LoadDocumentFromCache Event

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Document.Writer 
Imports Leadtools.Svg 
Imports Leadtools.Document 
Imports Leadtools.Caching 
Imports Leadtools.Annotations.Engine 
Imports Leadtools.Barcode 
Imports Leadtools.Ocr 
Imports LeadtoolsDocumentExamples.LeadtoolsExamples.Common 
Imports Leadtools.Document.Converter 
 
Public Sub LoadDocumentFromCacheTest() 
   ' The cache we are using 
   Dim cache As New FileCache() 
   cache.PolicySerializationMode = CacheSerializationMode.Json 
   cache.DataSerializationMode = CacheSerializationMode.Json 
   cache.CacheDirectory = "c:\cache-dir" 
 
   ' document IDs to use 
   Const virtualDocumentId As String = "virtual" 
   Const childDocumentId1 As String = "child1" 
   Const childDocumentId2 As String = "child2" 
 
   ' Create a new document 
   Dim createDocumentOptions As New CreateDocumentOptions() 
   createDocumentOptions.Cache = cache 
   createDocumentOptions.DocumentId = virtualDocumentId 
 
   Using document As LEADDocument = DocumentFactory.Create(createDocumentOptions) 
      document.Name = "Virtual" 
      Debug.Assert(virtualDocumentId = document.DocumentId) 
 
      ' Should have 0 pages and documents 
      Debug.Assert(document.Pages.Count = 0) 
      Debug.Assert(document.Documents.Count = 0) 
 
      ' Add page 1 and 2 from a PDF file 
      Dim loadDocumentOptions As New LoadDocumentOptions() 
      loadDocumentOptions.Cache = cache 
      loadDocumentOptions.DocumentId = childDocumentId1 
      Dim childDocument As LEADDocument = DocumentFactory.LoadFromFile("C:\LEADTOOLS21\Resources\Images\leadtools.pdf", loadDocumentOptions) 
      ' Set the name 
      childDocument.Name = "Child1" 
      childDocument.SaveToCache() 
      ' Now add the pages 
      document.Pages.Add(childDocument.Pages(0)) 
      document.Pages.Add(childDocument.Pages(1)) 
 
      ' Add an empty page 
      Dim documentPage As DocumentPage = document.Pages.CreatePage(LeadSizeD.Create(LEADDocument.UnitsPerInch * 8.5, LEADDocument.UnitsPerInch * 11), 300) 
      document.Pages.Add(documentPage) 
 
      ' Add page 3 and 4 from a TIF file 
      loadDocumentOptions = New LoadDocumentOptions() 
      loadDocumentOptions.Cache = cache 
      loadDocumentOptions.DocumentId = childDocumentId2 
      childDocument = DocumentFactory.LoadFromFile("C:\LEADTOOLS21\Resources\Images\ocr1-4.tif", loadDocumentOptions) 
      ' Set the name 
      childDocument.Name = "Child2" 
      ' Also save it into the cache 
      childDocument.SaveToCache() 
      ' Now add the pages 
      document.Pages.Add(childDocument.Pages(2)) 
      document.Pages.Add(childDocument.Pages(3)) 
 
      ' Should have 5 pages and 2 documents (the PDF and the TIF) 
      Debug.Assert(document.Pages.Count = 5) 
      Debug.Assert(document.Documents.Count = 2) 
 
      ' Tell the parent document to dispose any child documents when the parent is disposed 
      document.AutoDisposeDocuments = True 
 
      ' Now save, the parent document into the cache 
      document.SaveToCache() 
 
      ' And tell all documents to not delete themselves from the cache 
      document.AutoDeleteFromCache = False 
   End Using 
 
   ' Hook to the DocumentFactory.LoadDocumentFromCache event to log the documents being loaded 
   Dim loadDocumentFromCacheHandler As EventHandler(Of ResolveDocumentEventArgs) = 
      Sub(sender As Object, e As ResolveDocumentEventArgs) 
         Console.WriteLine("Loading child document from cache:") 
         Console.WriteLine($" Source DocumentId:{e.SourceDocument.DocumentId}") 
         Console.WriteLine($" DocumentId to load{e.LoadFromCacheOptions.DocumentId}") 
         ' Source document must be the virtual virtualDocumentId 
         Debug.Assert(virtualDocumentId = e.SourceDocument.DocumentId) 
         ' Child documents being loaded Is either childDocumentId1 Or childDocumentId2 
         Debug.Assert(childDocumentId1 = e.LoadFromCacheOptions.DocumentId OrElse childDocumentId2 = e.LoadFromCacheOptions.DocumentId) 
         ' If this Is childDocumentId2, we will load it ourselves, And change its name to indicate it has been loaded by us 
         If childDocumentId2 = e.LoadFromCacheOptions.DocumentId Then 
            ' Modify e.LoadFromCacheOptions if needed, Or create a New instance And use it 
            e.Document = DocumentFactory.LoadFromCache(e.LoadFromCacheOptions) 
            e.Document.Name = "LoadedByEvent" 
         End If 
         ' else, let the factory loaded it normally 
      End Sub 
 
   AddHandler DocumentFactory.LoadDocumentFromCache, loadDocumentFromCacheHandler 
 
   ' Now, load the document from the cache 
   Dim loadFromCacheOptions As New LoadFromCacheOptions() 
   loadFromCacheOptions.Cache = cache 
   loadFromCacheOptions.DocumentId = virtualDocumentId 
   Using document As LEADDocument = DocumentFactory.LoadFromCache(loadFromCacheOptions) 
      Console.WriteLine($"Loaded virtual document id{document.DocumentId} name:{document.Name}") 
      Debug.Assert(document.Name = "Virtual") 
      ' Should have 5 pages and 2 documents (the PDF and the TIF) 
      Debug.Assert(document.Pages.Count = 5) 
      Debug.Assert(document.Documents.Count = 2) 
 
      ' Show the child document names, it should be Child1 and then LoadedByEvent 
      Dim childDocument As LEADDocument = document.Documents(0) 
      Console.WriteLine($"First child document id{childDocument.DocumentId} name:{childDocument.Name}") 
      Debug.Assert(childDocument.Name = "Child1") 
      childDocument = document.Documents(1) 
      Console.WriteLine($"Second child document id{childDocument.DocumentId} name:{childDocument.Name}") 
      Debug.Assert(childDocument.Name = "LoadedByEvent") 
   End Using 
 
   RemoveHandler DocumentFactory.LoadDocumentFromCache, loadDocumentFromCacheHandler 
 
   ' Done, delete all documents from the cache 
   Dim isDeleted As Boolean = DocumentFactory.DeleteFromCache(New LoadFromCacheOptions With {.Cache = cache, .DocumentId = childDocumentId1}) 
   Debug.Assert(isDeleted) 
   isDeleted = DocumentFactory.DeleteFromCache(New LoadFromCacheOptions With {.Cache = cache, .DocumentId = childDocumentId2}) 
   Debug.Assert(isDeleted) 
   isDeleted = DocumentFactory.DeleteFromCache(New LoadFromCacheOptions With {.Cache = cache, .DocumentId = virtualDocumentId}) 
   Debug.Assert(isDeleted) 
End Sub