Multithreaded

1//---------------------------------------------------------------------------------------
2// Copyright (c) 2001-2024 by Apryse Software Inc. All Rights Reserved.
3// Consult legal.txt regarding legal and license information.	 
4//---------------------------------------------------------------------------------------
5
6using System;
7using System.Drawing;
8
9using pdftron;
10using pdftron.Common;
11using pdftron.PDF;
12using pdftron.SDF;
13using System.Threading;
14using System.Threading.Tasks;
15using System.Collections.Generic;
16
17namespace PDFDrawTestCS
18{
19	/// <summary>
20	//---------------------------------------------------------------------------------------
21	// The following sample illustrates how to use PDFDoc locking mechanisms to access the document
22	// concurrently.  PDFDoc uses a recursive shared lock model.  Multiple threads can read the document 
23	// at the same time, but only one thread can write to the document.  A given thread can acquire 
24	// as many locks of the same type as it wants, in a recursive fashion.
25	//
26	// It's important to note that you cannot upgrade a PDFDoc read lock to a write lock.  Because of
27	// the nature of the lock, this would cause a deadlock, and is not allowed.
28	//
29	// If a thread attempts to acquire a write lock while holding a read lock, an exception will be
30	// thrown.  As a side effect, this means certain PDFNet API calls which implicitly acquire a write
31	// lock on the document will throw an exception if called while holding a read lock.  The API
32	// documents which methods acquire a write lock on the document.
33	//
34	// For more information on document locking in PDFNet, please consult the following knowledge base
35	// article: https://groups.google.com/forum/#!topic/pdfnet-sdk/pDZsqrjCEdg
36	//---------------------------------------------------------------------------------------
37
38	class Class1
39	{
40		private static pdftron.PDFNetLoader pdfNetLoader = pdftron.PDFNetLoader.Instance();
41		static Class1() {}
42		
43		/// <summary>
44		/// A static method for rasterizing a given page to a file.
45		/// </summary>
46		static void DoDraw(PDFDoc doc, Page pg, string output_path)
47		{
48			//acquire a read lock, since we will be accessing the document.
49			doc.LockRead();
50
51			//Acquiring a write lock when holding a read lock is illegal,
52			//and would cause an exception to be thrown:
53			//doc.Lock();
54
55			//draw the page
56			using (PDFDraw draw = new PDFDraw())
57			{
58				draw.SetDPI(92);
59				draw.Export(pg, output_path);
60				Console.WriteLine("Rendered page: Result saved in {0}", output_path);
61			}
62
63			//release the read lock
64			doc.UnlockRead();
65		}
66
67		/// <summary>
68		/// The main entry point for the application.
69		/// </summary>
70		static void Main(string[] args)
71		{
72			// The first step in every application using PDFNet is to initialize the 
73			// library and set the path to common PDF resources. The library is usually 
74			// initialized only once, but calling Initialize() multiple times is also fine.
75			PDFNet.Initialize(PDFTronLicense.Key);				   
76			
77			// Relative path to the folder containing test files
78			string input_path =  "../../../../TestFiles/";
79			string output_path = "../../../../TestFiles/Output/";
80
81			//Example - Exporting images of each page in the document in parallel,
82			//          and annotating the document in the main thread.
83			try  
84			{
85				// Open the PDF document.
86				using (PDFDoc doc = new PDFDoc(input_path + "newsletter.pdf")) 
87				{
88					// Lock the document, since we are going to annotate it in this thread.
89					doc.Lock();
90
91					// Initialize the security handler, in case the PDF is encrypted.
92					doc.InitSecurityHandler();
93
94					List<Task> tasks = new List<Task>();
95
96					// Iterate through each page in the document
97					for (PageIterator itr=doc.GetPageIterator(); itr.HasNext(); itr.Next()) 
98					{
99						//note that locking a second time does not cause a deadlock:
100						doc.Lock();
101
102						// You can acquire a read lock while holding a write lock:
103						doc.LockRead();
104						doc.UnlockRead();
105
106						// Choose an output path for this page
107						string page_output_path = output_path + "newsletter_" + itr.GetPageNumber() + ".png";
108
109						// Create an asynchronous task to draw the page
110						Page pg = itr.Current();
111						Task t = new Task(() => DoDraw(doc, pg, page_output_path));
112						// Start the Task (although it won't be able to access the document, since we have a write lock)
113						t.Start();
114						// Add it to our list of Tasks so we can Wait() for it later.
115						tasks.Add(t);
116
117						Console.WriteLine("Adding stamp to PDFDoc, page " + itr.GetPageNumber());
118
119						// Create a stamp annotation (See AnnotationTest for more details)
120						pdftron.PDF.Annots.RubberStamp stamp = pdftron.PDF.Annots.RubberStamp.Create(doc.GetSDFDoc(), new Rect(30, 30, 300, 200));
121						stamp.SetIcon("Approved");
122						itr.Current().AnnotPushBack(stamp);
123
124						// Releasing the lock decrements our lock count, 
125						// but the thread still holds a write lock on the document:
126						doc.Unlock();
127					}
128	 
129					// Now we release the write lock, and the 
130					// PDFDraw tasks can begin execution
131					doc.Unlock();
132
133					// Wait for the PDFDraw tasks to complete.
134					foreach (Task t in tasks)
135					{
136						t.Wait();
137					}
138				}
139			}
140			catch (PDFNetException e) 
141			{
142				Console.WriteLine(e.Message);
143			}
144			PDFNet.Terminate();
145		}
146	}
147}