Thread: How to make sinusoid graphic

Do you know how to create a GDI layer ?

your going to need something like this

Code:

        Dim g As Graphics = PictureBox1.CreateGraphics

        g.DrawArc(New Pen(Color.Black), 1, 1, 100, 100, 5, 10)

Hi Zippo,

I posted a detailed example on another forum (under my other nom de plume boops boops) for someone wanting to plot the output from a serial port. It's a bit like a simple oscilloscope trace. In that case it was for plotting the varying DC voltage output of a solar cell, but maybe it will give you some ideas for displaying your ship inclination data. See post #47 in [RESOLVED] Converting voltage level into graphical display - Page 2 - VBForums.

@anthony.selby: I don't agree with you about using CreateGraphics for any kind of drawing. That seems to be a hangover from VB6. The idea of GDI+ is to use the Graphics object provided in the Paint event -- of a form, a picture box etc.

Hello Gentlemen,

First of all, thanks a lot to all for the kind help you give me.

Anthony, pleasure to listen you, but why I can take the signal from serial port to arc?!

Dear Vicj, thanks, I like very much thuis solution, but after try, the system is not works, and I have in debugging, one error on datapoints: parameter not valid.

What I can do for make this working?!?!?

waiting your light!!!

my best,
zippo

Hi Mister Zippo,

If you have a debugging problem you want solved here, please post the code you are using to this thread and indicate where the error occurs. The code I sent to the other forum probably needs some more error checking, but I can't remember all the details. I have no idea what you mean by "on datapoints". Besides, other people reading this thread may also want to know.

Please enclose code in [code] ... [ /code] tags, for readability.

ciao, VicJ

Ciao VicJ,

well, you're right.

I post here below my code.

Problem occurs then I debug the program, it not start and appear usual yellol window indicating the line: e.Graphics.DrawCurve(Pens.Green, DataPoints)
telling: "NO VALID PARAMETER"

Please help!!!!!!!

Public Class Form1
Dim volts As Single
Dim voltsQ As New Queue(Of Single)
Dim maxVolts As Single = 5
Dim WithEvents serialPort As New IO.Ports.SerialPort
Public Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Integer) 'for sleep statements
Dim Picaxeregisters(0 To 13) As Byte ' registers b0 to b13
Dim value As Integer


Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Enabled = True
Timer1.Interval = 100
Call Serialsensor()
End Sub

Sub Serialsensor()

Dim LabelString As String ' string to display byte values
Dim DataPacket(0 To 17) As Byte ' entire data packet "Data"+14 bytes
Dim ios As Integer ' i is always useful for loops etc
'Label1.Text = "" ' clear the text on the screen
For ios = 0 To 3
DataPacket(ios) = Asc(Mid("Data", ios + 1, 1)) ' add the word "Data" to the packet
Next
For ios = 0 To 13
DataPacket(ios + 4) = Picaxeregisters(ios) ' add all the bytes to the packet
Next
If serialPort.IsOpen Then
serialPort.Close() ' just in case already opened
End If
Try
With serialPort
.PortName = "COM1" ' Most new computers default to com1 but any pre 1999 computer with a serial mouse will probably default to com2
.BaudRate = 2400 ' 2400 is the maxiumum speed for small picaxes
.Parity = IO.Ports.Parity.None ' no parity
.DataBits = 8 ' 8 bits
.StopBits = IO.Ports.StopBits.One ' one stop bit
'.ReadTimeout = 800 ' milliseconds so times out in 1 second if no response
.Open() ' open the serial port
.DiscardInBuffer() ' clear the input buffer
.Write(DataPacket, 0, 18) ' send the datapacket array
Call Sleep(110) ' 100 milliseconds minimum to wait for data to come back and more if data stream is longer
.Read(DataPacket, 0, 18) ' read back in the data packet array
.Close() ' close the serial port
End With
For ios = 4 To 17
LabelString = LabelString + " " + Str(DataPacket(ios)) ' turn into a text string
Next
Label1.Text = LabelString ' put the text string on the screen
Catch ex As Exception
' MsgBox(ex.ToString) ' uncomment this if want to see the actual error message
Label1.Text = "Nothing Received" ' will display this if picaxe not connected etc
End Try
value = DataPacket(5)

End Sub





Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
'read the voltage:
volts = value 'get value from RS232 interface
'add the new reading to the end of the queue:

voltsQ.Enqueue(volts)
'remove the old reading at the head of the queue, to keep max. 40 data points:
If voltsQ.Count > 40 Then voltsQ.Dequeue()
'update the display with the new data:
Me.Refresh()


End Sub


Private Sub Form1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint

Dim Origin As New Point(200, 200)
Dim xAxisLength As Integer = 300
Dim yAxisLength As Integer = 150
Dim x As Integer
Dim y As Integer

'Turn the queue into an array:
Dim voltsQarray As Single() = voltsQ.ToArray
'Define an array of data points:
Dim DataPoints(voltsQ.Count - 1) As Point

'Fill in the array using the voltage readings:
For i As Integer = 0 To
'Get the volts value from the queue:
Dim v As Single = voltsQarray(i)
' Dim v As Single = voltsQ.ElementAt(i)
'Find the distance along the x axis:
x = Origin.X + CInt(i * xAxisLength / 40)
'find the height of the data point on the Y axis:
y = Origin.Y + CInt(v * yAxisLength / maxVolts)
'Put the point in the array
DataPoints(i) = New Point(x, y)
Next
'Draw the waveform:
e.Graphics.DrawCurve(Pens.Green, DataPoints)
End Sub
End Class

Waiting your kind reply.

My best,
zippo

Probably it is failing because there are not enough data points for DrawCurve: I forget whether the minimum is 2 or 3. There is not much point in trying to draw a curve until there are at least 3 data points anyway, so I suggest you enclose all the drawing code in the Paint sub in this If statement:

Code:

If voltsQ.Count > 2
...
End If

VicJ

Dear VicJ,

Ok, I have make the if statement, and now the form is opening, but, still there is no curve drawing.noting.

I cannot understand!

please, what I fail?!?

All my best.
zippo
zippo

do you call Serialsensor more then just on the load ... I only see where the data from your serial port is being read once ?

It looks to me that there will only ever be one value placed in the queue ?

Dear anthony,

I take one b, for example b1 that bring the value of inclination from PIC to PC, from 0 to 255, using serial communication serialsensor. and I would to have displayed one real time graphic, as a oscilloscope for example, of the track of that byte.
When b1=122 --->0 degree, b1=255-->+25 degree, b1=0--->-25 degrees.

as the sea motion is a period, what I should have will be like a sinusoid graphic!

hope to be clear.

Please, if you think it possible, help me!!!

big regards,
zippo