How to get caret position in ANY application from C#?

Andrey Nasonov 21

Like Clipboard in Windows 10/11 (Win + V) - it always know current caret position on the page in Google Chrome or MS Edge, also in other applications - WPF, WinForms, UWP, etc.

I'm trying to get caret position in windows. Even if it's not native.

Tried to use Win32 API GetCaretPos function (https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getcaretpos), and it's worked, but only for WPF/WinForms processes. In case if application has own caret implementation (like Google Chrome browser) that function doesn't work.

var hFore = GetForegroundWindow();
var idAttach = GetWindowThreadProcessId(hFore, out uint id);
var curThreadId = GetCurrentThreadId();

// To attach to current thread
var sa = AttachThreadInput(idAttach, curThreadId, true);

var caretPos = WindowsKeyboard.GetCaretPos(out POINT caretPoint);

ClientToScreen(hFore, ref caretPoint);

// To dettach from current thread
var sd = AttachThreadInput(idAttach, curThreadId, false);

var data = string.Format("X={0}, Y={1}", caretPoint.X, caretPoint.Y);

But caretPoint correct only for WPF/Win32/WinForms apps. Also, I noticed that solution https://www.codeproject.com/Articles/34520/Getting-Caret-Position-Inside-Any-Application doesn't work for some Windows Desktop apps like Google Chrome or VS Code, Slack, etc.

I expect to get cursor position to determine where to show popup window like it made by Microsoft with Clipboard History (Win + V) on Windows 10 or Windows 11.

Accepted answer

Castorix31 81,721 Reputation points

2022-04-20T11:30:27.31+00:00

I did a quick test with MS Edge (Search TextBox on this page) on Windows 10 21H1 and it worked with
GetForegroundWindow + GetGUIThreadInfo to get hwndFocus, then AccessibleObjectFromWindow with OBJID_CARET, then IAccessible.accLocation
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1 person found this answer helpful.
Andrey Nasonov 21 Reputation points

2022-04-20T13:15:34.31+00:00

Thanks, but when i tried to call IAccessible.accLocation it throw exception Values does not fall within the expected range. It throws for Google Chrome, VS Code windows, etc. But for others it works as expected.

Andrey Nasonov 21 Reputation points

2022-04-20T15:35:55.133+00:00

Thanks, everything working OK. I forgot about [in] VARIANT varChild in accLocation function. It should be set to zero - it's CHILDID_SELF = 0

Andrea Nagar 1 Reputation point

2022-05-09T20:46:47.66+00:00

Can you provide the full code that you used to do that in C#?
I'm a bit confused on how I should call AccessibleObjectFromWindow with OBJID_CARET and then IAccessible.accLocation

Thank you!

Andrey Nasonov 21 Reputation points

2022-05-10T16:23:37.693+00:00

var guid = typeof(IAccessible).GUID; object accessibleObject = null; var retVal = WinApiProvider.AccessibleObjectFromWindow(hwnd, WinApiProvider.OBJID_CARET, ref guid, ref accessibleObject); var accessible = accessibleObject as IAccessible; accessible.accLocation(out int left, out int top, out int width, out int height, WinApiProvider.CHILDID_SELF);

@Andrea Nagar

Andrey Nasonov 21 Reputation points

2022-05-10T16:25:38.79+00:00

You need to add COM reference UIAutomationClient

SkyD666 0 Reputation points

2023-02-01T15:56:47.3133333+00:00

AccessibleObjectFromWindow doesn't work in notepad.exe (or system default textbox)

Andrey Nasonov 21 Reputation points

2023-02-01T16:40:55.5866667+00:00

@SkyD666 Please use WinAPI to get caret position

Robert Andersen 0 Reputation points

2023-04-05T19:34:31.9733333+00:00

Andrew Nasonov No matter what I try I can't make your code work, maybe because I don't understand. But it seems you might be able to help me. I am writing a hotkey program that just displays current hotkeys for tutorial purposes. I need to detect if a caret is active in any application outside of mine. My program is in written WPF C#. The purpose of checking if a caret is active, is to ignore keyboard input (ie: not display) it as a shortcut, the user is actually entering data. I tried your solution, but WinApiProvider gets highlighted. Is there a more idiot solution, or more complete code example you could help with with to solve my problem ? Rob

-小TN- 0 Reputation points

2023-07-06T12:38:54.6233333+00:00

@Andrey Nasonov Can you provide a runnable demo project in C#? I looked at the code above, but I still don't know how to handle it, and I couldn't find some of the references. Thank you very much!
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1 additional answer

Andrea Nagar 1 Reputation point

2022-09-15T19:56:02.487+00:00

There's one thing that I noticed.
It looks like the function is not returning the proper coordinates if I'm working on a HighDPI monitor.
It seems that it's working differently based on the application. In particular, it's not reporting the proper position in Chrome, Word and Edge.

Has anyone noticed that?

Thank you.
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Andrey Nasonov 21 Reputation points

2022-09-15T23:15:00.963+00:00

You need to convert those coordinates according to your DPI and scaling factor. First step is to get DPI for nearest monitor and get scaling factor for display (Display settings in Windows). According to those parameters you can determine correct position. The default DPI is 96, scaling factor usually is 100%.
If you have multiple monitors with different DPI, scaling factor should be the same on them for testing or you need to get it too :)

Andrea Nagar 1 Reputation point

2022-09-16T20:19:45.93+00:00

Thanks Andrew. I've tried doing that but the reported cohordinates are different based on the application.
I could do that in Chrome, but it's completely off in Microsoft edge. And things get messy if there are multiple monitors with high DPI displays.

Do you have a running example for that? Or if not are you open to consulting to help me fix that?

Thank you.
Andrea

Andrey Nasonov 21 Reputation points

2022-09-17T15:14:33.91+00:00

For example you can use caret coordinates in the following way:

https://github.com/Erapchu/SinglePass.WPF/blob/master/SinglePass.WPF/Hotkeys/HotkeyDelegates.cs#L48

Andrea Nagar 1 Reputation point

2023-01-16T22:01:34.7833333+00:00

I've checked the code and even if I can retrieve the DPI setting the form is not positioned properly if there are multiple displays with different DPI settings.

And the problem with the wrong positioning seems to be dependent on the application as the cursor position is correct for some applications (eg. notepad) but wrong for others, like chrome.

I noticed that the tool you have created (SinglePass) has the same problem and the window is not positioned properly.

What I've tried is setting a display on the left with the standard DPI setting and the display on the right with high DPI settings.

When you try inside Chrome on the left display (normal DPI setting), the position is wrong.

I wonder if the problem is in the API itself that is not returning the position properly.

Andrey Nasonov 21 Reputation points

2023-01-17T03:28:42.1166667+00:00

@Andrea Nagar

I have the same case with monitors. It depends on what monitor you setup as default.

That's enough to setup default monitor with 96 DPI and check this with windows on monitor with 96 DPI and non-standard DPI. All positions are correct. Instead we need to multiply X and Y coordinates by scale factor. Those two monitors have different scale factor - standard (96 DPI) is 100%, the second is 125% or other scale factor.

Andrey Nasonov 21 Reputation points

2023-01-17T03:30:40.05+00:00

I just not implemented it for SinglePass, please try if you can - should be simple to determine scale factor of nearest monitor of caret point and multiply values

Robert Andersen 0 Reputation points

2023-04-05T19:39:19.4366667+00:00

Andrew Nasonov: No matter what I try I can't make your code work, maybe because I don't understand it. But it seems you might be able to help me. I am writing a hotkey program that just displays current hotkeys for tutorial purposes. I need to detect if a caret is active in any application outside of mine. My program is in written WPF C#. I don't actually need to know much about the caret (position etc) - all I need to know is if a caret is active or not. The purpose of checking if a caret is active, is to ignore keyboard input (ie: not display) it as a shortcut, the user is actually entering data. I tried your solution, but WinApiProvider gets highlighted. Is there a more idiot solution, or more complete code example you could help with with to solve my problem ? Rob

Andrey Nasonov 21 Reputation points

2023-04-11T07:04:58.67+00:00

Robert Andersen, please try to use UIAutomationClient for your purposes. You can get some ideas from here: https://stackoverflow.com/questions/61368790/how-can-i-get-the-caret-position-from-a-textbox-in-another-application-not-the Also, I suggest to search for some solution - it should be specific Windows API or COM library.
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