网页上生成一个印章。

参考Knight 的代码如下：

生成印章准备的类文件：

namespace Seal
...{
    using System;
    using System.Drawing;
    using System.Drawing.Drawing2D;
    using System.Diagnostics;
    /**//// <summary>
    /// Summary description for TextOnSeal.
    /// </summary>
    public class TextOnSeal
    ...{
        private string _text;
        private Font _font;
        private Color _pathcolor = Color.Red;
        private Color _color = Color.Black;
        private Color _fillcolor = Color.Black;
        private int _letterspace = 10;
        private bool _showpath = true;
        private Rectangle _rectcircle;
        private Rectangle _rect;
        private int _intentlength = 10;
        private Char_Direction _chardirect = Char_Direction.Center;
        private int _degree = 90;
        private string _basestring;
        Class_Properties#region Class_Properties
        public Char_Direction CharDirection
        ...{
            get ...{ return _chardirect; }
            set
            ...{
                if (_chardirect != value)
                ...{
                    _chardirect = value;
                    switch (_chardirect)
                    ...{
                        case Char_Direction.Center:
                            _degree = 90;
                            break;
                        case Char_Direction.ClockWise:
                            _degree = 0;
                            break;
                        case Char_Direction.OutSide:
                            _degree = -90;
                            break;
                        case Char_Direction.AntiClockWise:
                            _degree = 180;
                            break;
                    }
                }
            }
        }

        public string BaseString
        ...{
            get ...{ return _basestring; }
            set ...{ _basestring = value; }
        }



        public string Text
        ...{
            get ...{ return _text; }
            set ...{ _text = value; }
        }

        public Font TextFont
        ...{
            get ...{ return _font; }
            set ...{ _font = value; }
        }

        public Color PathColor
        ...{
            get ...{ return _pathcolor; }
            set ...{ _pathcolor = value; }
        }

        public Color ColorTOP
        ...{
            get ...{ return _color; }
            set ...{ _color = value; }
        }


        public Color FillColor
        ...{
            get ...{ return _fillcolor; }
            set ...{ _fillcolor = value; }
        }



        public int LetterSpace
        ...{
            get ...{ return _letterspace; }
            set ...{ _letterspace = value; }
        }



        public bool ShowPath
        ...{
            get ...{ return _showpath; }
            set ...{ _showpath = value; }
        }


        public int SealSize
        ...{
            set
            ...{
                _rect = new Rectangle(0, 0, value, value);
                _rectcircle = new Rectangle(
                    new Point(_rect.X + _intentlength, _rect.Y + _intentlength),
                    new Size(_rect.Width - 2 * _intentlength, _rect.Height - 2 * _intentlength));
            }
        }

        #endregion {Class_Properties}
        public void SetIndent(int IntentLength)
        ...{
            _intentlength = IntentLength;
            _rectcircle = new Rectangle(_intentlength, _intentlength,
                _rect.Width - _intentlength * 2, _rect.Height - _intentlength * 2);
        }

        public TextOnSeal()
        ...{

        }


        public Bitmap TextOnPathBitmap(
            Rectangle rectCircle,
            string strText,
            Font fntText,
            Color clrColor,
            Color clrFill,
            int nPercentage)
        ...{
            _rect = rectCircle;
            _rectcircle = new Rectangle(
                new Point(_rect.X + _intentlength, _rect.Y + _intentlength),
                new Size(_rect.Width - 2 * _intentlength, _rect.Height - 2 * _intentlength));
            _text = strText;
            _font = fntText;
            _color = clrColor;
            _fillcolor = clrFill;
            _letterspace = nPercentage;
            return TextOnPathBitmap();
        }



        /**//// <summary>
        /// Compute string total length and every char length
        /// </summary>
        /// <param name="sText"></param>
        /// <param name="g"></param>
        /// <param name="fCharWidth"></param>
        /// <param name="fIntervalWidth"></param>
        /// <returns></returns>
        private float ComputeStringLength(string sText, Graphics g, float[] fCharWidth,
            float fIntervalWidth,
            Char_Direction Direction)
        ...{
            // Init string format
            StringFormat sf = new StringFormat();
            sf.Trimming = StringTrimming.None;
            sf.FormatFlags = StringFormatFlags.NoClip | StringFormatFlags.NoWrap
                | StringFormatFlags.LineLimit;
            // Measure whole string length
            SizeF size = g.MeasureString(sText, _font, (int)_font.Style);
            RectangleF rect = new RectangleF(0f, 0f, size.Width, size.Height);
            // Measure every character size
            CharacterRange[] crs = new CharacterRange[sText.Length];
            for (int i = 0; i < sText.Length; i++)
                crs[i] = new CharacterRange(i, 1);
            // Reset string format
            sf.FormatFlags = StringFormatFlags.NoClip;
            sf.SetMeasurableCharacterRanges(crs);
            sf.Alignment = StringAlignment.Near;
            // Get every character size
            Region[] regs = g.MeasureCharacterRanges(sText,
                _font, rect, sf);
            // Re-compute whole string length with space interval width
            float fTotalWidth = 0f;
            for (int i = 0; i < regs.Length; i++)
            ...{
                if (Direction == Char_Direction.Center || Direction == Char_Direction.OutSide)
                    fCharWidth[i] = regs[i].GetBounds(g).Width;
                else
                    fCharWidth[i] = regs[i].GetBounds(g).Height;
                fTotalWidth += fCharWidth[i] + fIntervalWidth;
            }
            fTotalWidth -= fIntervalWidth;//Remove the last interval width
            return fTotalWidth;
        }



        /**//// <summary>
        /// Compute every char position
        /// </summary>
        /// <param name="CharWidth"></param>
        /// <param name="recChars"></param>
        /// <param name="CharAngle"></param>
        /// <param name="StartAngle"></param>
        private void ComputeCharPos(
            float[] CharWidth,
            PointF[] recChars,
            double[] CharAngle,
            double StartAngle)
        ...{
            double fSweepAngle, fCircleLength;
            //Compute the circumference
            fCircleLength = _rectcircle.Width * Math.PI;
            for (int i = 0; i < CharWidth.Length; i++)
            ...{
                //Get char sweep angle
                fSweepAngle = CharWidth[i] * 360 / fCircleLength;
                //Set point angle
                CharAngle[i] = StartAngle + fSweepAngle / 2;
                //Get char position
                if (CharAngle[i] < 270f)
                    recChars[i] = new PointF(
                        _rectcircle.X + _rectcircle.Width / 2
                        - (float)(_rectcircle.Width / 2 *
                        Math.Sin(Math.Abs(CharAngle[i] - 270) * Math.PI / 180)),
                        _rectcircle.Y + _rectcircle.Width / 2
                        - (float)(_rectcircle.Width / 2 * Math.Cos(
                        Math.Abs(CharAngle[i] - 270) * Math.PI / 180)));
                else
                    recChars[i] = new PointF(
                        _rectcircle.X + _rectcircle.Width / 2
                        + (float)(_rectcircle.Width / 2 *
                        Math.Sin(Math.Abs(CharAngle[i] - 270) * Math.PI / 180)),
                        _rectcircle.Y + _rectcircle.Width / 2
                        - (float)(_rectcircle.Width / 2 * Math.Cos(
                        Math.Abs(CharAngle[i] - 270) * Math.PI / 180)));
                //Get total sweep angle with interval space
                fSweepAngle = (CharWidth[i] + _letterspace) * 360 / fCircleLength;
                StartAngle += fSweepAngle;
            }
        }



        /**//// <summary>
        /// Generate seal bitmap
        /// </summary>
        /// <returns></returns>
        public Bitmap TextOnPathBitmap()
        ...{
            // Create bitmap and graphics
            Bitmap bit = new Bitmap(_rect.Width, _rect.Height);
            Graphics g = Graphics.FromImage(bit);
            // Compute string length in graphics
            float[] fCharWidth = new float[_text.Length];
            float fTotalWidth = ComputeStringLength(_text, g, fCharWidth,
                _letterspace, _chardirect);
            // Compute arc's start-angle and end-angle
            double fStartAngle, fSweepAngle;
            fSweepAngle = fTotalWidth * 360 / (_rectcircle.Width * Math.PI);
            fStartAngle = 270 - fSweepAngle / 2;
            // Compute every character's position and angle
            PointF[] pntChars = new PointF[_text.Length];
            double[] fCharAngle = new double[_text.Length];
            ComputeCharPos(fCharWidth, pntChars, fCharAngle, fStartAngle);
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.CompositingQuality = CompositingQuality.HighQuality;
            g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;
            DrawSealBase(g);
            // Draw every character
            for (int i = 0; i < _text.Length; i++)
            DrawRotatedText(g, _text[i].ToString(), (float)(fCharAngle[i] + _degree), pntChars[i]);
            g.Dispose();
            // Return bitmap
            return bit;
        }



        /**//// <summary>
        /// Draw seal base 
        /// </summary>
        /// <param name="g"></param>
        private void DrawSealBase(Graphics g)
        ...{
            // Draw background
            g.FillRectangle(Brushes.Black, _rect);
            g.FillEllipse(new SolidBrush(_fillcolor),
                new Rectangle(1, 1, _rect.Width - 2, _rect.Height - 2));
            g.FillEllipse(Brushes.White,
                new Rectangle(4, 4, _rect.Width - 8, _rect.Height - 8));
            // Draw start signal
            StringFormat sf = new StringFormat();
            string strStar = "★";
            Font fnt = new Font(_font.FontFamily, _font.Size * 3);
            sf.Alignment = StringAlignment.Center;
            sf.LineAlignment = StringAlignment.Center;
            SizeF siz = g.MeasureString(strStar, fnt);
            g.DrawString(strStar, fnt, new SolidBrush(_fillcolor),
                new RectangleF(_rect.Width / 2 - siz.Width / 2,
            _rect.Height / 2 - siz.Height / 2,
            siz.Width, siz.Height), sf);
            // Draw base string
            float[] fCharWidth = new float[_basestring.Length];
            float fTotalWidths = ComputeStringLength(_basestring, g, fCharWidth, 0,
                Char_Direction.Center);
            float fLeftPos = (_rect.Width - fTotalWidths) / 2;
            PointF pt;
            for (int i = 0; i < _basestring.Length; i++)
            ...{
                pt = new PointF(fLeftPos + fCharWidth[i] / 2,
                _rect.Height / 2 + siz.Height / 2 + 10);
                DrawRotatedText(g, _basestring[i].ToString(), 0, pt);
                fLeftPos += fCharWidth[i];
            }
        }



        /**//// <summary>
        /// Draw every rotated character
        /// </summary>
        /// <param name="g"></param>
        /// <param name="_text"></param>
        /// <param name="_angle"></param>
        /// <param name="_PointCenter"></param>
        private void DrawRotatedText(Graphics g, string _text, float _angle, PointF _PointCenter)
        ...{
            StringFormat sf = new StringFormat();
            sf.Alignment = StringAlignment.Center;
            sf.LineAlignment = StringAlignment.Center;
            GraphicsPath gp = new GraphicsPath(System.Drawing.Drawing2D.FillMode.Winding);
            int x = (int)_PointCenter.X;
            int y = (int)_PointCenter.Y;
            gp.AddString(_text, _font.FontFamily, (int)_font.Style,
            _font.Size, new Point(x, y), sf);
            Matrix m = new Matrix();
            m.RotateAt(_angle, new PointF(x, y));
            g.Transform = m;
            g.DrawPath(new Pen(_color), gp);
            g.FillPath(new SolidBrush(_fillcolor), gp);
        }
    }

    public enum Char_Direction
    ...{
        Center = 0,
        OutSide = 1,
        ClockWise = 2,
        AntiClockWise = 3,
    }

}

 Web 调用方法如下：

 

 TextOnSeal _top = new TextOnSeal();
        _top.TextFont = new Font("宋体", 20, FontStyle.Regular);
        _top.FillColor = Color.Red;
        _top.ColorTOP = Color.Black;
        _top.Text = "北京拓创股份有限公司";
        _top.BaseString = "邹氏印章";
        _top.ShowPath = true;
        _top.LetterSpace = 5;
        _top.SealSize = 220;
        _top.CharDirection = Char_Direction.Center;
        _top.SetIndent(20);
        //Graphics g = this.CreateGraphics();
        //g.DrawImage(_top.TextOnPathBitmap(), 0, 0);
        //画图初始化
        Bitmap bMap = new Bitmap(500, 500);
        Graphics gph = Graphics.FromImage(bMap);
        gph.Clear(Color.White);
        gph.DrawImage(_top.TextOnPathBitmap(), 0, 0);
        //保存输出图片
        bMap.Save(Response.OutputStream, ImageFormat.Gif);

 

显示结果如下：