Windows QPA: Avoid slowdown with UI Automation name change notification

A previous fix for QTBUG-70621, which allowed changes in the state of a
Quick combo box control to be detected by accessibility clients has
reportedly caused significant slowdowns under some difficult to reproduce
circumstances, probably associated with a large number of accessible
objects. This patch restricts the name change notification to combo
boxes, which seem to be the only kind of control requiring them for
accessibility, instead of sending it for all control types.

Fixes: QTBUG-97103
Change-Id: I18c0067478df5a80f7365195d3559b3f04faa815
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>
(cherry picked from commit bcd0a3220348778c0d72faac202efb97f4d6dd07)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 10 insertions, 6 deletions

diff --git a/src/plugins/platforms/windows/uiautomation/qwindowsuiamainprovider.cpp b/src/plugins/platforms/windows/uiautomation/qwindowsuiamainprovider.cpp
index 809a7a9a8f..63bf6bc87c 100644
--- a/src/plugins/platforms/windows/uiautomation/qwindowsuiamainprovider.cpp
+++ b/src/plugins/platforms/windows/uiautomation/qwindowsuiamainprovider.cpp
@@ -206,12 +206,16 @@ void QWindowsUiaMainProvider::notifyValueChange(QAccessibleValueChangeEvent *eve
 void QWindowsUiaMainProvider::notifyNameChange(QAccessibleEvent *event)
 {
     if (QAccessibleInterface *accessible = event->accessibleInterface()) {
-        if (QWindowsUiaMainProvider *provider = providerForAccessible(accessible)) {
-            VARIANT oldVal, newVal;
-            clearVariant(&oldVal);
-            setVariantString(accessible->text(QAccessible::Name), &newVal);
-            QWindowsUiaWrapper::instance()->raiseAutomationPropertyChangedEvent(provider, UIA_NamePropertyId, oldVal, newVal);
-            ::SysFreeString(newVal.bstrVal);
+        // Restrict notification to combo boxes, which need it for accessibility,
+        // in order to avoid slowdowns with unnecessary notifications.
+        if (accessible->role() == QAccessible::ComboBox) {
+            if (QWindowsUiaMainProvider *provider = providerForAccessible(accessible)) {
+                VARIANT oldVal, newVal;
+                clearVariant(&oldVal);
+                setVariantString(accessible->text(QAccessible::Name), &newVal);
+                QWindowsUiaWrapper::instance()->raiseAutomationPropertyChangedEvent(provider, UIA_NamePropertyId, oldVal, newVal);
+                ::SysFreeString(newVal.bstrVal);
+            }
         }
     }
 }