Add a QApplication::queryKeyboardModifiers() method.

QApplication::keyboardModifiers returns the keyboard modifiers
from the last keypress event in this process, as documented. However
there are use cases for querying keyboard modifiers as they currently are,
see QTBUG-11243.

Merge-request: 585
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@nokia.com>
(cherry picked from commit 3b5354386225974ea6db78c12f32cb81e2d50104)

Change-Id: I9b4e54ac79fc225e3ed8d2bcaba953a6eb59f0d2
Reviewed-on: http://codereview.qt.nokia.com/3581
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@nokia.com>

src/gui/kernel/qapplication.cpp

@@ -3319,7 +3319,7 @@ bool QApplication::desktopSettingsAware()
     one of the above events. If no keys are being held Qt::NoModifier is
     returned.
 
-    \sa mouseButtons()
+    \sa mouseButtons(), queryKeyboardModifiers()
 */
 
 Qt::KeyboardModifiers QApplication::keyboardModifiers()
@@ -3327,6 +3327,25 @@ Qt::KeyboardModifiers QApplication::keyboardModifiers()
     return QApplicationPrivate::modifier_buttons;
 }
 
+/*!
+    \fn Qt::KeyboardModifiers QApplication::queryKeyboardModifiers()
+
+    Queries and returns the state of the modifier keys on the keyboard.
+    Unlike keyboardModifiers, this method returns the actual keys held
+    on the input device at the time of calling the method.
+
+    It does not rely on the keypress events having been received by this
+    process, which makes it possible to check the modifiers while moving
+    a window, for instance. Note that in most cases, you should use
+    keyboardModifiers(), which is faster and more accurate since it contains
+    the state of the modifiers as they were when the currently processed
+    event was received.
+
+    \sa keyboardModifiers()
+
+    \since 4.8
+*/
+
 /*!
     Returns the current state of the buttons on the mouse. The current state is
     updated syncronously as the event queue is emptied of events that will

src/gui/kernel/qapplication.h

@@ -198,6 +198,7 @@ public:
     static void alert(QWidget *widget, int duration = 0);
 
     static Qt::KeyboardModifiers keyboardModifiers();
+    static Qt::KeyboardModifiers queryKeyboardModifiers();
     static Qt::MouseButtons mouseButtons();
 
     static void setDesktopSettingsAware(bool);

src/gui/kernel/qapplication_mac.mm

@@ -1395,6 +1395,11 @@ void QApplication::restoreOverrideCursor()
 }
 #endif // QT_NO_CURSOR
 
+Qt::KeyboardModifiers QApplication::queryKeyboardModifiers()
+{
+    return qt_mac_get_modifiers(GetCurrentEventKeyModifiers());
+}
+
 QWidget *QApplication::topLevelAt(const QPoint &p)
 {
 #ifndef QT_MAC_USE_COCOA

src/gui/kernel/qapplication_qws.cpp

@@ -2707,6 +2707,11 @@ void QApplication::alert(QWidget *, int)
 {
 }
 
+Qt::KeyboardModifiers QApplication::queryKeyboardModifiers()
+{
+    return keyboardModifiers(); // TODO proper implementation
+}
+
 int QApplication::qwsProcessEvent(QWSEvent* event)
 {
     Q_D(QApplication);

src/gui/kernel/qapplication_s60.cpp

@@ -114,6 +114,8 @@ QWidget *qt_button_down = 0;                     // widget got last button-down
 
 QSymbianControl *QSymbianControl::lastFocusedControl = 0;
 
+static Qt::KeyboardModifiers app_keyboardModifiers = Qt::NoModifier;
+
 QS60Data* qGlobalS60Data()
 {
     return qt_s60Data();
@@ -712,6 +714,7 @@ void QSymbianControl::HandlePointerEvent(const TPointerEvent& pEvent)
     Qt::MouseButton button;
     mapS60MouseEventTypeToQt(&type, &button, &pEvent);
     Qt::KeyboardModifiers modifiers = mapToQtModifiers(pEvent.iModifiers);
+    app_keyboardModifiers = modifiers;
 
     QPoint widgetPos = translatePointForFixedNativeOrientation(pEvent.iPosition);
     TPoint controlScreenPos = PositionRelativeToScreen();
@@ -2541,6 +2544,11 @@ void QApplication::setEffectEnabled(Qt::UIEffect /* effect */, bool /* enable */
     // TODO: Implement QApplication::setEffectEnabled(Qt::UIEffect effect, bool enable)
 }
 
+Qt::KeyboardModifiers QApplication::queryKeyboardModifiers()
+{
+    return app_keyboardModifiers;
+}
+
 TUint QApplicationPrivate::resolveS60ScanCode(TInt scanCode, TUint keysym)
 {
     if (!scanCode)

src/gui/kernel/qapplication_win.cpp

@@ -1319,6 +1319,11 @@ Qt::KeyboardModifiers qt_win_getKeyboardModifiers()
     return modifiers;
 }
 
+Qt::KeyboardModifiers QApplication::queryKeyboardModifiers()
+{
+    return qt_win_getKeyboardModifiers();
+}
+
 /*****************************************************************************
   Routines to find a Qt widget from a screen position
  *****************************************************************************/

src/gui/kernel/qapplication_x11.cpp

@@ -3061,6 +3061,21 @@ void QApplicationPrivate::_q_alertTimeOut()
     }
 }
 
+Qt::KeyboardModifiers QApplication::queryKeyboardModifiers()
+{
+    Window root;
+    Window child;
+    int root_x, root_y, win_x, win_y;
+    uint keybstate;
+    for (int i = 0; i < ScreenCount(X11->display); ++i) {
+        if (XQueryPointer(X11->display, QX11Info::appRootWindow(i), &root, &child,
+                          &root_x, &root_y, &win_x, &win_y, &keybstate))
+            return X11->translateModifiers(keybstate & 0x00ff);
+    }
+    return 0;
+
+}
+
 /*****************************************************************************
   Special lookup functions for windows that have been reparented recently
  *****************************************************************************/

src/gui/kernel/qdnd_x11.cpp

@@ -1112,21 +1112,6 @@ void qt_xdnd_send_leave()
     waiting_for_status = false;
 }
 
-// TODO: remove and use QApplication::currentKeyboardModifiers() in Qt 4.8.
-static Qt::KeyboardModifiers currentKeyboardModifiers()
-{
-    Window root;
-    Window child;
-    int root_x, root_y, win_x, win_y;
-    uint keybstate;
-    for (int i = 0; i < ScreenCount(X11->display); ++i) {
-        if (XQueryPointer(X11->display, QX11Info::appRootWindow(i), &root, &child,
-                          &root_x, &root_y, &win_x, &win_y, &keybstate))
-            return X11->translateModifiers(keybstate & 0x00ff);
-    }
-    return 0;
-}
-
 void QX11Data::xdndHandleDrop(QWidget *, const XEvent * xe, bool passive)
 {
     DEBUG("xdndHandleDrop");
@@ -1175,7 +1160,7 @@ void QX11Data::xdndHandleDrop(QWidget *, const XEvent * xe, bool passive)
 
         // Drop coming from another app? Update keyboard modifiers.
         if (!qt_xdnd_dragging) {
-            QApplicationPrivate::modifier_buttons = currentKeyboardModifiers();
+            QApplicationPrivate::modifier_buttons = QApplication::queryKeyboardModifiers();
         }
 
         QDropEvent de(qt_xdnd_current_position, possible_actions, dropData,