This lesson taught you how to use the printer for text reports and use the screen for fancy graphics. Although business and scientific data processing requires printed reports, this unit's real glamour appeared in Unit 22 when
you learned all about the line and shape controls.
The visual in Visual Basic becomes most apparent when you add graphics that capture the user's eye. Perhaps the control that provides more different
formats than any other is the shape control, which enables you to draw squares, circles, and
ovals of all shapes, sizes, and colors. This unit takes the shape control to the max by demonstrating a fancy form that blows up in your face with more than 150
sets of colored circles, squares, and ovals.
In this lesson, you saw the following:
Figure P11.1 shows the PROJEC11.MAK opening Form window. Wow! When you load and run the program, the program generates all kinds of
circles on the form. The entire collection of circles, as well as the subsequent graphic collections that appear after
the circles, all are different owing to the program's use of the Rnd() function introduced in project 10.
Figure P11.1. Project 11 runs circles around other applications.
As you click the Next Shape command button, the program replaces the circles with a similar mosaic of squares. Pressing Next Shape again
produces a series of ovals. You can continue cycling through the circles, squares, and ovals as often as you want
until you press the Exit command button to terminate the program.
The program contains a control array with 160 shape controls
named shpShape. Figure P11.2 shows the form at design time. The location of the shape controls at design time is irrelevant to the program because the code relies heavily on the Rnd() function
to display the shapes in random screen locations, with random
colors, sizes, and fill patterns.
Figure P11.2. project 11's design mode shows an interesting placement of a control array containing shapes.
The program depends so much
on the Rnd() function that a special function subroutine is included that converts Rnd() into a random number, from 1 to whatever argument is passed to the function. The function procedure's name is RndNum(); you'll see the
function in the code
description that appears in Listing P11.1.
Listing P11.1. The code that generates all the graphics on the form.
1: Option Explicit 2: 3: Sub Form_Activate () 4: ' Get things started by displaying circles 5: Call Circles 6: End Sub 7: 8: Sub Circles () 9: ' Draws several circles of different 10: ' colors and sizes on the form 11: Dim Count As Integer 12: lblShape.Caption = "Circles" 13: For Count = 0 To 159 ' 160 total shapes 14: shpShape(Count).Shape = SHAPE_CIRCLE 15: shpShape(Count).Visible = False 16: shpShape(Count).Top = RndNum(3000) 17: shpShape(Count).Width = RndNum(5000) 18: shpShape(Count).Height = RndNum(3000) 19: shpShape(Count).Left = RndNum(3000) 20: shpShape(Count).BackColor = QBColor(RndNum(16) - 1) ' Adjust for zero 21: shpShape(Count).FillColor = QBColor(RndNum(16) - 1) ' Adjust for zero 22: shpShape(Count).Visible = True 23: shpShape(Count).FillStyle = RndNum(8) - 1 ' Adjust for zero 24: Next Count 25: End Sub 26: 27: Sub Ovals () 28: ' Draws several ovals of different 29: ' colors and sizes on the form 30: Dim Count As Integer 31: lblShape.Caption = "Ovals" 32: For Count = 0 To 159 ' 160 total shapes 33: shpShape(Count).Shape = SHAPE_OVAL 34: shpShape(Count).Visible = False 35: shpShape(Count).Top = RndNum(3000) 36: shpShape(Count).Width = RndNum(4000) 37: shpShape(Count).Height = RndNum(3000) 38: shpShape(Count).Left = RndNum(3000) 39: shpShape(Count).BackColor = QBColor(RndNum(16) - 1) ' Adjust for zero 40: shpShape(Count).FillColor = QBColor(RndNum(16) - 1) ' Adjust for zero 41: shpShape(Count).Visible = True 42: shpShape(Count).FillStyle = RndNum(8) - 1 ' Adjust for zero 43: Next Count 44: End Sub 45: 46: Sub Squares () 47: ' Draws several squares of different 48: ' colors and sizes on the form 49: Dim Count As Integer 50: lblShape.Caption = "Squares" 51: For Count = 0 To 159 ' 160 total shapes 52: shpShape(Count).Shape = SHAPE_SQUARE 53: shpShape(Count).Visible = False 54: shpShape(Count).Top = RndNum(3000) 55: shpShape(Count).Width = RndNum(5000) 56: shpShape(Count).Height = RndNum(3000) 57: shpShape(Count).Left = RndNum(3000) 58: shpShape(Count).BackColor = QBColor(RndNum(16) - 1) ' Adjust for zero 59: shpShape(Count).FillColor = QBColor(RndNum(16) - 1) ' Adjust for zero 60: shpShape(Count).Visible = True 61: shpShape(Count).FillStyle = RndNum(8) - 1 ' Adjust for zero 62: Next Count 63: End Sub 64: 65: Sub cmdShape_Click () 66: ' Check the caption of the description 67: ' label to see what shapes to draw next 68: Select Case Left$(lblShape.Caption, 1) 69: Case "C": 70: Call Squares 71: Case "S" 72: Call Ovals 73: Case "O": 74: Call Circles 75: End Select 76: End Sub 77: 78: Sub cmdExit_Click () 79: End 80: End Sub 81: 82: Function RndNum (n) 83: ' Returns a random number from 1 to n 84: RndNum = Int(n * Rnd + 1) 85: End Function
1: Requires that all variables be defined before their use.
2: A blank line that
helps separate parts of the program.
3: The code for the event procedure that executes as soon as the user sees the form for the first time.
4: A remark that explains the procedure.
4: Always remember to generate an initial form.
5: Execute the subroutine procedure that draws the circles.
6: Terminate the procedure.
7: A blank line
separates procedures.
8: The subroutine procedure that draws circles.
9: A remark that explains the procedure.
10: The remark continues.
11: Define a variable that will control the loop.
12: Set the caption
on the description label.
13: Step through all 160 elements of the control array.
13: There are 160 elements in the shape control array to display.
14: Set the shape of each control to a circle.
15: Hide the control, temporarily, until the properties are set.
16: Set an appropriate placement from the top of the form.
17: Set an appropriate
width.
18: Set an appropriate height.
19: Set an appropriate placement from the left edge of the form.
20: Set the background color by calling the built-in QBColor() function and passing a value from 0 to 15.
21: Set
the fill color by calling the built-in QBColor() function and passing a value from 0 to 15.
22: Display the control now that the size and placement properties are set.
23: Fill the shape with a fill number from 0 to 8.
24:
Prepare for the next shape in the control array.
25: Terminate the procedure.
26: A blank line separates the procedures.
27: The subroutine procedure that draws ovals.
28: A remark that explains the procedure.
29: The remark continues.
30: Define a variable that will control the loop.
31: Set the caption on the description label.
32: Step through all 160 elements of the control array.
33: Set the shape of each control
to a oval.
34: Hide the control, temporarily, until the properties are set.
35: Set an appropriate placement from the top of the form.
36: Set an appropriate width.
37: Set an appropriate height.
38: Set an
appropriate placement from the left edge of the form.
39: Set the background color by calling the built-in QBColor() function and passing a value from 0 to 15.
39: The QBColor() function accepts a value from 0 to 15 that represents a different color.
40: Set the fill color by calling the built-in QBColor() function and passing a value from 0 to 15.
41:
Display the control now that the size and placement properties are set.
42: Fill the shape with a fill number from 0 to 8.
43: Prepare for the next shape in the control array.
44: Terminate the procedure.
45: A blank
line separates the procedures.
46: The subroutine procedure that draws squares.
47: A remark that explains the procedure.
48: The remark continues.
49: Define a variable that will control the loop.
50: Set
the caption on the description label.
51: Step through all 160 elements of the control array.
52: Set the shape of each control to a square.
52: The named constants in CONSTANT.TXT eliminate the need to remember numeric property equivalents.
53: Hide the control, temporarily, until the properties are set.
54: Set an appropriate placement from the
top of the form.
55: Set an appropriate width.
56: Set an appropriate height.
57: Set an appropriate placement from the left edge of the form.
58: Set the background color by calling the built-in QBColor() function
and passing a value from 0 to 15.
59: Set the fill color by calling the built-in QBColor() function and passing a value from 0 to 15.
60: Display the control now that the size and placement properties are set.
61: Fill the
shape with a fill number from 0 to 8.
62: Prepare for the next shape in the control array.
63: Terminate the procedure.
64: A blank line separates the procedures.
65: A procedure that executes to display the next set
of shapes when the user clicks the cmdShape command button.
66: A remark that explains the procedure.
67: The remark continues.
68: Determine the next shape by looking at the label that describes the previously displayed
shape.
68: The code looks at the first character of the label to decide what shape to display next.
69: If the label contains
Circles...
70: Change the display to random squares.
71: If the label contains Squares...
72: Change the display to random ovals.
73: If the label contains Ovals...
74: Change the display to random circles.
75: Terminate the Select statement.
76: Terminate the procedure.
77: A blank line separates the procedures.
78: A procedure that ends the program when the user clicks the cmdExit command button.
79:
Terminate the program's execution.
80: Terminate the procedure.
81: A blank line separates the procedures.
82: A function procedure that accepts an integer argument and that returns a random number from 1 to the argument.
83: A remark explains the function.
84: Set the function's return value to the generated random number.
84: A function procedure keeps you from having to repeat the same code throughout the program.
You now can exit the application and exit Visual Basic. The next lesson teaches you how to use the remaining controls and Visual Basic's online debugging tool to help locate and correct errors within code.
