Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

Consume Keystroke

Posted on 2004-10-02
5
Medium Priority
?
363 Views
Last Modified: 2010-07-27
Hi,

VC++6 Windows:

I need some help on, how can I consume keystrokes.
Say when the user presses a Tab key if the user has pressed some other or Tab key (either holding it) and I am in the process of processing first keystroke. I want to destroy all keystoks that the user may have triggered when first key was being processed.

Many thanks
0
Comment
Question by:msjammu
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
5 Comments
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 12206958
That will depend what kind of applications are you building: console, Win32, MFC. But a generica aproach is something like this:

c = getch();   // Wait to read first keystroke
// some processing
while (getch()) {}  // Read (comsume) all keystrokes triggered
// some other processing

0
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 12206970
Sorry, maybe not a good example. Try with this:

// this header is needed to use getch() and kbhit()
#include "conio.h"
 
int main ()
{
    // some code here

int c;
c = getch();   // Wait to read first keystroke
// some processing
while (kbhit())  // verify if key exist in buffer
      { getch(); }  // Read (comsume) all keystrokes triggered
// some other processing

    return 0;
}
0
 
LVL 6

Author Comment

by:msjammu
ID: 12207010
>>VC++6 Windows:
My application is windows application MDIBased;
containing many child forms
0
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 12207036
There are many tecniques, also you can control the PreTranslateMessage event in your application.
You can filter all the WM_CHAR messages is a flag is on

Create a flag member in your CWinApp derived object:
       bool m_IgnoreKeys;

Then create an event with the ClassWizard (Ctrl-W) for your app object, and control WM_CHAR specific message

(inside CYourApp::PreTranslateMessage)
   if (msg==WM_CHAR) {
       if (!m_IgnoreKeys)        // if m_IgnoreKeys = false
            return FALSE;          // Do nothing
   }
// else continue with pretranslatemessage


0
 
LVL 55

Accepted Solution

by:
Jaime Olivares earned 2000 total points
ID: 12207060
Sorry, must be 'return TRUE' to "swalow" the message. Will give you a more concrete example:

BOOL CTest55App::PreTranslateMessage(MSG* pMsg)
{
      if (pMsg->message==WM_CHAR && m_IgnoreKeys) {
            ::MessageBeep(MB_OK);     // Just for testing
            return TRUE;
      }
      // TODO: Add your specialized code here and/or call the base class
      
      return CWinApp::PreTranslateMessage(pMsg);
}

Now you decide when keys will be accepted by setting  the m_IgnoreKeys to true or false
0

Featured Post

VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

  Included as part of the C++ Standard Template Library (STL) is a collection of generic containers. Each of these containers serves a different purpose and has different pros and cons. It is often difficult to decide which container to use and …
Article by: evilrix
Looking for a way to avoid searching through large data sets for data that doesn't exist? A Bloom Filter might be what you need. This data structure is a probabilistic filter that allows you to avoid unnecessary searches when you know the data defin…
The goal of the video will be to teach the user the difference and consequence of passing data by value vs passing data by reference in C++. An example of passing data by value as well as an example of passing data by reference will be be given. Bot…
The viewer will be introduced to the member functions push_back and pop_back of the vector class. The video will teach the difference between the two as well as how to use each one along with its functionality.
Suggested Courses

618 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question