Board index » cppbuilder » How to "control" key Tab from keyboard

2006-03-11 05:21:24 AM
cppbuilder114
Hi guys, i'm totally new in BCB6 and i need some help here!
In my project's form i have several Edit boxes, DBEdit boxes, a Data source
and a DBGrid. In a data module now i have a table and several queries. I
have made my project to store the values which i pass through the edit boxes
to my table (at run time). I even found a way to change the already stored
values in the table with some help from the DBEdits but there is a serious
problem (again at run time). The values that i pass are checked from an
error function that i created and i placed it OnKeyPress Event of each
DBEdit box (if Key == 13....// then do the check for duplicate values). All
works fine when i press enter (at run time). The problem starts if I press
Tab to pass from one DBEdit to another (at run time). The values I write,
pass to the table without any warning for duplicate values!!! I tryied all
the numbers (0 to 32) from the table ASCII in the OnKeyPress function (the
code i wrote is if ((Key == 13)||(Key == X) where X = 1...32), but nothing
seems to work. By pressing the Tab key, it happens the following:
Project runs .... DBEdit1->SetFocus()....Then i press Tab
From DBEdit1->Text it goes to DBEdit2->Text,
From DBEdit2->Text it goes to DBEdit3->Text,
From DBEdit3->Text it goes to the last record of the table in DBGrid!!!
In OnKeyPress Event for DBEdit4 i wrote :
if ((Key == 13) || (Key == 9))
DBEdit1->SetFocus();
Is it or is it not the number 9 the decimal number of Horizontal Tab in
ASCII Table???
I even tried with the OnKeyDown Event where i wrote:
if (Key == VK_TAB)
DBEDit1->SetFocus();
but nothing changed!!!
How can i take control of the key Tab?
Thanks for your time!!!
 

"Jimakos Bilakis" < XXXX@XXXXX.COM >wrote in message
default. It is a navigation key that is reserved by the OS. In order for
the Tab key to trigger the events, you have to subclass each control in
order to intercept the WM_GETDLGCODE message. You can then specify
DLGC_WANTTAB in the message's return value.
Why not just configure the DB itself to not allow duplicate values for the
desired fields? Then you don't have to validate the values yourself.
Gambit
 

Hi Jim
void __fastcall TForm1::DBEdit4Exit(TObject *Sender)
{
DBEdit1->SetFocus();
}
You have to press Ctrl + I to catch a Key = = 9 in keyDown event (just to
know )
-minas charokopos
 

{smallsort}

I think i have heard it somewhere but i don't remember where....
it so,
cause i don't really understand what do you mean by that)
and what do i have to write in general words (of code of coursse - if it is
easy for you )?
Thank you very much for your reply Gambit!
 

it passes to the DBEdit1 and not to the DBGrid as exactly i wanted to do
so!!!
files)
in the OnKeyDown Event has more meaning to use the Virtual Keys (VK). For
example,
if (Key = = VK_TAB) or if (Key = = VK_ESCAPE) etc. Am i understand something
wrong?
Thank you so much for your reply too mina. BTW, are you greek???
 

Hi Jim,
combination and not TAB key although they have the same value (9).
according to tab order.Also never produces a KeyDown or KeyUp event.That is
what Remy said in his post.
You can change tab order by right clcking on your from or on a component
that contains other components and select Tab Order.
-minas
 

have Primary Keys, Indexes, Referential Integrities and so on...
One of the ordiary things when setting Indexes is to say if an
Indexed filed can accept Duplicated Values.
That way, the database is "secure" ond the 'system level' and does
not depend of the quality (bugs) of your interface.
So, you are not supposed to catch DBField and similar events, and
insted of that you could only catch OnPostError() for that.
That's the way you should deal with DB's.
--
Best Regards,
Vladimir Stefanovic
 

duplicate items from the DB that i use (Paradox). I believe to have this
ability. Thanks for your valuable informations. :)
 

Hi mina,
my question! Thanks a lot! You have helped me so much! BTW i'm greek too. :P
 

Hi Mina,
sorry to bother you again, i just don't understand a detail!
You told me that the TAB key is normally used to switch focus from one
control to another , according to tab order. I agree, but why every time
that i pass from a DBEdit to another through Tab, it applies the
"containment" of my DBEdit to the table of my database? Isn't that odd??? I
believed that it only set focus to another component in my form and just it.
Why does it keep "playing" the role of the transporter in my project? Is
there any way to avoid it?
I faced the same problem before! OnKeyPress Event i wrote code:
if (Key == 13)
{
if(!(DBEdit1->Text.IsEmpty()))
{
if (blah blah) // check for the validity of the
value
{
// everything ok pass the values to the
table.
DBEdit2->SetFocus();
}
else // The DBEdit is not empty but the value in it
is not acceptable.
{
MessageDlg("Problem", mtWarning,
TMsgDlgButtons() << mbOK, 0);
Abort(); // With this function i solve the
problem. :)
DM_Pinakas_Syntelestvn->PinakasSynt->Refresh();
// The datamodule (name = DM_Pinakas_Syntelestvn) where i keep my table (=
PinakasSynt)
}
}
else // totally empty DBEdit - something that i don't want
at all.
{
MessageDlg("Problem", mtWarning, TMsgDlgButtons() <<
mbOK, 0);
DBEdit1->Undo();
DBEdit1->SetFocus();
}
}
As you can see the function Abort() "saved" me! But now i face the same
problem with Tab! I tried with OnExit Event to do something similar but no
result till now..:((! Do you have any idea plz? Thank you in advance = Óå
åõ÷áñéóô?åê ôù?ðñïôÝñùí ãé?ôï ÷ñüí?óï?êá?ôç?èÝëçóÞ óï?íá ìå
âïçèÞóåé?:))
 

Óå êÜðïéï ìÞíõìá ìï?êÜíå äåîß êëßê ->éäéüôçôå?ãé?ôï ìáéë ìï?:-)
guys, sorry about these greeks :-)
-minas
 

Hi Jim,
Right :-)
-minas
 

"Jimakos Bilakis" < XXXX@XXXXX.COM >wrote:
listen for WM_KEYDOWN/UP, you can change the key value before
it ever gets to a control. For example:
private: // User declarations
void __fastcall AppMessage( TMsg &Msg, bool &Handled );
public: // User declarations
__fastcall ~TForm1();
//-------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner)
{
Application->OnMessage = AppMessage;
}
//-------------------------------------------------------------
__fastcall TForm1::~TForm1()
{
Application->OnMessage = NULL;
}
//-------------------------------------------------------------
void __fastcall TForm1::AppMessage( TMsg &Msg, bool &Handled )
{
if( Msg.message == WM_KEYDOWN || Msg.message == WM_KEYUP )
{
if( Msg.wParam == VK_TAB )
{
if( dynamic_cast<TDBEdit*>( Screen->Active->Control ) )
{
Msg.wParam = VK_RETURN;
}
}
}
}
//-------------------------------------------------------------
~ JD
 

"Jimakos Bilakis" < XXXX@XXXXX.COM >wrote in message
__fastcall TForm1::TForm1(TComponent *Owner)
: TForm(Owner)
{
OldWndProc = DBEdit1->WindowProc;
DBEdit1->WindowProc = DBWndProc;
}
void __fastcall TForm1::DBWndProc(TMessage &Message)
{
OldWndProc(Message);
if( Message.Msg == WM_GETDLGCODE )
Message.Result |= DLGC_WANTTAB;
}
worked with indexes or primary keys before? A primary key can be set up
inside the DB itself to ignore duplicate values that are posted to the DB.
Gambit
 

"Jimakos Bilakis" < XXXX@XXXXX.COM >wrote in message
newsgroups.
Gambit