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Получить первую или последнюю видимую строку в TRichEdit

01.01.2007
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;
 

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