SFML only handles the WM_SIZE event, which gets triggered after you've resized the window. So all you can do is catch the resize event and set the window size proportionally after the window was resized.
Its already have )).
People just start Dont Starve and look to border under mouse cursor when changing window size using mouse left click.
You will see about I say.
I think its must do from window handle with winApi functions to set proportional ratio.
Yeah, I found some...
Sounds exact what needed - WM_SIZING message
https://msdn.microsoft.com/en-us/library/windows/desktop/ms632647%28v=vs.85%29.aspxImmediately second question how access to it...
Here need to add new event logic for read WM_SIZING, and return(set) proportional drag form to resize window...
Some troubles - because we know - events parsed from "one door".
And its in private scope..
void WindowImplWin32::registerWindowClass()
{
WNDCLASSW windowClass;
windowClass.style = 0;
windowClass.lpfnWndProc = &WindowImplWin32::globalOnEvent;
Need to modify Sfml sources....
I wanted external add-on portable solution, but its impossible in this case.
Keys to success - add methods to get reference of MSG message.
To change lParam of checked before border type in wPparam.
Maybe MSG message will be better as field at private scope of class.