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Using InstallKeyHook [message #10378]

Wed, 04 July 2007 19:27

malaugh
Messages: 7
Registered: June 2007

Promising Member

I am trying to disable an entry field if the user types in another entry field. If the user enters data in the EditVakue control editVendData, then the EditValue control editVendLength, should be disabled. I thought I could do this with the Installkeyhook function. My basic logic is
1) Capture the key input for the application
2) In the key handler, if a key is hit when the user is in the editVendData, then disable editVendLength.

I have tried numerous methods, this is one of my attempts.

In the class
friend bool VendDataKeyHook(Ctrl *ctrl, dword key, int count);

In the constructor
InstallKeyHook(VendDataKeyHook);

The function
bool VendDataKeyHook(Ctrl *ctrl, dword key, int count)
{
USBConsole *panel = (USBConsole *)ctrl;

if(ctrl->GetFocusCtrl() == (Ctrl *)(&(panel->editVendData)))
{
panel->editVendLength.Disable();
}
return(FALSE);
}

The if statement is always FALSE, so editVendLength is never disabled. Also if I move the disable statement outside the if, the program crashes. What am I doing wrong?

I could not find any examples that use InstallKeyHook, is there one?

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Re: Using InstallKeyHook [message #10379 is a reply to message #10378]

Wed, 04 July 2007 20:18

mirek
Messages: 13975
Registered: November 2005

Ultimate Member

This is very complicated approach for such simple task.

This is quite common situation. I usually solve that by adding Sync method that gets invoked on WhenAction of any widget that affects other widget. Usually, it is OK to setup every aspect there - it is not required to have special Sync for particular widget, just place all enable/disable logic into the single place (Sync) and get it invoked when user alters the widget (WhenAction).

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Re: Using InstallKeyHook [message #10384 is a reply to message #10379]

Thu, 05 July 2007 06:09

malaugh
Messages: 7
Registered: June 2007

Promising Member

I guess I did not explain the problem too well. When the user enters characters in the data field, the requrement is to first disable the length field, and then add 1 to the length field for every character the user types. The length field should be updated immediately, the user hits the key.

I am not familier with the sync method you mention will it work in this case? Could you post a URL for the manual page, or even better, an example. I am new to Utlimate++.

Thanks

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Re: Using InstallKeyHook [message #10389 is a reply to message #10384]

Thu, 05 July 2007 11:39

mrjt
Messages: 705
Registered: March 2007
Location: London

Contributor

Something like this?

In window contructor

editVendData <<= THISBACK(SyncFields); // Sets WhenAction callback

Sync function:

SyncFields()
{
   if (editVendData.GetLength())
      // Disable length field and set data to length of data field
      editVendLength.Enable(false) <<= editVendData.GetLength();
   else 
      editVendLength.Enable(true);
}

James

[Updated on: Thu, 05 July 2007 11:39]

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