Called by the factory when loading child documents from the cache.
public event EventHandler<ResolveDocumentEventArgs> LoadDocumentFromCache
Public Event LoadDocumentFromCache As EventHandler(Of ResolveDocumentEventArgs)
public:
event EventHandler<ResolveDocumentEventArgs^>^ LoadDocumentFromCache
The LoadDocumentFromCache event is called during LoadFromCache(LoadFromCacheOptions) if the document being loaded contains child documents. The event is fired once for each child document and allow the application to customize this behavior.
Parameter | Type | Description |
---|---|---|
sender | object | The source of the event |
e | ResolveDocumentEventArgs | The event data |
ResolveDocumentEventArgs contains the following members:
Input: The source (owner) document being loaded.
Input: The options to use when loading this child document. The handler can modify the properties of this member (for example, replace LoadFromCacheOptions.Cache with a different cache).
Output: The loaded child document. If the handler leaves this value as null, then the factory will attempt to load the document using the options set in LoadFromCacheOptions.
This example will create a document from child documents, save it to the cache, and then re-load it. It will use the LoadDocumentFromCache event to manually load the child documents.
using Leadtools;
using Leadtools.Codecs;
using Leadtools.Document.Writer;
using Leadtools.Svg;
using LeadtoolsExamples.Common;
using Leadtools.Document;
using Leadtools.Caching;
using Leadtools.Annotations.Engine;
using Leadtools.Ocr;
using Leadtools.Barcode;
using Leadtools.Document.Converter;
public void LoadDocumentFromCacheTest()
{
// The cache we are using
FileCache cache = new FileCache();
cache.PolicySerializationMode = CacheSerializationMode.Json;
cache.DataSerializationMode = CacheSerializationMode.Json;
cache.CacheDirectory = @"c:\cache-dir";
// document IDs to use
const string virtualDocumentId = "virtual";
const string childDocumentId1 = "child1";
const string childDocumentId2 = "child2";
// Create a new document
var createDocumentOptions = new CreateDocumentOptions();
createDocumentOptions.Cache = cache;
createDocumentOptions.DocumentId = virtualDocumentId;
using (LEADDocument document = 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
var loadDocumentOptions = new LoadDocumentOptions();
loadDocumentOptions.Cache = cache;
loadDocumentOptions.DocumentId = childDocumentId1;
LEADDocument childDocument = DocumentFactory.LoadFromFile(@"C:\users\Public\Documents\LEADTOOLS 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
DocumentPage 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:\users\Public\Documents\LEADTOOLS 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;
}
// Hook to the DocumentFactory.LoadDocumentFromCache event to log the documents being loaded
EventHandler<ResolveDocumentEventArgs> loadDocumentFromCacheHandler = (sender, e) =>
{
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 || 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)
{
// Modify e.LoadFromCacheOptions if needed, or create a new instance and use it
e.Document = DocumentFactory.LoadFromCache(e.LoadFromCacheOptions);
e.Document.Name = "LoadedByEvent";
}
// else, let the factory loaded it normally
};
DocumentFactory.LoadDocumentFromCache += loadDocumentFromCacheHandler;
// Now, load the document from the cache
var loadFromCacheOptions = new LoadFromCacheOptions();
loadFromCacheOptions.Cache = cache;
loadFromCacheOptions.DocumentId = virtualDocumentId;
using (LEADDocument document = DocumentFactory.LoadFromCache(loadFromCacheOptions))
{
Console.WriteLine($"Loaded virtual document id{document.DocumentId} name:{document.Name}");
Debug.Assert(document.Name == "Virtual");
// Should have 5 pages and 2 documents (the PDF and the TIF)
Debug.Assert(document.Pages.Count == 5);
Debug.Assert(document.Documents.Count == 2);
// Show the child document names, it should be Child1 and then LoadedByEvent
LEADDocument childDocument = document.Documents[0];
Console.WriteLine($"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");
}
DocumentFactory.LoadDocumentFromCache -= loadDocumentFromCacheHandler;
// Done, delete all documents from the cache
bool isDeleted = DocumentFactory.DeleteFromCache(new LoadFromCacheOptions { Cache = cache, DocumentId = childDocumentId1 });
Debug.Assert(isDeleted);
isDeleted = DocumentFactory.DeleteFromCache(new LoadFromCacheOptions { Cache = cache, DocumentId = childDocumentId2 });
Debug.Assert(isDeleted);
isDeleted = DocumentFactory.DeleteFromCache(new LoadFromCacheOptions { Cache = cache, DocumentId = virtualDocumentId });
Debug.Assert(isDeleted);
}
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:\users\Public\Documents\LEADTOOLS 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:\users\Public\Documents\LEADTOOLS 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
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