Computer Programming Concepts and Visual Basic David I. Schneider

EXAMPLE 3
Write a program to draw the sector consisting of the bottom half of a circle and fill it with vertical lines.
SOLUTION:
Vertical lines correspond to a FillStyle of 3. See Figure 9-21 for the output of the following program.
Private Sub cmdDraw_Click()
Dim c As Single
‘Draw bottom half of circle filled with vertical lines
c = 2 * 3.14159
picSector.Cls
picSector.Scale (-3, 3)-(3, -3) ‘Specify coordinate system
picSector.FillStyle = 3 ‘Vertical lines
picSector.Circle (0, 0), 2, , -.5 * c, -1 * c
End Sub
FIGURE 9-21 Display from Example 3
The color used to fill the interior of a sector is determined by the value of the FillColor
property. If the FillStyle of a picture box is any value except 1, then the statement
picBox.FillColor = vbColor
where vbColor is a color constant, will cause new circles and sectors drawn in the picture box
to be filled with a colored pattern.
EXAMPLE 4
Write a program to subdivide a circle into four quadrants and fill in the second quadrant, that is, the quadrant
extending from radius line .25 to radius line .5, with magenta crosshatched lines.
SOLUTION:
Crosshatched lines correspond to a FillStyle of 6. See Figure 9-22 for the output of the following program.
Private Sub cmdDraw_Click()
Dim c As Single
‘Draw quarters of circle and paint upper-left quadrant
c = 2 * 3.14159
picBox.Cls picBox.Scale (-3, 3)-(3, -3) ‘Specify coordinate system
picBox.Circle (0, 0), 2, , -.0000001 * c, -.25 * c
picBox.FillStyle = 6 ‘Crosshatched
picBox.FillColor = vbMagenta
picBox.Circle (0, 0), 2, , -.25 * c, -.5 * c
picBox.FillStyle = 1 ‘Transparent
picBox.Circle (0, 0), 2, , -.5 * c, -.75 * c
picBox.Circle (0, 0), 2, , -.75 * c, -1 * c
End Sub
FIGURE 9-22 Display from Example 4
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