Document Viewer Operations

Summary

DocumentViewer fires the DocumentViewer.Operation event before and after it performs any operation to allow the user to monitor, modify, or abort the action as well as update the application's state when an operation is run.

The operation mechanism allows the application to modify the behavior when the action happens through the end-user interaction with the document viewer and not directly by the application calling a method.

The Operation event will receive data of type DocumentViewerOperationEventArgs that contains the following members:

Member Description
Operation

DocumentViewerOperation enumeration member that identifies the operation

IsPostOperation

Indicates whether the operation is about to run (false) or that the operation has been run (true)

Data1

First optional generic data object associated with the operation. The type and value of this depends on the operation

Data2

Second optional generic data object associated with the operation. The type and value of this depends on the operation

PageNumber

Page number associated with this operation. 0 if this operation is for the entire document

Error

The exception object if an error occurs during the running of the operation

Abort

Can be set by the application to abort running the application

Example

When the user clicks the mouse on an entry in the bookmarks container, the DocumentViewer.GotoBookmark method is called internally by the DocumentViewer. The application itself does not initiate the call and without the operation mechanism, it has no way of knowing what the user did. Instead, Operation is called and the application has a chance to log, modify, or even abort the action.

Here are the steps:

  1. The user clicks the entry in the bookmarks container.

  2. Operation fires with the following members:

Member Value Description
Operation DocumentViewerOperation.GotoBookmark

The operation type indicates what is about to happen. In this case, the DocumentViewer.GotoBookmark method is about to be called

IsPostOperation false

The action has not occurred yet. The document viewer is informing the application that it is about to call GotoBookmark

PageNumber 0

Since this is an operation for the entire document

Data1 DocumentBookmark instance

This is the DocumentBookmark object being passed to GotoBookmark as Data1. The application can perform any action here, including modifying the behavior based on certain bookmarks

Data2 null

Not used

Error null

Ignored. Error is never set to a value when IsPostOperation is false. The action has not happened yet to throw an error

Abort false

The application has the chance to gracefully abort this action. This can done as a result of prompting the user or to perform a custom action and override the default behavior of the operation

  1. When the event returns to the document viewer, it checks the value of Abort, and if it is not false, it will proceed to call GotoBookmark using the bookmark object in Data1.

  2. After the method returns, the Operation event fires again with the following members:

Member Value Description
Operation DocumentViewerOperation.GotoBookmark

Same operation type from before. Indicating the action that had just happened

IsPostOperation true

The action has run. The document viewer is informing the application that GotoBookmark had run and the content of the bookmark had been applied

PageNumber 0

Since this is an operation for the entire document

Data1 DocumentBookmark instance

The same DocumentBookmark object passed to GotoBookmark

Data2 null

Not used

Error

null or a value

If this value is null, then the operation was performed successfully. Otherwise, it will contain an exception object with the error details. The application can use this to show an error message to the user

Abort Not used

The operation has run and cannot be aborted anymore

Operations

The following is a list of the document viewer operations, when they occur and the value of Data1 and Data2. All the operations are members of the DocumentViewerOperation enumeration that are separated into logical categories below.

Command Operations

Operation Occurs Data1 Data2 PageNumber IsPostOperation false action IsPostOperation true action
RunCommand

Commands is running any of the built-in or custom commands

DocumentViewerCommand object being run

The optional value passed to DocumentViewerCommands.Run

Not used (0)

Setting Abort to true will cancel running the command

The command is run

DocumentViewer Operations

Operation Occurs Data1 Data2 PageNumber IsPostOperation false action IsPostOperation true action
SetDocument

DocumentViewer.SetDocument is called

The new Document object passed to the method

Not used

Not used (0)

Setting Abort to true will cancel replacing the new document in the viewer

The document is set in the viewer

GotoPage

DocumentViewer.GotoPage is being called as the result of the user clicking the thumbnails container

Not used

Not used

Page number

Setting Abort to true will leave the current page as is

The view moves to the new page

PrintPages

DocumentViewer.Print is preparing page images for printing

DocumentPrintData for this print operation

null if the page number is 0; otherwise, the DocumentPrintPageData for the page

Page number

Setting Abort to true will abort the entire operation.

The DocumentPrintPageData is finalized.

PagesAdded

User added pages to the Document object in the DocumentViewer

The 0-based start index of the first page added

A collection of DocumentPage objects being added

Not used (0)

Undefined behavior: Setting Abort to true will cancel adding to the viewer only and the document and viewer will be out of sync.

The pages are added to the viewer. The view, thumbnails, annotations, text, and bookmarks parts of the viewer are be updated.

PagesRemoved

User removed pages from the Document object in the DocumentViewer

The 0-based start index of the first page removed

A collection of DocumentPage objects being removed

Not used (0)

Undefined behavior: Setting Abort to true will cancel removing from the viewer only and the document and viewer will be out of sync.

The pages are removed from the viewer. The view, thumbnails, annotations, text and bookmarks parts of the viewer are be updated.

View Operations

Operation Occurs Data1 Data2 PageNumber IsPostOperation false action IsPostOperation true action
GetPage

View is calling DocumentPage.GetImageUrl or DocumentPage.GetSvg to obtain the image data for a page that has come into view, or DocumentViewer.Print is requesting page data to print with

The ImageLoader instance used for loading if loading the image, but null if loading a back image

The ImageLoader instance used for loading if loading the back image, or the DocumentPrintPageData if used for printing. Otherwise, null

Page number

Setting Abort to true will cancel this operation and the image data of this page not be used in the view. If DocumentViewer.Print is the caller, the printing page will have no image data.

The page image data is updated

RenderItemPlaceholder

View is rendering the place holder of a page that does not have its image data loaded. The default behavior is rendering the text "Loading..." on the page item in the ImageViewer using the ImageViewerRenderEventArgs set in Data1

ImageViewerRenderEventArgs that contains the rendering context to be used

Not used

Page number

Setting Abort to true will cancel the default behavior. Usually applications uses this to perform custom rendering of place holders

The default behavior of rendering "Loading..." is performed

RunLink

The user has clicked a link on a page using DocumentViewerPageLinksInteractiveMode and DocumentViewer.RunLinkTarget is about to be called

DocumentLink object. RunLinkTarget handles link targets that are locations within the same document DocumentLinkType.TargetPage. If the value of LinkType is DocumentLinkType.Value, then the document viewer will not perform any action. The application can use this operation to check for this value and then custom handle DocumentLink.Value - for example, by checking whether it is a hyperlink and starting a web browser instance pointing to it

The InteractiveEventArgs containing the mouse or touch current position and button status.

Page number

Setting Abort to true will cancel this and the link is not run

DocumentViewer.RunLinkTarget is called

HoverLink

The user has hovered the mouse over (entered) or hovered out of (left) a link area on a page using DocumentViewerPageLinksInteractiveMode

DocumentLink object if the mouse is over a link, or null if the mouse is not over any links. The application can use this operation to show rich user experience such as a tool tip with the link value.

The InteractiveEventArgs containing the mouse or touch current position and button status.

Page number

Setting Abort to true will cancel this

Nothing

ItemTypeChanged

When a new document is set to the viewer and DocumentViewerView.PreferredItemType cannot be used, the result is DocumentViewerView.ItemType being set to a new value. The LEADTOOLS Document Viewer uses this value to update the View As Image and View As SVG menu items

New value for DocumentViewerView.ItemType

Not used

Not used (0)

Setting Abort to true will cancel this operation and the item type is not changed.

The item type is changed.

Thumbnails Operations

Operation Occurs Data1 Data2 PageNumber IsPostOperation false action IsPostOperation true action
LoadingThumbnails

Thumbnails is starting the background thread to get the thumbnail images from the document

Not used

Not used

Not used (0)

Setting Abort to true will cancel starting the thread and the thumbnails will not be loaded

All thumbnails are loaded and the background thread exists. DocumentViewerThumbnails.IsLoading will be false.

GetThumbnail

The Thumbnails background thread is calling DocumentPage.GetThumbnailImageUrl for a page

Not used when IsPostOperation is false

The thumbnail image when IsPostOperation is true

Not used

Page number

Setting Abort to true will cancel this and the page will not have an associated image in the thumbnails container

The page thumbnail image is updated

Bookmarks Operations

Operation Occurs Data1 Data2 PageNumber IsPostOperation false action IsPostOperation true action
LoadingBookmarks

Bookmarks is starting the background thread to parse the document and get the bookmark items

Not used

Not used

Not used (0)

Setting Abort to true will cancel starting the thread and the bookmarks will not be parsed

All bookmarks are parsed and the background thread exists. DocumentViewerBookmarks.IsLoading will be false.

GotoBookmark

DocumentViewer.GotoBookmark is being called either directly or as a result of the user clicking an item in the bookmarks container

DocumentBookmark object

Not used

Not used (0)

Setting Abort to true will cancel the operation and the bookmarks target will not be applied

The bookmark target is applied

Annotations Operations

Operation Occurs Data1 Data2 PageNumber IsPostOperation false action IsPostOperation true action
LoadingAnnotations

Annotations is starting the background thread to load the annotation containers for each page from the document

Not used

Not used

Not used (0)

Application must disable all of the annotations user interface until CreateAutomation occurs.

Setting Abort to true will cancel starting the thread and the annotation containers will not be loaded. DocumentViewerAnnotations.IsLoading will be true

All the annotation containers are loaded and read. CreateAutomation operation will occur next. DocumentViewerAnnotations.IsLoading will be false

GetAnnotations

Annotations background thread is retrieving the annotations for all pages

null when IsPostOperation is false

The annotation container when IsPostOperation is true

Not used

Noe used (0)

Setting Abort to true will cancel this operation and the page will not have an annotation container associated with it

The annotations container for the page is saved internally

CreateAutomation

Annotations has finished loading the annotation containers for all the pages and is about to create the Automation object

null when IsPostOperation is false

AnnAutomation object when IsPostOperation is true

Not used

Not used (0)

Setting Abort to true will cancel cth creation of the Automation object and annotations automation support will not work

The Automation object has been created, the annotations containers for the pages are added to it and it is ready to use. Application must enable the annotations user interface elements and use AnnAutomation events if needed

DestroyAutomation

The current Document object in the viewer has been replaced or set to null

AnnAutomation object when IsPostOperation is false

null when IsPostOperation is true

Not used

Not used (0)

Application must unhook all the events subscribed in CreateAutomation and the annotations user interface elements must be disabled.

Setting Abort to true will cancel the operation and the automation object will not be destroyed

AnnAutomation is destroyed

AutomationStateChanged

The current designer or user mode of the AnnAutomation has been changed

Not used

Not used

Not used (0)

Cannot be aborted

The application can check the values of AnnAutomation and update the user interface element

Text Operations

Operation Occurs Data1 Data2 PageNumber IsPostOperation false action IsPostOperation true action
GetText

Text is calling DocumentPage.GetText to get the DocumentPageText object for a page

null when IsPostOperation is false

The DocumentPageText object when IsPostOperation is true

Not used

Page number

Setting Abort to true will cancel getting the text for the page.

Application can show a busy dialog to the user and disable the user interface

Application can remove the busy dialog and re-enable the user interface. All text operations for this page are available now

TextSelectionChanged

The selected text in the document is changing.

Not used

Not used

Not used (0)

Setting Abort to true will cancel changing the document text selection

Document viewer de-selects the annotations objects since only this or the text can be selected at one time

PageTextSelectionChanged

The selected text in a page has changed

Not used

Not used

Page number

Setting Abort to true will cancel changing the page text selection

Document viewer will invalidate the page in the View to highlight the selected text

RenderSelectedText

The selected text of a page is highlighted on the View

ImageViewerRenderEventArgs containing the target context to use for highlighting the text

A list of DocumentViewerTextItem that contains the new selected text items

Page Number

Setting Abort to true will cancel the operation and the default action does not occur. Application can use this to perform custom rendering of the selected text

The selected text is highlighted on the page

SelectedTextToReviewObject

The user has drawn a new AnnTextReviewObject derived annotation object on a page

Object that derives from AnnTextReviewObject

Not used

Page Number

Setting Abort to true will cancel the operation and the default action does not occur

The selected text item rectangles are set in the object. The object is added to the page annotation container and is selected

FindText

DocumentViewerText.Find has begun or is completed for a given page or all pages

A clone of the provided DocumentViewerFindText options

The results of the search, which will be null if isPostOperation is false or there are no matches

Page Number

Setting Abort to true will cancel the operation and the default action does not occur

Search has completed for the page(s)

RenderFoundText

A repaint occurs after a DocumentViewerText.Find completes successfully with results

ImageViewerRenderEventArgs containing the target context to use for rendering the found text

A list of DocumentViewerTextItem that contains the rendering found text items

Page Number

Setting Abort to true will cancel the operation and the default action does not occur

The found text is rendered on the page

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