ok113i平台——qt+tslib支持usb触摸屏热插拔功能实现

问题：重新插拔设备，需要软件重启才能接收到触摸事件
愿因：是因为qt程序的tslib库的操作逻辑是在构造函数里面连接一次usb触摸设备，具体看如下文件内容：
/home/forlinx/OK113i-linux-sdk/buildroot/buildroot-201902/dl/qt5base/qtbase/src/platformsupport/input/tslib/qtslib.cpp；
所以重新插拔usb后，qt程序并没有重新连接usb触摸设备，导致没有触摸数据接收；
解决方案：
参考：https://blog.csdn.net/alone4together/article/details/115269753
参考方案中的代码需要更改一下，完整的qtslib.cpp更改内容如下：

QTsLibMouseHandler::QTsLibMouseHandler(const QString &key,const QString &specification,QObject *parent): QObject(parent),m_notify(0), m_x(0), m_y(0), m_pressed(0), m_rawMode(false)
{m_dev=0;qCDebug(qLcTsLib) << "Initializing tslib plugin" << key << specification;setObjectName(QLatin1String("TSLib Mouse Handler"));......else{qErrnoWarning(errno, "tslib: Cannot open input device %s", device.constData());}QFileSystemWatcher *m_fileWatcher = new QFileSystemWatcher(this);// QString dev_=device;m_fileWatcher->addPath(QLatin1String("/dev/input/")); // "dev/input/"connect(m_fileWatcher, &QFileSystemWatcher::directoryChanged, this, &QTsLibMouseHandler::handleHotPlugWatch);
}void QTsLibMouseHandler::handleHotPlugWatch(const QString &path)
{QByteArray device = qgetenv("TSLIB_TSDEVICE");QFile file(QString::fromLocal8Bit(device)); // shoud be TSLIB_TSDEVICEqCDebug(qLcTsLib) << path << "is changing";if (file.exists()){qCDebug(qLcTsLib) << "tslib device disconnected .., try connecting ...";disconnect(m_notify, 0, 0, 0);if (m_notify){delete m_notify;m_notify = 0;}//  QByteArray device = qgetenv("TSLIB_TSDEVICE");m_dev = ts_open(device.constData(), 1);if (!m_dev){qCDebug(qLcTsLib) << " touchscreen doesn't exist";qErrnoWarning(errno, "ts_open() failed");}else{if (ts_config(m_dev)){qErrnoWarning(errno, "ts_config() failed");}int fd = ts_fd(m_dev);if (fd >= 0){qCDebug(qLcTsLib) << "tslib device is" << device;m_notify = new QSocketNotifier(fd, QSocketNotifier::Read, this);connect(m_notify, &QSocketNotifier::activated, this, &QTsLibMouseHandler::readMouseData);}else{qErrnoWarning(errno, "tslib: Cannot open input device %s", device.constData());}return;}qCDebug(qLcTsLib) << path << "is added";}else{if (m_dev){ts_close(m_dev);m_dev = 0;}qCDebug(qLcTsLib) << path << "is removed";}
}

改完qtslib.cpp需要编译buildroot，编译后的qtslib.cpp会在如下路径：
/home/OK113i-linux-sdk/out/t113_i/ok113i/longan/buildroot/build/qt5base-5.12.5/src/platformsupport/input/tslib/qtslib.cpp
需要注意单独编译的buildroot后，还需要全编译，才会将根文件系统镜像rootfs.ext2更新到系统镜像；