How can I get handle (IntPtr) to a "sub"-form in another application?

arnold_w

I would like to show a WinForms MessageBox centered on top of another application's (TortoiseGit) "sub"-form, i.e. a form (the TortoiseGit checkout form) on top of the main form (the TortoiseGit log window). I am able to successfully find the process (TortoiseGitProc) and from there I can successfully get a MainWindowHandle to the main form, but how do get from there to the "sub"-form (the TortoiseGit checkout form)?

Lost User

EnumChildWindows function (winuser.h) - Win32 apps | Microsoft Docs[^], or enumwindows. Example here; pinvoke.net: enumchildwindows (user32)[^]

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

arnold_w

When I use the code from PINVOKE: Getting all child handles of window · Software adventures and thoughts[^] to get all the children, I get 30 pointers. When I then log the Window texts using the following

        List allChildWindows = new WindowHandleInfo(parentMainWindowHandle).GetAllChildHandles();
        for (int i = 0; i < allChildWindows.Count; i++)
        {
            StringBuilder sb2 = new StringBuilder(1024);
            GetClassName(allChildWindows\[i\], sb2, sb2.Capacity);
            sb2 = new StringBuilder(1024);
            GetWindowText(allChildWindows\[i\], sb2, sb2.Capacity);
            Debug.WriteLine(sb2.ToString());
        }

then I get mostly empty strings, but I do get some strings that appears to come from the main form's (not the "sub"-form's) components (buttons, labels, etc), e.g. "", "Help", "Refresh", "Walk Be&haviour", "&View", "OK", etc. What am I doing wrong, why do I get pointers to the main form's components and not to the "sub"-form?

Lost User

See the parameter descriptions at EnumChildWindows function (winuser.h) - Win32 apps | Microsoft Docs[^].

arnold_w

I made a dump of all windows using Spy++ and this what I got:

Window 000C0678 "C:\\DummyRepo - Switch/Checkout - TortoiseGit" #32770 (Dialog)
	Window 000B0670 "" ScrollBar
	Window 00070482 "Switch To" Button
	Window 001D065E "&Branch" Button
	Window 000B01AE "" ComboBoxEx32
		Window 0004036E "ⴀ辘ȡ" ComboBox
	Window 0017069A "..." Button
	Window 001303D2 "&Tag" Button
	Window 000B04DE "" ComboBoxEx32
		Window 001105D4 "" ComboBox
	Window 00190620 "&Commit" Button
	Window 000F06D8 "c288b35fcabf74c51270fff36db3387517beda53" ComboBoxEx32
		Window 001406CE "Ɒ辘ȡ" ComboBox
			Window 001005CE "c288b35fcabf74c51270fff36db3387517beda53" Edit
	Window 00220458 "..." Button
	Window 00170604 "Option" Button
	Window 000E0684 "Create &New Branch" Button
	Window 002503EA "Branch\_c288b35f" Edit
	Window 00390628 "Overwrite working tree changes (&force)" Button
	Window 004404EE "&Merge" Button
	Window 00300666 "T&rack" Button
	Window 0040045C "&Override branch if exists" Button
	Window 001404DC "OK" Button
	Window 0008025E "Cancel" Button
	Window 00220396 "Help" Button
Window 00040616 "C:\\DummyRepo - Log Messages - TortoiseGit" #32770 (Dialog)
	Window 000D04E6 "" Static
	Window 002A0602 "" Static
	Window 00040622 "master" Static
	Window 002204CA "From:" Static
	Window 001104C2 "2020-07-31" SysDateTimePick32
	Window 001904A4 "To:" Static
	Window 001A0496 "2020-07-31" SysDateTimePick32
	Window 000F0560 "" Edit
	Window 00080638 "Author Email" ComboBox
	Window 000F01F2 "" Button
	Window 001904B0 "" Button
	Window 00190498 "" SysListView32
		Window 00150422 "" SysHeader32
	Window 00350426 "SHA-1: c288b35fcabf74c51270fff36db3387517beda53

* 1
" RICHEDIT50W
Window 005B04E4 "" Static
Window 001104F0 "" SysListView32
Window 0013045E "" SysHeader32
Window 004A06CA "Showing 2 revision(s), from revision c288b35f to revision b7a040a4 - 1 revision(s) selected, 0 file(s) selected; line: 1(+) 0(-) files: modified = 0 added = 1 deleted = 0 replaced = 0" Edit
Window 0017060A "Show &Whole Project" Button
Window 001705FC "&All Branches" Button
Window 00290424 "" Edit
Window 00460660 "Help" Button
Window 0019048C "Refresh" Button
Window 004A065C "S&tatistics" Button
Window 000D036A "Walk Be&haviour" Button
Window 00160492 "&View" Button
Window 0016048E "OK" Button
Window 004B069E "OK" Button
Window 0024064A "" msctls_progress32
Window 0004061A "" ScrollBar

So, it seems the Switch/Checkout window is not<

Lost User

Keep doing what you're doing; that's what it's all about. The documented and the undocumented. Maybe it's using a cloaking device. Sounds like a security hole otherwise. ("Masking") [automation - Enumerating Windows/Controls of another application from .Net - Stack Overflow](https://stackoverflow.com/questions/280818/enumerating-windows-controls-of-another-application-from-net)

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it. ― Confucian Analects: Rules of Confucius about his food

Richard Andrew x64

Isn't this the window you want?

arnold_w wrote:

Window 000C0678 "C:\DummyRepo - Switch/Checkout - TortoiseGit" #32770 (Dialog)

The difficult we do right away... ...the impossible takes slightly longer.

arnold_w

Yes, absolutely. But I don't want to have to use Spy++ to find it, I want to be able to find it in my C# application, but the C# application appears to find this window instead:

Window 00040616 "C:\DummyRepo - Log Messages - TortoiseGit" #32770 (Dialog)

It would be ok if I can find both, but then I would need to somehow obtain the heading strings ("C:\DummyRepo - Log Messages - TortoiseGit" and "C:\DummyRepo - Switch/Checkout - TortoiseGit") so that I have a way to distinguish which window (or actually, dialog) is which.

arnold_w

Instead of using Process.MainWindowHandle (which only returns the "C:\DummyRepo - Log Messages - TortoiseGit" window) I guess I could iterate through all windows using the technique described in Winforms-How can I make MessageBox appear centered on MainForm? - Stack Overflow[^]. However, when I do so and log the window texts, I never find the strings "C:\DummyRepo - Log Messages - TortoiseGit" and "C:\DummyRepo - Switch/Checkout - TortoiseGit":

    \[DllImport("user32.dll", EntryPoint = "GetWindowText",
    ExactSpelling = false, CharSet = CharSet.Auto, SetLastError = true)\]
    public static extern int GetWindowText(IntPtr hWnd, StringBuilder lpWindowText, int nMaxCount);

    private bool checkWindow(IntPtr hWnd, IntPtr lp)
    {
        // Checks if is a dialog
        StringBuilder sb = new StringBuilder(260);
        GetClassName(hWnd, sb, sb.Capacity);

        // My added code to log all window texts
        StringBuilder strbTitle = new StringBuilder(255);
        int nLength = GetWindowText(hWnd, strbTitle, strbTitle.Capacity + 1);
        string strTitle = strbTitle.ToString();
        Debug.WriteLine("The window text is: " + strTitle);

        if (sb.ToString() != "#32770")
        {
            return true;
        }
        return true;    // My modified code to check all windows

The strings I find appear to be much more low-level, e.g "Form1", "MSCTFIME UI", "Default IME", etc. Does anybody know which function I should use instead to obtain the window headings, "C:\DummyRepo - Log Messages - TortoiseGit" and "C:\DummyRepo - Switch/Checkout - TortoiseGit"?

Richard Andrew x64

This is kind of a side point, but I see that your CheckWindow function will return true in any circumstance.

The difficult we do right away... ...the impossible takes slightly longer.

Richard Andrew x64

See if this SO answer helps: c# - How to enumerate all windows belonging to a particular process using .NET? - Stack Overflow[^] (Particularly the second answer.)

The difficult we do right away... ...the impossible takes slightly longer.

arnold_w

Yes, I added the line

return true; // My modified code to check all windows

on purpose because I wanted to log all window texts. My goals was to find the particular window that has the window text "C:\DummyRepo - Switch/Checkout - TortoiseGit", but all I found was windows having window texts such as "Form1", "MSCTFIME UI" and "Default IME".

arnold_w

That's pretty much what I already do, I am able to get a bunch of windows but I can't tell which one corresponds to

Window 000C0678 "C:\DummyRepo - Switch/Checkout - TortoiseGit" #32770 (Dialog)

because I can't find any window that has the heading "C:\DummyRepo - Switch/Checkout - TortoiseGit" using GetWindowText. Now, on the other hand, the pure C# (no win32 pinvoke involved) property Process.MainWindowTitle seems to return the proper string, but I can only apply it to the de facto main window ("C:\DummyRepo - Log Messages - TortoiseGit"), not to the "secondary sibling"-window ("C:\DummyRepo - Switch/Checkout - TortoiseGit").

Richard Andrew x64

That's not what you're already doing. You must be looking at the first answer to the question. Look at the SECOND answer to the question on that page. The second answer uses the function EnumThreadWindows.

The difficult we do right away... ...the impossible takes slightly longer.

arnold_w

Ahhh, you mean this:

const uint WM_GETTEXT = 0x000D;
StringBuilder message = new StringBuilder(1000);
SendMessage(handle, WM_GETTEXT, message.Capacity, message);

Yes, that works great!!! Thank you! This is the complete code:

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
WindowWrapper parentForm = ProcessWindowsHelper.getHandleToAnotherProcessWindow("TortoiseGitProc", "Switch/Checkout");
MessageBoxEx.Show(parentForm, "Hello on top of TortoiseGit Switch/Checkout dialog");
}
}
public class ProcessWindowsHelper
{
private delegate bool EnumThreadWndProc(IntPtr hWnd, IntPtr lp);
[DllImport("user32.dll")]
private static extern bool EnumThreadWindows(int tid, EnumThreadWndProc callback, IntPtr lp);
[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, int wParam, StringBuilder lParam);
delegate bool EnumThreadDelegate(IntPtr hWnd, IntPtr lParam);

private const uint WM\_GETTEXT = 0x000D;

public static WindowWrapper getHandleToAnotherProcessWindow(string processName, string substringInAnotherProcessWindow)
{
    Process myProcess = findProcessByName(processName);
    IEnumerable allHandlesInMyProcess = EnumerateProcessWindowHandles(myProcess.Id);
    foreach (IntPtr handle in allHandlesInMyProcess)
    {
        StringBuilder message = new StringBuilder(1000);
        SendMessage(handle, WM\_GETTEXT, message.Capacity, message);
        if (message.ToString().Contains(substringInAnotherProcessWindow))
        {
            Debug.WriteLine(message);
            return new WindowWrapper(handle);
        }
    }
    return null;
}

private static IEnumerable EnumerateProcessWindowHandles(int processId)
{
    List handles = new List();
    ProcessThreadCollection processThreadCollection = Process.GetProcessById(processId).Threads;
    for (int i = 0; i < processThreadCollection.Count; i++)
    {
        ProcessThread thread;
        thread = processThreadCollection\[i\];
        EnumThreadWindows(thread.Id, 
            delegate(IntPtr hWnd, IntPtr lParam)
            {
                handles.Add(hWnd);
                return true;
            }, 
            IntPtr.Zero);
    }
    return handles;
}

private static Process find

Richard Andrew x64

Glad you got it sorted! 😉

The difficult we do right away... ...the impossible takes slightly longer.

arnold_w

Well, I guess no joy lasts forever... In case somebody is using bash.exe instead of TortoiseGit to Switch/Checkout, then I wanted to do the same thing with bash.exe as the parent form. But when I call

parentForm = ProcessWindowsHelper.getHandleToAnotherProcessWindow("bash", "MING")

then it seems the handles list inside the EnumerateProcessWindowHandles method doesn't get any elements.

private static IEnumerable EnumerateProcessWindowHandles(int processId)
{
    List handles = new List();
    ProcessThreadCollection processThreadCollection = Process.GetProcessById(processId).Threads;
    for (int i = 0; i < processThreadCollection.Count; i++)
    {
        ProcessThread thread;
        thread = processThreadCollection\[i\];
        EnumThreadWindows(thread.Id, 
            delegate(IntPtr hWnd, IntPtr lParam)
            {
                handles.Add(hWnd);
                return true;
            }, 
            IntPtr.Zero);
    }
    return handles;
}

The call to Process.GetProcessById(processId).Threads returns 3 threads, but nothing gets added to the handles list. Does anybody know why? When I look at the information in Spy++ I see the following:

Window OOOA9B72 "MINGW64:/c/dummyRepo" mintty

Windows Properties, General tab:

Window Caption: MINGW64:/c/dummyRepo
Window Handle: OOOA9B72
Window Proc: (Unavailable)(Unicode)
Rectangle: (86, 89)-(681, 466), 595x377
Restored Rect: (86, 89)-(681, 466), 595x377
Client Rect: (8, 31)-(570, 369), 562x338
Instance Handle 00400000
Menu Handle 00000000
User Data 00000000
Windows Bytes:

Richard Andrew x64

Have you stepped through it in the debugger? Does it find the correct process? Which line of code is failing?

The difficult we do right away... ...the impossible takes slightly longer.

arnold_w

Yes, I stepped it. I first rewrote the method EnumerateProcessWindowHandles according to this:

private static List handles;

private static IEnumerable EnumerateProcessWindowHandles(int processId)
{
handles = new List();
ProcessThreadCollection processThreadCollection = Process.GetProcessById(processId).Threads;
for (int i = 0; i < processThreadCollection.Count; i++)
{
ProcessThread thread; // If I put a breakpoint here, the debugger stops 3 times
thread = processThreadCollection[i];
EnumThreadWindows(thread.Id, myDelegate, IntPtr.Zero);
}
return handles;
}

private static bool myDelegate(IntPtr hWnd, IntPtr lParam)
{
handles.Add(hWnd); // If I put a breakpoint here, then the debugger never stops
return true;
}

So, something seems to go wrong inside the call to EnumThreadWindows, but that's a Win32 function and I don't know how to put a breakpoint inside it or how to step through it.

Richard Andrew x64

You need to put a breakpoint inside the "myDelegate" callback to see if ANY windows are being found, not just ones that match your substring. But first, verify that it is indeed finding the correct process. Compare the ProcessId to the one shown by Task Manager. EDIT: I'm sorry I didn't see that you had already tried the breakpoint inside the callback. The only thing I can think of at this moment is to make sure it is finding the correct process.

The difficult we do right away... ...the impossible takes slightly longer.