vb.net 教程 5-12 绘图实例之统计图3- VB

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继续上一期《绘图实例之统计图2》，继续讲解如何绘制饼图：

当按下“饼图”按钮时，调用三个函数，分别是绘制饼图、显示到窗口，由于不需要坐标轴，所以这里不再绘制坐标轴：

Private Sub btnPie_Click(sender As Object, e As EventArgs) Handles btnPie.Click
Call DrawPie()
Call DrawToForm()
End Sub
DrawToForm()在之前已经介绍，以下是DrawPie的代码：

'绘制饼图
Private Sub DrawPie()
'标注每个季度
Dim seasonValue(3) As Integer
seasonValue(0) = nudSeason1.Value
seasonValue(1) = nudSeason2.Value
seasonValue(2) = nudSeason3.Value
seasonValue(3) = nudSeason4.Value
Dim seasonName() As String = {"一季度", "二季度", "三季度", "四季度"}
'我们要获得4个季度总的盈利
Dim seasonSum As Integer = 0
For i As Integer = 0 To 3
seasonSum += seasonValue(i)
Next
'根据总赢利情况，来获得每个季度在饼图中所占的份额（角度）
'为了简化起见，这里直接取整数
Dim seasonAngle(4) As Integer
seasonAngle(0) = 0
seasonAngle(1) = seasonValue(0) * 360 \ seasonSum
seasonAngle(2) = seasonValue(1) * 360 \ seasonSum + seasonAngle(1)
seasonAngle(3) = seasonValue(2) * 360 \ seasonSum + seasonAngle(2)
seasonAngle(4) = 360
'分别用4种颜色表示不同季度的盈利--http://blog.csdn.net/uruseibest
Dim seasonColor() As Color = {Color.Red, Color.Blue, Color.Green, Color.GreenYellow}
For i As Integer = 0 To 3
g.FillPie(New SolidBrush(seasonColor(i)), New Rectangle(100, 100, 200, 200), seasonAngle(i), seasonAngle(i + 1) - seasonAngle(i))
'饼图中特别需要说明每个季度对应的颜色
g.FillRectangle(New SolidBrush(seasonColor(i)), New Rectangle(360, i * 50 + 80, 60, 40))
'标出每个季度
g.DrawString(seasonName(i), New Font("宋体", 12), New SolidBrush(Color.Black), New Point(450, i * 50 + 90))
Next

End Sub