Lazarus

Programming => LCL => Topic started by: egsuh on September 18, 2019, 11:48:52 am

Title: [SOLVED] Undoing text editing in TEdit, etc.
Post by: egsuh on September 18, 2019, 11:48:52 am

Is it possible to undo editings in TEdit, etc.?
For example, the original Edit1.Text = 'Edit1'.  And I tried to change some part of it, but I want to leave the EditBox just leaving the original 'Edit1' text, ignoring my own  changes?

Title: Re: Undoing text editing in TEdit, etc.
Post by: wp on September 18, 2019, 12:07:07 pm

Press ESC to restore the original content. I think it is not ready-made, but you can easily add it by yourself:

• Add a string variable to the form named FOldEdit1Text
• Write a handler for Edit1's OnEnter event copying is Text to FOldEdit1Text.
• Write a handler for Edit1's OnKeyDown event checking the pressed key for ESCAPE and replacing the Text by FOldEdit1Text.

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     Edit1: TEdit;
16.     Edit2: TEdit;
17.     procedure Edit1Enter(Sender: TObject);
18.     procedure Edit1KeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
19.     procedure Edit2Enter(Sender: TObject);
20.     procedure Edit2KeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
21.   private
22.     FOldEdit1Text: String;
23.     FOldEdit2Text: String;
24.  
25.   public
26.  
27.   end;
28.  
29. var
30.   Form1: TForm1;
31.  
32. implementation
33.  
34. {$R *.lfm}
35.  
36. uses
37.   LCLType;
38.  
39. { TForm1 }
40.  
41. procedure TForm1.Edit1Enter(Sender: TObject);
42. begin
43.   FOldEdit1Text := Edit1.Text;
44. end;
45.  
46. procedure TForm1.Edit1KeyDown(Sender: TObject; var Key: Word; Shift: TShiftState
47.   );
48. begin
49.   if Key = VK_ESCAPE then begin
50.     Edit1.Text := FOldEdit1Text;
51.     Edit1.SelectAll;
52.     Key := 0;
53.   end;
54. end;
55.  
56. procedure TForm1.Edit2Enter(Sender: TObject);
57. begin
58.   FOldEdit2Text := Edit2.Text;
59. end;
60.  
61. procedure TForm1.Edit2KeyDown(Sender: TObject; var Key: Word; Shift: TShiftState
62.   );
63. begin
64.   if Key = VK_ESCAPE then begin
65.     Edit2.Text := FOldEdit2Text;
66.     Edit2.SelectAll;
67.     Key := 0;
68.   end;
69. end;
70.  
71. end.  

Title: Re: Undoing text editing in TEdit, etc.
Post by: egsuh on September 18, 2019, 12:13:06 pm

@wp
I see. The function is not built-in. Writing such codes is not big deal.