获取Richedit的可见的起始行和最后可见行号

起始行：

用EM_GETFIRSTVISIBLELINE消息即可。

结束行：

Var

 r: TRect;

 lastvisibleline, lastlineindex: Integer;

Begin

 richedit1.perform( EM_GETRECT, 0, longint( @r ));

 r.left := r.left+1;

 r.top := r.bottom - 2;

 lastlineindex := richedit1.perform( EM_CHARFROMPOS, 0,integer(@r.topleft));

 lastvisibleline := richedit1.perform( EM_EXLINEFROMCHAR, 0,lastlineindex);

end;

************************

function RE_GetLastVisibleLine(RichEdit: TRichEdit): Integer;

const

EM_EXLINEFROMCHAR = WM_USER + 54;

var

 r: TRect;

 i: Integer;

begin

{

The EM_GETRECT message retrieves the formatting rectangle

of an edit control.

}

 RichEdit.Perform(EM_GETRECT, 0, Longint(@r));

 r.Left := r.Left + 1;

 r.Top := r.Bottom - 2;

{

The EM_CHARFROMPOS message retrieves information about the character

closest to a specified point in the client area of an edit control

}

 i := RichEdit.Perform(EM_CHARFROMPOS, 0, Integer(@r.topleft));

{

The EM_EXLINEFROMCHAR message determines which

line contains the specified character in a rich edit control

}

 Result := RichEdit.Perform(EM_EXLINEFROMCHAR, 0, i);

end;

{

Sending the EM_GETFIRSTVISIBLELINE message to a multi-line edit control

finds out which line is the first line visible.

This is the line that is currently displayed at the top of the control.

}

function RE_GetFirstVisibleLine(RichEdit: TRichEdit): Integer;

begin

Result := RichEdit.Perform(EM_GETFIRSTVISIBLELINE, 0, 0);

end;

　

procedure TForm1.Button1Click(Sender: TObject);

begin

Caption:=Format('%d,%d',[RE_GetFirstVisibleLine(RichEdit1),RE_GetLastVisibleLine(RichEdit1)]);

end;