The document provides steps to design and code a traffic light application in Borland C++ Builder. Key steps include: 1. Creating a form with a panel control and three shape controls to represent the red, yellow, and green lights. 2. Copying and pasting the shape controls, then adjusting their properties, to populate the panel with the three lights. 3. Adding a timer control to trigger light color changes. 4. Coding the timer's OnTimer event to change the brush color of each shape, representing the light transitions, on intervals representing the durations of each light.

1. Designing the Application
1. Start Borland C++ Builder with the default form
2. Change the Caption of the form to Traffic Light
3. Change its BorderStyle property to bsDialog
4. Change its dimensions to Height = 256 and Width = 112
5. From the Statndard tab of the Component Palette, double-click the Panel control
6. 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
7. While the panel is still selected on the form, from the Additional tab of the Component
Palette, double-click the Shape control
8. Change the following properties for the new Shape:
Brush: Color = clGray
Brush: Style = bsSolid
Height = 65
Left =8
Top =8
Width = 65
9. On the panel, click the newly added Shape to make sure it is selected. Press Ctrl + C to
copy it to the clipboard
10. Click anywhere on the panel to select it.
11. Press Ctrl + V to paste the Shape
12. While the new Shape is still selected, change its Left value to 8 and its Top value to 72
13. Click an empty area on the panel to select it and press Ctrl + V.
14. While the new shape is still selected, change its Left value to 8 and its Top value to 136
15. Click the panel on the form and ress Ctrl + V again
16. Change the properties of the new shape as follows:
Brush: Color = clRed
Height = 57
Left =8
Name = shpRed
Shape = stCircle
Top = 12
17. On the form, click the red circle and press Ctrl + C. Then press Ctrl + V to add a new Shape
18. Change its properties as follows:
Brush: Color = clSilver

2. Height = 57
Left =8
Name = shpYellow
Shape = stCircle
Top = 76
19. On the form, click the Panel and press Ctrl + V
20. Change the properties of the new Shape to:
Brush: Color = clSilver
Height = 57
Left =8
Name = shpGreen
Shape = stCircle
Top = 140
21. From the System tab of the Component Palette, double-click Timer
Coding the Application
1. On the Object Inspector, click the Events tab
2. Although the dialog box will be equipped with the system Close button, we should provide
our own meand of closing the application.
On the form, click the red circle.
3. Press and hold Shift, then click the other two circles
4. On the Object Inspector, double-click the empty area on the right side of OnMouseDown
5. Change the event as follows:
//---------------------------------------------------------------------------
void __fastcall TForm1::shpGreenMouseDown(TObject *Sender,
TMouseButton Button, TShiftState Shift, int X, int Y)
{
Close();
}
//---------------------------------------------------------------------------
6. Press F12 to display the form.
7. Double-click the Timer on the form to access its OnTimer event
8. Change its code as follows:
//---------------------------------------------------------------------------
void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
// If the current color is red
if( shpRed->Brush->Color == clRed )
{
// Change the color to green
Timer1->Interval = 3500;
shpRed->Brush->Color = clSilver;
shpYellow->Brush->Color = clSilver;
shpGreen->Brush->Color = clGreen;

3. }
// But if the color is green
else if( shpGreen->Brush->Color == clGreen )
{
// Change the color to yellow
Timer1->Interval = 2000;
shpRed->Brush->Color = clSilver;
shpYellow->Brush->Color = clYellow;
shpGreen->Brush->Color = clSilver;
}
// Otherwise, if the color is yellow
else // if(shpYellow->Brush->Color == clYellow
{
// Change the color to red
Timer1->Interval = 5000;
shpRed->Brush->Color = clRed;
shpYellow->Brush->Color = clSilver;
shpGreen->Brush->Color = clSilver;
}
}
//---------------------------------------------------------------------------
9. Test your program.