MSChart怎么清除其数据?

mcgill 2003-12-19 09:50:41
我通过label_click事件触发一个msChart的统计显示,数据正确从数据库中读出,一切正常,但是当我再次点击label时,统计图会在现有的柱状统计显示的基础上再次添加一次数据,所以我想知道,怎么才能让mschart控件首先清空数据呢?
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mcgill 2003-12-22
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问题已经得到解决,看来我自己才是高手!呵呵
Kugool8 i 2021-06-15
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@mcgill 怎么解决的呀。请赐教
mcgill 2003-12-21
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这里没有高手吗?这个问题很难回答吗?
mcgill 2003-12-20
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你写的数据库的东西挺详细的,但是我想知道怎么清除其默认的数据,我再次点击的时候,她就在我的统计同上添加了默认的统计图表,怎么能每次都清除统计信息呢
online 2003-12-19
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定义一个过程
Option Explicit
Private Values() As Variant
Private NumPoints As Integer

Private Sub LoadData()
Dim db As Database
Dim qdef As QueryDef
Dim rs As Recordset
Dim dbname As String
Dim i As Integer

' 打开数据库
dbname = App.Path
If Right$(dbname, 1) <> "\" Then dbname = dbname & "\"
dbname = dbname & "data.mdb"
Set db = OpenDatabase(dbname)

' 获得数据库记录
Set qdef = db.CreateQueryDef("", _
"SELECT 产品类别, 销售额 FROM 销售额")
Set rs = qdef.OpenRecordset(dbOpenSnapshot)

' 查看数据库中记录数
rs.MoveLast
NumPoints = rs.RecordCount
ReDim Values(1 To NumPoints, 1 To 2)

' 加载数据
rs.MoveFirst
For i = 1 To NumPoints
Values(i, 1) = rs!产品类别
Values(i, 2) = rs!销售额 / 10000
rs.MoveNext
Next i
rs.Close
db.Close
End Sub

Private Sub label_click()
LoadData
' 使用MSChart控件显示数据
MSChart1.ChartData = Values
End Sub

每次单击后重新绑定,这样数据就不会累加

mschart控件首先清空数据??
控件放置后默认的有数据
如何安装mschart#Region "定义变量" Const XOffset As Integer = 50, Yoffset As Integer = 20 Dim WithEvents PicCurve As PictureBox Dim xStep As Single = 5, yStep As Single Dim ValueArray As ArrayList Dim ThresHold() As Single 'HIHI、HI、LO、LOLO Dim Name As String = "参数名" Dim Unit As String = "单位" #End Region #Region "构造函数、析构函数" Public Sub New(ByVal mPictureBox As PictureBox, ByVal mThresHold() As Single, ByVal mName As String) ValueArray = New ArrayList PicCurve = mPictureBox ThresHold = mThresHold mPictureBox.BorderStyle = BorderStyle.None Name = mName End Sub Protected Overrides Sub Finalize() MyBase.Finalize() ValueArray.Clear() End Sub #End Region #Region "添加要绘制的点的信息" Public Sub AddValue(ByVal Value As Single) 'Value = ThresHold(0) * Rnd() + ThresHold(3) '测试代码 ValueArray.Add(Value) Call DrawCurve(GetGraphics(PicCurve)) End Sub Public Sub AddValues(ByVal Values() As Single, ByVal G As Graphics) For i As Integer = 0 To Values.Length - 1 ValueArray.Add(Values(i)) Next Call DrawCurve(G) End Sub #End Region #Region "绘制点之间的连线" Private Sub DrawCurve(ByVal G As Graphics, Optional ByVal mClear As Boolean = True) If ValueArray.Count > 0 Then If mClear Then G.Clear(Color.White) G.SmoothingMode = Drawing2D.SmoothingMode.HighQuality Dim mPoints(ValueArray.Count - 1) As Point, Position As Integer = XOffset For i As Integer = ValueArray.Count - 1 To 0 Step -1 Dim ThisValue As Single = CType(ValueArray(i), Single) 'If Position < PicCurve.Width Then Position += xStep Else Exit For Position += xStep mPoints(i) = New Point(Position, (ThresHold(0) - ThisValue) * yStep + Yoffset) Next G.DrawCurve(Pens.Blue, mPoints) mPoints = Nothing End If End Sub #End Region #Region "绘制坐标系统" Private Sub DrawReferenceFrame(ByVal G As Graphics) Dim mPoint1 As New Point, mPoint2 As New Point '定义绘图画笔 Dim MyPen As New Pen(Color.Black, 3) Dim MyStringFormat As New System.Drawing.StringFormat MyStringFormat.Alignment = StringAlignment.Center Dim mSize As New SizeF MyPen.SetLineCap(Drawing2D.LineCap.NoAnchor, Drawing2D.LineCap.ArrowAnchor, Drawing2D.DashCap.Flat) Dim mFont As Font = New Font(FontFamily.GenericSansSerif, 12.0F, FontStyle.Bold) '绘制Y轴 MyPen.Color = Color.Black mPoint1 = New Point(XOffset, PicCurve.Height) mPoint2 = New Point(XOffset, 0) G.DrawLine(MyPen, mPoint1, mPoint2) '绘制X轴 MyPen.Color = Color.LightGreen mPoint1 = New Point(XOffset, PicCurve.Height / 2) mPoint2 = New Point(PicCurve.Width, PicCurve.Height / 2) G.DrawLine(MyPen, mPoint1, mPoint2) '绘制参数名 MyStringFormat.FormatFlags = StringFormatFlags.DirectionVertical mSize = G.MeasureString(Name, mFont) mPoint1.Offset(-mSize.Height, 0) G.DrawString(Name, mFont, Brushes.Black, mPoint1, MyStringFormat) '绘制参数各门限 MyPen.DashStyle = Drawing2D.DashStyle.Dash : MyPen.Width = 2 MyPen.SetLineCap(Drawing2D.LineCap.NoAnchor, Drawing2D.LineCap.NoAnchor, Drawing2D.DashCap.Round) 'HI If ThresHold(1) <> ThresHold(0) Then MyPen.Color = Color.Yellow mPoint1 = New Point(XOffset, (ThresHold(0) - ThresHold(1)) * yStep + Yoffset) mPoint2 = New Point(PicCurve.Width, (ThresHold(0) - ThresHold(1)) * yStep + Yoffset) G.DrawLine(MyPen, mPoint1, mPoint2) mSize = G.MeasureString(ThresHold(1).ToString, mFont) mPoint1.Offset(-mSize.Width, -mSize.Height / 2) G.DrawString(ThresHold(1).ToString, mFont, Brushes.Yellow, mPoint1) End If 'LO If ThresHold(2) <> ThresHold(3) Then mPoint1 = New Point(XOffset, (ThresHold(0) - ThresHold(2)) * yStep + Yoffset) mPoint2 = New Point(PicCurve.Width, (ThresHold(0) - ThresHold(2)) * yStep + Yoffset) G.DrawLine(MyPen, mPoint1, mPoint2) mSize = G.MeasureString(ThresHold(2).ToString, mFont) mPoint1.Offset(-mSize.Width, -mSize.Height / 2) G.DrawString(ThresHold(2).ToString, mFont, Brushes.Yellow, mPoint1) End If 'HIHI MyPen.Color = Color.Red mPoint1 = New Point(XOffset, Yoffset) mPoint2 = New Point(PicCurve.Width, Yoffset) G.DrawLine(MyPen, mPoint1, mPoint2) mSize = G.MeasureString(ThresHold(0).ToString, mFont) mPoint1.Offset(-mSize.Width, -mSize.Height / 2) G.DrawString(ThresHold(0).ToString, mFont, Brushes.Red, mPoint1) 'LOLO mPoint1 = New Point(XOffset, PicCurve.Height - Yoffset) mPoint2 = New Point(PicCurve.Width, PicCurve.Height - Yoffset) G.DrawLine(MyPen, mPoint1, mPoint2) mSize = G.MeasureString(ThresHold(3).ToString, mFont) mPoint1.Offset(-mSize.Width, -mSize.Height / 2) G.DrawString(ThresHold(3).ToString, mFont, Brushes.Red, mPoint1) MyPen.Dispose() mFont.Dispose() End Sub #End Region #Region "要在其上绘制的控件事件" Private Sub PicCurve_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles PicCurve.Paint Call DrawReferenceFrame(e.Graphics) End Sub Private Sub PicCurve_Resize(ByVal sender As Object, ByVal e As System.EventArgs) Handles PicCurve.Resize On Error Resume Next xStep = 5 yStep = (PicCurve.Height - 2 * Yoffset) / (ThresHold(0) - ThresHold(3)) End Sub #End Region #Region "绘制永久图像" Function GetGraphics(ByRef pic As PictureBox) As Graphics Dim bmp As Bitmap = New Bitmap(pic.Width, pic.Height) pic.Image = bmp Dim g As System.Drawing.Graphics = Graphics.FromImage(bmp) Return g End Function #End Region #Region "保存图形" Public Sub SaveCurve(ByVal FileName As String) Dim bmp As New Bitmap(PicCurve.Width, PicCurve.Height) Dim g As Graphics = Graphics.FromImage(bmp) Call DrawReferenceFrame(g) Call DrawCurve(g, False) bmp.Save(FileName) End Sub #End Region End Class

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