ElementEdit

1//
2// Copyright (c) 2001-2021 by PDFTron Systems Inc. All Rights Reserved.
3//
4
5using System;
6using System.Collections.Generic;
7
8using pdftron;
9using pdftron.Common;
10using pdftron.Filters;
11using pdftron.SDF;
12using pdftron.PDF;
13
14using XSet = System.Collections.Generic.List<int>;
15
16using NUnit.Framework;
17
18namespace MiscellaneousSamples
19{
20	/// <summary>
21	/// The sample code shows how to edit the page display list and how to modify graphics state 
22	/// attributes on existing Elements. In particular the sample program strips all images from 
23	/// the page, changes path fill color to red, and changes text fill color to blue. 
24	/// </summary>
25	[TestFixture]
26	public class ElementEditTest
27	{
28		
29		static void ProcessElements(ElementReader reader, ElementWriter writer, XSet visited)
30		{
31			Element element;
32			while ((element = reader.Next()) != null) // Read page contents
33			{
34				switch (element.GetType())
35				{
36					case Element.Type.e_image:
37					case Element.Type.e_inline_image:
38							// remove all images by skipping them
39							break;
40					case Element.Type.e_path:
41						{
42							// Set all paths to red color.
43							GState gs = element.GetGState();
44							gs.SetFillColorSpace(ColorSpace.CreateDeviceRGB());
45							gs.SetFillColor(new ColorPt(1, 0, 0));
46                            writer.WriteElement(element);
47							break;
48						}
49					case Element.Type.e_text:
50						{
51							// Set all text to blue color.
52							GState gs = element.GetGState();
53							gs.SetFillColorSpace(ColorSpace.CreateDeviceRGB());
54							gs.SetFillColor(new ColorPt(0, 0, 1));
55                            writer.WriteElement(element);
56							break;
57						}
58					case Element.Type.e_form:
59						{
60							writer.WriteElement(element); // write Form XObject reference to current stream
61
62                            Obj form_obj = element.GetXObject();
63							if (!visited.Contains(form_obj.GetObjNum())) // if this XObject has not been processed
64							{
65								// recursively process the Form XObject
66								visited.Add(form_obj.GetObjNum());
67								ElementWriter new_writer = new ElementWriter();
68
69								reader.FormBegin();
70								new_writer.Begin(form_obj, true);
71
72								reader.ClearChangeList();
73								new_writer.SetDefaultGState(reader);
74
75                                ProcessElements(reader, new_writer, visited);
76								new_writer.End();
77								reader.End();
78							}
79							break;
80						}
81                    default:
82                        writer.WriteElement(element);
83                        break;
84				}
85			}
86		}
87
88		/// <summary>
89		/// The main entry point for the application.
90		/// </summary>
91		[Test]
92		public static void Sample()
93		{
94
95			// Relative path to the folder containing test files.
96			const string input_path =  "TestFiles/";
97			string input_filename = "newsletter.pdf";
98			string output_filename = "newsletter_edited.pdf";
99
100			try
101			{
102				Console.WriteLine("Opening the input file...");
103				using (PDFDoc doc = new PDFDoc(Utils.GetAssetTempFile(input_path + input_filename)))
104				{
105					doc.InitSecurityHandler();
106
107					ElementWriter writer = new ElementWriter();
108					ElementReader reader = new ElementReader();
109					XSet visited = new XSet();
110
111					PageIterator itr = doc.GetPageIterator();
112
113					while (itr.HasNext())
114					{
115						try
116						{
117							Page page = itr.Current();
118							visited.Add(page.GetSDFObj().GetObjNum());
119
120							reader.Begin(page);
121							writer.Begin(page, ElementWriter.WriteMode.e_replacement, false, true, page.GetResourceDict());
122
123                            ProcessElements(reader, writer, visited);
124							writer.End();
125							reader.End();
126
127							itr.Next();
128						}
129						catch (PDFNetException e)
130						{
131							Console.WriteLine(e.Message);
132							Assert.True(false);
133						}
134					}
135
136					doc.Save(Utils.CreateExternalFile(output_filename), SDFDoc.SaveOptions.e_remove_unused);
137					Console.WriteLine("Done. Result saved in {0}...", output_filename);
138				}
139			}
140			catch (PDFNetException e)
141			{
142				Console.WriteLine(e.Message);
143				Assert.True(false);
144			}
145		}
146	}
147}