qwindowsuiaprovidercache.cpp

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// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include <QtGui/qtguiglobal.h>
#if QT_CONFIG(accessibility)
 
#include "qwindowsuiaprovidercache.h"
#include "qwindowsuiautils.h"
#include "qwindowscontext.h"
 
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.
ComPtr<QWindowsUiaMainProvider> QWindowsUiaProviderCache::providerForId(QAccessible::Id id) const
{
    QMutexLocker guard{ &m_tableMutex };
 
    // Make sure lifetime is extended while holding the mutex
    ComPtr<QWindowsUiaMainProvider> provider = m_providerTable.value(id);
 
    return provider;
}
 
// Inserts a provider in the cache and associates it with an accessibility ID.
void QWindowsUiaProviderCache::insert(QAccessible::Id id, QWindowsUiaMainProvider *provider)
{
    QMutexLocker guard{ &m_tableMutex };
    // Remove id if it already exists
    m_inverseTable.remove(m_providerTable.value(id));
    m_providerTable.remove(id);
 
    // Add new provider
    if (provider) {
        m_providerTable[id] = provider;
        m_inverseTable[provider] = id;
        guard.unlock();
        // Connects the destroyed signal to our slot, to remove deleted objects from the cache.
        QObject::connect(provider, &QObject::destroyed, this, &QWindowsUiaProviderCache::remove, Qt::DirectConnection);
    }
}
 
// Removes deleted provider objects from the cache.
void QWindowsUiaProviderCache::remove(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.
    QMutexLocker guard{ &m_tableMutex };
    auto it = m_inverseTable.find(obj);
    if (it != m_inverseTable.end()) {
        m_providerTable.remove(*it);
        m_inverseTable.remove(obj);
    }
}
 
QT_END_NAMESPACE
 
#endif // QT_CONFIG(accessibility)