Bug 1793

Created attachment 727 [details]
screenshot

This problem occurs outside of TeeChart as can be seen in the screenshot attached. The code to reproduce this is the following:

 public partial class UserControl1 : Control
  {
    public UserControl1()
    {
      InitializeComponent();

      ControlStyles s =
  ControlStyles.AllPaintingInWmPaint |
  ControlStyles.ResizeRedraw |
  ControlStyles.UserPaint |
  ControlStyles.SupportsTransparentBackColor |
  ControlStyles.Selectable |
  ControlStyles.StandardClick |
  ControlStyles.StandardDoubleClick;

      SetStyle(s, true);

			SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
    }

    public static void DoArea(Graphics g, Rectangle r)
    {
      g.SmoothingMode = SmoothingMode.HighQuality;
      SolidBrush brush = new SolidBrush(Color.FromArgb(150, Color.Purple));   

      int count = 15;
      int width = r.Width / count;
      Random rnd = new Random();
      Point oldRightTop = Point.Empty;

      for (int i = 0; i < count; i++)
      {
        Rectangle shape = Rectangle.FromLTRB(r.Left + (width * i), r.Height - rnd.Next(r.Height), r.Left + (width * (i + 1)), r.Bottom);

        Point leftTop = shape.Location;
        Point rightTop = new Point(shape.Right, shape.Top);
        Point rightBottom = new Point(shape.Right, shape.Bottom);
        Point leftBottom = new Point(shape.Left, shape.Bottom);

        Point[] points = new Point[] { oldRightTop == Point.Empty ? leftTop : oldRightTop, rightTop, rightBottom, leftBottom };
        g.FillPolygon(brush, points);

        oldRightTop = rightTop;
      }
    }

    protected override void OnPaint(PaintEventArgs e)
    {
      DoArea(e.Graphics, e.ClipRectangle);
    }

    protected override void OnResize(EventArgs e)
    {
      Invalidate();
    }
  }

The screenshot is this UserControl1 placed on a Windows Form.

Created attachment 728 [details]
screenshot2

This is not a bug, as the problem occurs in a UserControl quite independently of TeeChart. To remedy this issue, please use SmoothingMode.HighSpeed (result seen in screenshot2):

    private void InitializeChart()
    {
      tChart1.Aspect.View3D = false;
      tChart1.Graphics3D.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighSpeed;

      tChart1.Aspect.View3D = false;
      var area = new Steema.TeeChart.Styles.Area();
      area.AreaLines.Visible = false;
      area.LinePen.Visible = false;
      area.Color = Color.Purple;
      area.Transparency = 50;
      area.FillSampleValues();
      tChart1.Chart.Series.Add(area);
    }