CODEWITHSUNDEEP
c#c++winapiui-automationuser32
unknown6656
unknown6656

Reputation: 2963

Fetching the HWND of a Win32 control using global screen coordinates

Background

I need to implement some Spy++-esque functionality for an Windows application automation project. For simplicity's sake, let us assume that my application A (written in C# or C++) is trying to automate an existing Win32 Application B (not a WPF or OpenGL application). Let us also assume that application B has a picture-box which I'd like to capture. The exact size and location of this picture box inside of B is not known at runtime, as it is dynamically created and resized by B. However, one can be certain that the global screen coordinates (x, y) will always be inside the picture box in question.

Question

I can retrieve the main window handle of B at runtime using [user32.dll] FindWindow. However, the picture box inside B has a HWND which is unknown to my application (A) at runtime. Can I retrieve the picture box' HWND if I know that it is positioned under the global screen coordinates (x, y) when B is maximized and in the foreground?

i.e. something like this:
enter image description here
when being positioned over a specific pair of screen coordinates.

Edit No.1:

I tried the solution proposed by @David Heffernan in the comments (namely the usage of the function ([user32.dll] WindowFromPoint)[https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-windowfrompoint], however this did NOT work:

void* window_hwnd = FindWindow(null, "<title of the window>");

SendMessage(window_hwnd, WM_SYSCOMMAND, SC_RESTORE, 0);
ShowWindow(window_hwnd, SW_MAXIMIZE);
SetForegroundWindow(window_hwnd);
SetActiveWindow(window_hwnd);
SetWindowPos(window_hwnd, null, 0, 0, 0, 0, SWP_SHOWWINDOW | SWP_NOMOVE | SWP_NOSIZE);
RedrawWindow(window_hwnd, null, null, RDW_FRAME | RDW_INVALIDATE | RDW_ALLCHILDREN);

void* control_hwnd = WindowFromPoint(300, 300);

This should theoretically give me the HWND to the control at position (x=300, y=300). However, control_hwnd has the same value as window_hwnd.

Upvotes: 1

Views: 442

Answers (1)

unknown6656
unknown6656

Reputation: 2963

Thanks to the comment of @Simon Mourier under my original post, I was able to create a working solution using the Windows UI Automation APIs by means of the FlaUI wrapper library for C#.

I will mark that (for now) as the accepted answer, however, if someone has a better alternative, I will be gladly accepting the respective answer.

Upvotes: -1

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