zedgraph, how to convert XAxis.Scale.Min to a date

问题

I use zedgraph to draw figures in my vb.net project. The x axis of figure is date. I have two text boxes showing the minimum and maximum values of x axis in date. The following code shows how to get x axis values when a figure is zoomed by using isEnableWheelZoom property, also see this link zedgraph EnableWheelZoom, how to get axis values after zooming?. But I found that I only get axis value, e.g. 4508.345, but NOT the date that I want. Actually on figure, it shows date correctly. My question is how to get the minimum and maximum date on figure?

    Friend WithEvents gcMain As ZedGraph.ZedGraphControl 
Me.gcMain.IsZoomOnMouseCenter = True 
Me.gcMain.IsEnableWheelZoom = True 

    Private Sub gcMain_ZoomEvent(ByVal sender As ZedGraphControl, ByVal oldState As ZoomState, ByVal newState As ZoomState) Handles gcMain.ZoomEvent
    tbxRangeStart.Text = CStr(New XDate(gcMain.GraphPane.XAxis.Scale.Min))
    tbxRangeEnd.Text = CStr(New XDate(gcMain.GraphPane.XAxis.Scale.Max))

End Sub

回答1:

You almost got it. You only need to convert it to DateTime:

Dim minDate As XDate = New XDate(gcMain.GraphPane.XAxis.Scale.Min)
tbxRangeStart.Text = minDate.DateTime.ToString()

See API for more information about the XData-Format.

回答2:

Actually, XAxis.Min and XAxis.Max are XLDate. So the answer is to use XLDateToCalendarDate

Private Sub gcMain_ZoomEvent(ByVal sender As ZedGraphControl, ByVal oldState As ZoomState, ByVal newState As ZoomState) Handles gcMain.ZoomEvent

    Dim xlMin, xlMax As Double
    Dim year, month, day, hour, minute As Integer
    Dim second As Double
    Dim dateStart As Date
    Dim dateEnd As Date

    xlMin = gcMain.GraphPane.XAxis.Scale.Min
    xlMax = gcMain.GraphPane.XAxis.Scale.Max

    ZedGraph.XDate.XLDateToCalendarDate(xlMin, year, month, day, hour, minute, second)
    dateStart = New Date(year, month, day, hour, minute, CInt(second))

    ZedGraph.XDate.XLDateToCalendarDate(xlMax, year, month, day, hour, minute, second)
    dateEnd = New Date(year, month, day, hour, minute, CInt(second))

                SetDateText(textbox1.TextBox, dateStart)
                SetDateText(text)

End Sub

    Private Sub SetDateText(ByRef tbx As TextBox, ByVal dte As Date)
    Try
        tbx.Text = dte.Hour.ToString("00") + " : " + dte.Minute.ToString("00")
    Catch
    End Try
End Sub

来源：https://stackoverflow.com/questions/8538353/zedgraph-how-to-convert-xaxis-scale-min-to-a-date

标签

vb.net

zedgraph