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Introduction
Pictures speak better than words. This
article helps you to display your data as a pie chart in
eVB. We all know that programming in eVb is easier than
other languages but drawing graphical charts like pie is
not that easy as we don't have any predefined functions
in eMbedded VB to draw pie charts. The application has a
form consisting of three controls PictureBox, textBox and
a command Button. When you click on the command button,
the pie chart and a legend is displayed in the Picture Box.
When you click on one of the legendry boxes, details of
that particular sector are displayed in the textbox.
What You Need
Microsoft
eMbedded Visual Basic version 3.0
Preface
Before answering your question "How
can I use this Pie Chart in my application?", let me first
tell you about the API calls and functions that have been
used in this application. To your surprise, drawline and
drawcircle are the only functions used in drawing the pie
chart. Calculating the sectors and painting them is complicated
and tricky. For those who aren't interested in the intricacies
can directly add the form to their application and with
minor changes done can represent their data as a pie chart.
In Command1_Click(), Initialize the
variable max_values and the array input_values with the
total number of values and actual values used in drawing
the pie chart.
Private Sub Command1_Click()
Command1.Enabled = False
Dim input_values() As Integer
Dim max_values As Integer
' initialize this variable with maximum
' number of values used to draw the chart
max_values = 4
' initialize this array with the actual
' values used to draw the chart
ReDim input_values(max_values)
input_values(0) = 10
input_values(1) = 30
input_values(2) = 75
input_values(3) = 60
' this function draws the pie chart.
Draw_Pie (input_values)
End Sub
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