不是最好的解决方案,但它有效:
function GetTextWidth(F: TFont; s: string): integer;
var
l: TLabel;
begin
l := TLabel.Create(nil);
try
l.Font.Assign(F);
l.Caption := s;
l.AutoSize := True;
result := l.Width + 8;
finally
l.Free;
end;
end;
并将以下代码添加到此答案中 Memo1.Onchange 事件的末尾
LineInd := Memo1.Perform(EM_LINEFROMCHAR, Memo1.SelStart, 0);//focused Memo1 line Index
Wd := GetTextWidth(Memo1.Font, Memo1.Lines[LineInd]);
//MaxWidthLineInd = index of the line which has the largest width.
//Init value of MaxWidthLineInd = 0
if MaxWidthLineInd = LineInd then
Memo1.Width := Wd
else begin
if Wd > Memo1.Width then
begin
Memo1.Width := Wd;
MaxWidthLineInd := LineInd;
end;
end;