qt6-bb10/src/corelib/kernel/qpermissions.cpp

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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 "qpermissions.h"
#include "qpermissions_p.h"
#include "qhashfunctions.h"
#include <QtCore/qshareddata.h>
#include <QtCore/qdebug.h>
QT_BEGIN_NAMESPACE
Q_LOGGING_CATEGORY(lcPermissions, "qt.permissions", QtWarningMsg);
/*!
\page permissions.html
\title Application Permissions
\brief Managing application permissions
Many features of today's devices and operating systems can have
significant privacy, security, and performance implications if
misused. It's therefore increasingly common for platforms to
require explicit consent from the user before accessing these
features.
The Qt permission APIs allow the application to check or request
permission for such features in a cross platform manner.
\section1 Usage
A feature that commonly requires user consent is access to the
microphone of the device. An application for recording voice
memos would perhaps look something like this initially:
\code
void VoiceMemoWidget::onRecordingInitiated()
{
m_microphone->startRecording();
}
\endcode
To ensure this application works well on platforms that
require user consent for microphone access we would extend
it like this:
\code
void VoiceMemoWidget::onRecordingInitiated()
{
#if QT_CONFIG(permissions)
QMicrophonePermission microphonePermission;
switch (qApp->checkPermission(microphonePermission)) {
case Qt::PermissionStatus::Undetermined:
qApp->requestPermission(microphonePermission, this
&VoiceMemoWidget::onRecordingInitiated);
return;
case Qt::PermissionStatus::Denied:
m_permissionInstructionsDialog->show();
return;
case Qt::PermissionStatus::Granted:
break; // Proceed
}
#endif
m_microphone->startRecording();
}
\endcode
We first check if we already know the status of the microphone permission.
If we don't we initiate a permission request to determine the current
status, which will potentially ask the user for consent. We connect the
result of the request to the slot we're already in, so that we get another
chance at evaluating the permission status.
Once the permission status is known, either because we had been granted or
denied permission at an earlier time, or after getting the result back from
the request we just initiated, we redirect the user to a dialog explaining
why we can not record voice memos at this time (if the permission was denied),
or proceed to using the microphone (if permission was granted).
The use of the \c{QT_CONFIG(permissions)} macro ensures that the code
will work as before on platforms where permissions are not available.
\section2 Declaring Permissions
Some platforms require that the permissions you request are declared
up front at build time.
\section3 Apple platforms
\target apple-usage-description
Each permission you request must be accompanied by a so called
\e {usage description} string in the application's \c Info.plist
file, describing why the application needs to access the given
permission. For example:
\badcode
<key>NSMicrophoneUsageDescription</key>
<string>The microphone is used to record voice memos.</string>
\endcode
The relevant usage description keys are described in the documentation
for each permission type.
\sa {Information Property List Files}.
\section3 Android
\target android-uses-permission
Each permission you request must be accompanied by a \c uses-permission
entry in the application's \c AndroidManifest.xml file. For example:
\badcode
<manifest ...>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
</manifest>
\endcode
The relevant permission names are described in the documentation
for each permission type.
\sa {Qt Creator: Editing Manifest Files}.
\section1 Available Permissions
The following permissions types are available:
\annotatedlist permissions
\section1 Best Practices
To ensure the best possible user experience for the end user we recommend
adopting the following best practices for managing application permissions:
\list
\li Request the minimal set of permissions needed. For example, if you only
need access to the microphone, do \e not request camera permission just in case.
Use the properties of individual permission types to limit the permission scope
even further, for example QContactsPermission::setReadOnly() to request read
only access.
\li Request permissions in response to specific actions by the user. For example,
defer requesting microphone permission until the user presses the button to record
audio. Associating the permission request to a specific action gives the user a clearer
context of why the permission is needed. Do \e not request all needed permission on
startup.
\li Present extra context and explanation if needed. Sometimes the action by the user
is not enough context. Consider presenting an explanation-dialog after the user has
initiated the action, but before requesting the permission, so the user is aware of
what's about to happen when the system permission dialog subsequently pops up.
\li Be transparent and explicit about why permissions are needed. In explanation
dialogs and usage descriptions, be transparent about why the particular permission
is needed for your application to provide a specific feature, so users can make
informed decisions.
\li Account for denied permissions. The permissions you request may be denied
for various reasons. You should always account for this situation, by gracefully
degrading the experience of your application, and presenting clear explanations
the user about the situation.
\li Never request permissions from a library. The request of permissions should
be done as close as possible to the user, where the information needed to make
good decisions on the points above is available. Libraries can check permissions,
to ensure they have the prerequisites for doing their work, but if the permission
is undetermined or denied this should be reflected through the library's API,
so that the application in turn can request the necessary permissions.
\endlist
*/
/*!
\class QPermission
\inmodule QtCore
\inheaderfile QPermissions
\brief An opaque wrapper of a typed permission.
The QPermission class is an opaque wrapper of a \l{typed permission},
used when checking or requesting permissions. You do not need to construct
this type explicitly, as the type is automatically used when checking or
requesting permissions:
\code
qApp->checkPermission(QCameraPermission{});
\endcode
When requesting permissions, the given functor will
be passed an instance of a QPermissions, which can be used
to check the result of the request:
\code
qApp->requestPermission(QCameraPermission{}, [](const QPermission &permission) {
if (permission.status() == Qt::PermissionStatus:Granted)
takePhoto();
});
\endcode
To inspect the properties of the original typed permission,
use the data() function:
\code
QLocationPermission locationPermission;
locationPermission.setAccuracy(QLocationPermission::Precise);
qApp->requestPermission(locationPermission, this, &LocationWidget::permissionUpdated);
\endcode
\code
void LocationWidget::permissionUpdated(const QPermission &permission)
{
if (permission.status() != Qt::PermissionStatus:Granted)
return;
auto locationPermission = permission.data<QLocationPermission>();
if (locationPermission.accuracy() != QLocationPerission::Precise)
return;
updatePreciseLocation();
}
\endcode
\target typed permission
\section2 Typed Permissions
The following permissions are available:
\annotatedlist permissions
\sa {Application Permissions}
*/
/*!
\fn template <typename Type> QPermission::QPermission(const Type &type)
Constructs a permission from the given \l{typed permission} \a type.
You do not need to construct this type explicitly, as the type is automatically
used when checking or requesting permissions.
*/
/*!
\fn template <typename Type> Type QPermission::data() const
Returns the \l{typed permission} of type \c Type.
The type must match the type that was originally used to request
the permission. Use type() for dynamically choosing which typed
permission to request.
*/
/*!
Returns the status of the permission.
*/
Qt::PermissionStatus QPermission::status() const
{
return m_status;
}
/*!
Returns the type of the permission.
*/
QMetaType QPermission::type() const
{
return m_data.metaType();
}
#define QT_DEFINE_PERMISSION_SPECIAL_FUNCTIONS(ClassName) \
ClassName::ClassName() : d(new ClassName##Private) {} \
ClassName::ClassName(const ClassName &other) noexcept = default; \
ClassName::ClassName(ClassName &&other) noexcept = default; \
ClassName::~ClassName() noexcept = default; \
ClassName &ClassName::operator=(const ClassName &other) noexcept = default;
/*!
\class QCameraPermission
\brief Access the camera for taking pictures or videos.
\section1 Requirements
\include permissions.qdocinc begin-usage-declarations
\row
\li Apple
\li \l{apple-usage-description}{Usage description}
\li \c NSCameraUsageDescription
\include permissions.qdocinc end-usage-declarations
\include permissions.qdocinc permission-metadata
*/
class QCameraPermissionPrivate : public QSharedData {};
QT_DEFINE_PERMISSION_SPECIAL_FUNCTIONS(QCameraPermission)
/*!
\class QMicrophonePermission
\brief Access the microphone for monitoring or recording sound.
\section1 Requirements
\include permissions.qdocinc begin-usage-declarations
\row
\li Apple
\li \l{apple-usage-description}{Usage description}
\li \c NSMicrophoneUsageDescription
\include permissions.qdocinc end-usage-declarations
\include permissions.qdocinc permission-metadata
*/
class QMicrophonePermissionPrivate : public QSharedData {};
QT_DEFINE_PERMISSION_SPECIAL_FUNCTIONS(QMicrophonePermission)
/*!
\class QBluetoothPermission
\brief Access Bluetooth peripherals.
\section1 Requirements
\include permissions.qdocinc begin-usage-declarations
\row
\li Apple
\li \l{apple-usage-description}{Usage description}
\li \c NSBluetoothAlwaysUsageDescription
\include permissions.qdocinc end-usage-declarations
\include permissions.qdocinc permission-metadata
*/
class QBluetoothPermissionPrivate : public QSharedData {};
QT_DEFINE_PERMISSION_SPECIAL_FUNCTIONS(QBluetoothPermission)
/*!
\class QLocationPermission
\brief Access the user's location.
By default the request is for approximate accuracy,
and only while the application is in use. Use
setAccuracy() and/or setAvailability() to override
the default.
\section1 Requirements
\include permissions.qdocinc begin-usage-declarations
\row
\li Apple
\li \l{apple-usage-description}{Usage description}
\li \c NSLocationWhenInUseUsageDescription, and
\c NSLocationAlwaysUsageDescription if requesting
QLocationPermission::Always
\include permissions.qdocinc end-usage-declarations
\include permissions.qdocinc permission-metadata
*/
class QLocationPermissionPrivate : public QSharedData
{
public:
using Accuracy = QLocationPermission::Accuracy;
Accuracy accuracy = Accuracy::Approximate;
using Availability = QLocationPermission::Availability;
Availability availability = Availability::WhenInUse;
};
QT_DEFINE_PERMISSION_SPECIAL_FUNCTIONS(QLocationPermission)
/*!
\enum QLocationPermission::Accuracy
This enum is used to control the accuracy of the location data.
\value Approximate An approximate location is requested.
\value Precise A precise location is requested.
*/
/*!
\enum QLocationPermission::Availability
This enum is used to control the availability of the location data.
\value WhenInUse The location is only available only when the
application is in use.
\value Always The location is available at all times, including when
the application is in the background.
*/
/*!
Sets the desired \a accuracy of the request.
*/
void QLocationPermission::setAccuracy(Accuracy accuracy)
{
d.detach();
d->accuracy = accuracy;
}
/*!
Returns the accuracy of the request.
*/
QLocationPermission::Accuracy QLocationPermission::accuracy() const
{
return d->accuracy;
}
/*!
Sets the desired \a availability of the request.
*/
void QLocationPermission::setAvailability(Availability availability)
{
d.detach();
d->availability = availability;
}
/*!
Returns the availability of the request.
*/
QLocationPermission::Availability QLocationPermission::availability() const
{
return d->availability;
}
/*!
\class QContactsPermission
\brief Access the user's contacts.
By default the request is for both read and write access.
Use setReadOnly() to override the default.
\section1 Requirements
\include permissions.qdocinc begin-usage-declarations
\row
\li Apple
\li \l{apple-usage-description}{Usage description}
\li \c NSContactsUsageDescription
\include permissions.qdocinc end-usage-declarations
\include permissions.qdocinc permission-metadata
*/
class QContactsPermissionPrivate : public QSharedData
{
public:
bool isReadOnly = false;
};
QT_DEFINE_PERMISSION_SPECIAL_FUNCTIONS(QContactsPermission)
/*!
Sets whether to \a enable read-only access to the contacts.
*/
void QContactsPermission::setReadOnly(bool enable)
{
d.detach();
d->isReadOnly = enable;
}
/*!
Returns whether the request is for read-only access to the contacts.
*/
bool QContactsPermission::isReadOnly() const
{
return d->isReadOnly;
}
/*!
\class QCalendarPermission
\brief Access the user's calendar.
By default the request is for both read and write access.
Use setReadOnly() to override the default.
\section1 Requirements
\include permissions.qdocinc begin-usage-declarations
\row
\li Apple
\li \l{apple-usage-description}{Usage description}
\li \c NSCalendarsUsageDescription
\include permissions.qdocinc end-usage-declarations
\include permissions.qdocinc permission-metadata
*/
class QCalendarPermissionPrivate : public QSharedData
{
public:
bool isReadOnly = false;
};
QT_DEFINE_PERMISSION_SPECIAL_FUNCTIONS(QCalendarPermission)
/*!
Sets whether to \a enable read-only access to the calendar.
*/
void QCalendarPermission::setReadOnly(bool enable)
{
d.detach();
d->isReadOnly = enable;
}
/*!
Returns whether the request is for read-only access to the calendar.
*/
bool QCalendarPermission::isReadOnly() const
{
return d->isReadOnly;
}
/*!
* \internal
*/
QPermissionPlugin::~QPermissionPlugin() = default;
#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug debug, const QPermission &permission)
{
const auto verbosity = debug.verbosity();
QDebugStateSaver saver(debug);
debug.nospace().setVerbosity(0);
if (verbosity >= QDebug::DefaultVerbosity)
debug << permission.type().name() << "(";
debug << permission.status();
if (verbosity >= QDebug::DefaultVerbosity)
debug << ")";
return debug;
}
#endif
QT_END_NAMESPACE
#include "moc_qpermissions.cpp"