【Delphi / C++Builder 10.2 Tokyo 新機能・改善点】ライブラリ周りの機能など ref: http://qiita.com/kazaiso/items/f100d480eaf2fd997668

file0.txt

for I := 0 to 10000 do
begin
  // thread work
  Canvas.BeginScene;
  try
    // drawing code
  finally
    Canvas.EndScene;
  end;
end;

file1.txt

Canvas.BeginScene;
try
  for I := 0 to 10000 do
  begin
    // thread code
    // drawing code
  end;
finally
  Canvas.EndScene;
end;