Media Center Automation: Difference between revisions

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For information on how to get access to MJAutomation interface from in-proc plug-ins see plug-in SDK.
For information on how to get access to MJAutomation interface from in-proc plug-ins see plug-in SDK.


==Automation Objects==
* [[MJAutomation]] - core object... provides access to all other objects
* [[MJPlaybackAutomation]] - controls playback and provides information about the currently playing track
* [[MJFilesAutomation]] - represents a collection of files
* [[MJFileAutomation]] - object for dealing with a single file
* [[MJCurPlaylistAutomation]] - interface for working with "Playing Now" (the current playlist)
* [[MJMixerAutomation]] - provides volume, balance, and mute control
* [[MJPlaylistsAutomation]] - represents a collection of playlists
* [[MJPlaylistAutomation]] - interface for working with a single playlist
* [[MJSchemeAutomation]] - interface for working with Media Library View Schemes
* [[MJVersionAutomation]] - interface for getting Media Center version information
* [[MJInternetAutomation]] - interface for helping in downloading files from internet
* [[MJViewItemAutomation]] - interface for creating / walking the Media Center tree structure
* [[MJFieldsAutomation]] - interface for working with database fields
* [[MJFieldAutomation]] - interface for working with an individual database field
* [[MJZonesAutomation]] - interface for working with multi-zone playback system
* [[MJZoneAutomation]] - interface for working with a single playback zone (requires MC 11.0.20 or later)
* [[MJTaskAutomation]] - Interface for working with a task
* [[MJServicesAutomation]] - interface for working with services
* [[MJServiceAutomation]] - interface for working with a single service
* [[MJCDDVDAutomation]] - interface for working with CD/DVDs


==Event Handling==
==MJAutomation - core object... provides access to all other objects==
MediaCenter version 11.1 and higher supports an event interface for automation clients.
===Functions===
MJPlaybackAutomation * GetPlayback()
Description: gets a MJPlaybackAutomation interface (see below)
Return Value: MJPlaybackAutomation interface


===Basics===
MJFilesAutomation * Search(string strSearch)
An event is fired upon certain actions with three string parameters:
Description: gets a MJFilesAutomation interface (see below) for the files matching the specified search
FireMJEvent(string1, string2, string3)
Parameters:
* strSearch: the search string to use... can be any search accepted by Media Center
Return Value: MJFilesAutomation interface


The first parameter is the event type and currently there is just one event type, namely "MJEvent type: MCCommand"
MJCurPlaylistAutomation * GetCurPlaylist()
The second parameter identifies the MCC command. See the list below.
Description: gets a MJCurPlaylistAutomation interface (see below)
The third parameter is optional and may contain information specific to the command.
Return Value: MJCurPlaylistAutomation interface


Here are the commands currently sent to the event handler:
MJPlaylistsAutomation * GetPlaylists()
* '''MCC: NOTIFY_TRACK_CHANGE'''
Description: gets a MJPlaylistsAutomation interface (see below) for all of the existing playlists
** Fired when a new track starts to play
Return Value: MJPlaylistsAutomation interface
** ''string3'' is the zone
* '''MCC: NOTIFY_PLAYERSTATE_CHANGE'''
** Fired when a the player state changes
*** A new track starts to play
*** Playback is stopped, paused, or started
** ''string3 '' is the zone
*'''MCC: NOTIFY_PLAYLIST_ADDED'''
** Fired when a playlist is added by the user
** ''string3'' is the playlist ID
*'''MCC: NOTIFY_PLAYLIST_INFO_CHANGED'''
** Fired when a playlist is renamed
** Fired when a smartlist rule is changed
** Fired when a station is added to My Stations
** ''string3'' is the playlist ID
*'''MCC: NOTIFY_PLAYLIST_FILES_CHANGED'''
** Fired when a playlist's files change
** Fired when a service notifies Media Center that the service's playlists need to be refreshed
** ''string3'' is the playlist ID
*'''MCC: NOTIFY_PLAYLIST_REMOVED'''
** Fired when a playlist is removed
** ''string3'' is the ID of the deleted playlist
*'''MCC: NOTIFY_PLAYLIST_COLLECTION_CHANGED'''
** Fired when a playlist is moved or copied
** ''string3'' is not used
*'''MCC: NOTIFY_PLAYLIST_PROPERTIES_CHANGED'''
** Fired when a playlist property is changed
** ''string3'' is the playlist ID
* '''MCC: NOTIFY_SKIN_CHANGED'''
** MC 12.0.211 or higher
** Fired when the skin is changed
** ''string3'' is not used
* '''MCC: NOTIFY_VOLUME_CHANGED'''
** MC 12.0.217 or higher
** Fired when the volume is changed
** ''string3'' is the zone
* '''MCC: NOTIFY_EQ_CHANGED'''
** MCC 12.0.217 or higher
** Fired when the Equalizer settings are changed, or the Equalizer is turned on or off.
** ''string3'' is not used
** Because of internal implementation considerations, you will receive multiple copies of this event for each trigger.


===Event Handling and Zones===
MJSchemeAutomation * GetViewScheme(string strPath)
The events '''MCC: NOTIFY_TRACK_CHANGE''' and '''MCC: NOTIFY_PLAYERSTATE_CHANGE''' contain the zone where the change occurred. Media Center, however, will only notify changes in the currently active zone. If a track changes in the non-active zone, there will be no event. Only track changes in the active zone will have events.
Description: gets a MJSchemeAutomation interface (see below) for the given library path
Parameters:
* strPath: the path to the view scheme delimited by backslashes. (i.e. "Media Library\Artist/Album\Metallica")
Return Value: MJSchemeAutomation interface


===Handling the events from Visual Basic===
MJMixerAutomation * GetMJMixer()
To add a handler in VB.NET for events coming from Media Center:
Description: gets a MJMixerAutomation interface (see below)
Return Value: MJMixerAutomationinterface


1. Add a reference to Media Center's type library ("Media Center 12.tlb"). In VB.NET use the Projects/Add Reference option, select the "COM" tab, then select "MediaCenter" from the list.
MJVersionAutomation * GetVersion()
Description: gets a MJVersionAutomation interface (see below).
Return Value: MJVersionAutomation interface


2. Add the "Imports MediaCenter" statement to declaration section of the code.
MJFileAutomation * GetFile(string strFilename)
Description: gets a MJFileAutomation interface (see below) for the given file.
Parameters:
* strFilename: the path to the file.
Return Value: MJFileAutomation interface


3. In the main class section for your project (e.g. - Form1) do the following:
void EnableSkinning(number bEnable)
A) Declare your MC automation variable to handle events, like this:
Description: Enables and disabled Media Center skinning. Useful in case when MC could not skin plug-in window correctly.
Dim WithEvents MC As MediaCenter.MCAutomation
Parameters:
* bEnable: TRUE - enable skinning, FALSE - disable.


B) Create a delagate class object and set it up to handle the three parameters passed by MEDIACENTER's object:
void SkinWindow(number nWindowHandle, boolean bSkin)
Private _RelayEvent As RelayEvent
Description: Skins or removes skinning from the specified window.
Delegate Sub RelayEvent(ByVal EventData1 As String, ByVal EventData2 As String, ByVal EventData3 As String)
Parameters:
* nWindowHandle: handle to the specific window (convert HWND to long)
* bSkin: TRUE - enables skinning of the specified window, FALSE - disables skinning for the window.


4. Create a subroutine to receive the event message and to perform actions based on it. It is triggered by the event handler created below in step 4:
MJInternetAutomation * GetInternet()
Private Sub MyRelayEvent(ByVal EventData1 As String, ByVal EventData2 As String, ByVal EventData3 As String)
Description: gets a MJInternetAutomation interface (see below).
lbParam1.Text = EventData1
Return Value: MJInternetAutomation interface
lbParam2.Text = Trim(EventData2)
lbParam3.Text = EventData3
Application.DoEvents()
End Sub


4. Declare a handler function for the event. In the handler function, your will need to assign the delegate pointer to the subroutine that will actually act on the event. Then use the BeginInvoke function to transfer the event data when it is received:
number GetSkinInfo(string strItem, string strAttribute)
Public Sub MC_FireMJEvent(ByVal s0 As String, ByVal s1 As String, ByVal s2 As String) Handles MC.FireMJEvent
Description: Retrieves information about current skin.
_RelayEvent = New RelayEvent(AddressOf MyRelayEvent)
Parameters:
BeginInvoke(_RelayEvent, s0, s1, s2)
* strItem: item name
End Sub
* strAttribute: attribute name.
Return Value: value of the specified skin item. -1 if the info was not found.
Example1: GetSkinInfo("Tree", "TextColor");
Example2: GetSkinInfo("StatusBar", "BackColor");


number IsPurchased()
Description: Retrieves registration information
Return Value: if Media Center is purchased return value will be -1. The value will be equal to 0 if trial period expired but the program was not purchased. If the value > 0 the function returned number of days left in the trial period.


5. Events fired from MediaCenter will be received by "MC_FireMJEvent" and it will use the delegate pointer to trigger "MyRelayEvent", which can act on the event.
MJViewItemAutomation * GetViewItem(string strPath)
Description: gets a MJViewItemAutomation interface (see below) for the given file.
Parameters:
* strPath: the path to a view item.
Return Value: MJViewItemAutomation interface


Note: The event handler is automatically created in a separate thread from the main routine/class. One thread cannot make changes to another thread, so it is necessary to use the delegate pointer to make the main thread aware that the event occured and to receive the information. Then the receiving subroutine, which is in the main thread, can make updates without creating an exception error.
number GetWindowHandle()
Description: Retrieves handle to Media Center's main window
Return Value: HWND to main application window.


===Handling the events from Visual C++ with MFC===
MJFileAutomation * GetFileByKey(number nKey)
In your C++ MFC application, you should have a class which is derived from CCmdTarget (or from CWnd or CDialog which derive from CCmdTarget). This class will sink the events from MC's automation object. In the sample code below, this class is called "CMyClass", substitute your class's name for CMyClass.
Description: gets a MJFileAutomation interface (see below) for the file denoted by the key.
In the header file of the class, add the following import using the correct tlb path for your system. Also add the afxctl.h include file if you get warnings of undefined AfxConnectionAdvise and AfxConnectionUnadvise.
Parameters:
* nKey: the key of a file.
Return Value: MJFileAutomation interface


#import "C:\\Program Files\\J River\\Media Center 12\\Media Center 12.tlb" no_namespace, named_guids
void ShowProgram(number bShow)
#include "afxctl.h"
Description: Changes visibility state of the program.
Parameters:
* bShow: 1 - show the app, 0 - hide.


Then within the header file's class declaration for CMyClass, add this code:
MJFileAutomation * ImportFile(string strFilename)
<pre>
Description: imports a new file into Media Center
DECLARE_DISPATCH_MAP()
Parameters:
DECLARE_INTERFACE_MAP()
* strFilename: the path to the file.
afx_msg void MJEvent(LPCTSTR strType, LPCTSTR strParam1, LPCTSTR strParam2);
Return Value: MJFileAutomation interface
IMJAutomationPtr m_pMJ;
DWORD m_SinkID;
</pre>


Now in the cpp file for the class, add these lines which connect your handler function to the correct entry in the dispatch map:
void SetGlobalFocusedWindow(number hwndNew, number bInvalidateNew)
<pre>
Description: Sets the focus to the new window.
BEGIN_DISPATCH_MAP(CMyClass, CCmdTarget)
Parameters:
DISP_FUNCTION_ID(CMyClass,"MJEvent",1,MJEvent,VT_EMPTY,VTS_BSTR VTS_BSTR VTS_BSTR)
* hwndNew: the handle of the window
END_DISPATCH_MAP()
* bInvalidateNew: Invalidate the new window so it knows the focus changed


BEGIN_INTERFACE_MAP(CMyClass, CCmdTarget)
MJFieldsAutomation * GetFields()
INTERFACE_PART(CMyClass, DIID_IMJAutomationEvents, Dispatch)
Description: gets a MJFieldsAutomation interface (see below)
END_INTERFACE_MAP()
Return Value: MJFieldsAutomation interface
</pre>


Now add the following code to the constructor or wherever you do initialization:
MJZonesAutomation * GetZones()
<pre>
Description: gets a MJZonesAutomation interface (see below)
CoInitialize(NULL);
Return Value: MJZonesAutomation interface
EnableAutomation();
HRESULT hr = m_pMJ.GetActiveObject (L"MediaJukebox Application");
if (hr != S_OK)
m_pMJ.CreateInstance(L"MediaJukebox Application");


// Get a pointer to the sink IDispatch interface
MJFilesAutomation * CreateFiles()
LPUNKNOWN pUnknownSink = GetIDispatch(FALSE);
Description: gets a MJFilesAutomation interface (see below) with no files
Return Value: MJFilesAutomation interface


// Connect the event source (MJ automation) to the sink
MJTaskAutomation * GetTask(string strTask)
AfxConnectionAdvise(m_pMJ, DIID_IMJAutomationEvents, pUnknownSink, FALSE, &m_SinkID);
Description: gets a MJTaskAutomation interface (see below).
</pre>
Parameters:
* strTask: the name of the task.
Return Value: MJTaskAutomation interface


Add the function body which receives the events:
MJServicesAutomation * GetServices()
Description: gets a MJServicesAutomation interface (see below).
Return Value: MJServicesAutomation interface


<pre>
void ReportEvent(string Name, string Data)
// MJAutomationSink message handler
Description: Reports an event.
void CMyClass::MJEvent(LPCTSTR strType, LPCTSTR strParam1, LPCTSTR strParam2)
Parameters:
{
* Name: the name of the event
// handle events here...
* Data: extra data.
}
</pre>


And finally, add this code to the destructor or wherever you do final cleanup. The release for m_pMJ has to be called prior to CoUninitialize.
IMJPlaylistAutomation *GetPlaylistByID(number nID)
<pre>
Description: Gets a playlist
LPUNKNOWN pUnknownSink = GetIDispatch(FALSE);
Parameters:
AfxConnectionUnadvise(m_pMJ, DIID_IMJAutomationEvents, pUnknownSink, FALSE, m_SinkID);
* nID: the ID of the playlist
m_pMJ.Release();
Return Value: MJPlaylistAutomation interface (see below)
CoUninitialize();
</pre>


===Handling the Events from Visual C++ with ATL===
void RegisterWindowWithRouter(number hwndRegister, number nRegisterState)
If you have a conventional Interface plugin that was generated using the ATL DLL and ATL composite controls, you can also sink MediaCenter's events. Simply implement the IMJAutomationEvents (perhaps using class view->Implement Interface) using the IDispEventImpl template. The wizard will default to IDispatch, but you will need to use IDispEventImpl and the SINK_MAP functions to handle events correctly.
Description: Register or unregister a window with the router
Parameters:
* hwndRegister: Handle of the window to register
* nRegisterState: TRUE for register, FALSE for unregister


Ensure that the type library is imported as for the MFC version above. Set your SINK_MAP as follows:
IMJCDDVDAutomation *GetCDDVD()
Description: Gets a CD/DVD Automation interface
Return Value: MJCDDVDAutomation Interface


<pre>
===Properties===
BEGIN_SINK_MAP(CEQdbCtrl)
number IVersion() (read only)
SINK_ENTRY_EX(1, DIID_IMJAutomationEvents, 1, MJEvent)
Description: retrieves version of MC Automation interface. (2 is current version)
END_SINK_MAP()
</pre>


and then implement the MJEvent handler function
==MJPlaybackAutomation - controls playback and provides information about the currently playing track==
===Functions===
void Pause()
Description: toggles the pause state


<pre>
void Stop()
STDMETHOD_(void, MJEvent)(LPCTSTR strType, LPCTSTR strParam1, LPCTSTR strParam2);
Description: stops playback
</pre>


Also, you need to advise the sink after attaching to the passed IDispatch* in your Init function.
void Next()
Description: plays the next track in "Playing Now"


<pre>
void Previous()
HRESULT hr;
Description: plays the previous track in "Playing Now"
hr = DispEventAdvise(m_pMJ, &DIID_IMJAutomationEvents);
if(hr == S_OK) {
// Successfully advised.
} else {
// Did not advise correctly.
}
</pre>


Here's the (somewhat) tricky part. Using the CComComposite class means that AtlAdviseSinkMap is called during the window constructor, and it will cause an ATLASSERT failure during debug builds. This produces the "Abort" "Retry" "Ignore" message box stating there's been an assertion failure in atlcom.h. Click ignore. Once you move to release builds, it will compile to nothing and will not cause you any trouble.
void FastForward()
Description: advances the position of the playing track (amount depends on file type)


[[Category:Developer]]
void Rewind()
Description: rewinds the position of the playing track (amount depends on file type)

boolean IsBuffering()
Description: queries to see if Media Center is buffering
Return Value: TRUE if buffering, FALSE if not buffering

void Play()
Description: begins playback of the current track in "Playing Now"

boolean IsVideo()
Description: queries to see if Media Center has video
Return Value: TRUE if MJ has video, FALSE if not.

===Properties===
MJPlaybackStates State() (read only)
Description: the current playback state (PLAYSTATE_STOPPED - Stopped, PLAYSTATE_PAUSED - Paused, PLAYSTATE_PLAYING - Playing, PLAYSTATE_WAITING - Waiting)

number Bitrate() (read only)
Description: the bitrate of the currently playing track (i.e. 128 kbps)

number Position() (read / write)
Description: the position in the currently playing track (i.e. 111 seconds)

number Duration() (read only)
Description: the duration of the currently playing track (i.e. 257 seconds)

number Channels() (read only)
Description: the number of channels in the currently playing track (i.e. 2 channels (stereo))

number Samplerate() (read only)
Description: the sample rate of the currently playing track (i.e. 44100 Hz)

number Bitspersample() (read only)
Description: the bits per sample of the currently playing track (i.e. 16 bits per sample)

==MJFilesAutomation - represents a collection of files==
===Functions===
number GetNumberFiles()
Description: returns the number of files contained in the collection
Return Value: number of files

void Sort()
Description: sorts the list of files using user selected sorting scheme.

MJFileAutomation * GetFile(number nFile)
Description: gets the MJFileAutomation interface (see below) for the given file index
Parameters:
* nFile: the index of the file to retrieve (0 to GetNumberFiles() - 1)
Return Value: MJFileAutomation interface

void Play()
Description: plays the list of files

void PlayOrShow()
Description: decides whether to play or show the list of files. If the list contains only image files then show command will be used, otherwise this function will use play command.

boolean AlbumGroup(boolean bSort, boolean bGroupIfOneAlbum)
Description: groups the list of files by album. If this function is used, the collection of files will contain one file from each album, which can be expanded using the MJFileAutomation::GetAlbumFiles(...) call.
Parameters:
* bSort: sort the list of files after grouping
* bGroupIfOneAlbum: instructs the function whether to group by album if the list contains only one album.
Return Value: if grouping by album is possible, the function will return true, otherwise false.

void AddFile(string strFilename)
Description: Add the file to the collection
Parameters:
* strFilename: the name of the file to add

void AddFileByKey(number nKey)
Description: Add the file to the collection
Parameters:
* nKey: the key of the file to add

boolean RemoveFile(number nIndex)
Description: Remove the file from the collection
Parameters:
* nIndex: the number of the file to remove
Return Value: true only if the file was removed

void RemoveAll()
Description: Remove all files from the collection

string Analyze(string strWhat)
Description: Analyze the files for information, currently size or duration is supported
Parameters:
* strWhat: size or duration
Return Value: the size or duration, or "-1" if it couldn't be computed

void MoveToTop(number nIndex)
Description: moves the specified file to the top position
Parameters:
* nIndex: the number of the file to move

void Shuffle()
Description: shuffles the order of the collection

void Set(number nIndex, string strField, string strValue)
Description: Changes the field of the specified file to a new value
Parameters:
* nIndex: the position of the file in the collection
* strField: the name of the field to change
* strValue: the new value

number AddNewFile()
* Description: Adds a new file to the end of the collection
* Return Value: non-zero only if a new file was added

number AddExistingFile(IDispatch *pdispFiles, long nIndex, nInsertIndex)
Description: Add a file from another MJFilesAutomation object
Parameters:
* pdispFiles: the IDispatch of the other MJFilesAutomation
* nIndex: the position of the file in the other object
* nInsertIndex: the position to insert at
Return Value: The position it was inserted at, or -1 if unable to insert

string Get(number nIndex, string strField)
Description: Get the value of a field for the specified file
Parameters:
* nIndex: the position of the file in the collection
* strField: the name of the field
Return Value: The value of the field

number Save(string strFilename, string strType, number nFlags)
Description: Save the files as a playlist, either m3u or mpl format
Parameters:
* strFilename: The name of the playlist file
* strType: "m3u" or "mpl"
* nFlags: For m3u, if nFlags & 0x1, then use relative paths
Return Value: Nonzero on success, zero on failure

void Filter(string strSearchString)
Description: Remove all files in the collection not meeting the criteria in strSearchString
Parameters:
* strSearchString: a Media Center search

void AddFileOverwriteExistingInfo(string strFilename)
Description: Add the file to the collection, overwriting the old information if it exists.
Parameters:
* strFilename: the name of the file

===Properties===
number Position() (read / write)
Description: the index of the selected file. When starting playback, the selected file will get played. Other interfaces and functions may also honor the position. Note that the position will be preserved through shuffles, removes, and other MJFiles functions. (-1 means no file is selected)

==MJFileAutomation - object for dealing with a single file==
===Functions===
MJPlaylistsAutomation * GetPlaylists()
Description: returns the collection of playlists that the given file is in
Return Value: MJPlaylistsAutomation interface (see below)

string GetImageFile(MJImageFileFlags nImageFileFlag)
Description: gets the filename of an image associated with the file
Parameters:
* nImageFileFlag:
** IMAGEFILE_DISPLAY - display image (tag or database) (uses MJ logo if file doesn't have an image)
** IMAGEFILE_IN_DATABASE - database image
** IMAGEFILE_IN_FILE - tag image (stored inside of file)
** IMAGEFILE_THUMBNAIL_SMALL, IMAGEFILE_THUMBNAIL_MEDIUM, IMAGEFILE_THUMBNAIL_LARGE - small, medium, and large thumbnail images for the file
** IMAGEFILE_DISPLAY_NO_DEFAULT - like IMAGEFILE_DISPLAY except that it won't return the logo when there is no art
** IMAGEFILE_DISPLAY_NO_DEFAULT_STANDARD_JPEG - like IMAGEFILE_DISPLAY_NO_DEFAULT except that it always returns a standard (non-progressive) JPEG
Note: Do not delete the files returned by this function. Media Center will do any necessary cleanup. Also, subsequent calls may return the same filename (if a temp file is being used) so you must load / cache the image instead of caching the filenames.
Return Value: a filename of the image file

string SetImageFile(string strImageFile, MJImageFileFlags nImageFileFlag)
Description: sets the image for the file
Parameters:
* strImageFile: filename of the image
* nImageFileFlag: IMAGEFILE_IN_DATABASE - database image, IMAGEFILE_IN_FILE - tag image (stored inside of file)
Return Value: 0 on failure, non-zero on success

string GetFormattedFileSize()
Description: gets the display friendly file size
Return Value: a string representing the file size (i.e. "23.434 MB")

string GetFormattedFileDate()
Description: gets the display friendly file date / time
Return Value: a string representing the file date / time (i.e. "2/30/2002 8:01 PM")

string GetFormattedDuration()
Description: gets the display friendly duration
Return Value: a string representing the duration (i.e. "3:04")

string GetFormattedLastPlayed()
Description: gets the display friendly last played date / time
Return Value: a string representing the duration (i.e. "2/30/2002 8:01 PM")

string GetAvailableFilename()
Description: returns the filename in the format that's available to the system, so that files on a removable device get returned, for example, as "D:\1.mp3" instead of "(0xF43EA231):\1.mp3"
Return Value: a string representing the filename

boolean SaveToTag()
Description: Forces Media Center to save the file information to the tag.
Return Value: 0 - failed, 1 - success.

string Get(string strField, boolean bFormatted)
Description: generic function to get value for the specified field.
Parameters:
* strField: name of the field (e.g. Artist, Album...)
* bFormatted: determines whether the return value should beformated.
Return Value: value of the field

boolean Set(string strField, string strValue)
Description: generic function to set value for the specified field.
Parameters:
* strField: name of the field (e.g. Artist, Album...)
* strValue: new value of the field
Return Value: 0 - failed, 1 - success.

MJFilesAutomation * GetAlbumFiles()
Description: retrieves the list of files which belong to the same album (use to expand after an album group)
Return Value: MJFilesAutomation interface

long GetKey()
Description: Gets the key of the file
Return Value: the key

boolean DeleteFile(long hwndParent)
Description: Deletes the file (with confirmation)
Parameters:
* hwndParent: The handle of the parent window or null
Return Value: nonzero on success, zero on failure

boolean RotateImage(long nDegrees)
Description: If the file is a JPEG, rotate the image
Parameters:
* nDegrees: How much to rotate
Return Value: TRUE

string GetFilledTemplate(string strTemplate)
Description: Evaluates an expresion for the file and returns the result
Parameters:
* strTemplate: the expression
Return Value: the result

boolean SilentDeleteFile()
Description: Deletes the file (no confirmation)
Return Value: nonzero on success, zero on failure

void UpdatePlaybackStats(long nPlays)
Description: Increases the file playcount by nPlays and sets the last played time to now
Parameters:
* nPlays: number of times the file was played

boolean SaveInfoToExternalFile(string strFilename)
Description: Save the database information (cover art and fields) for the file to an external file
Parameters:
* strFilename: the name of the external file
Return Value: TRUE

boolean UpdateFromFile(boolean bForce, boolean bOnlyNewFields)
Description: Updates the fields from the file
Parameters:
* bForce: if true, force the update, otherwise only update if the file has changed
* bOnlyNewFields: Only change fields that are new
Return Value: TRUE only if the file was updated

void UpdateDBLocation(long nAppendDBLocations, long nRemoveDBLocations)
Description: Select which portions of the database the file appears in
Parameters:
* nAppendDBLocations: Which portions to add the file to. Value is a bitwise OR of
** DB_LOCATION_INVALID
** DB_LOCATION_MAIN
** DB_LOCATION_PLAYING_NOW
** DB_LOCATION_CD
** DB_LOCATION_EXPLORER
** DB_LOCATION_UNASSIGNED
** DB_LOCATION
** DB_LOCATION_FILE_TRANSFER
** DB_LOCATION_HANDHELD
** DB_LOCATION_GROUPING
** DB_LOCATION_REMOVED
** DB_LOCATION_DOWNLOADING
** DB_LOCATION_PODCAST_FEED
* nRemoveDBLocations: Which portions to remove the file from, same value as nAppendDBLocations

boolean SetNoDirty(string strField, string strValue)
Description: Change a file's field without marking it as dirty
Parameters:
* strField: the field name
* strValue: the field value
Return Value: nonzero on success, zero on failure

===Properties===
string Filename() (read / write)
Description: the filename (i.e. "c:\Music\Good Song.mp3")

string Artist() (read / write)
Description: the artist (i.e. "Metallica")

string Album() (read / write)
Description: the album (i.e. "ReLoad")

string Name() (read / write)
Description: the name of the track (i.e. "Unforgiven II")

number Filesize() (read / write)
Description: the filesize in bytes

number Duration() (read / write)
Description: the file duration in seconds

string Genre() (read / write)
Description: the genre (i.e. "Rock")

number Year() (read / write)
Description: the year (i.e. 1997)

string Comment() (read / write)
Description: the comment

number Bitrate() (read / write)
Description: the bitrate (i.e. 128 kbps)

number Tracknumber() (read / write)
Description: the track number (i.e. 4)

number Filedate() (read / write)
Description: the file's date (seconds past 1970)

string Custom1() (read / write)
Description: the MJ-specific "Custom1" field

string Custom2() (read / write)
Description: the MJ-specific "Custom2" field

string Custom3() (read / write)
Description: the MJ-specific "Custom3" field

number PlayCounter() (read / write)
Description: the number of times the track has been played in Media Center

number LastPlayed() (read / write)
Description: the date the file was last played in Media Center (seconds past 1970)

number Rating() (read / write)
Description: the rating (MJ-specific) (note: 0 = ?, otherwise 1-5)

string Filetype() (read / write)
Description: the extension of the file (used by MJ to choose playback plugins, etc.) (i.e. "mp3")

string Lyrics() (read / write)
Description: the lyrics

string Notes() (read / write)
Description: the notes

string AlbumArtist() (read / write)
Description: the album artist

==MJCurPlaylistAutomation - interface for working with "Playing Now" (the current playlist)==
===Functions===
number GetNumberFiles()
Description: returns the number of files in "Playing Now"
Return Value: number of files

MJFileAutomation * GetFile(number nFile)
Description: gets the MJFileAutomation interface (see below) for the given file index
Parameters:
Return Value: MJFileAutomation interface

void RemoveAllFiles()
Description: removes all of the files from "Playing Now" (stops playback)

boolean RemoveFile(number nFile)
Description: removes a specific file from "Playing Now"
Parameters:
* nFile: the index of the file to retrieve (0 to GetNumberFiles() - 1)
Return Value: 0 on failure, non-zero on success

boolean AddFile(string strFilename, number nPosition)
Description: adds a file to "Playing Now"
Parameters:
* strFilename: the filename of the file to add
* nFile: the new index of the file
Return Value: 0 on failure, non-zero on success

boolean MoveFile(number nFileOld, number nFileNew)
Description: moves a file to a new location in "Playing Now"
Parameters:
* nFileOld: the index of the file to move
* nFileNew: the index to move the file to
Return Value: 0 on failure, non-zero on success

boolean ReShuffleFiles()

Description: shuffles "Playing Now" so it's in a random order
Return Value: 0 on failure, non-zero on success

number GetNextFile()

Description: gets the index of the file to play on "Next"
Return Value: index of file

boolean GetPreviousFile()

Description: gets the index of the file to play on "Previous"
Return Value: index of file

boolean GetCanPlayNext()

Description: Determine if there is another file to play after the currently playing file
Return Value: true only if there is one
===Properties===

number Position() (read / write)

Description: the index of the current track

number Shuffle() (read / write)

Description: the shuffle state (0 = off, 1 = on)

number Continuous() (read / write)

Description: the continuous state (0 = off, 1 = on)

==MJMixerAutomation - provides volume, balance, and mute control==
===Functions===

void SetEQBand(number nBand, number nValue)

Description: sets the value of an equalizer band
Parameters:

nBand: the equalizer band (0 = preamp, 1 - 10 = eq bands)
nValue: the new band value (-100 to 100 where -100 is full cut, 0 is no gain, and 100 is full gain)

number GetEQBand(number nBand)

Description: gets the value of an equalizer band
Parameters:

nBand: the equalizer band (0 = preamp, 1 - 10 = eq bands)

Return Value: value of the specified band (-100 to 100 where -100 is full cut, 0 is no gain, and 100 is full gain)

void UpdateEQSettings(number bUpdatePlayer, number bUpdateMiniMe)

Description: updates the internal settings to reflect outside changes (made in DSP Studio, etc.) -- not necessary in most cases
Parameters:

bUpdatePlayer: whether to update the player window (0 = no, 1 = yes)
bUpdateMiniMe: whether to update the mini-me window (0 = no, 1 = yes)

void ShowDSP()

Description: Activate the DSP

===Properties===
number Volume() (read / write)

Description: the volume (0 = no volume, 100 = full volume)

number Balance() (read / write)

Description: the balance between left and right (-100 = all left, 0 = centered, 100 = all right)

boolean Mute() (read / write)

Description: the mute state (0 = not muted, 1 = muted)

boolean EQOn() (read / write)

Description: whether the equalizer is on or off (0 = off, 1 = on)

==MJPlaylistsAutomation - represents a collection of playlists==
===Functions===

number GetNumberPlaylists()

Description: returns the number of playlists contained in the collection
Return Value: number of playlists

MJPlaylistAutomation * GetPlaylist(number nPlaylist)

Description: gets the MJPlaylistAutomation interface (see below) for the given playlist index
Parameters:

nPlaylist: the index of the playlist to retrieve (0 to GetNumberPlaylists() - 1). To retrieve Top Hits and Recently Imported playlists use index -1 and -2 respectively.

Return Value: MJPlaylistAutomation interface

MJPlaylistAutomation * CreatePlaylist(string PlaylistPath, string PlaylistName)

Description: creates new playlist at the specified location
Parameters:

PlaylistPath: location of the playlist. If empty, the playlist will be created in the root of the playlist tree.
PlaylistName: name of the new playlist

Return Value: MJPlaylistAutomation interface

boolean DeletePlaylist(string PlaylistPath, string PlaylistName)

Description: deletes existing playlist
Parameters:

PlaylistPath: location of theplaylist.
PlaylistName: name of the new playlist

Return Value: true - if success, otherwise false.

IMJPlaylistAutomation *CreateServicelist(string Path, string Name, string Service, string ServiceID, string ServiceData)

Description: Finds or creates the playlist associated with a service
Parameters:

Path: Not Used
Name: The name of the playlist
Service: The name of the service
ServiceID: The ID of the service
ServiceData: Service-specific data

Return Value: the MJPlaylistAutomation interface

==MJPlaylistAutomation - interface for working with a single playlist==
===Functions===

MJFilesAutomation * GetFiles()

Description: gets the collection of files in the playlist
Return Value: MJFilesAutomation interface

boolean AddFile(string strFilename, number nLocation)

Description: adds new file to the playlist
Parameters:

strFilename: the filename of the file to add
nLocation: position of the file in the playlist. If position -1, the file will be added to the end of the playlist.

Return Value: 0 on failure, non-zero on success

boolean RemoveFile(string strFilename)

Description: removes existing file from the playlist
Parameters:

strFilename: the filename of the file to delete

Return Value: 0 on failure, non-zero on success

long GetID()

Description: returns the ID associated with a playlist
Return Value: the ID

string Get(string bstrProperty)

Description: lookup a property associated with a playlist
Parameters:

bstrProperty: the name of the property

Return Value: the value of the property for this playlist

void Set(string strProperty, string bstrValue)

Description: change the value of a property for this playlist
Parameters:

strProperty: the property name
bstrValue: The new value

boolean SaveAsRSS(string strFilename, string strURLPrefix, string strUser, string strEmail)

Description: 11.1.134 or higher, saves the playlist as an RSS (PodCast/PerbCast) file
Parameters:

strFilename: the filename of the RSS file
strURLPrefix: The URL prefix which will be concatenated with the keys of the playlist files to form the URL for accessing them
strUser: the name of the PerbCast creator
strEmail: the e-mail address of the PerbCast creator

Return Value: 0 on failure, non-zero on success
===Properties===
string Name() (read / write)

Description: the name of the playlist (i.e. "My Playlist")

string Path() (read / write)

Description: the path of the playlist, delimited by backslashes (note: does not contain the name) (i.e. "Mixes\\New Playlist Group")

==MJSchemeAutomation - interface for working with Media Library==
===Functions===

string GetName()

Description: gets the name of the scheme item (i.e. "Classic Rock", "Artist\Album", etc.)
Return Value: a string containing the name of the scheme item

number GetNumberSchemes()

Description: gets the number of children schemes
Return Value: number of children schemes

MJSchemeAutomation * GetScheme(number nScheme)

Description: gets the specified child scheme
Parameters:

nScheme: the index of the child scheme to retrieve (0 to GetNumberSchemes() - 1)

Return Value: a MJSchemeAutomation interface for the specified child scheme

MJFilesAutomation * GetFiles()

Description: gets the collection of files in the scheme
Return Value: MJFilesAutomation interface of files

string GetSchemeName(number nScheme)

Description: gets the name of the specified child scheme (faster than GetScheme(...))
Parameters:

nScheme: the index of the child scheme to retrieve (0 to GetNumberSchemes() - 1)

Return Value: a string containing the name of the child scheme item

==MJVersionAutomation - interface for getting Media Center version information==
===Properties===

number Major (read only)

Description: Major version of the Media Center (i.e. 9)

number Minor (read only)

Description: Minor Version of the Media Center (i.e. 0)

number Build (read only)

Description: Build number of the Media Center (i.e. 160)

string Version (read only)

Description: string version of the Media Center (i.e. "9.0.160")

==MJInternetAutomation - interface for helping in downloading files from internet==
===Functions===
string DownloadToString(string URL)

Description: Downloads web page from the specified URL to a string. (should not be used with binary data, only web pages)
Parameters:

URL: The URL from which the web page will be downloaded

Return Value: a string containing the contents of the web page.

number DownloadToFile(string URL, string FileName)

Description: Downloads data from a resource identified by a URL to a local file.
Parameters:

URL: The URL from which the data will be downloaded.
FileName: The name of the local file to receive the data.

Return Value: True if the function completed successfully, otherwise FALSE.

string DownloadToTempFile(string URL)

Description: Downloads data from a resource identified by a URL to a local temp file.
Parameters:

URL: The URL from which the data will be downloaded.

Return Value: Returns the full path to the temp file.

void Cancel()

Description: Cancels previously called download function. Can be used only when DownloadMode set to DOWNLOADMODE_NO_UI or DOWNLOADMODE_NO_UI_BLOCKING.
===Properties===
MJInetDownloadModes DownloadMode (read / write)

Description: Gets or sets download mode.

DOWNLOAD_MODE_DEFAULT - displays UI while downloading files from the Internet
DOWNLOADMODE_NO_UI - does not display UI but processes the message loop so the Cancel function can be called from the same thread.
DOWNLOADMODE_BLOCKING - will lock the app until the download is finished.
DOWNLOAD_MODE_NO_AUTHENTICATION - disables authentication.

Example1: MJIA.DownloadMode = DOWNLOADMODE_NO_UI DOWNLOADMODE_BLOCKING;

==MJViewItemAutomation - interface for creating / walking the Media Center tree structure==
===Functions===

string GetName()

Description: gets the name of this item
Return Value: the name of the item

string GetFullName()

Description: gets the full name of this item (the whole path -- backslash delimited -- i.e. Media Library\Audio\Artist/Album\Bob Dylan)
Return Value: the full name of the item

MJFilesAutomation * GetFiles()

Description: gets the files associated with the current item
Return Value: MJFilesAutomation interface

void DoCommand(number nParam)

Description: performs the command associated with the current item (play / show, playing now command, etc.)
Parameters:

nParam: for future use -- must be zero

number GetNumberChildren()

Description: gets the number of child items
Return Value: the number of children

string GetChildName(number nIndex)

Description: gets the name of a child item
Parameters:

nIndex: the index of the child item (0 to GetNumberChildren() - 1)

Return Value: the name of the child item

MJViewItemAutomation * GetChild(number nIndex)

Description: gets the MJViewItemAutomation interface (see below) for the given child index
Parameters:

nIndex: the index of the child to retrieve (0 to GetNumberChildren() - 1)

Return Value: MJViewItemAutomation interface

boolean GetChildHasChildren(number nIndex)

Description: gets the name of a child item
Parameters:

nIndex: the index of the child item (0 to GetNumberChildren() - 1)

Return Value: whether the specified child has children of its own

MJViewItemAutomation * GetParent()

Description: gets the parent item
Return Value: MJViewItemAutomation interface

string GetThumbnailFilenames(number nThumbnailSize, number nMaxCount)

Description: not implemented
Parameters:

nThumbnailSize: N/A
nMaxCount: N/A

Return Value: N/A

boolean GetChildIsFolder(number nIndex)

Description: determine if the specified child contains sub-view items
Parameters:

nIndex: the number of the child

Return Value: true only if the child contains sub-view items

boolean GetIsSearch()

Description: not implemented
Return Value: FALSE

==MJFieldsAutomation - interface for working with database fields==
===Functions===

number GetNumberFields()

Description: gets the total number of database fields
Return Value: the number of fields

IMJFieldAutomation * GetField(number nField)

Description: gets the field at the given index
Parameters:

nField: the zero based index of the field

Return Value: MJFieldAutomation * to the field (see documentation below)

IMJFieldAutomation * CreateFieldSimple(string strFieldName, string strDisplayName, number bAllowEdit, long bSaveInTag)

Description: Creates a new field
Parameters:

strFieldName: the internal name of the new field
strDisplayName: the name displayed to the user
bAllowEdit: can field be changed by user
bSaveInTag: save the field in the tag in the content file

Return Value: the FieldAutomation interface for the new field

==MJFieldAutomation - interface for working with an individual database field==
===Functions===
string GetName(boolean bFormatted)

Description: gets the name of the field
Parameters:

bFormatted: 0 = returns the unique name of the field as used in DB lookups, 1 = returns the display name of the field (not necessarily unique)

Return Value: the field name

==MJZonesAutomation - interface for working with multi-zone playback system==
===Functions===

number GetNumberZones()

Description: gets the total number of playback zones
Return Value: the number of playback zones

number GetActiveZone()

Description: gets the index of the active zone
Return Value: index of active zone

void SetActiveZone(number nIndex)

Description: sets the index of the active zone.
Parameters:

nIndex: the zero based index of the new zone

string GetZoneName(number nIndex)

Description: gets the name of a given zone
Parameters:

nIndex: the zero based index of the new zone

Return Value: the name of the zone

MJZoneAutomation * GetZone(number nIndex) (requires MC 11.0.20 or later)

Description: gets a MJZoneAutomation interface for this zone (see below)
Return Value: MJZoneAutomationinterface

void SynchronizeZones(number nSource, number nDestination)

Description: attempts to have the two zones play the same content at the same time
Parameters:

nSource: the master zone
nDestination: the slave zone

==MJZoneAutomation - interface for working with a single playback zone (requires MC 11.0.20 or later)==
===Functions===

string GetName()

Description: gets the name of the zone
Return Value: the name of the zone

MJPlaybackAutomation * GetPlayback()

Description: gets a MJPlayback interface for this zone (see above)
Return Value: MJPlayback interface

MJCurPlaylistAutomation * GetCurPlaylist()

Description: gets a MJCurPlaylistAutomation interface for this zone (see above)
Return Value: MJCurPlaylistAutomation interface

IMJMixerAutomation * GetMixer()

Description: gets a MJMixerAutomation interface for this zone
Return Value: the interface

IMJFileAutomation * GetPlayingFile()

Description: get a MJFileAutomation interface for the file currently playing in this zone
Return Value: the interface

==MJTaskAutomation - Interface for working with a task==
===Functions===

void Pump()

Description: pumps the task's message loop

==MJServicesAutomation - interface for working with services==
===Functions===

VARIANT_BOOL GetLicense(string bstrFilename)

Description: Get a license for a content file
Parameters:

bstrFilename: the name of the content file

Return Value: true if the license was retrieved, false otherwise

IMJServiceAutomation *GetService(string bstrServiceName)

Description: Get a service by name
Parameters:

bstrServiceName: the name of the service

Return Value: a MJServiceAutomation interface

==MJServiceAutomation - interface for working with a single service==
===Functions===

BOOL Process(string bstrCurrentURL, string bstrNewURL, string bstrPostData)

Description: calls a service's Process function
Parameters:

bstrCurrentURL: the current URL for the service
bstrNewURL: the URL to visit
bstrPostData: empty or the name of a file containing POST data, the file will be deleted

Return Value: TRUE on success, FALSE otherwise

BOOL Execute(string bstrCommand, VARIANT vFileDisp, string *bstrResult)

Description: calls a service's Execute function
Parameters:

bstrCommand: the command
vFileDisp: MJFilesAutomation interface
bstrResult: a pointer to the result

Return Value: TRUE on success, FALSE otherwise

LPDISPATCH GetWebBrowserHTMLDocument()

Description: get the currently viewed service web page
Return Value: an IDispatch pointer to an IHTMLDocument2 interface

==MJCDDVDAutomation - interface for working with CD/DVDs==
===Functions===
IMJFilesAutomation *GetFiles(string strPath)

Description: Get the files on the device named
Parameters:

strPath: the name of the device

Return Value: MJFilesAutomation interface

Latest revision as of 15:30, 7 April 2014

Media Center exports much of its power and functionality through COM automation interfaces. This makes it easy to create your own plug-ins for Media Center that integrate tightly with its interface. Since automation interfaces are based on COM, these plug-ins can be written in almost any language. (C++, VB, Delphi, etc.). Also, the interfaces can be accessed in Metamorphis skins and Display plug-ins (see documentation for the plug-ins). Prior to build 9.1.238, the only way to access the automation interfaces was to write a plug-in for MC because the interfaces were not accessible by objects which were outside Media Center's process. Now, any application, including VBS and Java script, can start MC or just run it to query information about MC's database.

The functions in this document are for Media Center 11.1. Most will work with earlier versions, but not all.

Initialization

Media Center can be initialized by in-proc or out-of-proc objects.

Out-of-proc initialization (C++):

#import "Media Jukebox.tlb" no_namespace, named_guids

void GetMJAutomation()
{
    IMJAutomationPtr pMJ;

    HRESULT hr = pMJ.GetActiveObject (L"MediaJukebox Application");
    if (hr != S_OK)
        pMJ.CreateInstance(L"MediaJukebox Application");
}

Out-of-proc initialization (VB):

Private Sub Form_Load()
' First try to get an already running object
On Error Resume Next
Set myobj = GetObject(, "MediaJukebox Application")

If Err.Number = 429 Then
    'Then, create a new object
    Set myobj = CreateObject("MediaJukebox Application")

End Sub

NOTE: If Media Center was created as out-of-proc object, the main window of the program will be invisible. To show the window use ShowProgram function from MJAutomation interface.

For information on how to get access to MJAutomation interface from in-proc plug-ins see plug-in SDK.

Automation Objects

Event Handling

MediaCenter version 11.1 and higher supports an event interface for automation clients.

Basics

An event is fired upon certain actions with three string parameters:

FireMJEvent(string1, string2, string3)

The first parameter is the event type and currently there is just one event type, namely "MJEvent type: MCCommand" The second parameter identifies the MCC command. See the list below. The third parameter is optional and may contain information specific to the command.

Here are the commands currently sent to the event handler:

  • MCC: NOTIFY_TRACK_CHANGE
    • Fired when a new track starts to play
    • string3 is the zone
  • MCC: NOTIFY_PLAYERSTATE_CHANGE
    • Fired when a the player state changes
      • A new track starts to play
      • Playback is stopped, paused, or started
    • string3 is the zone
  • MCC: NOTIFY_PLAYLIST_ADDED
    • Fired when a playlist is added by the user
    • string3 is the playlist ID
  • MCC: NOTIFY_PLAYLIST_INFO_CHANGED
    • Fired when a playlist is renamed
    • Fired when a smartlist rule is changed
    • Fired when a station is added to My Stations
    • string3 is the playlist ID
  • MCC: NOTIFY_PLAYLIST_FILES_CHANGED
    • Fired when a playlist's files change
    • Fired when a service notifies Media Center that the service's playlists need to be refreshed
    • string3 is the playlist ID
  • MCC: NOTIFY_PLAYLIST_REMOVED
    • Fired when a playlist is removed
    • string3 is the ID of the deleted playlist
  • MCC: NOTIFY_PLAYLIST_COLLECTION_CHANGED
    • Fired when a playlist is moved or copied
    • string3 is not used
  • MCC: NOTIFY_PLAYLIST_PROPERTIES_CHANGED
    • Fired when a playlist property is changed
    • string3 is the playlist ID
  • MCC: NOTIFY_SKIN_CHANGED
    • MC 12.0.211 or higher
    • Fired when the skin is changed
    • string3 is not used
  • MCC: NOTIFY_VOLUME_CHANGED
    • MC 12.0.217 or higher
    • Fired when the volume is changed
    • string3 is the zone
  • MCC: NOTIFY_EQ_CHANGED
    • MCC 12.0.217 or higher
    • Fired when the Equalizer settings are changed, or the Equalizer is turned on or off.
    • string3 is not used
    • Because of internal implementation considerations, you will receive multiple copies of this event for each trigger.

Event Handling and Zones

The events MCC: NOTIFY_TRACK_CHANGE and MCC: NOTIFY_PLAYERSTATE_CHANGE contain the zone where the change occurred. Media Center, however, will only notify changes in the currently active zone. If a track changes in the non-active zone, there will be no event. Only track changes in the active zone will have events.

Handling the events from Visual Basic

To add a handler in VB.NET for events coming from Media Center:

1. Add a reference to Media Center's type library ("Media Center 12.tlb"). In VB.NET use the Projects/Add Reference option, select the "COM" tab, then select "MediaCenter" from the list.

2. Add the "Imports MediaCenter" statement to declaration section of the code.

3. In the main class section for your project (e.g. - Form1) do the following:

  A) Declare your MC automation variable to handle events, like this:
        Dim WithEvents MC As MediaCenter.MCAutomation
  B) Create a delagate class object and set it up to handle the three parameters passed by MEDIACENTER's object:
        Private _RelayEvent As RelayEvent
        Delegate Sub RelayEvent(ByVal EventData1 As String, ByVal EventData2 As String, ByVal EventData3 As String)

4. Create a subroutine to receive the event message and to perform actions based on it. It is triggered by the event handler created below in step 4:

  Private Sub MyRelayEvent(ByVal EventData1 As String, ByVal EventData2 As String, ByVal EventData3 As String)
     lbParam1.Text = EventData1
     lbParam2.Text = Trim(EventData2)
     lbParam3.Text = EventData3
     Application.DoEvents()
  End Sub

4. Declare a handler function for the event. In the handler function, your will need to assign the delegate pointer to the subroutine that will actually act on the event. Then use the BeginInvoke function to transfer the event data when it is received:

  Public Sub MC_FireMJEvent(ByVal s0 As String, ByVal s1 As String, ByVal s2 As String) Handles MC.FireMJEvent
     _RelayEvent = New RelayEvent(AddressOf MyRelayEvent)
     BeginInvoke(_RelayEvent, s0, s1, s2)
  End Sub


5. Events fired from MediaCenter will be received by "MC_FireMJEvent" and it will use the delegate pointer to trigger "MyRelayEvent", which can act on the event.

Note: The event handler is automatically created in a separate thread from the main routine/class. One thread cannot make changes to another thread, so it is necessary to use the delegate pointer to make the main thread aware that the event occured and to receive the information. Then the receiving subroutine, which is in the main thread, can make updates without creating an exception error.

Handling the events from Visual C++ with MFC

In your C++ MFC application, you should have a class which is derived from CCmdTarget (or from CWnd or CDialog which derive from CCmdTarget). This class will sink the events from MC's automation object. In the sample code below, this class is called "CMyClass", substitute your class's name for CMyClass. In the header file of the class, add the following import using the correct tlb path for your system. Also add the afxctl.h include file if you get warnings of undefined AfxConnectionAdvise and AfxConnectionUnadvise.

 #import "C:\\Program Files\\J River\\Media Center 12\\Media Center 12.tlb" no_namespace, named_guids
 #include "afxctl.h"

Then within the header file's class declaration for CMyClass, add this code:

  DECLARE_DISPATCH_MAP()
  DECLARE_INTERFACE_MAP()
  afx_msg void MJEvent(LPCTSTR strType, LPCTSTR strParam1, LPCTSTR strParam2);
  IMJAutomationPtr m_pMJ;
  DWORD m_SinkID;

Now in the cpp file for the class, add these lines which connect your handler function to the correct entry in the dispatch map:

  BEGIN_DISPATCH_MAP(CMyClass, CCmdTarget)
    DISP_FUNCTION_ID(CMyClass,"MJEvent",1,MJEvent,VT_EMPTY,VTS_BSTR VTS_BSTR VTS_BSTR)
  END_DISPATCH_MAP()

  BEGIN_INTERFACE_MAP(CMyClass, CCmdTarget)
    INTERFACE_PART(CMyClass, DIID_IMJAutomationEvents, Dispatch)
  END_INTERFACE_MAP()

Now add the following code to the constructor or wherever you do initialization:

  CoInitialize(NULL);
  EnableAutomation();
  HRESULT hr = m_pMJ.GetActiveObject (L"MediaJukebox Application");
  if (hr != S_OK)
    m_pMJ.CreateInstance(L"MediaJukebox Application");

  // Get a pointer to the sink IDispatch interface
  LPUNKNOWN pUnknownSink = GetIDispatch(FALSE);

  // Connect the event source (MJ automation) to the sink
  AfxConnectionAdvise(m_pMJ, DIID_IMJAutomationEvents, pUnknownSink, FALSE, &m_SinkID);

Add the function body which receives the events:

  // MJAutomationSink message handler
  void CMyClass::MJEvent(LPCTSTR strType, LPCTSTR strParam1, LPCTSTR strParam2)
  {
    // handle events here...
  }

And finally, add this code to the destructor or wherever you do final cleanup. The release for m_pMJ has to be called prior to CoUninitialize.

  LPUNKNOWN pUnknownSink = GetIDispatch(FALSE);
  AfxConnectionUnadvise(m_pMJ, DIID_IMJAutomationEvents, pUnknownSink, FALSE, m_SinkID);
  m_pMJ.Release();
  CoUninitialize();

Handling the Events from Visual C++ with ATL

If you have a conventional Interface plugin that was generated using the ATL DLL and ATL composite controls, you can also sink MediaCenter's events. Simply implement the IMJAutomationEvents (perhaps using class view->Implement Interface) using the IDispEventImpl template. The wizard will default to IDispatch, but you will need to use IDispEventImpl and the SINK_MAP functions to handle events correctly.

Ensure that the type library is imported as for the MFC version above. Set your SINK_MAP as follows:

BEGIN_SINK_MAP(CEQdbCtrl)
  SINK_ENTRY_EX(1, DIID_IMJAutomationEvents, 1, MJEvent)
END_SINK_MAP()

and then implement the MJEvent handler function

STDMETHOD_(void, MJEvent)(LPCTSTR strType, LPCTSTR strParam1, LPCTSTR strParam2);

Also, you need to advise the sink after attaching to the passed IDispatch* in your Init function.

HRESULT hr;
hr = DispEventAdvise(m_pMJ, &DIID_IMJAutomationEvents);
if(hr == S_OK) {
  // Successfully advised.
} else {
  // Did not advise correctly.
}

Here's the (somewhat) tricky part. Using the CComComposite class means that AtlAdviseSinkMap is called during the window constructor, and it will cause an ATLASSERT failure during debug builds. This produces the "Abort" "Retry" "Ignore" message box stating there's been an assertion failure in atlcom.h. Click ignore. Once you move to release builds, it will compile to nothing and will not cause you any trouble.