SystemCos (Delphi)

Description

This example displays the cosine of any value between 0 and 12. Since the scrollbar position is an integer between the scrollbar min and max, multiply the range and divide the position to regulate it. With the scrollbar selected, use the left and right buttons to change the position by 1E-6. You can also use the Dec function to decrement (or increment) by a specific amount.

Code

procedure TForm1.Button1Click(Sender: TObject);
var
  new : Integer;
begin
  new := ScrollBar1.Position;
  System.Dec(new, Round(StrToFloat(Edit3.Text)*1000000));
  ScrollBar1.Position := new;
  Edit1.Text := FloatToStr(ScrollBar1.Position/1000000);
  Edit2.Text := FloatToStr(Cos(ScrollBar1.Position/1000000));
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ScrollBar1.Max := Round(Pi * 4000000);   // 4 * Pi
end;

procedure TForm1.ScrollBar1Scroll(Sender: TObject; ScrollCode: TScrollCode;
  var ScrollPos: Integer);
begin
  Edit1.Text := FloatToStr(ScrollPos/1000000);
  Edit2.Text := FloatToStr(Cos(ScrollPos/1000000));
end;

Uses

• System.Cos ( fr | de | ja )
• System.Round ( fr | de | ja )
• System.Dec ( fr | de | ja )