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# Listening to Document Events

Listening to document events can help in the following situations:

- Identify a new document at opening time, as opposed to existing ones, and perform a dedicated setup.

- Control the processing of document save, document copy, print or mailmerge requests.

- Recalculate table of contents, indexes or table entries of a Writer document when document is going to be closed

- Import math Python packages before opening a Calc document. Release these packages when the document closes.

Next to assigning macros to events, one can monitor events raised by LibreOffice documents. Application Programming Interface (API) broadcasters are responsible for calling event scripts. Unlike listeners that require to define all supported methods, even if unused, document monitors require only two methods next to hooked event scripts.

## Monitoring Document Events

Monitoring is illustrated herewith for Basic and Python languages using object-oriented programming. Assigning OnLoad script, to the Open Document event, suffices to initiate and terminate document event monitoring. Tools - Customize menu Events tab is used to assign either scripts.

Intercepting events helps setting scripts pre- and post-conditions such as loading and unloading libraries or track script processing in the background. Access2Base.Trace module usage is illustrating that second context.

### With Python

Events monitoring starts from object instantiation and ultimately stops when Python releases the object. Raised events are reported using Access2Base console.

OnLoad and OnUnload events can be used to respectively set and unset Python programs path. They are described as Open document and Document closed.

             # -*- coding: utf-8 -*-
             from __future__ import unicode_literals

             import os.path, uno, unohelper
             from com.sun.star.document import DocumentEvent, \
                 XDocumentEventListener as AdapterPattern
             from com.sun.star.lang import EventObject

             class UiDocument(unohelper.Base, AdapterPattern):
                 """ Monitor document events """
                 '''
                 adapted from 'Python script to monitor OnSave event' at
                 https://forum.openoffice.org/en/forum/viewtopic.php?t=68887
                 '''
                 def __init__(self):
                     """ Document events monitor """
                     ''' report using Access2Base.Trace console OR
                     report in 1st sheet, 1st column for Calc docs '''
                     ctx = uno.getComponentContext()
                     smgr = ctx.getServiceManager()
                     desktop = smgr.createInstanceWithContext(
                     'com.sun.star.frame.Desktop' , ctx)
                     self.doc = desktop.CurrentComponent
                     #self.row = 0  # uncomment for Calc documents only
                     Console.setLevel("DEBUG")
                     self.listen()  # Start monitoring doc. events

                 @property
                 def Filename(self) -> str:
                     sys_filename = uno.fileUrlToSystemPath(self.doc.URL)
                     return os.path.basename(sys_filename)

                 def setCell(self, calcDoc, txt: str):
                     """ Output doc. events on 1st column of a Calc spreadsheet """
                     sheet = calcDoc.getSheets().getByIndex(0)
                     sheet.getCellByPosition(0,self.row).setString(txt)
                     self.row = self.row + 1

                 def listen(self, *args):  # OnLoad/OnNew at the earliest
                     """ Start doc. events monitoring """
                     self.doc.addDocumentEventListener(self)
                     Console.log("INFO", "Document events are being logged", True)

                 def sleep(self, *args):  # OnUnload at the latest (optional)
                     """ Stop doc. events monitoring """
                     self.doc.removeDocumentEventListener(self)
                     Console.log("INFO", "Document events have been logged", True)

                 def documentEventOccured(self, event: DocumentEvent):
                     """ Intercepts all doc. events """
                     #self.setCell(event.Source, event.EventName) # only for Calc docs
                     Console.log("DEBUG",
                         event.EventName+" in "+self.Filename,
                         False)

                 def disposing(self, event: EventObject):
                     """ Release all activities """
                     self.sleep()
                     Console.show()

             def OnLoad(*args):  # 'Open Document' event
                 listener = UiDocument()  # Initiates listening

             def OnUnload(*args):  # 'Document has been closed' event
                 pass  # (optional) performed when disposed

             g_exportedScripts = (OnLoad,)

             from com.sun.star.script.provider import XScript
             class Console():
                 """
                 (Back/Fore)ground console to report/log program execution.
                 """
                 @staticmethod
                 def trace(*args,**kwargs):
                     """ Print free item list to console """
                     scr = Console._a2bScript(script='DebugPrint', module='Compatible')
                     scr.invoke((args),(),())
                 @staticmethod
                 def log(level: str, text: str, msgBox=False):
                     """ Append log message to console, optional user prompt """
                     scr = Console._a2bScript(script='TraceLog')
                     scr.invoke((level,text,msgBox),(),())
                 @staticmethod
                 def setLevel(logLevel: str):
                     """ Set log messages lower limit """
                     scr = Console._a2bScript(script='TraceLevel')
                     scr.invoke((logLevel,),(),())
                 @staticmethod
                 def show():
                     """ Display console content/dialog """
                     scr = Console._a2bScript(script='TraceConsole')
                     scr.invoke((),(),())
                 @staticmethod
                 def _a2bScript(script: str, library='Access2Base',
                     module='Trace') -> XScript:
                     ''' Grab application-based Basic script '''
                     sm = uno.getComponentContext().ServiceManager
                     mspf = sm.createInstanceWithContext(
                         "com.sun.star.script.provider.MasterScriptProviderFactory",
                         uno.getComponentContext())
                     scriptPro = mspf.createScriptProvider("")
                     scriptName = "vnd.sun.star.script:"+library+"."+module+"."+script+"?language=Basic&location=application"
                     xScript = scriptPro.getScript(scriptName)
                     return xScript

Mind the misspelled documentEventOccured method that inherits a typo from LibreOffice Application Programming Interface (API).

Start application and Close application events can respectively be used to set and to unset Python path for user scripts or LibreOffice scripts. In a similar fashion, document based Python libraries or modules can be loaded and released using Open document and Document closed events. Refer to Importing Python Modules for more information.

### With LibreOffice Basic

Using Tools - Customize menu Events tab, the Open document event fires a ConsoleLogger initialisation. _documentEventOccured routine - set by ConsoleLogger - serves as a unique entry point to trap all document events.

#### controller.Events module

            Option Explicit

            Global _obj As Object ' controller.ConsoleLogger instance

            Sub OnLoad(evt As com.sun.star.document.DocumentEvent) ' >> Open Document <<
                _obj = New ConsoleLogger : _obj.StartAdapter(evt)
            End Sub ' controller.OnLoad
            Sub _documentEventOccured(evt As com.sun.star.document.DocumentEvent)
                ''' ConsoleLogger unique entry point '''
                 _obj.DocumentEventOccurs(evt)
            End Sub ' controller._documentEventOccured

#### controller.ConsoleLogger class module

Events monitoring starts from the moment a ConsoleLogger object is instantiated and ultimately stops upon document closure. StartAdapter routine loads necessary Basic libraries, while caught events are reported using Access2Base.Trace module.

              Option Explicit
              Option Compatible
              Option ClassModule

              ' ADAPTER design pattern object to be instantiated in the "Open Document" event
              Private Const UI_PROMPT = True
              Private Const UI_NOPROMPT = False ' Set it to True to visualise documents events

              ' MEMBERS
              Private _evtAdapter As Object ' com.sun.star.document.XDocumentEventBroadcaster
              Private _txtMsg As String ' text message to log in console

              ' PROPERTIES
              Private Property Get FileName As String
                  ''' System-dependent filename '''
                  Const _LIBRARY = "Tools" : With GlobalScope.BasicLibraries
                      If Not .IsLibraryLoaded(_LIBRARY) Then .LoadLibrary(_LIBRARY)
                  End With
                  Filename = Tools.Strings.FilenameOutofPath(ThisComponent.URL)
              End Property ' controller.ConsoleLogger.Filename

              ' METHODS
              Public Sub DocumentEventOccurs(evt As com.sun.star.document.DocumentEvent)
                  ''' Monitor document events '''
                  Access2Base.Trace.TraceLog("DEBUG", _
                      evt.EventName &" in "& Filename(evt.Source.URL), _
                      UI_NOPROMPT)
                  Select Case evt.EventName
                      Case "OnUnload" : _StopAdapter(evt)
                  End Select
              End Sub ' controller.ConsoleLogger.DocumentEventOccurs

              Public Sub StartAdapter(Optional evt As com.sun.star.document.DocumentEvent)
                  ''' Initialize document events logging '''
                  Const _LIBRARY = "Access2Base" : With GlobalScope.BasicLibraries
                      If Not .IsLibraryLoaded(_LIBRARY) Then .LoadLibrary(_LIBRARY)
                  End With : Access2Base.Trace.TraceLevel("DEBUG")
                  If IsMissing(evt) Then _txtMsg = "" Else _txtMsg = evt.EventName & "-"
                  Access2Base.Trace.TraceLog("INFO", _txtMsg & "Document events are being logged", UI_PROMPT)
                  _evtAdapter = CreateUnoListener( "_", "com.sun.star.document.XDocumentEventListener" )
                  ThisComponent.addDocumentEventListener( _evtAdapter )
              End Sub ' controller.ConsoleLogger.StartAdapter

              Private Sub _StopAdapter(Optional evt As com.sun.star.document.DocumentEvent)
                  ''' Terminate document events logging '''
                  ThisComponent.removeDocumentEventListener( _evtAdapter )
                  If IsMissing(evt) Then _txtMsg = "" Else _txtMsg = evt.EventName & "-"
                  Access2Base.Trace.TraceLog("INFO", _txtMsg & "Document events have been logged", UI_PROMPT)
                  Access2Base.Trace.TraceConsole() ' Captured events dialog
              End Sub ' controller.ConsoleLogger._StopAdapter

              ' EVENTS
              ' Your code for handled events goes here

Mind the misspelled _documentEventOccured method that inherits a typo from LibreOffice Application Programming Interface (API).

## Discovering Documents Events

The broadcaster API object provides the list of events it is responsible for:

### With Python

             # -*- coding: utf-8 -*-
             from __future__ import unicode_literals

             import uno, apso_utils as ui

             def displayAvailableEvents():
                 """ Display document events """
                 '''
                 adapted from DisplayAvailableEvents() by A. Pitonyak
                 https://forum.openoffice.org/en/forum/viewtopic.php?&t=43689
                 '''
                 ctx = XSCRIPTCONTEXT.getComponentContext()
                 smgr = ctx.ServiceManager
                 geb = smgr.createInstanceWithContext(
                     "com.sun.star.frame.GlobalEventBroadcaster", ctx)
                 events = geb.Events.getElementNames()
                 ui.msgbox('; '.join(events))

             g_exportedScripts = (displayAvailableEvents,)

The Alternative Python Script Organizer (APSO) extension is used to render events information on screen.

### With LibreOffice Basic

             Sub DisplayAvailableEvents
                 ''' Display document events '''
                 Dim geb As Object ' com.sun.star.frame.GlobalEventBroadcaster
                 Dim events() As String
                 geb = CreateUnoService("com.sun.star.frame.GlobalEventBroadcaster")
                 events = geb.Events.ElementNames()
                 MsgBox Join(events, "; ")
             End Sub

נושאים קשורים

Creating Event Listeners

Importing Python Modules

Creating a Dialog Handler

Python programming examples

Programming with Python Scripts

Calling Basic Macros from Python

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