Create a margin in a rich edit control?

Posted on 2002-07-23
Medium Priority
Last Modified: 2010-04-04
I want to create a working margin at the left of a rich edit control. This makes the text easier to read. At present I have a panel (white with no borders) beside the rich edit and this gives the desired look.

| Panel| Rich edit                   |
|      |                             |
|      |                             |

The problem is when users try to select text from the beginning of a line in the rich edit but start their selection on the panel. This means the selection operation does not work as they continue to drag the mouse from the panel over the rich edit.

Can someone tell me how to write code for mouse events on the panel that will let the selection action work in the rich edit even though it starts from the panel.
Or can someone show me how to alter the width of the very narrow margin that is at the left of rich edit controls.

With thanks - Dan
Question by:seabear
  • 2
LVL 27

Expert Comment

ID: 7172713
here is sample
it applys to the current paragraph,
just set it before inserting text

unit re_left_margin_u;


  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ComCtrls,
  richedit;  //richedit is used

  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    RichEdit1: TRichEdit;
    procedure Button1Click(Sender: TObject);
    { Private declarations }
    { Public declarations }

  Form1: TForm1;


{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
  ParaFormat : TParaFormat;
  ParaFormat.cbSize := SizeOf(ParaFormat);
  ParaFormat.dxStartIndent := strtoint(edit1.text);

  ParaFormat.dwMask := PFM_STARTINDENT;


hope this helps

meikl ;-)
LVL 27

Expert Comment

ID: 7172720
use high values (50, 100, 200 or more)
as you need
LVL 35

Accepted Solution

Slick812 earned 800 total points
ID: 7173092
hello seabear, I tried using a method similar to kretzschmar's except usint the RichEdit Paragraph -
RichEdit1.Paragraph.LeftIndent := 16;
a while back to get a type of margin on a TRichedit, I tried looping through the Lines Count and setting the LeftIndent in the RichEdit.OnChange, but I had no Luck? ? But with your method of using a TPanel you could try using the panel's OnMouseDown

procedure TForm1.Panel1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
{first get the focus to the RichEdit}
{get the mouse messages to go to RichEdit}
SendMessage(RichEdit1.Handle, WM_LBUTTONDOWN, MK_LBUTTON, MAKELONG(0,Y));
{fire a mouse click on the RichEdit}

- - - - -  - -- - -  - - - -
this seemed to work for me


Author Comment

ID: 7175821
Hi Slick812 and Meikle,
  Thank you both for your answers. Sending a mouse down message to the panel fits simply into my existing design and is independant of what is being done to the text so that is the approach I will use. I am very pleased by how nicely it works.

Thanks again - Dan

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