前序
使用PdfSharpCore请注意使用XGraphics基类，与System.Drawing 的Graphics类似，XGraphics 提供XColor（颜色）、XPen（画笔）、XBrush（画刷）、XFont(字体)、XPoint(位置)等对象。提供很多画线，矩形，圆，扇形，多边形，图，文本等方法。源码请查看https://github.com/ststeiger/PdfSharpCore/blob/master/PdfSharpCore/Drawing/XGraphics.cs
1.设置PDF拥有者的密码，让PDF防篡改。
代码很简单设置PdfDocument.SecuritySettings.OwnerPassword
PdfDocument doc = PdfReader.Open(@"a.pdf", PdfDocumentOpenMode.Modify);
doc.SecuritySettings.OwnerPassword = "123";
var filePath = $"b.pdf";
doc.Save(filePath);
2.PDF添加页眉和页脚
（1）添加页码显示
XStringFormats 指定文本的位置：详请查看https://github.com/ststeiger/PdfSharpCore/blob/master/PdfSharpCore/Drawing/XStringFormats.cs
XFont font = new XFont("SimHei", 8);
XBrush brush = XBrushes.Black;
PdfDocument doc = PdfReader.Open(@"a.pdf", PdfDocumentOpenMode.Modify);
for (int i = 0; i < doc.Pages.Count; i++)
{
PdfPage page = doc.Pages[i];
XRect layoutRectangle = new XRect(0, page.Height - font.Height, page.Width, font.Height);
using (XGraphics gfx = XGraphics.FromPdfPage(page))
{
gfx.DrawString(
$"第{(i + 1).ToString()}页/共{doc.Pages.Count}页",
font,
brush,
layoutRectangle,
XStringFormats.BottomLeft);
}
}
（2）添加页眉
XFont font = new XFont("SimHei", 8);
XBrush brush = new XSolidBrush(XColor.FromArgb(128, 255, 0, 0));
XPoint point = new XPoint(90, 20);
PdfDocument doc = PdfReader.Open(@"a.pdf", PdfDocumentOpenMode.Modify);
for (int i = 0; i < doc.Pages.Count; i++)
{
var renderer = XGraphics.FromPdfPage(doc.Pages[i]);
XSize pageSize = renderer.PageSize;
renderer.DrawString("xxx有限公司", font, brush, point);
XPen pen = new XPen(XBrushes.Gray, 0.5f);
renderer.DrawLine(pen, point.X, point.Y, pageSize.Width - point.X, point.Y);
}
doc.Save("b.pdf");
（3）添加页脚
XFont font = new XFont("SimHei", 8);
XBrush brush = new XSolidBrush(XColor.FromArgb(128, 255, 0, 0));
PdfDocument doc = PdfReader.Open(@"a.pdf", PdfDocumentOpenMode.Modify);
for (int i = 0; i < doc.Pages.Count; i++)
{
var renderer = XGraphics.FromPdfPage(doc.Pages[i]);
XSize pageSize = renderer.PageSize;
XPoint point = new XPoint(90, pageSize.Height-20);
renderer.DrawString("xxx有限公司", font, brush, point);
XPen pen = new XPen(XBrushes.Gray, 0.5f);
renderer.DrawLine(pen, point.X, point.Y-10, pageSize.Width - point.X, point.Y-10);
}
doc.Save("b.pdf");
3.PDF添加水印文字
XFont font = new XFont("SimHei", 8);
XBrush brush =new XSolidBrush(XColor.FromArgb(128, 255, 0, 0));
PdfDocument doc = PdfReader.Open(@"a.pdf", PdfDocumentOpenMode.Modify);
for (int i = 0; i < doc.Pages.Count; i++)
{
XStringFormat stringFormat = new XStringFormat();
stringFormat.Alignment = XStringAlignment.Center;
stringFormat.LineAlignment = XLineAlignment.Center;
PdfPage page = doc.Pages[i];
var gfx = XGraphics.FromPdfPage(page, XPageDirection.Downwards);
gfx.DrawString(
$"xxx公司版权所有",
font,
brush,
new XPoint(500, 500),
stringFormat);
}
doc.Save("b.pdf");
4.PDF 添加图片
//第一步先加载PDF文件
PdfDocument doc = PdfReader.Open(@"a.pdf", PdfDocumentOpenMode.Modify);
//导入图片（地址，文件流）
var background = XImage.FromFile(@"QRCode.png");
// var background = XImage.FromStream(()=> stream);
//指定PDF 的页
PdfPage page = doc.Pages[0];
var gfx = XGraphics.FromPdfPage(page, XPageDirection.Downwards);
//写入指定位置
gfx.DrawImage(background, 20, 20, 250, 140);
doc.Save("b.pdf");
