DocumentViewer 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 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 if 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 whole document |
| Error |
The exception object if an error occur during 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:
-
The user clicks the entry in the bookmarks container.
-
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 whole document |
| Data1 | DocumentBookmark instance |
This is the DocumentBookmark object being passed to GotoBookmark is in 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 happen 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 overriding the default behavior of the operation |
-
When the event returns to the document viewer, it checks the value of Abort, and it is not false, it will proceed to call GotoBookmark using the bookmark object in Data1.
-
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 whole 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 we cannot abort it anymore |
Operations
The following is a list of the document viewer operations, when do 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 a 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 |
| 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 as the result of the user clicking on 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 |
| 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 |
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 |
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 virtualizer is calling DocumentPage.GetImageUrl or DocumentPage.GetSvg to obtain the image data for a page that has come into view |
null when IsPostOperation is false The image data when IsPostOperation is true |
Not used |
Page number |
Setting Abort to true will cancel this and the image data of this page not be used in the view |
The page image data is updated |
| RenderItemPlaceholder |
View virtualizer is rendering the place holder of a page that does not have the image data loaded. Default behavior is rendering the text |
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 |
| RunLink |
The user has clicked on a link on a page using DocumentViewerPageLinksInteractiveMode and DocumentViewer.RunLinkTarget is about to be called |
DocumentLink object. RunLinkTarget handles link targets that are locations in 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 if 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 using 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 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, resulting in DocumentViewerView.ItemType being set to a new value. The LEADTOOLS Document Viewer uses this value to update the |
New value for DocumentViewerView.ItemType |
Not used |
Not used (0) |
Setting Abort to true will cancel this and 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 are not loaded |
All thumbnails are loaded and the background thread exists. DocumentViewerThumbnails.IsLoading will be false. |
| GetThumbnail |
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 are not 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 the annotations user interface till CreateAutomation occurs. Setting Abort to true will cancel starting the thread and the annotation containers are not loaded. DocumentViewerAnnotations.IsLoading will be true |
All the annotation containers are and read. CreateAutomation operation will occur next. DocumentViewerAnnotations.IsLoading will be false |
| GetAnnotations |
Annotations background thread is retreiving the annotations for all page |
null when IsPostOperation is false The annotation container when IsPostOperation is true |
Not used |
Noe used (0) |
Setting Abort to true will cancel this and the page will not have an associated annotation container |
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 create 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 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 for 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 is not 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 either 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 |
