.net通过iText操作pdf文件实现查找关键字签字盖章（新）
作者：互联网
因为上一篇文章确认有问题，后面复测发现bug，现在重新写了，是基于iText写的，复测多次，基本上没问题了。其他需要使用者自行扩展了
直接贴代码吧。
1 using iText.IO.Image;
2 using iText.Kernel.Geom;
3 using iText.Kernel.Pdf;
4 using iText.Kernel.Pdf.Canvas;
5 using iText.Kernel.Pdf.Canvas.Parser;
6 using iText.Kernel.Pdf.Canvas.Parser.Listener;
7 using iText.Layout;
8 using iText.Layout.Element;
9 using South.Tools.Logger;
10 using System;
11 using System.Collections.Generic;
12 using System.IO;
13 using System.Linq;
14
15 namespace South.Tools.Helper
16 {
17 public class SealSignHelper
18 {
19 private static int ReSizeMaxWidth = 45;
20
21 private static int ReSizeMaxHeight = 45;
22
23 /// <summary>
24 ///
25 /// </summary>
26 /// <param name="bytePdf">pdf文件</param>
27 /// <param name="SignImgBase64">签字base64图片</param>
28 /// <param name="SignKeyWord">关键字</param>
29 /// <param name="StartPageIndex">自定义开始页</param>
30 /// <param name="EndPageIndex">自定义结束页</param>
31 /// <returns></returns>
32 public static Tuple<bool, string, byte[]> SignBase64Img(byte[] bytePdf, string SignImgBase64, string SignKeyWord, int StartPageIndex = 0, int EndPageIndex = 0)
33 {
34 byte[] array;
35 Tuple<bool, string, byte[]> tuple;
36 int num = 0;
37 try
38 {
39 using (MemoryStream memoryStream = new MemoryStream())
40 {
41 using (PdfReader pdfReader = new PdfReader(new MemoryStream(bytePdf)))
42 {
43 using (PdfDocument pdfDocument = new PdfDocument(pdfReader, new PdfWriter(memoryStream)))
44 {
45 //获取总页数
46 int numberOfPages = pdfDocument.GetNumberOfPages();
47 int startPageIndex = 1;
48 if (StartPageIndex > 0)
49 {
50 //已知关字键所在页码，自定义开始页
51 startPageIndex = StartPageIndex;
52 }
53 if (EndPageIndex > startPageIndex && EndPageIndex <= numberOfPages)
54 {
55 //已知关字键所在页码，自定义结束页
56 numberOfPages = EndPageIndex;
57 }
58 //遍历pdf文档
59 for (int i = startPageIndex; i <= numberOfPages; i++)
60 {
61 //获取页对象
62 PdfPage page = pdfDocument.GetPage(i);
63 PdfCanvas pdfCanva = new PdfCanvas(page);
64 //创建关键字坐标对象
65 RegexBasedLocationExtractionStrategy regexBasedLocationExtractionStrategy = new RegexBasedLocationExtractionStrategy(SignKeyWord);
66 (new PdfCanvasProcessor(regexBasedLocationExtractionStrategy)).ProcessPageContent(page);
67 //获取当前页所有查询到的关键字坐标
68 List<IPdfTextLocation> list = regexBasedLocationExtractionStrategy.GetResultantLocations().ToList<IPdfTextLocation>();
69 if (list.Count > 0)
70 {
71 num++;
72 //多个关键字，默认取第一个
73 IPdfTextLocation item = list[0];
74 //获取关键字左上角开始坐标
75 float left = item.GetRectangle().GetLeft();
76 float top = item.GetRectangle().GetTop();
77 //获取关键字右下角结束坐标
78 float right = item.GetRectangle().GetRight();
79 float bottom = item.GetRectangle().GetBottom();
80 //计算得到关键字的中心点
81 float x = (right - left) / 2f + left;
82 float y = (top - bottom) / 2f + bottom;
83 //Convert.FromBase64String(SignImgBase64);
84 //等比调整签字图片大小
85 ImageData imageDatum = ImageDataFactory.Create(Convert.FromBase64String(SignImgBase64));
86 float reSizeMaxWidth = 0f;
87 float height = 0f;
88 if (imageDatum.GetWidth() > imageDatum.GetHeight() && imageDatum.GetWidth() > (float)SealSignHelper.ReSizeMaxWidth)
89 {
90 reSizeMaxWidth = (float)SealSignHelper.ReSizeMaxWidth;
91 height = reSizeMaxWidth * imageDatum.GetHeight() / imageDatum.GetWidth();
92 }
93 else if (imageDatum.GetHeight() > imageDatum.GetWidth() && imageDatum.GetHeight() > (float)SealSignHelper.ReSizeMaxHeight)
94 {
95 height = (float)SealSignHelper.ReSizeMaxHeight;
96 reSizeMaxWidth = height * imageDatum.GetWidth() / imageDatum.GetHeight();
97 }
98 //签字图片设置背景透明
99 imageDatum.SetTransparency(new int[] { 255, 255, 255, 255, 255, 255 });
100 Image image = new Image(imageDatum);
101 image.ScaleAbsolute(reSizeMaxWidth, height);
102 Canvas canva = new Canvas(pdfCanva, new Rectangle(x - reSizeMaxWidth / 2f, y - height / 2f, reSizeMaxWidth, height));
103 //盖上关键字上面
104 canva.Add(image);
105 canva.Close();
106 }
107 }
108 }
109 }
110 array = memoryStream.ToArray();
111 }
112 tuple = (num != 0 ? new Tuple<bool, string, byte[]>(true, "签字成功", array) : new Tuple<bool, string, byte[]>(false, "未找到签字关键字", null));
113 }
114 catch (Exception exception1)
115 {
116 Exception exception = exception1;
117 SaveLogUtil.Error(exception.Message, exception, "SignPicPDF");
118 tuple = new Tuple<bool, string, byte[]>(false, "签字异常", null);
119 }
120 return tuple;
121 }
122 }
123 }
标签：int,float,new,iText,imageDatum,pdf,using,net 来源： https://www.cnblogs.com/abcde102978/p/16657502.html