Android A11Y: execute C++ code on main Qt thread

The C++ code, which is called from Java, was executed on Java thread.
However Qt has its own main GUI thread, where all GUI elements and their
accessibility instances are created.
As a result we have threading issues when accessing A11Y objects from
Java thread.

This patch uses QMetaObject::invokeMethod calls to dispatch all the
critical parts of the C++ code to the main thread.
It uses BlockingQueuedConnection, so that Java thread can still use
these methods synchronously.
The proper context is based on the m_accessibilityContext object, which
is created as a child of the base accessibility QObject of the
application (which is the QGuiApplication instance in most cases).

Task-number: QTBUG-95764
Pick-to: 6.3 6.2 5.15
Change-Id: Iff4f3f2645657f6aca426fa19ccc86a2cbe4d4d0
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>
Reviewed-by: Jarkko Koivikko <jarkko.koivikko@code-q.fi>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/plugins/platforms/android/qandroidplatformaccessibility.h b/src/plugins/platforms/android/qandroidplatformaccessibility.h
index 8216c05fa6..df3fe43a04 100644
--- a/src/plugins/platforms/android/qandroidplatformaccessibility.h
+++ b/src/plugins/platforms/android/qandroidplatformaccessibility.h
@@ -52,6 +52,7 @@ public:
     ~QAndroidPlatformAccessibility();
 
     void notifyAccessibilityUpdate(QAccessibleEvent *event) override;
+    void setRootObject(QObject *obj) override;
 };
 
 QT_END_NAMESPACE