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// Copyright (C) 2022 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 "dbusconnection_p.h"
#include <QtDBus/QDBusMessage>
#include <QtDBus/QDBusServiceWatcher>
#include <qdebug.h>
#include <QDBusConnectionInterface>
#include "bus_interface.h"
#include <QtGui/qguiapplication.h>
#include <qpa/qplatformnativeinterface.h>
QT_BEGIN_NAMESPACE
using namespace Qt::StringLiterals;
/* note: do not change these to QStringLiteral;
we are unloaded before QtDBus is done using the strings.
*/
#define A11Y_SERVICE "org.a11y.Bus"_L1
#define A11Y_PATH "/org/a11y/bus"_L1
/*!
\class DBusConnection
\internal
\brief Connects to the accessibility dbus.
This is usually a different bus from the session bus.
*/
DBusConnection::DBusConnection(QObject *parent)
: QObject(parent), m_a11yConnection(QString()), m_enabled(false)
{
// If the bus is explicitly set via env var it overrides everything else.
QByteArray addressEnv = qgetenv("AT_SPI_BUS_ADDRESS");
if (!addressEnv.isEmpty()) {
m_enabled = true;
connectA11yBus(QString::fromLocal8Bit(addressEnv));
return;
}
// Start monitoring if "org.a11y.Bus" is registered as DBus service.
QDBusConnection c = QDBusConnection::sessionBus();
if (!c.isConnected()) {
return;
}
dbusWatcher = new QDBusServiceWatcher(A11Y_SERVICE, c, QDBusServiceWatcher::WatchForRegistration, this);
connect(dbusWatcher, SIGNAL(serviceRegistered(QString)), this, SLOT(serviceRegistered()));
// If it is registered already, setup a11y right away
if (c.interface()->isServiceRegistered(A11Y_SERVICE))
serviceRegistered();
if (QGuiApplication::platformName().startsWith("xcb"_L1)) {
// In addition try if there is an xatom exposing the bus address, this allows applications run as root to work
QString address = getAddressFromXCB();
if (!address.isEmpty()) {
m_enabled = true;
connectA11yBus(address);
}
}
}
QString DBusConnection::getAddressFromXCB()
{
QGuiApplication *app = qobject_cast<QGuiApplication *>(QCoreApplication::instance());
if (!app)
return QString();
QPlatformNativeInterface *platformNativeInterface = app->platformNativeInterface();
QByteArray *addressByteArray = reinterpret_cast<QByteArray*>(
platformNativeInterface->nativeResourceForIntegration(QByteArrayLiteral("AtspiBus")));
if (addressByteArray) {
QString address = QString::fromLatin1(*addressByteArray);
delete addressByteArray;
return address;
}
return QString();
}
// We have the a11y registry on the session bus.
// Subscribe to updates about a11y enabled state.
// Find out the bus address
void DBusConnection::serviceRegistered()
{
// listen to enabled changes
QDBusConnection c = QDBusConnection::sessionBus();
OrgA11yStatusInterface *a11yStatus = new OrgA11yStatusInterface(A11Y_SERVICE, A11Y_PATH, c, this);
//The variable was introduced because on some embedded platforms there are custom accessibility
//clients which don't set Status.ScreenReaderEnabled to true. The variable is also useful for
//debugging.
static const bool a11yAlwaysOn = qEnvironmentVariableIsSet("QT_LINUX_ACCESSIBILITY_ALWAYS_ON");
bool enabled = a11yAlwaysOn || a11yStatus->screenReaderEnabled() || a11yStatus->isEnabled();
if (enabled != m_enabled) {
m_enabled = enabled;
if (m_a11yConnection.isConnected()) {
emit enabledChanged(m_enabled);
} else {
QDBusConnection c = QDBusConnection::sessionBus();
QDBusMessage m = QDBusMessage::createMethodCall(A11Y_SERVICE, A11Y_PATH, A11Y_SERVICE,
"GetAddress"_L1);
c.callWithCallback(m, this, SLOT(connectA11yBus(QString)), SLOT(dbusError(QDBusError)));
}
}
// connect(a11yStatus, ); QtDbus doesn't support notifications for property changes yet
}
void DBusConnection::serviceUnregistered()
{
emit enabledChanged(false);
}
void DBusConnection::connectA11yBus(const QString &address)
{
if (address.isEmpty()) {
qWarning("Could not find Accessibility DBus address.");
return;
}
m_a11yConnection = QDBusConnection(QDBusConnection::connectToBus(address, "a11y"_L1));
if (m_enabled)
emit enabledChanged(true);
}
void DBusConnection::dbusError(const QDBusError &error)
{
qWarning() << "Accessibility encountered a DBus error:" << error;
}
/*!
Returns the DBus connection that got established.
Or an invalid connection if not yet connected.
*/
QDBusConnection DBusConnection::connection() const
{
return m_a11yConnection;
}
QT_END_NAMESPACE
#include "moc_dbusconnection_p.cpp"
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