• 自动生成电子印章

           网络办公正逐渐成为常态，无纸化办公也是一个潮流，这二者需要电子签章，最简单的方法就是在纸上盖一个章然后扫描成电子图片文件，最后在你的系统加载这个签章电子图片文件。但这样就会些不理想的地方，如果不是透明的，叠加在有文字等的地方会遮盖了原来的内容；如果做成透明的，图片会失真，看上去很不真实。

           那就用代码画一个签章吧，本来以为是挺简单，其实不是。大小、形状、颜色这些都很受容易处理，难点就在文字按椭圆曲线排列上，涉及到字间距、倾斜角度等，实现起来还是要花一点时间的。

            既然是要用代码来画，那就要用到 Graphics 这个GDI了。为了画出高质量边缘无锯齿的透明图形，需要对Graphics的绘画质量进行设置，并清除背景色。

    1.             Image img = new Bitmap(imgWidth, imgHeight);
    2.             Graphics g = Graphics.FromImage(img);
    3.             g.SmoothingMode = SmoothingMode.HighQuality;
    4.             g.InterpolationMode = InterpolationMode.HighQualityBicubic;
    5.             g.CompositingQuality = CompositingQuality.HighQuality;
    6.             g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;
    7.             g.Clear(Color.Transparent);

           印章形状有圆形和椭圆形二种，圆形的话高和宽调成165的话打印出来和实际印章大小比较接近，椭圆形的宽和高则设置成197和131，当然在实际中是有不同大小的印章，只要调整宽和高就可。设置好宽和高后就可定义要画的图形大小和位置了，这里包含印章外边框和印章名称二个。

           印章外边框的大小和位置

           Rectangle rect = new Rectangle(new Point(2, 2), new Size(imgWidth - 5, imgHeight - 5));

            圆形印章名称的大小和位置

            Rectangle rectString = new Rectangle(new Point(6, 6), new Size(imgWidth - 12, imgHeight - 12));

           椭圆形印章名称的大小和位置

           rectString = new Rectangle(new Point(9, 9), new Size(imgWidth - 16, imgHeight - 16));

           画印章外边框比较容易，直接画一个宽度为4的椭圆开就好了，圆形当椭圆一处理

           g.DrawEllipse(new Pen(foreColor, 4), rect);

          还要确定印章中心点的坐标

          Point center = new Point((imgWidth - 1) / 2, (imgHeight - 1) / 2);

           印章名称的绘画就复杂一点，为了文字的左右对称，需要设置绘画文字的起始角度、字间距和字体。实质上是把文字文字均匀地附加在圆形路径上。

    1. public void DrawEllipseString(Rectangle rect, Graphics g, Font font, Color foreColor, float startAngle, string str, bool isFill, int split)
    2.         {
    3.             Point origin = new Point(rect.X + rect.Width / 2, rect.Y + rect.Height / 2);
    4.             StringFormat format = new StringFormat()
    5.             {
    6.                 Alignment = StringAlignment.Center,
    7.                 LineAlignment = StringAlignment.Center,
    8.             };
    9.             if (rect.Width == rect.Height)
    10.             {
    11.                 try
    12.                 {
    13.                     g.TranslateTransform(origin.X, origin.Y);
    14.                     g.RotateTransform(startAngle);
    15.                     float angle = startAngle + 90;
    16.                     foreach (var c in str)
    17.                     {
    18.                         SizeF txtSize = g.MeasureString(c.ToString(), font);
    19.                         Point pointB = GetPiePoint(rect, angle);
    20.                         Double distance = GetRealDistance(origin, pointB);
    21.                         int radius = (int)(distance - txtSize.Height / 2);
    22.                         PointF pointF = new PointF(0, -radius);
    23.                         g.DrawString(c.ToString(), font, new SolidBrush(foreColor), pointF, format);
    24.                         float fltAngle = 360f / str.Length;
    25.                         if (!isFill) fltAngle = (float)((txtSize.Width + split - 2) / (rect.Width * Math.PI) * 360);
    26.                         g.RotateTransform(fltAngle);
    27.                         angle += fltAngle;
    28.                     }
    29.                     g.ResetTransform();
    30.                 }
    31.                 catch { }
    32.             }
    33.             else
    34.             {
    35.                 float angle = startAngle - 90;
    36.                 SizeF txtSize = g.MeasureString(str.ToString(), font);
    37.                 rect = new Rectangle(rect.X + (int)txtSize.Height / 2, rect.Y + (int)txtSize.Height / 2, rect.Width - (int)txtSize.Height, rect.Height - (int)txtSize.Height);
    38.                 try
    39.                 {
    40.                     for (int i = 0; i < str.Length; i++)
    41.                     {
    42.                         txtSize = g.MeasureString(str[i].ToString(), font);
    43.                         Point pointB = GetPiePoint(rect, angle);
    44.                         double distance = GetRealDistance(origin, pointB);
    45.                         g.TranslateTransform(pointB.X, pointB.Y);
    46.                         if (angle == -90)
    47.                         {
    48.                             g.RotateTransform(angle + 90);
    49.                         }
    50.                         else if (angle == 0)
    51.                         {
    52.                             g.RotateTransform(angle + 90);
    53.                         }
    54.                         else if (angle == 90)
    55.                         {
    56.                             g.RotateTransform(angle + 90);
    57.                         }
    58.                         else if (angle == 180)
    59.                         {
    60.                             g.RotateTransform(angle + 90);
    61.                         }
    62.                         else if (angle == 270)
    63.                         {
    64.                             g.RotateTransform(angle + 90);
    65.                         }
    66.                         else if (angle == 360)
    67.                         {
    68.                             g.RotateTransform(angle - 45);
    69.                         }
    70.                         else
    71.                         {
    72.                             double a = rect.Width / 2;
    73.                             double b = rect.Height / 2;
    74.                             if (rect.Height > rect.Width)
    75.                             {
    76.                                 a = rect.Height / 2;
    77.                                 b = rect.Width / 2;
    78.                             }
    79.                             double c = Math.Sqrt(a * a - b * b);
    80.                             Point f1 = new Point((int)(origin.X - c), origin.Y);
    81.                             Point f2 = new Point((int)(origin.X + c), origin.Y);
    82.                             if (rect.Height > rect.Width)
    83.                             {
    84.                                 f1 = new Point(origin.X, (int)(origin.Y - c));
    85.                                 f2 = new Point(origin.X, (int)(origin.Y + c));
    86.                             }
    87.                             double pf1 = GetRealDistance(f1, pointB);
    88.                             double pf2 = GetRealDistance(f2, pointB);
    89.                             double f1f2 = GetRealDistance(f1, f2);
    90.                             double PC = Math.Acos((distance * distance + pf2 * pf2 - c * c) / (2 * distance * pf2)) / Math.PI * 180;
    91.                             if (angle > 270) PC = Math.Acos((distance * distance + pf1 * pf1 - c * c) / (2 * distance * pf1)) / Math.PI * 180;
    92.                             if (angle < 90) PC = Math.Acos((distance * distance + pf1 * pf1 - c * c) / (2 * distance * pf1)) / Math.PI * 180;
    93.                             if (PC.ToString() == "NaN") PC = 0;
    94.                             double P = Math.Acos((pf1 * pf1 + pf2 * pf2 - f1f2 * f1f2) / (2 * pf1 * pf2)) / Math.PI * 180;
    95.                             double Q = P / 2 - PC;
    96.                             if (P < 0) Q = 0;
    97.                             if (P == 0) Q = 0;
    98.                             if (Q.ToString() == "非数字") Q = 0;
    99.                             if (Q < 0) Q = 0;
    100.                             float angleQ = angleQ = angle + 90 + (float)Q;
    101.                             if (angle > 90 && angle < 180) angleQ = angle + 90 - (float)Q;
    102.                             if (angle > 270 && angle < 360) angleQ = angle + 90 - (float)Q;
    103.                             if (rect.Height > rect.Width) angleQ = angle + 90 - (float)Q;
    104.                             g.RotateTransform(angleQ);
    105.                         }
    106.                         g.TranslateTransform(-pointB.X, -pointB.Y);
    107.                         g.DrawString(str[i].ToString(), font, new SolidBrush(foreColor), pointB, format);
    108.                         g.ResetTransform();
    109.                         float fltAngle = 360f / str.Length;
    110.                         if (!isFill)
    111.                         {
    112.                             double stringWidth = txtSize.Width + split - 2;
    113.                             for (float n = angle; n < 720; n += 0.1F)
    114.                             {
    115.                                 Point pointN = GetPiePoint(rect, n);
    116.                                 double stringN = GetRealDistance(pointN, pointB);
    117.                                 if (stringN > stringWidth)
    118.                                 {
    119.                                     fltAngle = n - angle;
    120.                                     break;
    121.                                 }
    122.                             }
    123.                         }
    124.                         angle += fltAngle;
    125.                         if (angle > 360) angle -= 360;
    126.                     }
    127.                 }
    128.                 catch { }
    129.             }
    130.         }

    这里面要计算每一个文字的起始角度和坐标，还要计算二个点之间的距离

    1. public Point GetPiePoint(Rectangle lpRect, float angle)
    2.         {
    3.             Point pt = new Point();
    4.             double a = lpRect.Width / 2.0f;
    5.             double b = lpRect.Height / 2.0f;
    6.             if (a == 0 || b == 0) return new Point(lpRect.X, lpRect.Y);
    7.             //弧度            
    8.             double radian = angle * Math.PI / 180.0f;
    9.             //获取弧度正弦值            
    10.             double yc = Math.Sin(radian);
    11.             //获取弧度余弦值            
    12.             double xc = Math.Cos(radian);
    13.             //获取曲率 r = ab/\Sqrt((a.Sinθ)^2+(b.Cosθ)^2 
    14.             double radio = (a * b) / Math.Sqrt(Math.Pow(yc * a, 2.0) + Math.Pow(xc * b, 2.0));
    15.             //计算坐标            
    16.             double ax = radio * xc;
    17.             double ay = radio * yc;
    18.             pt.X = (int)(lpRect.X + a + ax);
    19.             pt.Y = (int)(lpRect.Y + b + ay);
    20.             return pt;
    21.         }
    22.  
    23.  
    24. public double GetRealDistance(Point pointA, Point pointB)
    25.         {
    26.             double distance = Math.Sqrt(Math.Pow(pointA.X - pointB.X, 2.0) + Math.Pow(pointA.Y - pointB.Y, 2.0));
    27.             return distance;
    28.         }

    印章中间的五角星形可以用特殊字符来做，但大小等的控制不如直接画线来得方便。

    1.                 int radius = 27;
    2.                 PointF[] pentagons = new PointF[] { new PointF(center.X, center.Y - radius),
    3.                 new PointF((float)(center.X + radius * Math.Sin(72 * Math.PI / 180)), (float)(center.Y - radius * Math.Cos(72 * Math.PI / 180))),
    4.                 new PointF((float)(center.X + radius * Math.Sin(36 * Math.PI / 180)), (float)(center.Y + radius * Math.Cos(36* Math.PI / 180))),
    5.                 new PointF((float)(center.X - radius * Math.Sin(36 * Math.PI / 180)),(float)( center.Y + radius * Math.Cos(36 * Math.PI / 180))),
    6.                 new PointF((float)(center.X - radius * Math.Sin(72 * Math.PI / 180)), (float)(center.Y - radius * Math.Cos(72 * Math.PI / 180))),
    7.                 };
    8.  
    9.                 GraphicsPath path = new GraphicsPath(FillMode.Winding);
    10.                 path.AddLine(pentagons[0], pentagons[2]);
    11.                 path.AddLine(pentagons[2], pentagons[4]);
    12.                 path.AddLine(pentagons[4], pentagons[1]);
    13.                 path.AddLine(pentagons[1], pentagons[3]);
    14.                 path.AddLine(pentagons[3], pentagons[0]);
    15.                 path.CloseFigure();
    16.                 g.FillPath(new SolidBrush(foreColor), path);

           印章的中间和底部文字相对简单，把字体设置小一点直接画就是，注意区分圆形和椭圆形。

    1. if (showCenterString)
    2.             {
    3.                 if (isEllipse)
    4.                 {
    5.                     g.DrawString(centerString, new Font(font.Name, font.Size - 1), new SolidBrush(foreColor), center, format);
    6.                 }
    7.                 else
    8.                 {
    9.                     g.DrawString(centerString, new Font(font.Name, font.Size - 4), new SolidBrush(foreColor), center, format);
    10.                 }
    11.             }
    12.             if (showBottomString)
    13.             {
    14.                 if (isEllipse)
    15.                 {
    16.                     g.DrawString(bottomString, new Font(font.Name, font.Size - 1), new SolidBrush(foreColor), center.X, center.Y + 35, format);
    17.                 }
    18.                 else
    19.                 {
    20.                     g.DrawString(bottomString, new Font(font.Name, font.Size - 4), new SolidBrush(foreColor), center.X, center.Y + 50, format);
    21.                 }
    22.             }

    自动生成电子印章完整实例下载

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  • 原文地址：https://blog.csdn.net/xgh815/article/details/126452134