Make QWindow's windowState a QFlags of the WindowState

This reflects QWidget API, and restores some behavior from Qt4.
Some WM can have several state at the same time. On Plasma for example,
when a window is both maximized and minimized, the "maximized" checkbox
is checked from the taskbar entry.

The API of QPlatformWindow was changed to take a QFlag and the platform
plugins were adapted.

 - On XCB: Always send the full state to the WM. And read the full state.

 - On Windows: The code was originally written with '&' in Qt4, and was changed
   to == when porting. Some adaptation had to be made so the states would be
   preserved.

 - On macOS: Only a single state can be set and is reported back for now,
   with the possibly to expand this in the future.

 - Other platforms: Just do as before with the effective state.

Task-number: QTBUG-57882
Task-number: QTBUG-52616
Task-number: QTBUG-52555
Change-Id: I7a1f7cac64236bbd4c591f796374315639233dad
Reviewed-by: Gunnar Sletta <gunnar@crimson.no>
Reviewed-by: Robin Burchell <robin.burchell@crimson.no>

2 files changed, 8 insertions, 6 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoawindow.h b/src/plugins/platforms/cocoa/qcocoawindow.h
index 567eb7438b..586e59bff4 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.h
+++ b/src/plugins/platforms/cocoa/qcocoawindow.h
@@ -168,7 +168,7 @@ public:
     void hide(bool becauseOfAncestor = false);
     void setVisible(bool visible) Q_DECL_OVERRIDE;
     void setWindowFlags(Qt::WindowFlags flags) Q_DECL_OVERRIDE;
-    void setWindowState(Qt::WindowState state) Q_DECL_OVERRIDE;
+    void setWindowState(Qt::WindowStates state) Q_DECL_OVERRIDE;
     void setWindowTitle(const QString &title) Q_DECL_OVERRIDE;
     void setWindowFilePath(const QString &filePath) Q_DECL_OVERRIDE;
     void setWindowIcon(const QIcon &icon) Q_DECL_OVERRIDE;
@@ -292,7 +292,7 @@ protected:
     void removeChildWindow(QCocoaWindow *child);
 
     Qt::WindowState windowState() const;
-    void applyWindowState(Qt::WindowState newState);
+    void applyWindowState(Qt::WindowStates newState);
     void toggleMaximized();
     void toggleFullScreen();
     bool isTransitioningToFullScreen() const;
@@ -313,7 +313,7 @@ public: // for QNSView
     bool m_viewIsToBeEmbedded; // true if the m_view is intended to be embedded in a "foreign" NSView hiearchy
 
     Qt::WindowFlags m_windowFlags;
-    Qt::WindowState m_lastReportedWindowState;
+    Qt::WindowStates m_lastReportedWindowState;
     Qt::WindowModality m_windowModality;
     QPointer<QWindow> m_enterLeaveTargetWindow;
     bool m_windowUnderMouse;
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 75c13d6bbc..77f88cc061 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -762,7 +762,7 @@ void QCocoaWindow::setVisible(bool visible)
 
             // setWindowState might have been called while the window was hidden and
             // will not change the NSWindow state in that case. Sync up here:
-            applyWindowState(window()->windowState());
+            applyWindowState(window()->windowStates());
 
             if (window()->windowState() != Qt::WindowMinimized) {
                 if ((window()->modality() == Qt::WindowModal
@@ -1010,7 +1010,7 @@ void QCocoaWindow::setWindowFlags(Qt::WindowFlags flags)
     m_windowFlags = flags;
 }
 
-void QCocoaWindow::setWindowState(Qt::WindowState state)
+void QCocoaWindow::setWindowState(Qt::WindowStates state)
 {
     if (window()->isVisible())
         applyWindowState(state); // Window state set for hidden windows take effect when show() is called
@@ -1812,9 +1812,11 @@ QRect QCocoaWindow::nativeWindowGeometry() const
     updated yet, so window()->windowState() will reflect the previous state that was
     reported to QtGui.
 */
-void QCocoaWindow::applyWindowState(Qt::WindowState newState)
+void QCocoaWindow::applyWindowState(Qt::WindowStates requestedState)
 {
     const Qt::WindowState currentState = windowState();
+    const Qt::WindowState newState = QWindowPrivate::effectiveState(requestedState);
+
     if (newState == currentState)
         return;