TMemo: what changed

Revision 0 to 1. Removed lines have a minus sign; added lines have a plus sign.

Title: TMemo

New		Line
1	+	A TMemo ![](/wiki-images/1/1b/Tmemo.png) is a control with multiple lines of editable text. It is available from the [[Standard tab]] of the [[Component Palette]].
2	+
3	+	## Usage
4	+
5	+	To use a TMemo on a [[TForm\|form]], you can simply select it on the Standard component pallet and place it by clicking on the form. In this text box, you can now edit a multiline text at run time.
6	+
7	+	For example, have you added a TMemo Memo1 to your form Form1, you can use `Memo1.Text:='this is a singleline text';` to assign a [[String]].
8	+
9	+	Also you can use anywhere in the source code the stored text of Memo1 with `myString:=Memo1.Text;`.
10	+
11	+	It is also possible to assign a multiline text with `Memo1.Text:='This'+LineEnding+'is'+LineEnding+'a'+LineEnding+'multiline'+LineEnding+'text';`.
12	+
13	+	### Assignment of a TStrings or TStringList
14	+
15	+	Common, to assign a text to a TMemo is the use of a [[TStringList-TStrings Tutorial\|TStringList]] or its parent [[TStringList-TStrings Tutorial\|TStrings]]. The following example shows this (in the event handler of an inserted [[TButton]] Button1 in a [[TForm\|form]] Form1 and a TMemo Memo1 on it):
16	+
17	+	``` pascal
18	+	procedure TForm1.Button1Click(Sender: TObject);
19	+	var
20	+	myStringList: TStringList;
21	+	begin
22	+	myStringList:=TStringList.Create; //Create my StringList
23	+	myStringList.Add('This is the first line.'); //add a line
24	+	myStringList.Add('This is the second line.');
25	+	myStringList.Add('This is the third line.');
26	+	myStringList.Add('etc.');
27	+	Memo1.Lines.Assign(myStringList); //assign text content
28	+	myStringList.Free; //free my StringList
29	+	end;
30	+	```
31	+
32	+	### Insert lines directly
33	+
34	+	You can add directly the contents of the memo for example:
35	+
36	+	``` pascal
37	+	procedure TForm1.Button1Click(Sender: TObject);
38	+	begin
39	+	Memo1.Lines.Clear; //delete all lines of Memo1
40	+	Memo1.Lines.Add('This is the first line.'); //add a line
41	+	Memo1.Lines.Add('This is the second line.');
42	+	Memo1.Lines.Add('This is the third line.');
43	+	Memo1.Lines.Add('etc.');
44	+	end;
45	+	```
46	+
47	+	### Read a line
48	+
49	+	If you want to know what is in a particular line, you can check it directly with `myString:=Memo1.Lines[Index];`. Note, the index of TMemo.Lines is zero based, i.e. the first line would be: `myString:=Memo1.Lines[0];`
50	+
51	+	The preceding example add yet a TButton Button2, you can display the third line as follows:
52	+
53	+	``` pascal
54	+	procedure TForm1.Button2Click(Sender: TObject);
55	+	begin
56	+	ShowMessage(Memo1.Lines[2]);
57	+	end;
58	+	```
59	+
60	+	### Selected text
61	+
62	+	You can mark text parts at run time by holding the left mouse button or press and hold the \[Shift\] key and select the text with the mouse or keyboard. This text ([[String]]) you can display like this:
63	+
64	+	``` pascal
65	+	procedure TForm1.Button2Click(Sender: TObject);
66	+	begin
67	+	ShowMessage(Memo1.SelText);
68	+	end;
69	+	```
70	+
71	+	### Search text
72	+
73	+	Contrary to the previous example, you can also looking for a text ([[String]]) in a TMemo and return the place where it is: `Position:=Memo1.SelStart;`
74	+
75	+	The following example shows how you can search and search further for a text in a memo:
76	+
77	+	- Create a new application with a [[TEdit]] Edit1, a TMemo Memo1 and two [[TButton]] Button1 and Button2.
78	+	- Complete the uses clause to LCLProc and strutils.
79	+	- In the event handler OnClick of Button1 fill the memo with any text, as in the example [[TMemo\|Insert lines directly]].
80	+	- In the source text editor add following function (based on the [example](http://www.lazarusforum.de/viewtopic.php?p=39260#p39260) from the German Lazarusforum):
81	+
82	+	``` pascal
83	+	// FindInMemo: Returns the position where the string to search was found
84	+	function FindInMemo(AMemo: TMemo; AString: String; StartPos: Integer): Integer;
85	+	begin
86	+	Result := PosEx(AString, AMemo.Text, StartPos);
87	+	if Result > 0 then
88	+	begin
89	+	AMemo.SelStart := UTF8Length(PChar(AMemo.Text), Result - 1);
90	+	AMemo.SelLength := Length(AString);
91	+	AMemo.SetFocus;
92	+	end;
93	+	end;
94	+	```
95	+
96	+	- Now, add following code in the event handler OnClick from Button2:
97	+
98	+	``` pascal
99	+	procedure TForm1.Button2Click(Sender: TObject);
100	+	const
101	+	SearchStr: String = ''; // The string to search for
102	+	SearchStart: Integer = 0; // Last position of the string to search for
103	+	begin
104	+	if SearchStr <> Edit1.Text then begin // Falls sich der zu suchende String geändert hat
105	+	SearchStart := 0;
106	+	SearchStr := Edit1.Text;
107	+	end;
108	+	SearchStart := FindInMemo(Memo1, SearchStr, SearchStart + 1);
109	+
110	+	if SearchStart > 0 then
111	+	Caption := 'Found at position['+IntToStr(SearchStart)+']!'
112	+	else
113	+	Caption := 'No further finds!';
114	+	end;
115	+	```
116	+
117	+	- Now at run time, you can fill the memo with a text with Button1, paste the text to be searched in Edit1 and looking or keep looking for these in memo with Button2.
118	+
119	+	#### EM_SCROLLCARET
120	+
121	+	Messages like EM_SCROLLCARET as used in windows are not available in Lazarus and thus need a workaround...
122	+
123	+	### Save and load
124	+
125	+	You can quite easily save and load the contents of a memo by using the methods SaveToFile and LoadFromFile of the class [[TStringList-TStrings Tutorial\|TStrings]].
126	+
127	+	The following example shows you how:
128	+
129	+	- Create a new application with a TMemo Memo1 and three [[TButton]] Button1, Button2 and Button3.
130	+	- Additionally put a [[TSaveDialog]] and a [[TOpenDialog]] from the component palette Dialogs on the form.
131	+	- Change Caption of Button1 to "Fill memo".
132	+	- In the event handler OnClick of Button1 fill the memo with any text, as in the example [[TMemo\|Insert lines directly]].
133	+	- Change Caption of Button2 to "Save memo".
134	+	- Change Caption of Button3 to "Load memo".
135	+	- now modify the event handler OnClick of the buttons:
136	+
137	+	``` pascal
138	+	procedure TForm1.Button2Click(Sender: TObject);
139	+	begin
140	+	if SaveDialog1.Execute then
141	+	Memo1.Lines.SaveToFile(SaveDialog1.FileName);
142	+	end;
143	+
144	+	procedure TForm1.Button3Click(Sender: TObject);
145	+	begin
146	+	if OpenDialog1.Execute then
147	+	Memo1.Lines.LoadFromFile(OpenDialog1.FileName);
148	+	end;
149	+	```
150	+
151	+	## See also
152	+
153	+	- [[doc:lcl/stdctrls/tmemo.html\|TMemo doc]]
154	+	- [[RichMemo\|TRichMemo]] - Like Delphi TRichEdit component: formatted text (color, size, etc.)
155	+	- [[TListBox]] - A scrollable list of strings
156	+
157	+	---
158	+	From the Free Pascal wiki, page "TMemo", as it stood on 2021-05-25 after a change by Arent, 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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