C++ Builder - Timer

	The Timer Control

Designing the Application

Start Borland Delphi with the default form
Change the Caption of the form to Traffic Light
Change its BorderStyle property to bsDialog
Change its dimensions to Height = 256 and Width = 112
From the Standard tab of the Component Palette, double-click the Panel control
Change the properties of the panel as follows:
    BevelInner = bvNone
    BevelOuter = bvLowered
    BevelWidth = 5
    Caption      = Empty
    Color         = clBlack
    Height        = 209
    Left            = 17
    Top            = 8
    Width         = 81
While the panel is still selected on the form, from the Additional tab of the Component Palette, double-click the Shape control
Change the following properties for the new Shape:
    Brush: Color    = clGray
    Brush: Style    = bsSolid
    Height             = 65
    Left                  = 8
    Top                  = 8
    Width               = 65
On the panel, click the newly added Shape to make sure it is selected. Press Ctrl + C to copy it to the clipboard
Click anywhere on the panel to select it.
Press Ctrl + V to paste the Shape
While the new Shape is still selected, change its Left value to 8 and its Top value to 72
Click an empty area on the panel to select it and press Ctrl + V.
While the new shape is still selected, change its Left value to 8 and its Top value to 136
Click the panel on the form and ress Ctrl + V again
Change the properties of the new shape as follows:
    Brush: Color = clRed
    Height            = 57
    Left                = 8
    Name             = shpRed
    Shape            = stCircle
    Top                = 12
On the form, click the red circle and press Ctrl + C. Then press Ctrl + V to add a new Shape
Change its properties as follows:
    Brush: Color    = clSilver
    Height            = 57
    Left                = 8
    Name               = shpYellow
    Shape                = stCircle
    Top                    = 76
On the form, click the Panel and press Ctrl + V
Change the properties of the new Shape to:
    Brush: Color    = clSilver
    Height            = 57
    Left                = 8
    Name            = shpGreen
    Shape            = stCircle
    Top                = 140
From the System tab of the Component Palette, double-click Timer

Coding the Application

On the Object Inspector, click the Events tab
Although the dialog box will be equipped with the system Close button, we should provide our own means of closing the application.
On the form, click the red circle
Press and hold Shift, then click the other two circles, and release Shift
On the Object Inspector, double-click the empty area on the right side of OnMouseDown

Change the event as follows:

procedure TForm1.shpRedMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
     Close
end;

Press F12 to display the form.
Double-click the Timer on the form to access its OnTimer event

Change its code as follows:

procedure TForm1.Timer1Timer(Sender: TObject);
begin
     // If the current color is red
    if shpRed.Brush.Color = clRed then
    begin
        // Change the color to green
        Timer1.Interval       := 3500;
        shpRed.Brush.Color    := clSilver;
        shpYellow.Brush.Color := clSilver;
        shpGreen.Brush.Color  := clGreen;
    end
    // But if the color is green
    else if shpGreen.Brush.Color = clGreen then
    begin
        // Change the color to yellow
        Timer1.Interval       := 2000;
        shpRed.Brush.Color    := clSilver;
        shpYellow.Brush.Color := clYellow;
        shpGreen.Brush.Color  := clSilver;
    end
    // Otherwise, if the color is yellow
    else // if(shpYellow->Brush->Color == clYellow
    begin
        // Change the color to red
        Timer1.Interval       := 5000;
        shpRed.Brush.Color    := clRed;
        shpYellow.Brush.Color := clSilver;
        shpGreen.Brush.Color  := clSilver;
    end;
end;

end.

Test your program.