TComboBoxEx and TCheckComboBox

[Blaazen]

Hi,

two new components derived from TCustomComboBox can be downloaded from here:
http://bugs.freepascal.org/view.php?id=26515 (download comboex3.zip)

TComboBoxEx is known from Delphi7, it is combo with images. Property Items: TStrings is covered and ItemsEx: TCollection is used instead.
Contrary to Delphi, Lazarus implementation is read-only due to technical reasons (we need csOwnerDrawFixed).

TCheckComboBox is combo with check-boxes. Each item can be unchecked/grayed/checked and disabled/enabled.

Both components are painted via Themes, read-only and support right-to-left BiDiMode.

There are some limitaitons so please read readme.txt before you start to use it.

Enjoy!

[engkin]

Using comboex3 on Windows.

My first test:
Created a TComboBoxEx at run-time and added a few items using AddItem, as soon as I touched it, it gave me "List index (0) out of bounds." error message. Test code:

Code: [Select]

uses
..., comboex;

procedure TForm1.Button1Click(Sender: TObject);
var
  C1:TComboBox;
  C2:TComboBoxEx;

  procedure Test1(C: TCustomComboBox; vTop: integer);
  var
    i:integer;
  begin
    with C do
    begin
      Left := 10;
      Top := vTop;
      Parent := Self;
      for i := 1 to 10 do
        if C is TComboBoxEx then
          (C as TComboBoxEx).AddItem(Format('AddItem %d',[i]), TObject.Create)
        else
          Items.Add(Format('Add %d',[i]));
    end;
  end;

begin
  C1:=TComboBox.Create(Self);
  Test1(C1, 100);

  C2:=TComboBoxEx.Create(Self);
  Test1(C2, 200);
end;


[Never]

Same here @Blaazen win7 64bit

[Blaazen]

This is not really a bug since correct line is:

Code: [Select]

(C as TComboBoxEx).ItemsEx.Add(Format('AddItem %d',[i]))
But I can override or reintroduce TCustomComboBox.AddItem(); and I am going to do it.

Method AddItem(); is valid for TCheckComboBox.

Note that TCheckComboBox and TComboBoxEx are different and they are implemented differently. The only thing is that they are both derived from TCustomComboBox and they are in the same unit.

[wp]

Just tested these new components. Nice!

An idea for an alternative operation mode of the checkedCombo: Shouldn't the text displayed in the non-dropped down field be shown as a combination of all checked items? Currently the combo displays only the most-recently selected item. Say, if the combobox contains the items "Asia", "America", "Asia", "Australia", "Europe", and the first two are checked, then the "result" in the always visible line should be "Asia;America". When nothing is checked the field should be empty, or show a user-defined text such as "nothing selected"

[Mike.Cornflake]

Nicely done.  I for one am hoping these get incorporated in the standard controls and shipped with Lazarus.

[engkin]

Check the attached image. Using TCheckComboBox, changing width to 200. How to reproduce:
1-Open the list
2-Choose one item
3-Click on the edit anywhere between the check box and the drop-down button
4-Move the form.

Here is the code I used:

Code: [Select]

procedure TForm1.Button1Click(Sender: TObject);
var
  C1: TComboBox;
  C2: TCheckComboBox;

  procedure Test1(C: TCustomComboBox; vTop: integer);
  var
    i:integer;
  begin
    with C do
    begin
      Left := 10;
      Top := vTop;
      Width := 200;
      Parent := Self;
      for i := 1 to 10 do
        if (C is TCheckComboBox) then
          (C as TCheckComboBox).AddItem(Format('AddItem %d',[i]), cbChecked)
        else
          Items.Add(Format('Add %d',[i]));
    end;
  end;

begin
  C1:=TComboBox.Create(Self);
  Test1(C1, 100);

  C2:=TCheckComboBox.Create(Self);
  Test1(C2, 200);
end;

Notice that I use an old version of Lazarus 2.7.1 on Windows XP.

[Blaazen]

I can reproduce but the same is with normal TComboBox  , so it is inherited behaviour and it should go to bugtracker.

[engkin]

I can reproduce but the same is with normal TComboBox

I could not reproduce it with the normal TComboBox. I tried adding:

Code: [Select]

  C1.Style:=csOwnerDrawFixed;
  C1.ReadOnly:=True;
to the previous code to imitate your control, but that did not give the same behavior. 

[Blaazen]

I could not reproduce it with the normal TComboBox.

I have only Wine, not a real Windows. I can reproduce with normal TComboBox and I can reproduce it with Delphi7 too.
It's easy.
1) Run demo
2) Open combo
3) Drag Form title-bar and move it

What happens with normal combo when you try to move form?

[taazz]

closes the combo box before moving, its a wine side effect.

[Blaazen]

closes the combo box before moving, its a wine side effect.

@ engkin
Is there different behavior between TComboBoxEx and TCheckComboBox ?

Thanks.

[engkin]

Is there different behavior between TComboBoxEx and TCheckComboBox ?

Yes, the problem is only in TCheckComboBox.

[Blaazen]

Thanks, but I will hardly repair it because I have only Wine (where this bug is by design) and also, I cannot see anything wrong it the code.

[engkin]

Yes, I understand. It is not just moving the form, that was just an example. What happens that the list gets stuck and does not close. If you see previous image I posted earlier, you'll notice that the list items were highlighted.