Windows QPA: Add support to UiaRaiseNotificationEvent()

This change adds support to UiaRaiseNotificationEvent() in the
UI Automation-based accessibility code, and uses it to notify changes
in string-typed values, allowing Narrator, NVDA and other screen readers
to notice changes in the application state that were previously missed.

Fixes: QTBUG-75003
Change-Id: I646ca3a851ab7b69817d900b002eb91a3bf607a6
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

4 files changed, 49 insertions, 6 deletions

diff --git a/src/platformsupport/windowsuiautomation/qwindowsuiawrapper.cpp b/src/platformsupport/windowsuiautomation/qwindowsuiawrapper.cpp
index 79541fe636..8038e1a3c3 100644
--- a/src/platformsupport/windowsuiautomation/qwindowsuiawrapper.cpp
+++ b/src/platformsupport/windowsuiautomation/qwindowsuiawrapper.cpp
@@ -53,6 +53,7 @@ QWindowsUiaWrapper::QWindowsUiaWrapper()
         m_pUiaHostProviderFromHwnd = reinterpret_cast<PtrUiaHostProviderFromHwnd>(uiaLib.resolve("UiaHostProviderFromHwnd"));
         m_pUiaRaiseAutomationPropertyChangedEvent = reinterpret_cast<PtrUiaRaiseAutomationPropertyChangedEvent>(uiaLib.resolve("UiaRaiseAutomationPropertyChangedEvent"));
         m_pUiaRaiseAutomationEvent = reinterpret_cast<PtrUiaRaiseAutomationEvent>(uiaLib.resolve("UiaRaiseAutomationEvent"));
+        m_pUiaRaiseNotificationEvent = reinterpret_cast<PtrUiaRaiseNotificationEvent>(uiaLib.resolve("UiaRaiseNotificationEvent"));
         m_pUiaClientsAreListening = reinterpret_cast<PtrUiaClientsAreListening>(uiaLib.resolve("UiaClientsAreListening"));
     }
 }
@@ -68,7 +69,7 @@ QWindowsUiaWrapper *QWindowsUiaWrapper::instance()
     return &wrapper;
 }
 
-// True if all symbols resolved.
+// True if most symbols resolved (UiaRaiseNotificationEvent is optional).
 BOOL QWindowsUiaWrapper::ready()
 {
     return m_pUiaReturnRawElementProvider
@@ -113,5 +114,12 @@ HRESULT QWindowsUiaWrapper::raiseAutomationEvent(IRawElementProviderSimple *pPro
     return m_pUiaRaiseAutomationEvent(pProvider, id);
 }
 
+HRESULT QWindowsUiaWrapper::raiseNotificationEvent(IRawElementProviderSimple *provider, NotificationKind notificationKind, NotificationProcessing notificationProcessing, BSTR displayString, BSTR activityId)
+{
+    if (!m_pUiaRaiseNotificationEvent)
+        return UIA_E_NOTSUPPORTED;
+    return m_pUiaRaiseNotificationEvent(provider, notificationKind, notificationProcessing, displayString, activityId);
+}
+
 QT_END_NAMESPACE
 
diff --git a/src/platformsupport/windowsuiautomation/qwindowsuiawrapper_p.h b/src/platformsupport/windowsuiautomation/qwindowsuiawrapper_p.h
index 3ebc3008d3..9208acbc31 100644
--- a/src/platformsupport/windowsuiautomation/qwindowsuiawrapper_p.h
+++ b/src/platformsupport/windowsuiautomation/qwindowsuiawrapper_p.h
@@ -80,17 +80,20 @@ public:
     HRESULT hostProviderFromHwnd(HWND hwnd, IRawElementProviderSimple **ppProvider);
     HRESULT raiseAutomationPropertyChangedEvent(IRawElementProviderSimple *pProvider, PROPERTYID id, VARIANT oldValue, VARIANT newValue);
     HRESULT raiseAutomationEvent(IRawElementProviderSimple *pProvider, EVENTID id);
+    HRESULT raiseNotificationEvent(IRawElementProviderSimple *provider, NotificationKind notificationKind, NotificationProcessing notificationProcessing, BSTR displayString, BSTR activityId);
 
 private:
     typedef LRESULT (WINAPI *PtrUiaReturnRawElementProvider)(HWND, WPARAM, LPARAM, IRawElementProviderSimple *);
     typedef HRESULT (WINAPI *PtrUiaHostProviderFromHwnd)(HWND, IRawElementProviderSimple **);
     typedef HRESULT (WINAPI *PtrUiaRaiseAutomationPropertyChangedEvent)(IRawElementProviderSimple *, PROPERTYID, VARIANT, VARIANT);
     typedef HRESULT (WINAPI *PtrUiaRaiseAutomationEvent)(IRawElementProviderSimple *, EVENTID);
+    typedef HRESULT (WINAPI *PtrUiaRaiseNotificationEvent)(IRawElementProviderSimple *, NotificationKind, NotificationProcessing, BSTR, BSTR);
     typedef BOOL (WINAPI *PtrUiaClientsAreListening)();
     PtrUiaReturnRawElementProvider             m_pUiaReturnRawElementProvider = nullptr;
     PtrUiaHostProviderFromHwnd                 m_pUiaHostProviderFromHwnd = nullptr;
     PtrUiaRaiseAutomationPropertyChangedEvent  m_pUiaRaiseAutomationPropertyChangedEvent = nullptr;
     PtrUiaRaiseAutomationEvent                 m_pUiaRaiseAutomationEvent = nullptr;
+    PtrUiaRaiseNotificationEvent               m_pUiaRaiseNotificationEvent = nullptr;
     PtrUiaClientsAreListening                  m_pUiaClientsAreListening = nullptr;
 };
 
diff --git a/src/platformsupport/windowsuiautomation/uiatypes_p.h b/src/platformsupport/windowsuiautomation/uiatypes_p.h
index afbc957094..0d2e1161e4 100644
--- a/src/platformsupport/windowsuiautomation/uiatypes_p.h
+++ b/src/platformsupport/windowsuiautomation/uiatypes_p.h
@@ -162,6 +162,22 @@ enum ExpandCollapseState {
     ExpandCollapseState_LeafNode          = 3
 };
 
+enum NotificationKind {
+    NotificationKind_ItemAdded       = 0,
+    NotificationKind_ItemRemoved     = 1,
+    NotificationKind_ActionCompleted = 2,
+    NotificationKind_ActionAborted   = 3,
+    NotificationKind_Other           = 4
+};
+
+enum NotificationProcessing {
+    NotificationProcessing_ImportantAll          = 0,
+    NotificationProcessing_ImportantMostRecent   = 1,
+    NotificationProcessing_All                   = 2,
+    NotificationProcessing_MostRecent            = 3,
+    NotificationProcessing_CurrentThenMostRecent = 4
+};
+
 struct UiaRect {
     double left;
     double top;
diff --git a/src/plugins/platforms/windows/uiautomation/qwindowsuiamainprovider.cpp b/src/plugins/platforms/windows/uiautomation/qwindowsuiamainprovider.cpp
index 9adc5c78dd..59360616a1 100644
--- a/src/plugins/platforms/windows/uiautomation/qwindowsuiamainprovider.cpp
+++ b/src/plugins/platforms/windows/uiautomation/qwindowsuiamainprovider.cpp
@@ -166,11 +166,27 @@ void QWindowsUiaMainProvider::notifyValueChange(QAccessibleValueChangeEvent *eve
         }
         if (event->value().type() == QVariant::String) {
             if (QWindowsUiaMainProvider *provider = providerForAccessible(accessible)) {
-                // Notifies changes in string values.
-                VARIANT oldVal, newVal;
-                clearVariant(&oldVal);
-                setVariantString(event->value().toString(), &newVal);
-                QWindowsUiaWrapper::instance()->raiseAutomationPropertyChangedEvent(provider, UIA_ValueValuePropertyId, oldVal, newVal);
+
+                // Tries to notify the change using UiaRaiseNotificationEvent(), which is only available on
+                // Windows 10 version 1709 or newer. Otherwise uses UiaRaiseAutomationPropertyChangedEvent().
+
+                BSTR displayString = bStrFromQString(event->value().toString());
+                BSTR activityId = bStrFromQString(QString());
+
+                HRESULT hr = QWindowsUiaWrapper::instance()->raiseNotificationEvent(provider, NotificationKind_Other,
+                                                                                    NotificationProcessing_ImportantMostRecent,
+                                                                                    displayString, activityId);
+
+                ::SysFreeString(displayString);
+                ::SysFreeString(activityId);
+
+                if (hr == static_cast<HRESULT>(UIA_E_NOTSUPPORTED)) {
+                    VARIANT oldVal, newVal;
+                    clearVariant(&oldVal);
+                    setVariantString(event->value().toString(), &newVal);
+                    QWindowsUiaWrapper::instance()->raiseAutomationPropertyChangedEvent(provider, UIA_ValueValuePropertyId, oldVal, newVal);
+                    ::SysFreeString(newVal.bstrVal);
+                }
             }
         } else if (QAccessibleValueInterface *valueInterface = accessible->valueInterface()) {
             if (QWindowsUiaMainProvider *provider = providerForAccessible(accessible)) {