passing values to another form in SDI Or to make a form set values differently depending on which button launched it.

Posted on 2008-10-07
Last Modified: 2012-05-05
Hi Experts,
I have lets say a 'MainForm" which has among a lot of other things two buttons, lets say 'buttonorig' and 'buttonnew'. Clicking 'buttonorig' launches a form lets say 'FormSEC'. 'FormSEC' has many components which are set in its "OnCreate" procedure. I want to set some of the components in 'FormSEC' to different values if 'buttonnew' is clicked. Can I pass there values to the 'FormSEC'? if not can I set the components differently in the "OnCreate" procedure depending on which button was clicked?
Question by:QurbanDurrani
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LVL 14

Accepted Solution

SteveBay earned 500 total points
ID: 22663593
I would suggest setting a pubilc variable in MainForm based upon which button was clicked:

procedure TForm1.ButtonClick(Sender: TObject);
     if Sender = ButtonOrig then
          WhichButton := 0
     else if Sender = ButtonNew then
          WhichButton := 1;


then in the OnFormCreate in FormSec do this:

procedure TFormSec.FormCreate(Sender: TObject);
     if MainForm.WhichButton = 0 then
          // do this stuff
     else if MainForm.WhichButton = 1 then
          // do that stuff

Author Comment

ID: 22664037
Declaration of variable 'whichbutton" as shown in the attachment throws an error saying "'END' expected but 'VAR' found'. Should I be declaring it somewhere else?

<other Procedure declaration above. 
procedure IPCollectionSheetShow(Sender: TObject);
    procedure IPCollectionSheetHide(Sender: TObject);
    procedure ViewGroupClick(Sender: TObject);
    procedure ViewCOTClick(Sender: TObject);
    { Private declarations }
    { Public declarations }
      whichbutton : integer;

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Author Comment

ID: 22664090
Ok I figured out where to declare the variable. Will post again after adding the rest.
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Author Comment

ID: 22664564
Thanks SteveBay for all you help.
That works.
LVL 38

Expert Comment

by:Geert Gruwez
ID: 22666620
my 2 cents:
you will have circular references and many subforms dependent on your mainform
you can only use the SecForm in combination with your mainform
if you want to use your secform from any form
do it this way
<see code snippet>

and use it from the mainform (or any form) like

procedure TMainForm.ButtonClick(Sender: TObject);
  if ShowSecForm(Self, IfThen(Sender = ButtonOrig, 0, 1)) then
    ShowMessage('Result of form = mrOk');

Why ?
1: No circular reference
2: If you work with 2 monitors and set Position of the form to poOwnerFormCenter
the SecForm will stay in the same monitory as the Form calling it

  TSecForm = class(TForm)
    fVar1: integer;
var SecForm: TSecForm;
function ShowSecForm(AOwner: TComponent; AButton: Integer);
var frm: TSecForm;
  Result := False;
  frm := TSecForm.Create(AOwner);
    frm.fVar1 := aButton;
    if frm.ShowModal = mrOk then 
      Result := True;    

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LVL 14

Expert Comment

ID: 22668868
Your solution allows to SecForm to know WhichButton during the OnShow event. QurbanDurrani asked how to know in the OnCreate Event.

I had originally started answering this question with a solution similar to yours but I changed it because QurbanDurrani was looking for a way that made sense with the way the FormSEC was currently being implemented. I can think of no way to assign values in an TForm prior to its OnCreateEvent.

I can imagine though, that we could have a lively discussion about how to create dynamic forms - OnCreate vs. OhShow events. Personally I agree with you - I prefer do to the heavy lifting in the OnShow using form-local variables, not just to avoid circular reference but because it a clearer way to code.


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