DocumentPreviewCache Class

DocumentPreviewCache is a persistent cache that provides thumbnails for browsing in PDFNet. The cache is placed in the sub - directory 'trn_DocumentPreviewCache' of the PDFNet Resources folder, which can be set by calling PDFNet::SetPersistentCachePath.In the case the PersistentCachePath is not set the files will be stored in the system temp path (PDFNet::GetSystemTempPath()).The cache will be used by any PDFNet process that uses the resource path.If more than one PDFNet process is running concurrently, the first process to acquire a lock on the cache will use it.Subsequent processes will not read or modify the cache. DocumentPreviewCache will store references to generated JPG thumbnails and keeps track of the dimensions of the thumbnail and the filesize of the specific pdf documents. Furthermore it takes care that the size constraints(max_cache_bytes, max_disk_percentage) are met and it cleans the oldest(in terms of last request) thumbs from the cache in case of a overflow. If the user requests a file that is already in the cache and the requested thumb dimensions are smaller or equal than the ones of the cache - version the URL of the cached thumb is given back.If the dimensions are bigger the thumb gets rendered again, the old thumb gets replaced and the URL is given back. If the size of the pdf document changes the thumb will be rendered again even when there is a version of that thumbnail in the cache.In case that the user wants to suppress the re-rendering of that specific thumb(e.g.when the change on the pdf document was made on another page than the first page which is used for the thumb), IrrelevantChangeMade has to be called.

public sealed class DocumentPreviewCache : DependencyObject

Public NotInheritable Class DocumentPreviewCache
	Inherits DependencyObject

public ref class DocumentPreviewCache sealed : public DependencyObject

pdftron.PDF.DocumentPreviewCache = function();

Type.createClass(
	'pdftron.PDF.DocumentPreviewCache',
	Windows.UI.Xaml.DependencyObject);