delphi的 memo1.PaintTo()方法能干什么？

就是把这个控件画到某个Device Content（在Delphi里，你可以理解为Canvas）上面。
procedure TForm1.Button1Click(Sender:TObject);

var
I, Start, Stop: Integer;
begin
PrintDialog1.Options := [poPageNums, poSelection];
PrintDialog1.FromPage := 1;
PrintDialog1.MinPage := 1;
PrintDialog1.ToPage := PageControl1.PageCount;
PrintDialog1.MaxPage := PageControl1.PageCount;
if PrintDialog1.Execute then
begin
{ determine the range the user wants to print }
with PrintDialog1 do
begin
if PrintRange = prAllPages then

begin
Start := MinPage - 1;
Stop := MaxPage - 1;
end
else if PrintRange = prSelection then
begin
Start := PageControl1.ActivePage.PageIndex;
Stop := Start;
end
else { PrintRange = prPageNums }
begin
Start := FromPage - 1;
Stop := ToPage - 1;