自动生成电子印章 |
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自动生成电子印章
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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。 Image img = new Bitmap(imgWidth, imgHeight); Graphics g = Graphics.FromImage(img); g.SmoothingMode = SmoothingMode.HighQuality; g.InterpolationMode = InterpolationMode.HighQualityBicubic; g.CompositingQuality = CompositingQuality.HighQuality; g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias; 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。 public void DrawEllipseString(Rectangle rect, Graphics g, Font font, Color foreColor, float startAngle, string str, bool isFill, int split) { Point origin = new Point(rect.X + rect.Width / 2, rect.Y + rect.Height / 2); StringFormat format = new StringFormat() { Alignment = StringAlignment.Center, LineAlignment = StringAlignment.Center, }; if (rect.Width == rect.Height) { try { g.TranslateTransform(origin.X, origin.Y); g.RotateTransform(startAngle); float angle = startAngle + 90; foreach (var c in str) { SizeF txtSize = g.MeasureString(c.ToString(), font); Point pointB = GetPiePoint(rect, angle); Double distance = GetRealDistance(origin, pointB); int radius = (int)(distance - txtSize.Height / 2); PointF pointF = new PointF(0, -radius); g.DrawString(c.ToString(), font, new SolidBrush(foreColor), pointF, format); float fltAngle = 360f / str.Length; if (!isFill) fltAngle = (float)((txtSize.Width + split - 2) / (rect.Width * Math.PI) * 360); g.RotateTransform(fltAngle); angle += fltAngle; } g.ResetTransform(); } catch { } } else { float angle = startAngle - 90; SizeF txtSize = g.MeasureString(str.ToString(), font); 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); try { for (int i = 0; i < str.Length; i++) { txtSize = g.MeasureString(str[i].ToString(), font); Point pointB = GetPiePoint(rect, angle); double distance = GetRealDistance(origin, pointB); g.TranslateTransform(pointB.X, pointB.Y); if (angle == -90) { g.RotateTransform(angle + 90); } else if (angle == 0) { g.RotateTransform(angle + 90); } else if (angle == 90) { g.RotateTransform(angle + 90); } else if (angle == 180) { g.RotateTransform(angle + 90); } else if (angle == 270) { g.RotateTransform(angle + 90); } else if (angle == 360) { g.RotateTransform(angle - 45); } else { double a = rect.Width / 2; double b = rect.Height / 2; if (rect.Height > rect.Width) { a = rect.Height / 2; b = rect.Width / 2; } double c = Math.Sqrt(a * a - b * b); Point f1 = new Point((int)(origin.X - c), origin.Y); Point f2 = new Point((int)(origin.X + c), origin.Y); if (rect.Height > rect.Width) { f1 = new Point(origin.X, (int)(origin.Y - c)); f2 = new Point(origin.X, (int)(origin.Y + c)); } double pf1 = GetRealDistance(f1, pointB); double pf2 = GetRealDistance(f2, pointB); double f1f2 = GetRealDistance(f1, f2); double PC = Math.Acos((distance * distance + pf2 * pf2 - c * c) / (2 * distance * pf2)) / Math.PI * 180; if (angle > 270) PC = Math.Acos((distance * distance + pf1 * pf1 - c * c) / (2 * distance * pf1)) / Math.PI * 180; if (angle < 90) PC = Math.Acos((distance * distance + pf1 * pf1 - c * c) / (2 * distance * pf1)) / Math.PI * 180; if (PC.ToString() == "NaN") PC = 0; double P = Math.Acos((pf1 * pf1 + pf2 * pf2 - f1f2 * f1f2) / (2 * pf1 * pf2)) / Math.PI * 180; double Q = P / 2 - PC; if (P < 0) Q = 0; if (P == 0) Q = 0; if (Q.ToString() == "非数字") Q = 0; if (Q < 0) Q = 0; float angleQ = angleQ = angle + 90 + (float)Q; if (angle > 90 && angle < 180) angleQ = angle + 90 - (float)Q; if (angle > 270 && angle < 360) angleQ = angle + 90 - (float)Q; if (rect.Height > rect.Width) angleQ = angle + 90 - (float)Q; g.RotateTransform(angleQ); } g.TranslateTransform(-pointB.X, -pointB.Y); g.DrawString(str[i].ToString(), font, new SolidBrush(foreColor), pointB, format); g.ResetTransform(); float fltAngle = 360f / str.Length; if (!isFill) { double stringWidth = txtSize.Width + split - 2; for (float n = angle; n < 720; n += 0.1F) { Point pointN = GetPiePoint(rect, n); double stringN = GetRealDistance(pointN, pointB); if (stringN > stringWidth) { fltAngle = n - angle; break; } } } angle += fltAngle; if (angle > 360) angle -= 360; } } catch { } } }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 public Point GetPiePoint(Rectangle lpRect, float angle) { Point pt = new Point(); double a = lpRect.Width / 2.0f; double b = lpRect.Height / 2.0f; if (a == 0 || b == 0) return new Point(lpRect.X, lpRect.Y); //弧度 double radian = angle * Math.PI / 180.0f; //获取弧度正弦值 double yc = Math.Sin(radian); //获取弧度余弦值 double xc = Math.Cos(radian); //获取曲率 r = ab/\Sqrt((a.Sinθ)^2+(b.Cosθ)^2 double radio = (a * b) / Math.Sqrt(Math.Pow(yc * a, 2.0) + Math.Pow(xc * b, 2.0)); //计算坐标 double ax = radio * xc; double ay = radio * yc; pt.X = (int)(lpRect.X + a + ax); pt.Y = (int)(lpRect.Y + b + ay); return pt; } public double GetRealDistance(Point pointA, Point pointB) { double distance = Math.Sqrt(Math.Pow(pointA.X - pointB.X, 2.0) + Math.Pow(pointA.Y - pointB.Y, 2.0)); return distance; }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。 int radius = 27; PointF[] pentagons = new PointF[] { new PointF(center.X, center.Y - radius), new PointF((float)(center.X + radius * Math.Sin(72 * Math.PI / 180)), (float)(center.Y - radius * Math.Cos(72 * Math.PI / 180))), new PointF((float)(center.X + radius * Math.Sin(36 * Math.PI / 180)), (float)(center.Y + radius * Math.Cos(36* Math.PI / 180))), new PointF((float)(center.X - radius * Math.Sin(36 * Math.PI / 180)),(float)( center.Y + radius * Math.Cos(36 * Math.PI / 180))), new PointF((float)(center.X - radius * Math.Sin(72 * Math.PI / 180)), (float)(center.Y - radius * Math.Cos(72 * Math.PI / 180))), }; GraphicsPath path = new GraphicsPath(FillMode.Winding); path.AddLine(pentagons[0], pentagons[2]); path.AddLine(pentagons[2], pentagons[4]); path.AddLine(pentagons[4], pentagons[1]); path.AddLine(pentagons[1], pentagons[3]); path.AddLine(pentagons[3], pentagons[0]); path.CloseFigure(); 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。 if (showCenterString) { if (isEllipse) { g.DrawString(centerString, new Font(font.Name, font.Size - 1), new SolidBrush(foreColor), center, format); } else { g.DrawString(centerString, new Font(font.Name, font.Size - 4), new SolidBrush(foreColor), center, format); } } if (showBottomString) { if (isEllipse) { g.DrawString(bottomString, new Font(font.Name, font.Size - 1), new SolidBrush(foreColor), center.X, center.Y + 35, format); } else { g.DrawString(bottomString, new Font(font.Name, font.Size - 4), new SolidBrush(foreColor), center.X, center.Y + 50, format); } }自动生成电子印章完整实例下载 |
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