TCheckListBox: what changed

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Title: TCheckListBox

New		Line
1	+	A TCheckListBox ![](/wiki-images/9/98/Tchecklistbox.png) is a component that shows a (scrollable) list of checkboxes where user can make multiple selections. It is available from the [[Additional tab]] of the [[Component Palette]].
2	+
3	+	<figure>
4	+	<img src="CheckListBoxDemo.png" title="CheckListBoxDemo.png" />
5	+	<figcaption>CheckListBoxDemo.png</figcaption>
6	+	</figure>
7	+
8	+	## Usage
9	+
10	+	Think of TCheckListBox as having two parts, the strings in a [[TListBox]] shown to the right and the checkboxes to the left. The strings are typically descriptions of what the user is selecting if they click a checkbox. The strings may be loaded individually using (eg) -
11	+
12	+	``` pascal
13	+	CheckListBox1.AddItem('Line One', Nil);
14	+	CheckListBox1.AddItem('Line Two', Nil);
15	+	```
16	+
17	+	Or you can assign an existing string list filled elsewhere -
18	+
19	+	``` pascal
20	+	CheckListBox1.Items.Assign(MyStringList);
21	+	```
22	+
23	+	Its a good idea to then put the checkboxes in a know state -
24	+
25	+	``` pascal
26	+	for I := 0 to CheckListBox1.Count-1 do
27	+	CheckListBox1.Checked[I] := False;
28	+	```
29	+
30	+	TCheckListBox allows the user to select as many or as few checkboxes as they like. Use the OnItemClick event to force no more than one -
31	+
32	+	``` pascal
33	+	procedure TNoteBookPick.CheckListBox1ItemClick(Sender: TObject; Index: integer);
34	+	var
35	+	I : integer;
36	+	begin
37	+	if (Sender as TCheckListBox).Checked[Index] then begin
38	+	for I := 0 to CheckListBox1.Count -1 do
39	+	CheckListBox1.Checked[I] := False;
40	+	CheckListBox1.Checked[Index] := True;
41	+	end;
42	+	end;
43	+	```
44	+
45	+	To read the Check Boxes when (eg) the user has finished -
46	+
47	+	``` pascal
48	+	for I := 0 to CheckListBox1.Count -1 do
49	+	if CheckListBox1.Checked[I] then DebugLn('Checked Item ' + CheckListBox1.Items[I]);
50	+	```
51	+
52	+	## Comparison with TCheckGroup
53	+
54	+	There is a similar control named TCheckGroup on Standard component pallette tab. The differences are
55	+
56	+	1\) The items within TCheckGroup are spaced evenly, while TCheckListBox allows scroll down.
57	+
58	+	2\) TCheckListBox has property of AllowGrayed.
59	+
60	+	## See also
61	+
62	+	- [[doc:lcl/checklst/tchecklistbox.html\|TCheckListBox doc]]
63	+	- [[TCheckBox]]
64	+	- [[TListBox]]
65	+
66	+	---
67	+	From the Free Pascal wiki, page "TCheckListBox", as it stood on 2022-04-04 after a change by Egsuh, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).

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