Windows: Add hit test handling for non-client areas.

Suppress resize cursor for fixed size windows.

Task-number: QTBUG-32663
Change-Id: I9579bb13d494fe21e5db7b75d01a3cf1b693c7f6
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

src/plugins/platforms/windows/qtwindowsglobal.h

@@ -88,6 +88,7 @@ enum WindowsEventType // Simplify event types
     CursorEvent = MouseEventFlag + 3,
     TouchEvent = TouchEventFlag + 1,
     NonClientMouseEvent = NonClientEventFlag + MouseEventFlag + 1,
+    NonClientHitTest = NonClientEventFlag + 2,
     KeyEvent = KeyEventFlag + 1,
     KeyDownEvent = KeyEventFlag + KeyDownEventFlag + 1,
     InputMethodKeyEvent = InputMethodEventFlag + KeyEventFlag + 1,
@@ -142,6 +143,10 @@ inline QtWindows::WindowsEventType windowsEventType(UINT message, WPARAM wParamI
         return QtWindows::ResizeEvent;
     case WM_NCCALCSIZE:
         return QtWindows::CalculateSize;
+#ifndef Q_OS_WINCE
+    case WM_NCHITTEST:
+        return QtWindows::NonClientHitTest;
+#endif // !Q_OS_WINCE
     case WM_GETMINMAXINFO:
         return QtWindows::QuerySizeHints;
     case WM_KEYDOWN:                        // keyboard event

src/plugins/platforms/windows/qwindowscontext.cpp

@@ -819,7 +819,9 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
         return true;// maybe available on some SDKs revisit WM_NCCALCSIZE
     case QtWindows::CalculateSize:
         return QWindowsGeometryHint::handleCalculateSize(platformWindow->customMargins(), msg, result);
-#endif
+    case QtWindows::NonClientHitTest:
+        return platformWindow->handleNonClientHitTest(QPoint(msg.pt.x, msg.pt.y), result);
+#endif // !Q_OS_WINCE
     case QtWindows::ExposeEvent:
         return platformWindow->handleWmPaint(hwnd, message, wParam, lParam);
     case QtWindows::NonClientMouseEvent:

src/plugins/platforms/windows/qwindowswindow.cpp

@@ -1796,6 +1796,47 @@ void QWindowsWindow::getSizeHints(MINMAXINFO *mmi) const
     if (QWindowsContext::verboseWindows)
         qDebug() << __FUNCTION__ << window() << *mmi;
 }
+
+bool QWindowsWindow::handleNonClientHitTest(const QPoint &globalPos, LRESULT *result) const
+{
+    // QTBUG-32663, suppress resize cursor for fixed size windows.
+    const QWindow *w = window();
+    if (!w->isTopLevel() // Task 105852, minimized windows need to respond to user input.
+        || (m_windowState != Qt::WindowNoState && m_windowState != Qt::WindowActive)
+        || (m_data.flags & Qt::FramelessWindowHint)) {
+        return false;
+    }
+    const QSize minimumSize = w->minimumSize();
+    if (minimumSize.isEmpty())
+        return false;
+    const QSize maximumSize = w->maximumSize();
+    const bool fixedWidth = minimumSize.width() == maximumSize.width();
+    const bool fixedHeight = minimumSize.height() == maximumSize.height();
+    if (!fixedWidth && !fixedHeight)
+        return false;
+    const QPoint localPos = w->mapFromGlobal(globalPos);
+    const QSize size = w->size();
+    if (fixedHeight) {
+        if (localPos.y() >= size.height()) {
+            *result = HTBORDER; // Unspecified border, no resize cursor.
+            return true;
+        }
+        if (localPos.y() < 0) {
+            const QMargins margins = frameMargins();
+            const int topResizeBarPos = margins.left() - margins.top();
+            if (localPos.y() < topResizeBarPos) {
+                *result = HTCAPTION; // Extend caption over top resize bar, let's user move the window.
+                return true;
+            }
+        }
+    }
+    if (fixedWidth && (localPos.x() < 0 || localPos.x() >= size.width())) {
+        *result = HTBORDER; // Unspecified border, no resize cursor.
+        return true;
+    }
+    return false;
+}
+
 #endif // !Q_OS_WINCE
 
 #ifndef QT_NO_CURSOR

src/plugins/platforms/windows/qwindowswindow.h

@@ -234,7 +234,8 @@ public:
     void releaseDC();
 #ifndef Q_OS_WINCE // maybe available on some SDKs revisit WM_GETMINMAXINFO
     void getSizeHints(MINMAXINFO *mmi) const;
-#endif
+    bool handleNonClientHitTest(const QPoint &globalPos, LRESULT *result) const;
+#endif // !Q_OS_WINCE
 
 #ifndef QT_NO_CURSOR
     QWindowsWindowCursor cursor() const { return m_cursor; }