qpipewire_cameranode.cpp

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// Copyright (C) 2026 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 "qpipewire_cameranode_p.h"
 
#include <QtCore/qloggingcategory.h>
 
QT_BEGIN_NAMESPACE
 
namespace QtPipeWire {
 
using namespace Qt::StringLiterals;
using namespace std::string_view_literals;
 
namespace {
 
QByteArray toByteArray(std::string_view sv)
{
    return QByteArray(sv.data(), qsizetype(sv.size()));
}
 
QString toString(std::string_view sv)
{
    return QString::fromUtf8(sv.data(), qsizetype(sv.size()));
}
 
} // namespace
 
bool isCameraNode(const PwPropertyDict &nodeProperties)
{
    // An escape hatch for triaging a camera that we filter out but should not.
    static const bool acceptAll =
            qEnvironmentVariableIntValue("QT_PIPEWIRE_CAMERA_ACCEPT_ALL") != 0;
 
    const std::optional<std::string_view> mediaClass = getMediaClass(nodeProperties);
    if (!mediaClass)
        return false;
 
    if (mediaClass != "Video/Source"sv)
        return false;
 
    if (acceptAll)
        return true;
 
    if (getMediaRole(nodeProperties) == "Camera"sv)
        return true;
 
    const std::optional<std::string_view> deviceApi = getDeviceApi(nodeProperties);
    return deviceApi == "v4l2"sv || deviceApi == "libcamera"sv;
}
 
QByteArray cameraDeviceId(const PwPropertyDict &nodeProperties)
{
    // node.name is derived from the device's sysfs path: stable and unique
    if (auto nodeName = getNodeName(nodeProperties))
        return "pw:" + toByteArray(*nodeName);
 
    // object.path less stable, based on the devfs name, e.g. v4l2:/dev/video0
    if (auto objectPath = getObjectPath(nodeProperties))
        return "pw:" + toByteArray(*objectPath);
 
    // Last resort: not stable across runs, but better than an empty id, which
    // would make the device unusable.
    if (auto serial = getObjectSerial(nodeProperties))
        return "pw:serial:" + QByteArray::number(qulonglong(serial->value));
 
    return {};
}
 
QString cameraDescription(const PwPropertyDict &nodeProperties,
                          const PwPropertyDict &deviceProperties)
{
    if (auto description = getNodeDescription(nodeProperties))
        return toString(*description);
    if (auto nick = getNodeNick(nodeProperties))
        return toString(*nick);
    if (auto description = getDeviceDescription(deviceProperties))
        return toString(*description);
    if (auto nodeName = getNodeName(nodeProperties))
        return toString(*nodeName);
    return {};
}
 
QCameraDevice::Position cameraPosition(const PwPropertyDict &nodeProperties)
{
    // Only libcamera reports where a camera faces; v4l2 has no notion of it.
    if (getDeviceApi(nodeProperties) != "libcamera"sv)
        return QCameraDevice::UnspecifiedPosition;
 
    const auto location = nodeProperties.find("api.libcamera.location"sv);
    if (location == nodeProperties.end())
        return QCameraDevice::UnspecifiedPosition;
 
    if (location->second == "front"sv)
        return QCameraDevice::FrontFace;
    if (location->second == "back"sv)
        return QCameraDevice::BackFace;
 
    // "external" and anything unrecognised.
    return QCameraDevice::UnspecifiedPosition;
}
 
} // namespace QtPipeWire
 
QT_END_NAMESPACE