Reliably identifying any window's client area

0
votes

I am working on a program that will replicate, and then extend the functionality of Aero Snap.

Aero Snap restores a maximized window, if the user "grabs" it's title bar, and I am having difficulties identifying this action.

Given a cursor position in screen coordinates, how would I check if the position is within the window's title bar? I am not really at home in the Win32 API, and could not find a way that works reliably for complicated scenarios such as:

example for a difficult title bar

Note that tabs that chrome inserts into the title bar. Office does something similar with the quick launch menu.

1
c++winapi
WM_NCHITTEST may be what you're looking for. - Captain Obvlious
Both Chrome and Office make use of the DwmExtendFrameIntoClientArea function. This really complicates things, since this effectively makes part of the window that is rendered as part of the Non-Client area actually belong to the client area. In these instances, you simply cannot tell where the title-bar ends and the client area begins. See: msdn.microsoft.com/en-us/library/windows/desktop/… I reckon, your best bet might be to explicitly send WM_NCHITTEST messages to the application. Since it should return HTCAPTION (provided it also self-handles WM_NCHITTEST) - enhzflep
Nice, I think this is what I was looking for. This works nicely for Chrome, but Excel always reports "client area" anywhere. I guess that's Excel's fault, though =) - Jens

1 Answers

1
votes

title bar hits are via the message "non client" messages - ie the area of a window that is not the client (or inner) window.

WM_NCLBUTTONDOWN is probably the message you want to trap.

You also probably want to set a window hook to hook mouse messages, if its the NC message you want, you handle it your way, if not - pass it on to the message chain.

Edit: if Chrome is using the DwmExtendFrameIntoClientArea calls to draw the tabs, then you will need to use WM_NCHITTEST.