procedure TForm1.Chart1BeforeDrawAxes(Sender: TObject);
var
  p1,p2,T : Double;
  tmpRect:TRect;
begin
  p1 := StrToFloat(Edit1.Text); // 下限
  p2 := StrToFloat(Edit2.Text); // 上限
  if p1 > p2 then
    begin
      t := p2;
      p2 := p1;
      p1 := t;
    end;
    tmpRect := Chart1.ChartRect;
    Chart1.Canvas.Brush.Style := bsSolid;
    Chart1.Canvas.Pen.Style := psClear;
    { adjust the rectangle dimension }
    if ((P1 < Chart1.LeftAxis.Minimum) and (p2 > Chart1.LeftAxis.Minimum)) then
      P1 := Chart1.LeftAxis.Minimum;
    if ((p1 < Chart1.LeftAxis.Maximum) and (p2 > Chart1.LeftAxis.Maximum)) then
      P2 := Chart1.LeftAxis.Maximum;
    tmpRect.Bottom := Chart1.LeftAxis.CalcYPosValue(P1);
    tmpRect.Top := Chart1.LeftAxis.CalcYPosValue(P2);
    { set the brush color }
    Chart1.Canvas.Brush.Color := clCream; // 顏色
    { paint !!! }
    if  ((p1 > Chart1.LeftAxis.Minimum) and (p1 < Chart1.LeftAxis.Maximum)) or
        ((p2 > Chart1.LeftAxis.Minimum) and (p2 < Chart1.LeftAxis.Maximum)) or
        ((p1 <= Chart1.LeftAxis.Minimum) and (p2 >= Chart1.LeftAxis.Maximum))then
    Chart1.Canvas.Rectangle(tmpRect.Left   Chart1.Width3D,
                            tmpRect.Top - Chart1.Height3D,
                            tmpRect.Right   Chart1.Width3D,
                            tmpRect.Bottom - Chart1.Height3D);
end;