DWORD keyState)
     return buttons;
 }
 
+static Qt::KeyboardModifiers lastModifiers = Qt::NoModifier;
+static Qt::MouseButtons lastButtons = Qt::NoButton;
+
 /*!
     \class QWindowsOleDropSource
     \brief Implementation of IDropSource
@@ -403,7 +407,7 @@ QWindowsOleDropSource::QueryContinueDrag(BOOL fEscapePressed, DWORD grfKeyState)
         case DRAGDROP_S_DROP:
         case DRAGDROP_S_CANCEL:
             if (!m_windowUnderMouse.isNull() && m_mode != TouchDrag && fEscapePressed == FALSE
-                && buttons != QGuiApplicationPrivate::mouse_buttons) {
+                && buttons != lastButtons) {
                 // QTBUG 66447: Synthesize a mouse release to the window under mouse at
                 // start of the DnD operation as Windows does not send any.
                 const QPoint globalPos = QWindowsCursor::mousePosition();
@@ -503,13 +507,14 @@ void QWindowsOleDropTarget::handleDrag(QWindow *window, DWORD grfKeyState,
 
     QWindowsDrag *windowsDrag = QWindowsDrag::instance();
     const Qt::DropActions actions = translateToQDragDropActions(*pdwEffect);
-    const Qt::KeyboardModifiers keyboardModifiers = toQtKeyboardModifiers(grfKeyState);
-    const Qt::MouseButtons mouseButtons = toQtMouseButtons(grfKeyState);
+
+    lastModifiers = toQtKeyboardModifiers(grfKeyState);
+    lastButtons = toQtMouseButtons(grfKeyState);
 
     const QPlatformDragQtResponse response =
           QWindowSystemInterface::handleDrag(window, windowsDrag->dropData(),
                                              m_lastPoint, actions,
-                                             mouseButtons, keyboardModifiers);
+                                             lastButtons, lastModifiers);
 
     m_answerRect = response.answerRect();
     const Qt::DropAction action = response.acceptedAction();
@@ -521,7 +526,7 @@ void QWindowsOleDropTarget::handleDrag(QWindow *window, DWORD grfKeyState,
     *pdwEffect = m_chosenEffect;
     qCDebug(lcQpaMime) << __FUNCTION__ << m_window
         << windowsDrag->dropData() << " supported actions=" << actions
-        << " mods=" << keyboardModifiers << " mouse=" << mouseButtons
+        << " mods=" << lastModifiers << " mouse=" << lastButtons
         << " accepted: " << response.isAccepted() << action
         << m_answerRect << " effect" << *pdwEffect;
 }
@@ -572,6 +577,9 @@ QWindowsOleDropTarget::DragLeave()
 
     qCDebug(lcQpaMime) << __FUNCTION__ << ' ' << m_window;
 
+    lastModifiers = QWindowsKeyMapper::queryKeyboardModifiers();
+    lastButtons = QWindowsMouseHandler::queryMouseButtons();
+
     QWindowSystemInterface::handleDrag(m_window, nullptr, QPoint(), Qt::IgnoreAction,
                                        Qt::NoButton, Qt::NoModifier);
 
@@ -598,12 +606,15 @@ QWindowsOleDropTarget::Drop(LPDATAOBJECT pDataObj, DWORD grfKeyState,
 
     QWindowsDrag *windowsDrag = QWindowsDrag::instance();
 
+    lastModifiers = toQtKeyboardModifiers(grfKeyState);
+    lastButtons = toQtMouseButtons(grfKeyState);
+
     const QPlatformDropQtResponse response =
         QWindowSystemInterface::handleDrop(m_window, windowsDrag->dropData(),
                                            m_lastPoint,
                                            translateToQDragDropActions(*pdwEffect),
-                                           toQtMouseButtons(grfKeyState),
-                                           toQtKeyboardModifiers(grfKeyState));
+                                           lastButtons,
+                                           lastModifiers);
 
     m_lastKeyState = grfKeyState;