Windows: Disable Windows input context when another context is used.

Remove QWindowsContext::instance() method and use
QPlatformIntegration::inputContext() with proper check instead.
Extract static method to disable Windows IME on a window
by associating a null context from QWindowsInputContext
and use that to disable the IME if another context is
in use.

Amends change b46fe39d94.

Change-Id: Icaad99d390cea5559167602ffbf994660d4717a5
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

src/plugins/platforms/windows/qwindowscontext.cpp

@@ -33,6 +33,7 @@
 ****************************************************************************/
 
 #include "qwindowscontext.h"
+#include "qwindowsintegration.h"
 #include "qwindowswindow.h"
 #include "qwindowskeymapper.h"
 #include "qwindowsguieventdispatcher.h"
@@ -907,16 +908,30 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
             return true;
         }
     }
+    if (et & QtWindows::InputMethodEventFlag) {
+        QWindowsInputContext *windowsInputContext =
+            qobject_cast<QWindowsInputContext *>(QWindowsIntegration::instance()->inputContext());
+        // 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) {
+            QWindowsInputContext::setWindowsImeEnabled(platformWindow, false);
+            return false;
+        }
+        switch (et) {
+        case QtWindows::InputMethodStartCompositionEvent:
+            return windowsInputContext->startComposition(hwnd);
+        case QtWindows::InputMethodCompositionEvent:
+            return windowsInputContext->composition(hwnd, lParam);
+        case QtWindows::InputMethodEndCompositionEvent:
+            return windowsInputContext->endComposition(hwnd);
+        case QtWindows::InputMethodRequest:
+            return windowsInputContext->handleIME_Request(wParam, lParam, result);
+        default:
+            break;
+        }
+    } // InputMethodEventFlag
 
     switch (et) {
-    case QtWindows::InputMethodStartCompositionEvent:
-        return QWindowsInputContext::instance()->startComposition(hwnd);
-    case QtWindows::InputMethodCompositionEvent:
-        return QWindowsInputContext::instance()->composition(hwnd, lParam);
-    case QtWindows::InputMethodEndCompositionEvent:
-        return QWindowsInputContext::instance()->endComposition(hwnd);
-    case QtWindows::InputMethodRequest:
-        return QWindowsInputContext::instance()->handleIME_Request(wParam, lParam, result);
     case QtWindows::GestureEvent:
 #if !defined(Q_OS_WINCE) && !defined(QT_NO_SESSIONMANAGER)
         return platformSessionManager()->isInteractionBlocked() ? true : d->m_mouseHandler.translateGestureEvent(platformWindow->window(), hwnd, et, msg, result);

src/plugins/platforms/windows/qwindowsinputcontext.cpp

@@ -219,21 +219,24 @@ void QWindowsInputContext::updateEnabled()
         const bool accepted = inputMethodAccepted();
         if (QWindowsContext::verbose > 1)
             qCDebug(lcQpaInputMethods) << __FUNCTION__ << window << "accepted=" << accepted;
-        if (accepted) {
-            // Re-enable IME by associating default context saved on first disabling.
-            if (platformWindow->testFlag(QWindowsWindow::InputMethodDisabled)) {
-                ImmAssociateContext(platformWindow->handle(), QWindowsInputContext::m_defaultContext);
-                platformWindow->clearFlag(QWindowsWindow::InputMethodDisabled);
-            }
-        } else {
-            // Disable IME by associating 0 context. Store context first time.
-            if (!platformWindow->testFlag(QWindowsWindow::InputMethodDisabled)) {
-                const HIMC oldImC = ImmAssociateContext(platformWindow->handle(), 0);
-                platformWindow->setFlag(QWindowsWindow::InputMethodDisabled);
-                if (!QWindowsInputContext::m_defaultContext && oldImC)
-                    QWindowsInputContext::m_defaultContext = oldImC;
-            }
-        }
+            QWindowsInputContext::setWindowsImeEnabled(platformWindow, accepted);
+    }
+}
+
+void QWindowsInputContext::setWindowsImeEnabled(QWindowsWindow *platformWindow, bool enabled)
+{
+    if (!platformWindow || platformWindow->testFlag(QWindowsWindow::InputMethodDisabled) == !enabled)
+        return;
+    if (enabled) {
+        // Re-enable Windows IME by associating default context saved on first disabling.
+        ImmAssociateContext(platformWindow->handle(), QWindowsInputContext::m_defaultContext);
+        platformWindow->clearFlag(QWindowsWindow::InputMethodDisabled);
+    } else {
+        // Disable Windows IME by associating 0 context. Store context first time.
+        const HIMC oldImC = ImmAssociateContext(platformWindow->handle(), 0);
+        platformWindow->setFlag(QWindowsWindow::InputMethodDisabled);
+        if (!QWindowsInputContext::m_defaultContext && oldImC)
+            QWindowsInputContext::m_defaultContext = oldImC;
     }
 }
 
@@ -306,11 +309,6 @@ void QWindowsInputContext::invokeAction(QInputMethod::Action action, int cursorP
     ImmReleaseContext(m_compositionContext.hwnd, himc);
 }
 
-QWindowsInputContext *QWindowsInputContext::instance()
-{
-    return static_cast<QWindowsInputContext *>(QWindowsIntegration::instance()->inputContext());
-}
-
 static inline QString getCompositionString(HIMC himc, DWORD dwIndex)
 {
     enum { bufferSize = 256 };

src/plugins/platforms/windows/qwindowsinputcontext.h

@@ -42,6 +42,7 @@
 QT_BEGIN_NAMESPACE
 
 class QInputMethodEvent;
+class QWindowsWindow;
 
 class QWindowsInputContext : public QPlatformInputContext
 {
@@ -62,14 +63,14 @@ public:
     explicit QWindowsInputContext();
     ~QWindowsInputContext();
 
+    static void setWindowsImeEnabled(QWindowsWindow *platformWindow, bool enabled);
+
     bool hasCapability(Capability capability) const Q_DECL_OVERRIDE;
     void reset() Q_DECL_OVERRIDE;
     void update(Qt::InputMethodQueries) Q_DECL_OVERRIDE;
     void invokeAction(QInputMethod::Action, int cursorPosition) Q_DECL_OVERRIDE;
     void setFocusObject(QObject *object) Q_DECL_OVERRIDE;
 
-    static QWindowsInputContext *instance();
-
     bool startComposition(HWND hwnd);
     bool composition(HWND hwnd, LPARAM lParam);
     bool endComposition(HWND hwnd);

src/plugins/platforms/windows/qwindowskeymapper.cpp

@@ -33,6 +33,7 @@
 
 #include "qwindowskeymapper.h"
 #include "qwindowscontext.h"
+#include "qwindowsintegration.h"
 #include "qwindowswindow.h"
 #include "qwindowsguieventdispatcher.h"
 #include "qwindowsinputcontext.h"
@@ -1074,7 +1075,9 @@ bool QWindowsKeyMapper::translateKeyEventInternal(QWindow *window, const MSG &ms
         // results, if we map this virtual key-code directly (for eg '?' US layouts). So try
         // to find the correct key using the current message parameters & keyboard state.
         if (uch.isNull() && msgType == WM_IME_KEYDOWN) {
-            if (!QWindowsInputContext::instance()->isComposing())
+            const QWindowsInputContext *windowsInputContext =
+                qobject_cast<const QWindowsInputContext *>(QWindowsIntegration::instance()->inputContext());
+            if (!(windowsInputContext && windowsInputContext->isComposing()))
                 vk_key = ImmGetVirtualKey((HWND)window->winId());
             BYTE keyState[256];
             wchar_t newKey[3] = {0};