Mega Code Archive
Get the firstlast visible line of a TRichEdit
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Title: get the first/last visible line of a TRichEdit?
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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