CODEWITHSUNDEEP
c++winapiatlwtl
fire xzanderr
fire xzanderr

Reputation: 213

partially click through on layered windows win32

In using layered windows in win32 or atl/wtl c++ if I set the main window's alpha to 0 and paint on the child, fake window so that it is viewable and click the window, the entire window is a click through. I want to be able to make only regions of the window click through, not the entire window, let's say if I want to paint a rounded corner window, I make the bottom/main window to be click through but I don't want the upper "fake" window to be click through, i want to be able to click on it. How do I do that? Where I am so far: In the OnInitDialog function of the main window :

::SetWindowLong( m_hWnd, GWL_EXSTYLE, ::GetWindowLong(m_hWnd, GWL_EXSTYLE) | WS_EX_LAYERED);
BYTE bTran = 0;
::SetLayeredWindowAttributes( m_hWnd, 0, bTran, LWA_ALPHA);

and when I create the fake window:

m_hFakeWnd = ::CreateWindowEx( WS_EX_LAYERED | WS_EX_TRANSPARENT | WS_EX_NOACTIVATE | WS_EX_LEFT
        , m_strWndClassName
        , NULL
        , WS_VISIBLE | WS_OVERLAPPED
        , rc.left
        , rc.top
        , rc.Width()
        , rc.Height()
        , GetSafeHwnd()
        , NULL
        , ::GetModuleHandle(NULL)
        , NULL
        );

IF, I set eliminate the WS_EX_TRANSPARENT flag the fake window is click-able while the main is click through, but! it doesn't respond to anything! click/drag. none.

Upvotes: 1

Views: 2879

Answers (3)

DEBDUTTA PANDA
DEBDUTTA PANDA

Reputation: 41

Make two windows, one with click-through properties and another with normal ones.

Upvotes: 0

Jonathan Potter
Jonathan Potter

Reputation: 37122

Use alpha 1 instead of 0 in the regions you want to accept clicks. The window will still be completely invisible but the areas of alpha 1 will register clicks and mouse movements as normal.

Note that to get per-pixel alpha you'll need to use UpdateLayeredWindow rather than SetLayeredWindowAttributes.

Upvotes: 0

Roman Ryltsov
Roman Ryltsov

Reputation: 69632

It sounds like you are covering another window solely for the purpose of intercepting clicks?

Anyway, you need to handle window's WM_NCHITTEST message in order to be able to let system know that particular position is transparent, in which case you return HTTRANSPARENT:

In a window currently covered by another window in the same thread (the message will be sent to underlying windows in the same thread until one of them returns a code that is not HTTRANSPARENT).

Upvotes: 1

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