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Detecting modified lines in richedit control

Posted on 2001-07-21
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Last Modified: 2013-11-22
I'm writing an application which uses TRichEdit.
When an user modifies anything in a richedit control an OnChange event is launched. What I need is to detect which lines were actually modified by the user.
In most cases this is easy, as the line modified is the same where the caret is. The problem is when someone pastes 2 or more lines of text, or drag-drops a selection of text...

How can I do this?

Thanks
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Question by:wizcool
3 Comments
 
LVL 5

Accepted Solution

by:
alanwhincup earned 800 total points
ID: 6306319
Try this:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ComCtrls;

type
  TForm1 = class(TForm)
    RichEdit1: TRichEdit;
    Label1: TLabel;
    procedure RichEdit1Enter(Sender: TObject);
    procedure RichEdit1KeyPress(Sender: TObject; var Key: Char);
    procedure RichEdit1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure RichEdit1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  PreLine : Integer;

implementation

{$R *.DFM}

procedure TForm1.RichEdit1Enter(Sender: TObject);
begin
  PreLine := RichEdit1.CaretPos.Y + 1;
end;

procedure TForm1.RichEdit1KeyPress(Sender: TObject; var Key: Char);
begin
  PreLine := RichEdit1.CaretPos.Y + 1;
end;

procedure TForm1.RichEdit1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  PreLine := RichEdit1.CaretPos.Y + 1;
end;

procedure TForm1.RichEdit1Change(Sender: TObject);
var
  LineChanged : Integer;
begin
  LineChanged := RichEdit1.CaretPos.Y + 1;
  if PreLine = LineChanged then
    Label1.Caption := 'Line Changed: ' + IntToStr(LineChanged);
  if PreLine > LineChanged then
    Label1.Caption := 'Lines Changed: ' + IntToStr(LineChanged) + ' - ' + IntToStr(PreLine);
  if PreLine < LineChanged then
    Label1.Caption := 'Lines Changed: ' + IntToStr(PreLine) + ' - ' + IntToStr(LineChanged);
  PreLine := LineChanged;
end;

end.

Cheers,

Alan
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LVL 1

Expert Comment

by:filipecorreia
ID: 6309913
;)
0
 

Author Comment

by:wizcool
ID: 6310316
That worked fine, although I had to change the "TForm1.RichEdit1KeyPress" to "keyup" as the "keypress" event doesn't trigger when the cursor keys are pressed...

Thanks ;)
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