Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

How access key-states?

Posted on 1998-05-07
5
Medium Priority
?
219 Views
Last Modified: 2010-04-06
Hi!

Here's an easy one... How can I check whether Ctrl, Alt or L/R Shift is pressed in an IF-statement. Like:

if (bla bla bla) then begin
  CtrlPressed := True;
end;

In good, old DOS (may she rest in peace) there was a particular address where some bits indicated the key-states, but hey!... it's the 90ties now!

Thanks!

//Daniel, Sweden
0
Comment
Question by:Dippen
[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
  • 3
  • 2
5 Comments
 

Accepted Solution

by:
westphal earned 200 total points
ID: 1342815
use the windows function

GetKeyState(nVirtKey : integer)

where nVirtKey is one of the following value:
VK_LSHIFT      
VK_RSHIFT
VK_LCONTROL      
VK_RCONTROL
VK_LMENU      
VK_RMENU

the return value is
if the high-order bit is 1, the key is down; otherwise, it is up. If the low-order bit is 1, the key is toggled. A key, such as the CAPS LOCK key, is toggled if it is turned on. The key is off and untoggled if the low-order bit is 0. A toggle key's indicator light (if any) on the keyboard will be on when the key is toggled, and off when the key is untoggled.
0
 

Expert Comment

by:westphal
ID: 1342816
here is an example:
if you have a form with 2 buttons you can test the GetKeyState with the following code:

procedure TForm1.Button1Click(Sender: TObject);
begin
 if GetKeyState(vk_LControl) and $80 = $80 then
   MessageDlg('left control key is down',mtInformation,[mbOk],0)
 else
   MessageDlg('left control key is up',mtInformation,[mbOk],0);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
 if GetKeyState(vk_NumLock) and $1 = $1 then
   MessageDlg('NumLock is toggled',mtInformation,[mbOk],0)
 else
   MessageDlg('NumLock is untoggled',mtInformation,[mbOk],0);
end;

0
 

Author Comment

by:Dippen
ID: 1342817
Hi, westphal!

I can't get your first procedure to work using the VK_LCONTROL constant, but if I change it to VK_CONTROL it works for both Ctrl keys. Is it because I use Win95? And if it IS because of Win95, is there any workaround in case I want to distinguish between Left and right Shift or Ctrl?

0
 

Expert Comment

by:westphal
ID: 1342818
you are right, win95 does'nt know the difference between right and left :) but you can use in win95 a direct access to bios or harware (old way in dos program's)

0
 

Author Comment

by:Dippen
ID: 1342819
OK. Thanks for your help!
0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

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

Objective: - This article will help user in how to convert their numeric value become words. How to use 1. You can copy this code in your Unit as function 2. than you can perform your function by type this code The Code   (CODE) The Im…
In my programming career I have only very rarely run into situations where operator overloading would be of any use in my work.  Normally those situations involved math with either overly large numbers (hundreds of thousands of digits or accuracy re…
This tutorial will teach you the special effect of super speed similar to the fictional character Wally West aka "The Flash" After Shake : http://www.videocopilot.net/presets/after_shake/ All lightning effects with instructions : http://www.mediaf…
How to fix incompatible JVM issue while installing Eclipse While installing Eclipse in windows, got one error like above and unable to proceed with the installation. This video describes how to successfully install Eclipse. How to solve incompa…
Suggested Courses

670 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