[DUG] MouseWheel and DBGrid in D6

[Dennis Chuah]

Range checking turned off perhaps?

----- Original Message ----- 
From: "Wayne Roser" <rr at kristin.school.nz>
To: "NZ Borland Developers Group - Delphi List" <delphi at ns3.123.co.nz>
Sent: Tuesday, May 30, 2006 2:47 PM
Subject: [DUG] MouseWheel and DBGrid in D6


>I found an article in Delphi.about.com and got this code to fix MouseWheel 
>behaviour in a DBGrid:
>
> procedure TForm1.ApplicationEvents1Message (var Msg: TMsg; var Handled: 
> Boolean) ;
> var
>   i: SmallInt;
> begin
>   if Msg.message = WM_MOUSEWHEEL then  begin
>     Msg.message := WM_KEYDOWN;
>     Msg.lParam := 0;
>     i := HiWord(Msg.wParam) ; //  this line gives me a problem
>     if i > 0 then
>       Msg.wParam := VK_UP
>     else
>       Msg.wParam := VK_DOWN;
>     Handled := False;
>   end;
> end;
>
> So I dropped a TApplicationEvents component on my form and used the code.
>
> I get a problem at the line
> i := HiWord(Msg.wParam) ;
> Msg.wParam is -7864320 and an ERangeError pops up with message 'Range 
> check error'
>
> My working version has
>     i := Msg.wParam div abs(Msg.wParam);
> in place of the offending line but I'd like to know wassup with the 
> original code.
>
> Wayne Roser
>
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