TcheckListBox: Hiding the Values?

[PeterPanettone 158]

In Delphi 10.4, I fill a TCheckListBox in a loop adding name= value pairs:

 

for i := 1 to 32 do
  CheckListBox1.Items.AddPair(GetName(i), GetValue(i));

 

Of course, the CheckListBox then shows:

 

Quote

Name1=Value1
Name2=Value2
Name3=Value3
etc.

 

Well, is there a "trick" to show only the NAMES and HIDE the VALUES in the CheckListBox?

 

I would like to avoid AddObject or messing around with multiple string-lists.

 

Any idea?

[Mahdi Safsafi 225]

For me I'd go with AddObject as its better than using Pair<Name, Value>. However you can either set CheckListBox1.Style to lbVirtual and then handle all data event. Or simply set Style to lbOwnerDrawFixed and owner draw your control:

// CheckListBox1.Style := lbOwnerDrawFixed;

procedure TMain.CheckListBox1DrawItem(Control: TWinControl; Index: Integer; Rect: TRect; State: TOwnerDrawState);
var
  Flags: Longint;
  Data: String;
  FCanvas: TCanvas;
  CheckListBox: TCheckListBox;
begin
  CheckListBox := TCheckListBox(Control);
  FCanvas := CheckListBox.Canvas;
  FCanvas.FillRect(Rect);
  if Index < CheckListBox.Count then
  begin
    Flags := DrawTextBiDiModeFlags(DT_SINGLELINE or DT_VCENTER or DT_NOPREFIX);
    if not UseRightToLeftAlignment then
      Inc(Rect.Left, 2)
    else
      Dec(Rect.Right, 2);
    Data := CheckListBox.Items.Names[Index];

    DrawText(FCanvas.Handle, Data, Length(Data), Rect, Flags);
  end;
end;

EDIT:

Removed ExtractName function.

Edited July 15, 2020 by Mahdi Safsafi

[aehimself 399]

I don't feel fine storing information in the UI. I'd rather create a separate TList<TMyValue> and add the values to it as I'm adding the checkboxes. This way the index of the CheckBox will be equal to the index of it's value in the TList.

 

[PeterPanettone 158]

12 hours ago, Mahdi Safsafi said:

set Style to lbOwnerDrawFixed and owner draw your control:

Thank you for your code! It's much appreciated!

[PeterPanettone 158]

3 hours ago, aehimself said:

I don't feel fine storing information in the UI.

That's what I call "user-centric" programming. 

 

And BTW, the stored information is HIDDEN by using the code of @Mahdi Safsafi

Edited July 16, 2020 by PeterPanettone

[aehimself 399]

1 minute ago, PeterPanettone said:

That's what I call "user-centric" programming. 

In a more advanced project (especially after a UI change or refactoring) you'll quickly realize why separating the UI and data storage/handling extremely important.

In your example, let's say a user doesn't like CheckListBox and wants you to change it to something else. Apart from the visual changes, you'll have to re-code your business logic as well.

 

It is not that important in "personal use" applications, but lately I have a separate class for data storage everywhere. The UI only displays, validation, (de)serialization, everything is handled by the class itself.

[PeterPanettone 158]

5 minutes ago, aehimself said:

In a more advanced project (especially after a UI change or refactoring) you'll quickly realize why separating the UI and data storage/handling extremely important.

In your example, let's say a user doesn't like CheckListBox and wants you to change it to something else. Apart from the visual changes, you'll have to re-code your business logic as well.

Generally, you are right. But in this particular case, it's more a prototype feature/application.

Edited July 16, 2020 by PeterPanettone

[PeterPanettone 158]

BTW, I wonder why something useful like this is not natively BUILT-IN. TCheckListBox should have a boolean property HideValues which does exactly what Mahdi's code does.

[aehimself 399]

Because - TCheckListBox.Items is TStrings, and .Values are supported by TStrings. I would not be surprised if this was not meant to be used as value storage; due to the reason you just very asked.

[PeterPanettone 158]

That's why I love PROGRAMMING: It's ABSOLUTE FREEDOM as opposed to the old [political terms removed by OP] rule.

Edited July 16, 2020 by PeterPanettone

[Esteban Pacheco 16]

[aehimself 399]

Yep, you have so much freedom you can easily do

Var
 tb: TBytes;
 a: Integer;
Begin
 SetLength(tb, 5);
 For a := 0 To 5 Do
  tb[a] := 1;
End;

or...

Var
 pc: PChar;
Begin
 GetMem(pc, 5 + 1);
 StrPCopy(pc, 'abcde', 5);
End;

or even:

Var
 obj: TObject;
 proc: TProcedure;
Begin
 proc := addr(obj);
 proc;
End;

Just because you have the possibility of doing something it doesn't mean you are supposed to or should.

 

Btw, I thought this forum is a politic-free area. Please take those ideologies to Reddit.

[PeterPanettone 158]

58 minutes ago, aehimself said:

Just because you have the possibility of doing something it doesn't mean you are supposed to or should.

You are completely right.

Edited July 16, 2020 by PeterPanettone