如何检测窗口已最大化？

Question

I have my application and third-party application. And I need to know that the window of third-party application has been maximized. Is there any way to know it?
At first, I thought that I could use my own callback function for handling events of this window.

SetWindowLong(hwnd, GWL_WNDPROC, (LONG)WindowProc);

But this function fails with error "Access denied". And this happens for a reason. It's not very wise to change something in the window that you don't own.

So what should I do?

Answer 1

You can actually get notified when a window is about to be minimized or maximized. You will need to use the SetWindowsHook procedure to install and listen to a WH_CBT_Hook.

Here's the general information about WIndowsHooks:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/WinUI/WindowsUserInterface/Windowing/Hooks/AboutHooks.asp

Here's a thread that shows you how to do something smiliar (for a WH_Mouse_Hook) in VB:

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=581752&SiteID=1

Hope this helps,

Answer 2

Use GetWindowPlacement function. Make sure you set the length member of WINDOWPLACEMENT to sizeof(WINDOWPLACEMENT) before calling GetWindowPlacement.

The showCmd field of the returned WINDOWPLACEMENT structure should be equal to SW_MAXIMIZE (3) if the window is maximized.