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| Title | Graph XY plots using MSChart |
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| Keywords | MSChart, plot, XY plot, graph, equation, chart |
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| Categories | Graphics, Controls |
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When the program loads, it builds a two-dimensional array of X and Y values that it wants to plot. It then sets the MSChart control's ChartData property to the array. To make this an XY plot, the program sets the MSChart control's ChartType property to VtChChartType2dXY.
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Private Sub Form_Load()
Dim theta_min As Single
Dim theta_max As Single
Dim dtheta As Single
Dim theta As Single
Dim r As Single
Dim values() As Single
Dim i As Integer
Dim num_theta As Integer
theta_min = 0
theta_max = 3.14159265
num_theta = 100
dtheta = theta_max / (num_theta - 1)
ReDim values(1 To num_theta, 1 To 2)
' Compute the data values.
theta = theta_min
For i = 1 To num_theta
r = Cos(3 * theta)
values(i, 1) = r * Sin(theta) * 100
values(i, 2) = r * Cos(theta) * 100
theta = theta + dtheta
Next i
' Send the data to the chart.
Chart1.chartType = VtChChartType2dXY
Chart1.RowCount = 2
Chart1.ColumnCount = num_theta
Chart1.ChartData = values
End Sub
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My book Custom Controls Library implements a control that does simple graphics without the MSChart control.
Tip: Setting properties in code like this rather than at design time can be very useful for controls such as MSChart that get upgraded frequently. If you install a newer version of the control and remove the old version, then when you open an application the old control is replaced by a PictureBox and all of its properties are lost (although you can still read them in the .frm file with a text editor). If you set the properties in the code, you only need to replace the control and the code can set the properties for the new control.
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