Windows: Implement QPlatformInputContext::locale().

Initialize locale from current keyboard value and listen
to WM_INPUTLANGCHANGE.

Task-number: QTBUG-48772
Change-Id: I53b6ef4e2cf538bb81b41ea497ed0cb66991b104
Reviewed-by: Liang Qi <liang.qi@theqtcompany.com>
Reviewed-by: Oliver Wolff <oliver.wolff@theqtcompany.com>

src/plugins/platforms/windows/qwindowscontext.cpp

@@ -860,6 +860,11 @@ QByteArray QWindowsContext::comErrorString(HRESULT hr)
     return result;
 }
 
+static inline QWindowsInputContext *windowsInputContext()
+{
+    return qobject_cast<QWindowsInputContext *>(QWindowsIntegration::instance()->inputContext());
+}
+
 /*!
      \brief Main windows procedure registered for windows.
 
@@ -909,8 +914,7 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
         }
     }
     if (et & QtWindows::InputMethodEventFlag) {
-        QWindowsInputContext *windowsInputContext =
-            qobject_cast<QWindowsInputContext *>(QWindowsIntegration::instance()->inputContext());
+        QWindowsInputContext *windowsInputContext = ::windowsInputContext();
         // Disable IME assuming this is a special implementation hooking into keyboard input.
         // "Real" IME implementations should use a native event filter intercepting IME events.
         if (!windowsInputContext) {
@@ -1006,11 +1010,13 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
     }
 
     switch (et) {
+    case QtWindows::KeyboardLayoutChangeEvent:
+        if (QWindowsInputContext *wic = windowsInputContext())
+            wic->handleInputLanguageChanged(wParam, lParam); // fallthrough intended.
     case QtWindows::KeyDownEvent:
     case QtWindows::KeyEvent:
     case QtWindows::InputMethodKeyEvent:
     case QtWindows::InputMethodKeyDownEvent:
-    case QtWindows::KeyboardLayoutChangeEvent:
     case QtWindows::AppCommandEvent:
 #if !defined(Q_OS_WINCE) && !defined(QT_NO_SESSIONMANAGER)
         return platformSessionManager()->isInteractionBlocked() ? true : d->m_keyMapper.translateKeyEvent(platformWindow->window(), hwnd, msg, result);

src/plugins/platforms/windows/qwindowsinputcontext.cpp

@@ -84,6 +84,18 @@ static inline void imeNotifyCancelComposition(HWND hwnd)
     ImmReleaseContext(hwnd, himc);
 }
 
+static inline LCID languageIdFromLocaleId(LCID localeId)
+{
+    return localeId & 0xFFFF;
+}
+
+static inline LCID currentInputLanguageId()
+{
+    return languageIdFromLocaleId(reinterpret_cast<quintptr>(GetKeyboardLayout(0)));
+}
+
+Q_CORE_EXPORT QLocale qt_localeFromLCID(LCID id); // from qlocale_win.cpp
+
 /*!
     \class QWindowsInputContext
     \brief Windows Input context implementation
@@ -153,7 +165,9 @@ QWindowsInputContext::CompositionContext::CompositionContext() :
 
 QWindowsInputContext::QWindowsInputContext() :
     m_WM_MSIME_MOUSE(RegisterWindowMessage(L"MSIMEMouseOperation")),
-    m_endCompositionRecursionGuard(false)
+    m_endCompositionRecursionGuard(false),
+    m_languageId(currentInputLanguageId()),
+    m_locale(qt_localeFromLCID(m_languageId))
 {
     connect(QGuiApplication::inputMethod(), &QInputMethod::cursorRectangleChanged,
             this, &QWindowsInputContext::cursorRectChanged);
@@ -371,7 +385,7 @@ bool QWindowsInputContext::startComposition(HWND hwnd)
     QWindow *window = QGuiApplication::focusWindow();
     if (!window)
         return false;
-    qCDebug(lcQpaInputMethods) << __FUNCTION__ << fo << window;
+    qCDebug(lcQpaInputMethods) << __FUNCTION__ << fo << window << "language=" << m_languageId;
     if (!fo || QWindowsWindow::handleOf(window) != hwnd)
         return false;
     initContext(hwnd, fo);
@@ -555,6 +569,21 @@ bool QWindowsInputContext::handleIME_Request(WPARAM wParam,
     return false;
 }
 
+void QWindowsInputContext::handleInputLanguageChanged(WPARAM wparam, LPARAM lparam)
+{
+    const LCID newLanguageId = languageIdFromLocaleId(lparam);
+    if (newLanguageId == m_languageId)
+        return;
+    const LCID oldLanguageId = m_languageId;
+    m_languageId = newLanguageId;
+    m_locale = qt_localeFromLCID(m_languageId);
+    emitLocaleChanged();
+
+    qCDebug(lcQpaInputMethods) << __FUNCTION__ << hex << showbase
+        << oldLanguageId  << "->" << newLanguageId << "Character set:"
+        << DWORD(wparam) << dec << noshowbase << m_locale;
+}
+
 /*!
     \brief Determines the string for reconversion with selection.
 

src/plugins/platforms/windows/qwindowsinputcontext.h

@@ -36,6 +36,7 @@
 
 #include "qtwindows_additional.h"
 
+#include <QtCore/QLocale>
 #include <QtCore/QPointer>
 #include <qpa/qplatforminputcontext.h>
 
@@ -66,6 +67,8 @@ public:
     static void setWindowsImeEnabled(QWindowsWindow *platformWindow, bool enabled);
 
     bool hasCapability(Capability capability) const Q_DECL_OVERRIDE;
+    QLocale locale() const Q_DECL_OVERRIDE { return m_locale; }
+
     void reset() Q_DECL_OVERRIDE;
     void update(Qt::InputMethodQueries) Q_DECL_OVERRIDE;
     void invokeAction(QInputMethod::Action, int cursorPosition) Q_DECL_OVERRIDE;
@@ -79,6 +82,7 @@ public:
     int reconvertString(RECONVERTSTRING *reconv);
 
     bool handleIME_Request(WPARAM wparam, LPARAM lparam, LRESULT *result);
+    void handleInputLanguageChanged(WPARAM wparam, LPARAM lparam);
 
 private slots:
     void cursorRectChanged();
@@ -94,6 +98,8 @@ private:
     static HIMC m_defaultContext;
     CompositionContext m_compositionContext;
     bool m_endCompositionRecursionGuard;
+    LCID m_languageId;
+    QLocale m_locale;
 };
 
 QT_END_NAMESPACE