Regarding setWindowState(Qt::WindowMaximized) , showMaximized() and width and height getting from QRect are they same?
For the generic to get the screen size
QRect rect = qApp->primaryScreen()->geometry();
int width = rect.width();
int height = rect.height();
Are these three usage one at the same or any much difference?.
(1) and (2) should result in the same. Although for (1) you should use the following instead widget->setWindowState(widget->windowState() | Qt::WindowMaximized);
(3) is definitly different since there you only set the size but not the state of the window. But i guess it depends on the platforms window system if the appearance is different. But there is a reason for a window state being available.
k then what is the difference between state and width and height of QRect of screen taken?.
the state itself. In MS Windows for example watch the different window buttons between the normal and maximized states. Also note that a maximized window doesnt have a border where the just resized one does.
Different states may result in different available actions, etc