iTextSharp的4.1.6 - 删除从PDF模板

Question

既有线我在LibreOffice中创建的PDF模板，我加油吧使用AcroFields。在一些罕见的情况下，我想隐藏一个特定的字段，因此我使用RemoveField方法将其删除。它是边界，但留在那里。从我搜索的内容看来，它可能是LibreOffice创建表单的方式。

我已经与到目前为止想出了是让现场的矩形，并用白色图像覆盖。然而问题是，客户使用计划，使我目前的解决方案几乎无法使用

的问题因此背景图像和/或其他背景颜色较白的创建模板 - 是有一些方法我可以去掉的边界？ [例如。通过访问iTextSharp的一些低级别的对象模型，或类似的东西]

感谢很多提前

Answer 1

卸下单独的图形对象可能会变得有些棘手，但它不是不可能的。最难的部分是决定要删除哪些对象。下面是一些示例代码靶向iTextSharp的4.1.6，首先创建一个带有两个矩形组成的PDF，然后创建基于第一移除了矩形之一的第二PDF。你需要运用你的逻辑来找出你想要删除的矩形。有可能你实际上没有矩形，而是直线形成一个矩形，在这种情况下，你也需要修改一下代码。

这第一位刚在桌面上创建一个基本的PDF与两个矩形：

//Create a file on the desktop with two rectangles 
var file1 = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "File1.pdf"); 
using (var fs = new FileStream(file1, FileMode.Create, FileAccess.Write, FileShare.None)) { 
    var doc = new Document(); 
    var writer = PdfWriter.GetInstance(doc, fs); 
    doc.Open(); 

    var cb = writer.DirectContent; 

    //Draw two rectangles 
    cb.SaveState(); 
    cb.SetColorStroke(iTextSharp.text.Color.RED); 
    cb.Rectangle(40, 60, 200, 100); 
    cb.Stroke(); 
    cb.RestoreState(); 

    cb.SaveState(); 
    cb.SetColorStroke(iTextSharp.text.Color.BLUE); 
    cb.Rectangle(500, 80, 90, 50); 
    cb.Stroke(); 
    cb.RestoreState(); 

    doc.Close(); 
} 

接下来的这个部分是更加复杂的部分。我鼓励你做一个Console.WriteLine(tokenizer.StringValue);内while循环的看到所有的PDF命令。你会注意到他们使用RPN syntax这可能需要一点时间才能使用。有关更多问题，请参阅代码中的注释。

//Bind a reader to our first file 
var reader = new PdfReader(file1); 
//Get the first page (this would normally be done in a loop) 
var page = reader.GetPageN(1); 
//Get the "contents" of that page 
var objectReference = (PdfIndirectReference)page.Get(PdfName.CONTENTS); 
//Get the actual stream of the "contents" 
var stream = (PRStream)PdfReader.GetPdfObject(objectReference); 
//Get the raw bytes of the stream 
var streamBytes = PdfReader.GetStreamBytes(stream); 
//Convert the bytes to actual PDF tokens/commands 
var tokenizer = new PRTokeniser(new RandomAccessFileOrArray(streamBytes)); 
//We're going to re-append each token to this below buffer and remove the ones that we don't want 
List<string> newBuf = new List<string>(); 
//Loop through each PDf token 
while (tokenizer.NextToken()) { 
    //Add them to our master buffer 
    newBuf.Add(tokenizer.StringValue); 
    //The "Other" token is used for most commands, so if we're on "Other" and the current command is "re" which is rectangle 
    if (
     tokenizer.TokenType == PRTokeniser.TK_OTHER && //The "Other" token is used for most commands 
     newBuf[newBuf.Count - 1] == "re" &&   //re is the rectangle command 
     newBuf[newBuf.Count - 5] == "40"    //PDFs use RPN syntax so the red rectangle command was "40 60 200 100 re" 
     ) { 
     newBuf.RemoveRange(newBuf.Count - 5, 5);  //If the above conditions were met remove the last 5 commands 
    } 
} 

//Convert our array to a string with newlines between each token, convert that to an ASCII byte array and push that back into the stream (erasing the current contents) 
stream.SetData(System.Text.Encoding.ASCII.GetBytes(String.Join("\n", newBuf.ToArray()))); 

//Create a new file with the rectangle removed 
var file2 = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "File2.pdf"); 
using (var fs = new FileStream(file2, FileMode.Create, FileAccess.Write, FileShare.None)) { 
    //Bind a stamper to our read above which has the altered stream 
    var stamper = new PdfStamper(reader, fs); 
    //Loop through each page 
    int total = reader.NumberOfPages; 
    for (int i = 1; i <= total; i++) { 
     //Push the content over page by page 
     reader.SetPageContent(i, reader.GetPageContent(i)); 
    } 
    stamper.Close(); 
} 
reader.Close();