VB.net to implement drawing, and TrackBar and draw the binding of graphics

Graphics

Graphics are used to show the opening of a valve and the opening of the control valve. Originally is to use what company to buy the control in the pie chart and so on, but I think it is trouble, think, or painting it yourself.

First add a trackbar, the name is "TrackBar1", a label, the name is "L_a_shang", a GroupBox, the name is "Gb_right", and then add the processing function when pulling the scroll bar

' Host computer control
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 () ' re-painting gb_right
End Sub

Add a handler function when Gb_right is repaint

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 +, I, 120)
Next

Me.l_a_shang. Text = Me.TrackBar1.Value.ToString + "%"
End Sub

When this and the pull bar can be implemented, the image changes and displays the percentage.