[Solved] A component that contains another
lazarus / 31-LCL

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lainz · 2017-01-03 22:59

Hi, I'm working on a component that's like this:

- Panel
-- Listbox

A panel containing a listbox. The problem I have is if I add in
'published' the ListBox property and I change it with the object
inspector then when I run the program the properties (say for example
Items property) is not loaded at all.

I create the ListBox on create event of the panel container.

The source code is here:
https://github.com/bgrabitmap/bgracontrols/blob/master/bclistbox.pas

In the source I not publish the property because it doesn't works and
well but is usable at least without it.

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minesadorada · 2017-01-04 03:55

Just a guess (a long time since I did it)
Use SetSubComponent for the listbox in the register proc and a
Propertyeditor for it?

Example here: http://wiki.freepascal.org/Poweredby#Other_uses

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lainz · 2017-01-04 04:42

Thanks for your reply, is too late here I will try tomorrow.

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balazsszekely · 2017-01-04 06:18

Hi @lainz,

Only publish the properties you need, something like this:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
//...type TBCPaperListBox = class(TBCPaperPanel)  private    FListBox:
TBCListBox;    function GetListBoxItems: TStrings;    procedure
SetListBoxItems(AItems: TStrings);  public    constructor
Create(TheOwner: TComponent); override;  published    property Items:
TStrings read GetListBoxItems write SetListBoxItems;  end;      
  //...{ TBCPaperListBox } constructor
TBCPaperListBox.Create(TheOwner: TComponent);begin  inherited
Create(TheOwner);  Self.ChildSizing.ControlsPerLine := 1; 
Self.ChildSizing.LeftRightSPacing := 4; 
Self.ChildSizing.TopBottomSpacing := 5;  FListBox :=
TBCListBox.Create(Self);  FListBox.Align := alClient;  FListBox.Parent
:= Self;end; function TBCPaperListBox.GetListBoxItems: TStrings;begin 
Result := FListBox.Items;end; procedure
TBCPaperListBox.SetListBoxItems(AItems: TStrings);begin  if
FListBox.Items <> AItems then    FListBox.Items := AItems;end;

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lainz · 2017-01-04 13:26

Oh I see. That has some kind of advantages, for example that the user
for error clears the ListBox assigned in the property I publish, with
your way it will not happen.

Edit: Well tested the minesadorada code and works fine. To avoid the
user to clear the property we must register the property editor for
the class, as displayed in the wiki.