ElementEdit

1//
2// Copyright (c) 2001-2020 by PDFTron Systems Inc. All Rights Reserved.
3//
4
5using System;
6using System.IO;
7using System.Threading.Tasks;
8using Windows.Foundation;
9
10using pdftron.PDF;
11using pdftron.SDF;
12
13using PDFNetUniversalSamples.ViewModels;
14
15namespace PDFNetSamples
16{
17    public sealed class ElementEditTest : Sample
18    {
19        public ElementEditTest() :
20            base("ElementEdit", "The sample code shows how to edit the page display list and how to modify graphics state attributes on existing Elements. In particular the sample program strips all images from the page and changes text color to blue.")
21        {
22        }
23
24        public override IAsyncAction RunAsync()
25        {
26            return Task.Run(new System.Action(async () => {
27                WriteLine("--------------------------------");
28                WriteLine("Starting ElementEdit Test...");
29                WriteLine("--------------------------------\n");
30
31			    try
32                {
33                    string input_file_path = Path.Combine(InputPath, "newsletter.pdf");
34                    WriteLine("Opening input file " + input_file_path);
35                    PDFDoc doc = new PDFDoc(input_file_path);
36				    doc.InitSecurityHandler();
37
38				    int num_pages = doc.GetPageCount();
39
40                    PageIterator itr = doc.GetPageIterator();
41
42				    ElementWriter writer = new ElementWriter();
43				    ElementReader reader = new ElementReader();
44
45                    while (itr.HasNext())
46                    {
47                        Page page = itr.Current();
48				        reader.Begin(page);
49					    writer.Begin(page, ElementWriterWriteMode.e_replacement, false);
50					    ProcessElements(reader, writer);
51					    writer.End();
52					    reader.End();
53
54                        itr.Next();
55				    }
56                    
57                    String output_file_path = Path.Combine(OutputPath, "newsletter_edited.pdf");
58                    await doc.SaveAsync(output_file_path, SDFDocSaveOptions.e_remove_unused);
59				    doc.Destroy();
60                    WriteLine("Done. Result saved in " + output_file_path);
61                    await AddFileToOutputList(output_file_path).ConfigureAwait(false);
62			    }
63			    catch (Exception e)
64			    {
65				    WriteLine(GetExceptionMessage(e));
66			    }
67
68                WriteLine("\n--------------------------------");
69                WriteLine("Done ElementEdit Test.");
70                WriteLine("--------------------------------\n");
71		    })).AsAsyncAction();
72        }
73
74		void ProcessElements(ElementReader reader, ElementWriter writer)
75		{
76			Element element;
77			while ((element = reader.Next()) != null) 	// Read page contents
78			{
79				switch (element.GetType())
80				{
81					case ElementType.e_image:
82					case ElementType.e_inline_image:
83						// remove all images by skipping them
84						continue;
85                    case ElementType.e_path:				// Process path data...
86                        {
87                            // Set all paths to red color.
88                            GState gs = element.GetGState();
89                            gs.SetFillColorSpace(ColorSpace.CreateDeviceRGB());
90                            gs.SetFillColor(new ColorPt(1, 0, 0));
91                            writer.WriteElement(element);
92                            break;
93                        }
94					case ElementType.e_text: 				// Process text strings...
95						{
96							// Set all text to blue color.
97							GState gs = element.GetGState();
98							gs.SetFillColorSpace(ColorSpace.CreateDeviceRGB());
99							gs.SetFillColor(new ColorPt(0, 0, 1));
100							writer.WriteElement(element);
101							break;
102						}
103					case ElementType.e_form:				// Recursively process form XObjects
104						{
105							writer.WriteElement(element);
106
107							reader.FormBegin();
108							ElementWriter new_writer = new ElementWriter();
109							new_writer.Begin(element.GetXObject(), true);
110							ProcessElements(reader, new_writer);
111							new_writer.End();
112							reader.End();
113
114							break;
115						}
116					default:
117						{
118							writer.WriteElement(element);
119							break;
120						}		
121				}
122			}
123		}
124	}
125}