多屏显示

QDesktopWidget* desktopWidget = QApplication::desktop();

//获取可用桌面大小
QRect deskRect = desktopWidget->availableGeometry();

//获取设备屏幕大小
QRect screenRect = desktopWidget->screenGeometry();

int sceenSizeX = screenRect.width();
int  sceenSizeY = screenRect.height();

//获取系统设置的屏幕个数（屏幕拷贝方式该值为1）
int  i= desktopWidget->screenCount();