Add support for Windows UI Automation

Replaces the Qt Accessibility Windows back end, formerly based on legacy
MSAA, with a new implementation based on UI Automation. Fixes issues with
accessibility tools like screen readers and magnifiers, and with the
automatic showing and hiding of the virtual keyboard in touchscreen-based
Windows computers.

[ChangeLog][Windows] The Windows Accessibility back end, formerly based on
Microsoft Active Accessibility, was replaced with a new implementation
based on Microsoft UI Automation.

Task-number: QTPM-487
Task-number: QTBUG-53024
Task-number: QTBUG-43190
Task-number: QTBUG-61926
Task-number: QTBUG-38499
Task-number: QTBUG-38337
Task-number: QTBUG-38501
Task-number: QTBUG-38502
Task-number: QTBUG-38504
Task-number: QTBUG-38505
Task-number: QTBUG-38507
Change-Id: I20b4f8f5e938fef791c6e9c577fcd919140999bd
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 106 insertions, 0 deletions

diff --git a/src/plugins/platforms/windows/uiautomation/qwindowsuiaprovidercache.cpp b/src/plugins/platforms/windows/uiautomation/qwindowsuiaprovidercache.cpp
new file mode 100644
index 0000000000..9f0a1e126f
--- /dev/null
+++ b/src/plugins/platforms/windows/uiautomation/qwindowsuiaprovidercache.cpp
@@ -0,0 +1,106 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtCore/QtConfig>
+#ifndef QT_NO_ACCESSIBILITY
+
+#include "qwindowsuiaprovidercache.h"
+#include "qwindowsuiautils.h"
+#include "qwindowscontext.h"
+
+#include <QtCore/QDebug>
+
+QT_BEGIN_NAMESPACE
+
+using namespace QWindowsUiAutomation;
+
+
+// Private constructor
+QWindowsUiaProviderCache::QWindowsUiaProviderCache()
+{
+}
+
+// shared instance
+QWindowsUiaProviderCache *QWindowsUiaProviderCache::instance()
+{
+    static QWindowsUiaProviderCache providerCache;
+    return &providerCache;
+}
+
+// Returns the provider instance associated with the ID, or nullptr.
+QWindowsUiaBaseProvider *QWindowsUiaProviderCache::providerForId(QAccessible::Id id) const
+{
+    return providerTable.value(id);
+}
+
+// Inserts a provider in the cache and associates it with an accessibility ID.
+void QWindowsUiaProviderCache::insert(QAccessible::Id id, QWindowsUiaBaseProvider *provider)
+{
+    remove(id);
+    if (provider) {
+        providerTable[id] = provider;
+        inverseTable[provider] = id;
+        // Connects the destroyed signal to our slot, to remove deleted objects from the cache.
+        QObject::connect(provider, &QObject::destroyed, this, &QWindowsUiaProviderCache::objectDestroyed);
+    }
+}
+
+// Removes deleted provider objects from the cache.
+void QWindowsUiaProviderCache::objectDestroyed(QObject *obj)
+{
+    // We have to use the inverse table to map the object address back to its ID,
+    // since at this point (called from QObject destructor), it has already been
+    // partially destroyed and we cannot treat it as a provider.
+    auto it = inverseTable.find(obj);
+    if (it != inverseTable.end()) {
+        providerTable.remove(*it);
+        inverseTable.remove(obj);
+    }
+}
+
+// Removes a provider with a given id from the cache.
+void QWindowsUiaProviderCache::remove(QAccessible::Id id)
+{
+    inverseTable.remove(providerTable.value(id));
+    providerTable.remove(id);
+}
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_ACCESSIBILITY