项目中要用图形来显示一个阀门的开度，以及控制阀的开度。本来是要用什么公司买的控件中的饼图之类的实现，不过我觉得也是麻烦，就想，还是自己画吧。
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首先添加一个TrackBar，名字是“TrackBar1”，一个label，名字是“L_A_SHANG”，一个GroupBox，名字是“GB_RIGHT”,，然后添加拉动滚动条时的处理函数
'上位机控制
Dim m_start As Integer
Dim RcDraw As System.Drawing.Rectangle
Private Sub TrackBar1_Scroll(ByVal sender As Object, ByVal e As System.EventArgs) Handles TrackBar1.Scroll
m_start = (100 - TrackBar1.Value)
Me.L_A_SHANG.Text = Me.TrackBar1.Value.ToString
GB_RIGHT.Invalidate() '重画GB_RIGHT
End Sub
添加GB_RIGHT重画时的处理函数
Private Sub GB_RIGHT_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles GB_RIGHT.Paint
RcDraw.X = TrackBar1.Location.X - 40
RcDraw.Y = 20
RcDraw.Height = 100
RcDraw.Width = 20
e.Graphics.DrawRectangle(New Pen(Color.Blue, 5), RcDraw)
Dim i = TrackBar1.Location.X - 40
For i = TrackBar1.Location.X - 40 To TrackBar1.Location.X - 20
e.Graphics.DrawLine(New Pen(Color.Blue, 5), i, m_start + 20, i, 120)
Next
Me.L_A_SHANG.Text = Me.TrackBar1.Value.ToString + "%"
End Sub
到此以及可以实现拉动条的时候，图像跟着变化，并显示百分比。
您好，您是想问vb.net连续绘制曲线图不消失怎么办？b.net连续绘制曲线图不消失的解决办法如下：
1、首先必须创建bitmap,关联到picturebox1.image上。
2、再在picturebox1.image上创建Graphics,再进行作图。即可显示线图。
代码：
Public Class Form1
'*********************************************************************
'作者：章鱼哥，QQ：3107073263 群：309816713
'如有疑问或好的建议请联系我，大家一起进步
'*********************************************************************
'绘制圆角矩形函数
Private Function GetRoundedRectPath(ByVal rect As Rectangle, ByVal radius As Integer) As System.Drawing.Drawing2D.GraphicsPath
rect.Offset(-1, -1)
Dim RoundRect As New Rectangle(rect.Location, New Size(radius - 1, radius - 1))
Dim path As New System.Drawing.Drawing2D.GraphicsPath
path.AddArc(RoundRect, 180, 90) '左上角
RoundRect.X = rect.Right - radius '右上角
path.AddArc(RoundRect, 270, 90)
RoundRect.Y = rect.Bottom - radius '右下角
path.AddArc(RoundRect, 0, 90)
RoundRect.X = rect.Left '左下角
path.AddArc(RoundRect, 90, 90)
path.CloseFigure()
Return path
End Function
'绘制矩形
Private Sub DrawingRect()
Dim g As Graphics = Me.CreateGraphics
Dim Pen As New Pen(Brushes.DarkRed, 2)
Dim Hei As Integer = Me.Height
Dim Wid As Integer = Me.Width
'矩形的位置和长宽随着窗体的变化而改变
Dim Rec As New Rectangle(Int(Wid / 5), Int(Hei / 5), Int(Wid / 2), Int(Hei / 2))
' g.DrawRectangle(Pen, Rec)
'清楚现有的矩形
g.Clear(Me.BackColor)
g.DrawPath(Pen, GetRoundedRectPath(Rec, 30))
End Sub
Private Sub Form1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
DrawingRect()
End Sub
Private Sub Form1_SizeChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.SizeChanged
Me.Invalidate() '此函数可引发Paint事件
End Sub
End Class
效果截图:
原窗口：
缩小后：
VB.net与VB不同。
VB.net已经有专门绘图的类。
可以定义笔刷然后用Drawing类中的方法绘制。
Private Sub DrawEllipse()
Dim myPen As New System.Drawing.Pen(System.Drawing.Color.Red)
Dim formGraphics as System.Drawing.Graphics
formGraphics = Me.CreateGraphics()
formGraphics.DrawEllipse(myPen, New Rectangle(0,0,200,300))
myPen.Dispose()
formGraphics.Dispose()
End Sub
Private Sub DrawRectangle()
Dim myPen As New System.Drawing.Pen(System.Drawing.Color.Red)
Dim formGraphics as System.Drawing.Graphics
formGraphics = Me.CreateGraphics()
formGraphics.DrawRectangle(myPen, New Rectangle(0,0,200,300))
myPen.Dispose()
formGraphics.Dispose()
End Sub
重庆分公司
重庆分公司
