GroupBox problem
lazarus / 9-Editor

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pvlazusr · 2011-02-12 00:09

I am having an issue with Groupboxes that I am finding frustrating and
seems to defeat the purpose of the Group. I encountered it when using
my own component but have found the same issue with some standard
components.

I have added a control, call it MyStaticText that is a descendent of
TStaticText. To this I have added new properties, to keep it simple
let us call the new property MyCaption. This takes the caption
entered, modifies it then displays it in the caption. For this it does
not really matter what the property is or what it does. I do all the
package stuff and it appears in the pallet and I can add it to a group
box, also the new property is visible in the object inspect and can be
accessed by the program. Everything works.

I want to put a series of these in the groupbox and fill them from an
array. The simple way seems to be to address them as
MyGroupBox.Control.MyCaption := MyArray
however MyCaption is not recognised. While editing I enter the full
point after the Control and I get a drop down list that includes
'Caption' but not 'MyCaption'. When the program runs the MyStaticText
object MyCaption can be accessed, it is design time that does not
recognise the property and only when it is addressed as a GroupBox
control..

I have tried this with regular LCL components such as TButtonPanel
where the drop down list includes such properties as Color but not
OkButton. The same issues are seen with methods as well as properties.
I was under the impression that the GroupBox was intended to allow
access to its controls by indexing them but this only seems to apply
to a subset of the controls properties. Add a property or method and
it cannot be seen at design time when addressed this way.

A little help please.

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Phil · 2011-02-12 02:34

Is it possible that the listed properties are for the group box, not
your control?

I would test this on Delphi. If it works as expected there, that
probably indicates a Laz IDE bug that you should report with a bug
report. If it does not work as expected there, then it's likely you're
doing something that's not supported.

Thanks.

-Phil

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pvlazusr · 2011-02-12 03:39

I have tried using MyGroupBox.Control(i),Color and the appropriate
control changes colour so I do not believe these are the GroupBox
properties/procedures.

Please note I have used (i) to represent squarebracket i squarebracket
as they disappeared from my original post. This
MyGroupBox.Control.MyCaption := MyArray
should be (using the same change)
MyGroupBox.Control(i).MyCaption := MyArray(i)

To test on Delphi I would need to set up a virtual machine, install
Windows, dig out my old Delphi installer CD, install Delphi and then
it would only be version 5  so I am hoping someone might be able to
take a look. I'm hoping for some feedback before posting a bug. I
would expect a control to be indexable in a GroupBox even an added
component. That is the idea of grouping the things in the first place.
The issue is why aren't all the properties etc being picked up.

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Phil · 2011-02-12 04:00

Yes, but isn't the type of the Controls property's elements just
TControl?

Does it make any difference if you cast it like this:

MyStaticText(MyGroupBox.Controls).

Thanks.

-Phil

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pvlazusr · 2011-02-12 21:30

Controls property is derived from TWinControls, would this mean that
the only properties are those found in TWinControls and below? That
prevents any further properties derived from TWinControls from being
referred to. Does it not parse down the controls in the object tree?

MyStaticText(MyGroupBox.Controls)
Doesn't help as the GroupBox would have several controls in it eg
MYStaticText1, MyStaticText2 etc
The idea of using Controls[ i ] is to index these controls to avoid
having to assign values one by one.

BTW how can I put in square brackets without the spaces?

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User137 · 2011-02-12 22:20

Didn't really understand the problem well without seeing code, my
thoughts anyway:

Code: [Select]TMyButton = class(TButton)
public
  MyCaption: string;
end;

var button: TButton;
begin
  button:=TMyButton.Create(form1);
  button.MyCaption:='Test'; // <-- This will not work
  TMyButton(button).MyCaption:='Test'; // <-- This will
  TMyButton(button).Free; // I assume simple button.Free would not
free it completely
Most problems would be solved with this if possible in the case:
Code: [Select]var button: TMyButton;