C#: Some applications don't respond to events created by API Keybd_event

Question

5.00/5 (1 vote)

See more:

C#

[DllImport("user32.dll")]
       static extern void keybd_event(byte key, byte scan, int flags, int extraInfo);

I'm writing a Test tool in C# (.Net 4) and it generates Key events using the above API wrapper. I'm using this API for the purpose of creating KeyUp\KeyDown events.

The API works with nearly all applications, but I have found it doesn't work with a few applications. Those applications do not respond to events recreated by keybd_event; the key events are totally ignored.

However, if I use AutoHotKeys, those applications do respond to Key event generated by AHK scripts.

Any educated guesses as to why a few applications don't respond to events created by Keybd_ events, and what other solutions I might uses to generate Key events? Or maybe I'm not passing the the correct parms to the this API, thus key events are ignored by some apps.

Thanks

Posted 4-Sep-11 7:27am

nrnoble

Updated 4-Sep-11 7:50am

v2

Add a Solution

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)

Wonde Tadesse · Answer 1 · 2011-09-04T08:14:00

Solution 1

You didn't mentioned the applications that are unable to respond to the API. In any case take a look at the following link. It shows clearly how to work with keybe_event API http://pinvoke.net/default.aspx/user32.keybd_event[^]

Posted 4-Sep-11 8:14am

Wonde Tadesse

Updated 4-Sep-11 15:10pm

v2

Comments

nrnoble 4-Sep-11 19:36pm

Thanks.... I have looked over the pinvoke options and not seeing anything that's would alter the results.

Keybd_ events works fine with standard Windows applications, but its game engines that are not responding the events created by the API Keybd_ event.

Wonde Tadesse 6-Dec-11 11:20am

You 're welcome

Sergey Alexandrovich Kryukov · Answer 2 · 2011-09-04T19:02:00

This API is low-level; so applications do not respond to it directly. The function is called by interrupt handler. Maybe you are generating not exactly same input which you think you need for this application to respond. Also, this API is currently superseded by the function SendInput which I recommend to use instead of keybd_event.

Please see http://msdn.microsoft.com/en-us/library/ms646310%28v=vs.85%29.aspx[^].

[EDIT — in respond to OP's comment about direct access to hardware]

It's not easy to tap to hardware directly from the application; if it's even possible without having a kernel-mode (only) custom driver installed, it would suggest OS has a huge security hole. I would rather suggest the problem in your application.
Here is what you can do: create a clear code sample which manifest this problem. You should try to scale down your code to obtain something really minimal, essentially an application skeleton.

Chances are: 1) you will find a problem down the road and fix it; 2) a problem disappears in the skeleton; you will retrace your steps and find out where you added a problem, then the problem will be reduced to case #1 or; 3) your skeleton will not give you a clue but it will be so small that you could post in to CodeProject; in this case, don't create a new page; use "Improve question" on this page; if it happens, please notify me as well by adding a comment to this post — let's see.

—SA