Creating a Menu
For this project, you will create a program where the only Controls are a Timer and a Menu with the following structure (suggested Names are italicized in parentheses following the Caption names):
| Menu Table | ||||
| Level 1 Text |
Level 2 Text |
Level 3 Text |
Name | Checked |
| &File | (default name) | |||
| &Shape | (default name) | |||
| &Square | mnuSquares | True | ||
| &Rectangle | mnuRectangles | False | ||
| &Circle | mnuCircles | False | ||
| &Ellipse | mnuEllipses | False | ||
| &Clear | mnuClear | False | ||
| &Go | mnuGoStop | False | ||
| (Insert Separator) | ||||
| E&xit | mnuExit | False | ||
The Menu Table above builds this menu:
Adding a MainMenu control to the form
Double-click on the MainMenu item on the Control toolbox to add a MainMenu control (MainMenu1) to the Component Tray. Once added to your project, the MainMenu control appears in the Component Tray, like this:
To add MainMenu1 to the form, set the Menu property of the form to MainMenu1, like this (this illustration is from Project 8):
After setting the Menu property to MainMenu1 (which may have been set automatically when you added it to the component tray) click once on the MainMenu1 control in the Component Tray to selected it. Once ManuMenu1 is selected in the Component Tray, the new menu blank should appear in the upper left corner of the form, like this (this illustration is from Project 8):
Use the Menu Table above to guide you, and complete the rest of the menu.
Adding a Timer control to the form
When the user selects a Shape (Squares will be the default), and then chooses the Go menu item, the Timer control will be enabled. The Go menu item’s Text changes to Stop once the
Timer has started. The shape the user selected will be drawn on the Form at random places, in random sizes, and with random colors. Each tic of the Timer will draw another shape, until the user selects Stop from the Menu. When the user selects Stop, the Timer is disabled, and the Stop menu item’s Text changes back to Go. Choosing the Clear menu item erases any shapes on the form.Add the Timer control to the Component Tray by double clicking on the Timer control icon in the Control Toolbox (You may need to scroll down to the bottom of the component list to find it). The Timer control appears as a small stop watch icon in the Component Tray, like this:
Set these properties of the Timer control:
|
Timer |
|
| Property | Value |
| Name | tmrDraw |
| Enabled | False |
| Interval | 200 |
A Timer control has only 1 event procedure—Tick. The code that you place in the tmrDraw_Tick event procedure is executed every time the Tick event procedure happens. The number of ticks per second is set with the Interval property which uses milliseconds (milliseconds is thousandths of a second). So setting the Interval property to 200 milliseconds makes the Tick event go off every 2/10’s of a second, and setting the Interval property to 1000 milliseconds makes the Tick event go off once a second.
Add the following code to the Declarations section:
'Create a constant with a unique value for each shape
Const SQUARE As Integer = 1
Const CIR As Integer = 2
Const RECT As Integer = 3
Const ELLIPSE As Integer = 4
'iDrawWhat will be set to the shape the user
' selects. SQUARE is the default shape.
Dim iDrawWhat As Integer = SQUARE
The code for the mnuGoStop event procedure
Here is the code that goes into the mnuGoStop_Click event procedure:
'Does the mnuGoStop menu item say Go?
If mnuGoStop.Text= "&Go" Then
'Change the mnuGoStop menu item to Stop
mnuGoStop.Text = "&Stop"
'Turn on the tmrDraw timer
tmrDraw.Enabled = True
Else
'Change the mnuGoStop menu back to Go
mnuGoStop.Text = "&Go"
'Turn off the tmrDraw timer
tmrDraw.Enabled = False
End If
Notice how a Menu’s Text property value can be examined and changed dynamically. The Timer is also turned on and off within this procedure by setting its Enabled property to True or False.
The code for the tmrDraw_Tick event procedure
Here is the code from the tmrDraw_Tick event procedure that generates the random number values needed to draw the shapes with random colors (iColor), at random sizes (iSize), and at random places on the screen (iX, iY):
_'Values for all these variables will be randomly generated
Dim iRed, iGreen, iBlue As Integer
Dim iX, iY As Integer
Dim iSize As Integer
'Determines the width of rectangles and ellipses
Dim iRectWidth As Integer
'Create a Graphics class reference variable
Dim g As Graphics
'Refer g to the Graphics object of the form (Me). This will allow
' us to use the DrawRectangle and DrawEllipse methods.
g = Me.CreateGraphics'Seed the random-number generator. We really only need to do this
' once, so you could move this line of code to the frmProj9_Load.
Randomize()'Generate a random values between 0 and 255 for the color
' luminosity values--remember Project 2.
iRed = Int(Rnd() * 256)
iGreen = Int(Rnd() * 256)
iBlue = Int(Rnd() * 256)
'Create a drawing Pen, specifying it's color and thickness
Dim DrawPen As New
Pen(System.Drawing.Color.FromArgb(iRed, _
iGreen, iBlue), 1)
'Generate a random value between
5 and 50, for the size
' of the shapes in pixels.
iSize =
Int(Rnd()
* 46)
+ 5
'Generate X and
Y
starting points for drawing the shape
' within the form area.
iX =
Int(Rnd()
* Me.Width)
+ 1
iY =
Int(Rnd()
* Me.Height)
+ 1
