Question

I’m making a Windows application that captures keyboard input globally. When a user uses the CTRL + ALT + G shortcut combo the application uses

SendKey.Send(Guid.NewGuid().ToString());

to type a generaged GUID into whatever text field is in focus. And it should do this regardless of the application taking the input.

It works exactly as I intended the first time you type CTRL + ALT + G but subsequent attempts result in nothing, or just very infrequent successes.

I mean, it all should be very simple and consistent. I have a working global keyboard hook which works all the time, I’ve tested it, but the SendKey.Send() method doesn’t work every time.

I’ve looked all over Google at anything related to my issue but nothing has worked so far.

Anyone have any insight?

EDIT 1:
I’ve tried using SendKey.SendWait() as well, does the same thing. I really want a more responsive way to generate new GUID using this keyboard shortcut approach.

EDIT 2:

Below is the essential parts of the code:

/* Initialization Code Here */
// register the event that is fired after the key press.
hook.KeyPressed += new EventHandler<KeyPressedEventArgs>(hook_KeyPressed);
// register the control + alt + F12 combination as hot key.
hook.RegisterHotKey((uint)(HotkeyModifiers.Control | HotkeyModifiers.Alt), Keys.G);

The event code is quite simple:

void hook_KeyPressed(object sender, KeyPressedEventArgs e)
{
    SendKeys.SendWait(Guid.NewGuid().ToString());
}

Everything else in my project is just fluff.

Update 1:

I do have more questions about this subject, but I am out of time to continue working on this for today. I have implemented Jon Raynor’s suggestion of using the app.config approach to some degree of success. Once I isolate my new problems I’ll post an edit and possibly close this question if I get my application functioning as intended.

Answer 1

You may be running into timing issues. According to the MSDN documentation:

The SendKeys class has been updated for the .NET Framework 3.0 to
enable its use in applications that run on Windows Vista. The enhanced
security of Windows Vista (known as User Account Control or UAC)
prevents the previous implementation from working as expected.

The SendKeys class is susceptible to timing issues, which some
developers have had to work around. The updated implementation is
still susceptible to timing issues, but is slightly faster and may
require changes to the workarounds. The SendKeys class tries to use
the previous implementation first, and if that fails, uses the new
implementation. As a result, the SendKeys class may behave differently
on different operating systems. Additionally, when the SendKeys class
uses the new implementation, the SendWait method will not wait for
messages to be processed when they are sent to another process.

If your application relies on consistent behavior regardless of the
operating system, you can force the SendKeys class to use the new
implementation by adding the following application setting to your
app.config file.

<appSettings> 

<add key="SendKeys" value="SendInput"/> 

</appSettings> 

To force the SendKeys class to use the previous implementation, use
the value “JournalHook” instead.