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標題: 如何在Chart中选取部分？ [打印本頁]

作者: mhfo 時間: 2017-6-9 11:43 標題: 如何在Chart中选取部分？

如何在Chart中选取部分？

Hi lilin,

根据您的要求，建议您使用矩形来选择捕获的点，具体如何实现请参考以下代码:

Private mdown As Point = Point.Empty

Private selectedPoints As List(Of DataPoint) = Nothing

Private Sub chart1_MouseDown(sender As Object, e As MouseEventArgs)

      mdown = e.Location

      selectedPoints = New List(Of DataPoint)()

End Sub

Private Sub chart1_MouseMove(sender As Object, e As MouseEventArgs)

      If e.Button = System.Windows.Forms.MouseButtons.Left Then

         Chart1.Refresh()

         Using g As Graphics = Chart1.CreateGraphics()

            g.DrawRectangle(Pens.Red, GetRectangle(mdown, e.Location))

         End Using

      End If

End Sub

Private Sub chart1_MouseUp(sender As Object, e As MouseEventArgs)

      Dim ax As Axis = Chart1.ChartAreas(0).AxisX

      Dim ay As Axis = Chart1.ChartAreas(0).AxisY

      Dim rect As Rectangle = GetRectangle(mdown, e.Location)

      For Each dp As DataPoint In Chart1.Series(0).Points

         Dim x As Integer = CInt(ax.ValueToPixelPosition(dp.XValue))

         Dim y As Integer = CInt(ay.ValueToPixelPosition(dp.YValues(0)))

         If rect.Contains(New Point(x, y)) Then

            selectedPoints.Add(dp)

         End If

      Next

      ' optionally color the found datapoints:

      For Each dp As DataPoint In Chart1.Series(0).Points

         dp.Color = If(selectedPoints.Contains(dp), Color.Red, Color.Black)

      Next

End Sub

Public Shared Function GetRectangle(p1 As Point, p2 As Point) As Rectangle

      Return New Rectangle(Math.Min(p1.X, p2.X), Math.Min(p1.Y, p2.Y), Math.Abs(p1.X - p2.X), Math.Abs(p1.Y - p2.Y))

End Function

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