Automatically allowing Ctrl+A to select all in a TMemo?

Question

In Delphi 7‘s TMemo control, an attempt to do the key combo Ctrl + A to select all does not do anything (doesn‘t select all). So I‘ve made this procedure:

procedure TForm1.Memo1KeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
var
  C: String;
begin
  if ssCtrl in Shift then begin
    C:= LowerCase(Char(Key));
    if C = ‘a‘ then begin
      Memo1.SelectAll;
    end;
  end;
end;

Is there a trick so that I don‘t have to do this procedure? And if not, then does this procedure look OK?

Personally I‘d sooner create a component derived from the standard memo and handle the key press there so that you don‘t need to pollute all your forms with special handling code. – David Heffernan Dec 11 ‘11 at 19:33 — David Heffernan, Dec 11 ‘11 at 19:33
@David: Do you know if a standard Windows edit control in multiline mode disallows the Ctrl+A command, or if there is a problem with the VCL wrapper? (TheTEdit handles Ctrl+A as one would expect.) – Andreas Rejbrand Dec 11 ‘11 at 19:35 — Andreas Rejbrand, Dec 11 ‘11 at 19:35
@Andreas Once I can get to a machine with a compiler I‘ll try and produce a raw win32 petzold prog and check it out. – David Heffernan Dec 11 ‘11 at 19:51 — David Heffernan, Dec 11 ‘11 at 19:51
It seems to be an OS issue with no documented explanation. Many posts about it are just based on code this by your own. – TLama Dec 11 ‘11 at 19:54 — TLama, Dec 11 ‘11 at 19:54
@David: If I am not mistaken, Raymond asks his readers every now and then about things to write about. This would be an interesting topic. – Andreas Rejbrand Dec 11 ‘11 at 20:56 — Andreas Rejbrand, Dec 11 ‘11 at 20:56

Andreas Rejbrand · Accepted Answer · 2011-12-11 19:30:08Z

up vote 20down voteaccepted

This is more elegant:

procedure TForm1.Memo1KeyPress(Sender: TObject; var Key: Char);
begin
  if Key = ^A then  牛人搞了一个更简单的
  begin
    (Sender as TMemo).SelectAll;
    Key := #0;  这里 为#0后，就没有BEEP声音了，Windows系统接不到按了什么键。
  end;
end;

answered Dec 11 ‘11 at 19:30

Andreas Rejbrand
60.4k3152244

4

I know I‘m going on a bit but could you possibly explain the ^A for the uninitiated (e.g. me!) – David Heffernan Dec 11 ‘11 at 19:44

9

The Ctrl+A keystroke is send as a character with ordinal value 1 (Ctrl+B as 2, Ctrl+C as 3, etc.). Basically I think that this is a remnant from older times. These ‘characters‘ are usually written ^A, ^B, etc., and Delphi supports these. You can see them in ASCII tables, like at Wikipedia. – Andreas Rejbrand Dec 11 ‘11 at 19:48

2

Haven‘t seen that for years, must be from TP days. – Tony Hopkinson Dec 11 ‘11 at 20:01

5

@Jerry: The result is not exactly the same. Your code will not handle the annoying ‘beep‘ sound! – Andreas Rejbrand Dec 11 ‘11 at 21:46 这个结果和你的代码效果，不是完全相同的，你的代码没有处理这个烦人的 BEEP声音。

2

@Jerry - AFAIK there‘s no fix to this. This is the default behavior of a windows edit control, you can read about expected behavior of an edit control here. – Sertac Akyuz Dec 11 ‘11 at 22:43

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TMemo Ctrl + A

Automatically allowing Ctrl+A to select all in a TMemo?

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How to add the "Select All (CTRL+A)" functionality to TMemo/TDBMemo