Shape line issue with drawing shape in .NET, c#

I want to draw a shape with square, diamond, and cross shape. The square line is solid, and fine. However, the line of both diamond and cross look like dashed or dotted. I want all shapes have solid line.

Any ideas?

Below is the code, and shapes:

http://www.sendspace.com/file/n3wljs

private void CreateVariousShapes()
{
    Bitmap bitmap = new Bitmap(17, 17);
    Graphics graphics = Graphics.FromImage(bitmap);
    Pen pen = new Pen(Color.Black);
    pen.Width = 1;
    pen.DashStyle = DashStyle.Solid;
    Brush brush = new SolidBrush(Color.White);

    //graphics.FillRectangle(brush, 0, 0, 16, 16);

    //graphics.DrawRectangle(pen, 0开发者_如何学Go, 0, 16, 16);

    FillDiamond(brush, graphics);
    DrawDiamond(pen, graphics);

    DrawCross(pen, graphics);

    //bitmap.Save(MapPath("SquareDiamondCross.png"),ImageFormat.Png);
    //bitmap.Save(MapPath("SquareCross.png"), ImageFormat.Png);
    //bitmap.Save(MapPath("SquareDiamond.png"), ImageFormat.Png);
    bitmap.Save(MapPath("DiamondCross.png"), ImageFormat.Png);
}

private void FillDiamond(Brush brush, Graphics graphics)
{
    Point[] points = new Point[]
                        { new Point(0,8), 
                        new Point(8,16), 
                        new Point(16,8), 
                        new Point(8,0), 

                        };

    graphics.FillPolygon(brush, points);
}

private void DrawDiamond(Pen pen, Graphics graphics)
{
    Point[] points = new Point[]
                        { new Point(0,8), 
                        new Point(8,16), 
                        new Point(16,8), 
                        new Point(8,0), 
                        };
    graphics.DrawPolygon(pen, points);
}

private void DrawCross(Pen pen, Graphics graphics)
{
    graphics.DrawLine(pen, 4, 2, 2, 4);

    graphics.DrawLine(pen, 2, 12, 4, 14);

    graphics.DrawLine(pen, 12, 14, 14, 12);

    graphics.DrawLine(pen, 12, 2, 14, 4);

    graphics.DrawLine(pen, 2, 4, 6, 8);
    graphics.DrawLine(pen, 2, 12, 6, 8);

    graphics.DrawLine(pen, 4, 14, 8, 10);
    graphics.DrawLine(pen, 12, 14, 8, 10);

    graphics.DrawLine(pen, 14, 12, 10, 8);
    graphics.DrawLine(pen, 14, 4, 10, 8);

    graphics.DrawLine(pen, 12, 2, 8, 6);
    graphics.DrawLine(pen, 4, 2, 8, 6);
}

Set the following graphics properties:

graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.SmoothingMode = SmoothingMode.HighQuality;

Hopefully you will get what you want.