How can I access a component caption dynamically? 1

planix · Mar 16, 2005

Hi,

I have a form with a multiple number of labels on it. Each label is named "l1" "l2" ... "ln". I need to select a label at random to display some text.

So I want to randomly generate a number between 1 and n - easy.

Then I want to use that number to point to the label with that number in it's name so as to change the caption property of that label... this bit I am not at all sure about.

My dummy code idea would look something like this...

Code:

procedure TForm1.Button1Click(Sender: TObject);
var
  alabelobject: TLabel;
  i: integer;

begin

  alabelobject := TLabel.Create();

//randomly select one of the letters from the alphabet and //then display in the caption
  Randomize;

  i:=Random(48)

  alabelobject.name(i).Caption := alphabet.Strings[Random(25)];

end;

But of course this is doomed to fail. So, does anyone know how I can do this?

Cheers

Alistair
Townsville, Qld

Nordlund · Mar 16, 2005

Hi.
This code example has no Random code.
The fun thing is you can add a object into a StringList, and search for object captions by the use of IndexOf...

Good luck...

Code:

procedure TForm1.Button1Click(Sender: TObject);
var
  LabelList: TStringList;
  i: Integer;
begin
  LabelList := TStringList.Create;

  // Add a List to hold every TLabel
  for i := 0 to ControlCount -1 do
    if Components[i].ClassType = TLabel then
      LabelList.AddObject(TLabel(Components[i]).Caption, Components[i]);

  // Search for Label3
  i := LabelList.IndexOf('Label3');

  if i <> -1 then
  begin
    // Label3 was found, now change caption
    TLabel(LabelList.Objects[i]).Caption := 'Threre it was!';

    // Remember to change the List too, if you want to continue to use indexof.....
    LabelList.[i].Caption := 'Threre it was!';
  end;

  // clean up
  LabelList.Clear;
  LabelList.Free;
end;

//Nordlund

sggaunt · Mar 16, 2005

Take a look at the 'findcomponenet' method of whatever it is that has the buttons on it (the main form perhaps)
This code changes an image on a panel which is itself on another panel.
The panels are called 'Motor' plus a number and 'Mpars' + a number.

Code:

var Panel,Button: TComponent;
begin
   Panel := findcomponent('motor' + inttostr(Address));
   {test for nil return here to prevent crashes}
   if (panel <> nil)  then
      begin
         with Panel do
             begin
                Button := findcomponent('Mpars' + inttostr(Address));
                Tbitbtn(Button).glyph.Assign(nil);
                MotorImages.GetBitmap(0,  TbitBtn(Button).Glyph);
              end;

Steve

Life is like a Grapefruit, sort of orangey-yellow and dimpled on the outside, wet and squidgy in the middle, it's got pips inside too. Oh and some people have half a one for breakfast. Ford Prefect.

Want to do more with TGML Download Star

planix · Mar 16, 2005

Hi,

Thanks for the ideas. They were both really helpful and gave me the push in the right direction.

The simplest solution, though I haven't implemented it fully- just testing the idea, was to use the FindComponents method.

Here is what I have so far;

Code:

procedure TForm1.Button1Click(Sender: TObject);
var
  aLabel:TComponent;
  i:integer;

begin
//randomly select one of the letters from the alphabet and then display in
//the caption
  Randomize;
  i:= Random(2);
  aLabel:= findcomponent('l' + IntToStr(i+1));
  TLabel(aLabel).Caption := alphabet.Strings[Random(25)];

end;

It seems very simple and straightforward so I should be able to scale it up from the testbed of two labels and I can see how I can hive it off into a separate procedure.

Thanks to both of you.

Alistair

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How can I access a component caption dynamically? 1

planix

Technical User

Nordlund

Programmer

sggaunt

Programmer

planix

Technical User

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