I am using ASP.NET to create a .gif file using the Bitmap and Graphics classes. My file will be made up of only ellipses of equal width and height, placed side by side (basically a grid of circles), created using the FillEllipse method of the Graphics class. However, my results created the following image (shown here in Windows Paint so you can see the individual pixels):



Notice that each so-called ellipse is not an ellipse. The method used to create each of these ellipses is as follows:


ledgraphic.FillEllipse(New SolidBrush(Color.Green),x,y,4,4)     'x and y are always multiples of 4, such as 0,4,8,etc


Why are my so-called ellipses not circles? Any help would be appreciated. Thanks.

Hi Nathan,

it seems to me that it's just the way dot net handles the smaller ellipses, in the test (see the code below) the ellipses start looking the way you want when they are 7 by 7 but they only look like real elipses when then width and heigth are odd numbers, if the numbers are even you have that one extra colored pixel on the left. The draw Arc method seems to have less problems with this but it hasn't got a fill method.

For my example to work you need a button and a picturebox(450x450) on a form:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim myBmp As New Bitmap(450, 450)
        Dim g As Graphics
        g = Graphics.FromImage(myBmp)
        g.Clear(Color.Black)
        Dim posX As Integer = 10
        Dim myWidth, myHeight As Integer
        myWidth = 4
        myHeight = 4
        For i As Integer = 0 To 21
            If i <= 10 Then
                drawCircles(g, 0, posX, myWidth, myHeight)
            Else
                drawCircles(g, 1, posX, myWidth, myHeight)
            End If
            posX += 20
            myWidth += 1
            myHeight += 1
            If i = 10 Then
                myWidth = 4
                myHeight = 4
            End If
        Next
        g.Dispose()
        PictureBox1.Image = myBmp
        myBmp.Save("c:\testEllipse.bmp", Drawing.Imaging.ImageFormat.Bmp)
MsgBox("c:\testEllipse.bmp Saved", MsgBoxStyle.Information, "Saved")


    End Sub

Private Sub drawCircles(ByVal g As Graphics, ByVal drawType As Integer, ByVal x As Integer, ByVal width As Integer, ByVal _ height As Integer)
        Dim intY As Integer = 5
        For i As Integer = 0 To 20
            Select Case drawType
                Case 0
                    g.FillEllipse(Brushes.LawnGreen, x, intY, width, height)
                Case 1
                    g.DrawArc(Pens.LawnGreen, x, intY, width, height, 0, 360)
            End Select
            intY += 18
    Next
End Sub


Hth, Greetz Peter

  I am using ASP.NET to create a .gif file using the Bitmap and Graphics classes. My file will be made up of only ellipses of equal width and height, placed side by side (basically a grid of circles), created using the FillEllipse method of the Graphics class. However, my results created the following image (shown here in Windows Paint so you can see the individual pixels):



  Notice that each so-called ellipse is not an ellipse. The method used to create each of these ellipses is as follows:


  ledgraphic.FillEllipse(New SolidBrush(Color.Green),x,y,4,4)     'x and y are always multiples of 4, such as 0,4,8,etc


  Why are my so-called ellipses not circles? Any help would be appreciated. Thanks.
  --
  Nathan Sokalski
  njsokal***@hotmail.com
  http://www.nathansokalski.com/

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