WindowFromPoint problem

Question

5.00/5 (1 vote)

See more:

For some reason, I'm not getting the correct class of the component under the cursor with the following code. I get the parentWindow class instead. And I get exactly the same result if I try with ChildWindowFromPoint. When I retrieve a list of childWindows under the parent, I get Buttons and Edit fields, so why cant I catch them with this code ?

VB

[DllImport("user32.dll")]
        public static extern IntPtr WindowFromPoint(POINTAPI pt);


        [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        public static extern int GetClassName(IntPtr hWnd, System.Text.StringBuilder lpClassName, int nMaxCount);


	    Point p = Cursor.Position;
            POINTAPI papi = new POINTAPI();
            papi.x = p.X;
            papi.y = p.Y;
            
            IntPtr window = WindowFromPoint;

            int nRet;
            System.Text.StringBuilder ClassName = new System.Text.StringBuilder(100);
            nRet = GetClassName(window, ClassName, ClassName.Capacity);

            string userInfo = "";

            if (nRet != 0)
                userInfo = ClassName.ToString();
            else
                userInfo = "n/a";

Posted 18-Dec-10 20:50pm

funnymoney

Updated 18-Dec-10 20:56pm

TweakBird

v2

Add a Solution

Comments

TweakBird 19-Dec-10 2:56am

<pre> tag added.

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

jean Davy · Answer 1 · 2010-12-19T00:42:00

Hello,
So your got parent instead of child, that's right ?
Reading this ChildWindowFromPoint [^] doc, it appears that RealChildWindowFromPoint[^] say "Retrieves a handle to the child window at the specified point", this should solve your problem...

HWND WINAPI RealChildWindowFromPoint(
  __in  HWND hwndParent, // window in your code
  __in  POINT ptParentClientCoords // p in your code
);

Be care that as p is in screen coordinate, you have to convert in client coordinate of window ( ScreenToClient function ).

I didn't test my solution, this is just the way I think to do it...

Regards

pasztorpisti · Answer 2 · 2010-12-19T06:41:00

Your theory seems to be OK and the simple WindowFromPoint() should do the job well for you. WindowFromPoint() usually does not work when the WindowProc of specified HWND returns HTTRANSPARENT in response to WM_NCHITTEST, but this is very-very rare. In that case WindowFromPoint() returns the window behind the specified HWND but in our scenario this isn't the problem. I think something must be wrong in your function declaration, and I don't really understand where do you pass the point to the WindowFromPoint() function call. Check the correct function declaration here[^], and then pass the current cursor position to the function. Let's try it again! :D

WindowFromPoint problem

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0