VisionPlus_V3.0/SoftNumKeyBoard/main.cpp

#include "softnumkeyboardwidget.h"
#include <QDesktopWidget>
#include <QApplication>
#include <QSharedMemory>

int main(int argc, char *argv[])
{
    QApplication::addLibraryPath("./plugins");
    QSharedMemory *shareMem = new QSharedMemory(QString("SingleInstanceIdentifySoftNumKeyBoard"));
    /* if the sharedmemory has not been created, it returns false, otherwise true.
     * But if the application exit unexpectedly, the sharedmemory will not detach.
     * So, we try twice.
     */
    volatile short i = 2;
    while (i--)
    {
        if (shareMem->attach(QSharedMemory::ReadOnly)) /* no need to lock, bcs it's read only */
        {
            shareMem->detach();
        }
    }

    if (shareMem->create(1))
   {
        QApplication a(argc, argv);
        QFont font  = a .font();
        font.setPointSize(14);
        a.setFont(font);
        SoftNumKeyboardWidget w;
        QDesktopWidget *pDesk = QApplication::desktop();
        w.show();
        w.move((pDesk->width() - w.width()) / 2, (pDesk->height() - w.height()) / 2);// ĬÈϾÓÖÐ

        a.exec();

        if (shareMem->isAttached())
            shareMem->detach();
        delete shareMem;
    }

    return 0;
}