{"id":5193,"date":"2007-11-13T13:09:00","date_gmt":"2007-11-13T13:09:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/vbteam\/2007\/11\/13\/one-is-the-loneliest-number-matt-gertz\/"},"modified":"2024-07-05T14:38:45","modified_gmt":"2024-07-05T21:38:45","slug":"one-is-the-loneliest-number-matt-gertz","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/vbteam\/one-is-the-loneliest-number-matt-gertz\/","title":{"rendered":"One is the Loneliest Number (Matt Gertz)"},"content":{"rendered":"

(This post assumes that you\u2019ve read my previous post on Windows Media at http:\/\/blogs.msdn.com\/vbteam\/archive\/2007\/10\/30\/let-the-music-play-matt-gertz.aspx<\/font><\/a> <\/span>\u2013 I will be modifying that code in this post.)<\/font><\/p>\n

After posting my media player blog sample a couple of weeks ago, I got a few questions from a reader called Saleem on how to adapt it to take multiple files as arguments when launching the app.  <\/span>After a few exchanges, I figured that it made sense for me to write up a post on command line arguments, since it\u2019s actually a really fascinating topic.<\/font><\/p>\n

The first \u201cgiven\u201d in this problem is that your application is set to be a single-instance application.  <\/span>A single instance application is an app which only ever has one instance loaded into memory (hence the title of this blog) \u2013 when you double-click a file which is registered to that application, it looks for an existing instance and uses it if available before trying to create a new instance.  <\/span>Windows Media Player itself is a single instance application \u2013 double-clicking a .WMA file while the player is open will use the existing instance rather than creating a new one, so that you don\u2019t get two media players competing for the sound card. <\/font>J<\/span><\/span><\/font><\/p>\n

To make your application single-instance, you\u2019ll need to click a checkbox the project properties.  <\/span>Right-click on the project in the Solution Explorer and choose \u201cProperties,\u201d and in the \u201cApplication\u201d tab put a check in the \u201cMake single instance application\u201d checkbox.  <\/span><\/font><\/font><\/p>\n

While you\u2019re on that tab, you should also click the \u201cView Application Events\u201d button \u2013 that will bring up a file called \u201cApplicationEvents.vb\u201d.  <\/span>That file defines the event handlers for the application itself (not the main form).  <\/span>Don\u2019t touch anything in that file yet; we\u2019ll get to it later.<\/font><\/p>\n

Now, the goal of our application will be to allow the user to specify multiple playlists to be randomized — they should all get mixed up together, but arcs (songs that are required to play together) should be preserved.  <\/span>In my last post, I hard-coded the original playlist path; I now want to modify the app so that it gets the names of the playlists from playlists I invoke.  <\/span>There are two ways that this might happen:<\/font><\/p>\n

(1)<\/font>    <\/span><\/span><\/span>Using the command line:  <\/span>the user opens a command shell and calls the application with a list of playlist files as arguments.  <\/span>In this case, the filenames are passed as arguments to the application and are available in the Load event of the form (as well as elsewhere).  <\/span>However, a subsequent call from the command line would then trigger the StartupNextInstance event of our single-instance app, and I\u2019ll have to examine the new command line in that handler to get each of those new filenames.<\/font><\/p>\n

(2)<\/font>    <\/span><\/span><\/span>Selecting a bunch of file files and pressing \u201cEnter\u201d (or choosing \u201cOpen\u201d from the context menu):  <\/span>in this case, the app is launched with one of the files specified on a command line (usually the last selected), and then Windows attempts to relaunch the app with the names of the other files.  <\/span>So, in the case where three files are invoked, the first filename is available in the Form_Load event via the My.Application.CommandLineArgs, and then StartupNextInstance gets called twice for each of the two remaining filenames.  <\/span>Those arguments get retrieved from the EventArgs object passed to the event handler.<\/font><\/p>\n

So, in order to handle filenames coming from two different sources, I\u2019m going to need to centralize my randomization code from the last post so that both entry points can use it.  <\/span>Also, I\u2019m going to need to reverse the order in which I do the randomization.  That is, i<\/span>nstead of picking a random file from an existing playlist and appending it (or its arc, if any) to a new playlist, I\u2019ll instead go through the old playlist in track order and copy each track (or its arc, if any) to a random location in the new playlist.  <\/span>If I didn’t do that, then the new playlist won\u2019t be truly random since music from the second playlist will always follow music from the first playlist, etc.<\/font><\/p>\n

The first thing I\u2019m going to do is move all of my randomization code out of Form1_Load (which I\u2019ve renamed to VBJukeboxForm_Load) and into a new method called MergePlaylist().  <\/span>The resulting handler will just call MergePlaylist() for each argument that it finds in the command line:<\/font><\/p>\n

    <\/span>Private<\/span> Sub<\/span> VBJukeboxForm_Load(ByVal<\/span> sender As<\/span> System.Object, ByVal<\/span> e As<\/span> System.EventArgs) Handles<\/span> MyBase<\/span>.Load<\/span><\/p>\n

        <\/span>‘ Make sure we have a random series<\/span><\/span><\/p>\n

        <\/span>Microsoft.VisualBasic.Randomize()<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>‘ Initialization<\/span><\/span><\/p>\n

        <\/span>Player.settings.autoStart = False<\/span> ‘ Playlist should not automatically play when added to the player<\/span><\/span><\/p>\n

        <\/span>Me<\/span>.SavePlaylistBt.Enabled = False<\/span> ‘ Don’t enable the “save playlist” button until there’s something to save<\/span><\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>‘ This playlist is initially empty, and we’ll fill it with songs.  <\/span><\/span><\/span><\/p>\n

        <\/span>‘ You could give the user the option of picking the name<\/span><\/span><\/p>\n

        <\/span>‘ by reading it from a label control.<\/span><\/span><\/p>\n

        <\/span>newplaylist = Me<\/span>.Player.newPlaylist(“Smart Shuffled Playlist”<\/span>, “”<\/span>)<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>‘ Merge in the old playlists that were passed via the command line<\/span><\/span><\/p>\n

        <\/span>For<\/span> Each<\/span> Argument In<\/span> My<\/span>.Application.CommandLineArgs<\/span><\/p>\n

            <\/span>MergePlaylist(Argument)<\/span><\/p>\n

        <\/span>Next<\/span><\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>‘ Point player at the new playlist so it can be played<\/span><\/span><\/p>\n

        <\/span>Player.currentPlaylist = newplaylist<\/span><\/p>\n

    <\/span>End<\/span> Sub<\/span><\/span><\/p>\n

 <\/span><\/p>\n

Note that I\u2019ve added a button called SavePlaylistBtn to the form.  <\/span>The user will click that button to save the sorted playlist to the library if desired.  <\/span>It will be disabled until there are actually songs in the new playlist.  <\/span>The button’s click handler is very simple:<\/font><\/p>\n

    <\/span>Private<\/span> Sub<\/span> SavePlaylistBtn_Click(ByVal<\/span> sender As<\/span> System.Object, ByVal<\/span> e As<\/span> System.EventArgs) Handles<\/span> SavePlaylistBtn.Click<\/span><\/p>\n

        <\/span>‘ Save new playlist to library and Music\\Playlists<\/span><\/span><\/p>\n

        <\/span>Player.playlistCollection.importPlaylist(newplaylist)<\/span><\/p>\n

    <\/span>End<\/span> Sub<\/span><\/span><\/p>\n

 <\/span><\/p>\n

Now, I need to merge in playlists for the case where StartupNextInstance is used to \u201crelaunch\u201d the application (or, rather, connect to the existing instance of the app with new filenames).  <\/span>I’ll insert the following code in the ApplcationEvents.vb file we opened previously, into the My namespace:<\/font><\/p>\n

    <\/span>Partial<\/span> Friend<\/span> Class<\/span> MyApplication<\/span><\/p>\n

        <\/span>Private<\/span> Sub<\/span> MyApplication_StartupNextInstance( _<\/span><\/p>\n

            <\/span>ByVal<\/span> sender As<\/span> Object<\/span>, _<\/span><\/p>\n

            <\/span>ByVal<\/span> e As<\/span> Microsoft.VisualBasic.ApplicationServices.StartupNextInstanceEventArgs _<\/span><\/p>\n

        <\/span>) Handles<\/span> Me<\/span>.StartupNextInstance<\/span><\/p>\n

 <\/span><\/p>\n

            <\/span>For<\/span> Each<\/span> s As<\/span> String<\/span> In<\/span> e.CommandLine<\/span><\/p>\n

                <\/span>My<\/span>.Forms.VBJukeboxForm.MergePlaylist(s)<\/span><\/p>\n

            <\/span>Next<\/span><\/span><\/p>\n

        <\/span>End<\/span> Sub<\/span><\/span><\/p>\n

 <\/span><\/p>\n

Note that in this case the filenames are passed in by the EventArgs object \u2013 we don\u2019t have to query for them from the application, unlike in the Load handler.<\/font><\/p>\n

MergePlaylist is very much like the code I wrote for the last post, except that we always take songs from the front of the old list and find a random spot to insert them into the new list:<\/font><\/p>\n

    <\/span>Sub<\/span> MergePlaylist(ByVal<\/span> Argument As<\/span> String<\/span>)<\/span><\/p>\n

        <\/span>Dim<\/span> oldplaylist As<\/span> WMPLib.IWMPPlaylist<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>‘ Make sure that the argument points to an actual file<\/span><\/span><\/p>\n

        <\/span>If<\/span> My<\/span>.Computer.FileSystem.FileExists(Argument) Then<\/span><\/span><\/p>\n

            <\/span>‘ Get the file inforation and make sure it’s a playlist<\/span><\/span><\/p>\n

            <\/span>Dim<\/span> fileData As<\/span> FileInfo = My<\/span>.Computer.FileSystem.GetFileInfo(Argument)<\/span><\/p>\n

            <\/span>If<\/span> fileData.Extension = “.wpl”<\/span> Then<\/span><\/span><\/p>\n

                <\/span>‘ Create a copy of the playlist to merge in so that we don’t damage the original.<\/span><\/span><\/p>\n

                <\/span>‘ Note that playlists get initialized with URLs.<\/span><\/span><\/p>\n

  <\/span>              <\/span>oldplaylist = Me<\/span>.Player.newPlaylist(“Original Sorted Playlist”<\/span>, “file:\/\/\/”<\/span> & Argument)<\/span><\/p>\n

 <\/span><\/p>\n

                <\/span>‘ Get the number of songs to merge in<\/span><\/span><\/p>\n

                <\/span>Dim<\/span> numberOfSongs As<\/span> Integer<\/span> = oldplaylist.count<\/span><\/p>\n

 <\/span><\/p>\n

                <\/span>‘ The value songsRemaining will keep track of the number of songs left to copy,<\/span><\/span><\/p>\n

                <\/span>‘ which in turn helps us keep track of the range for valid random numbers.<\/span><\/span><\/p>\n

                <\/span>For<\/span> songsRemaining As<\/span> Integer<\/span> = numberOfSongs – 1 To<\/span> 0 Step<\/span> -1<\/span><\/p>\n

                  <\/span>  <\/span>‘ Pick the next song from whatever remains in the old list:<\/span><\/span><\/p>\n

                    <\/span>Dim<\/span> mediaItem As<\/span> WMPLib.IWMPMedia = oldplaylist.Item(0)<\/span><\/p>\n

 <\/span><\/p>\n

                    <\/span>‘ Check the “Part of set” attribute — see http:\/\/msdn2.microsoft.com\/en-us\/library\/bb248408.aspx<\/span><\/span><\/p>\n

                    <\/span>‘ for a list of attributes for different media types.<\/span><\/span><\/p>\n

                    <\/span>Dim<\/span> sPartOfSet As<\/span> String<\/span> = mediaItem.getItemInfo(“WM\/PartOfSet”<\/span>)<\/span><\/p>\n

                    <\/span>‘ See if the value is a number.<\/span><\/span><\/p>\n

                    <\/span>If<\/span> sPartOfSet <> “”<\/span> AndAlso<\/span> IsNumeric(sPartOfSet) AndAlso<\/span> CInt<\/span>(sPartOfSet) = 1 Then<\/span><\/span><\/p>\n

                        <\/span>‘ It’s a number.  <\/span>We may have an arc of songs here.  <\/span><\/span><\/span><\/p>\n

                        <\/span>‘ If we run into anything unexpected then just do a normal copy.<\/span><\/span><\/p>\n

                        <\/span>Dim<\/span> currentSongToCopy As<\/span> Integer<\/span> = 0<\/span><\/p>\n

                        <\/span>Dim<\/span> currentMediaItem As<\/span> WMPLib.IWMPMedia = mediaItem<\/span><\/p>\n

                        <\/span>Dim<\/span> sCurrentPartOfSet As<\/span> String<\/span> = sPartOfSet<\/span><\/p>\n

 <\/span><\/p>\n

                        <\/span>‘ OK, we’re probably good to go, unless we coincidentally got the beginning of another arc instead<\/span><\/span><\/p>\n

                        <\/span>‘ due to discontinuous numbers.  <\/span>Worse thing that happens in that case is that we just copy a different arc, and we’ll<\/span><\/span><\/p>\n

                        <\/span>‘ pick up these pieces later.<\/span><\/span><\/p>\n

   <\/span>                     <\/span>Dim<\/span> iPartOfSet As<\/span> Integer<\/span> = 0<\/span><\/p>\n

                        <\/span>Dim<\/span> placeToInsert As<\/span> Integer<\/span> = FindInsertionLocation()<\/span><\/p>\n

                        <\/span>While<\/span> sCurrentPartOfSet <> “”<\/span> AndAlso<\/span> IsNumeric(sCurrentPartOfSet) _<\/span><\/p>\n

                            <\/span>AndAlso<\/span> CInt<\/span>(sCurrentPartOfSet) = iPartOfSet + 1<\/span><\/p>\n

                            <\/span>Insert(placeToInsert + iPartOfSet, currentMediaItem)<\/span><\/p>\n

                            <\/span>oldplaylist.removeItem(currentMediaItem)<\/span><\/p>\n

                            <\/span>iPartOfSet = iPartOfSet + 1 ‘ Copied one song<\/span><\/span><\/p>\n

 <\/span><\/p>\n

                            <\/span>‘ Check next song if there are any remaining<\/span><\/span><\/p>\n

                            <\/span>If<\/span> currentSongToCopy = oldplaylist.count Then<\/span> Exit<\/span> While<\/span><\/span><\/p>\n

 <\/span><\/p>\n

                            <\/span>currentMediaItem = oldplaylist.Item(currentSongToCopy)<\/span><\/p>\n

                            <\/span>sCurrentPartOfSet = currentMediaItem.getItemInfo(“WM\/PartOfSet”<\/span>)<\/span><\/p>\n

                        <\/span>End<\/span> While<\/span><\/span><\/p>\n

 <\/span><\/p>\n

                        <\/span>If<\/span> iPartOfSet > 0 Then<\/span><\/span><\/p>\n

                            <\/span>‘ We may have copied more than one song.  <\/span>Update the For loop variable<\/span><\/span><\/p>\n

                            <\/span>‘ appropriately to compensate, since For loop will only decrement by one.<\/span><\/span><\/p>\n

                            <\/span>songsRemaining = songsRemaining – (iPartOfSet – 1)<\/span><\/p>\n

                        <\/span>Else<\/span><\/span><\/p>\n

                        <\/span>    <\/span>‘ Didn’t copy anything yet — must have been a discontinuity.  <\/span><\/span><\/span><\/p>\n

                            <\/span>‘ Just copy the original song, since user apparently doesn’t care.<\/span><\/span><\/p>\n

                            <\/span>GoTo<\/span> NormalCopy<\/span><\/p>\n

                        <\/span>End<\/span> If<\/span><\/span><\/p>\n

                  <\/span>  <\/span>Else<\/span><\/span><\/p>\n

                        <\/span>‘ Just copy like normal<\/span><\/span><\/p>\n

NormalCopy:             <\/span>Insert(mediaItem)<\/span><\/p>\n

                        <\/span>oldplaylist.removeItem(mediaItem)<\/span><\/p>\n

 <\/span><\/p>\n

                    <\/span>End<\/span> If<\/span><\/span><\/p>\n

                <\/span>Next<\/span><\/span><\/p>\n

            <\/span>Else<\/span><\/span><\/p>\n

                <\/span>‘ Random file.  <\/span>Could be clever here and check the file info to see if it’s a media file, and if so<\/span><\/span><\/p>\n

                <\/span>‘ insert it via newplaylist.insertItem(FindInsertionLocation(), mediaItem).<\/span><\/span><\/p>\n

                <\/span>‘ But that’s left as an exercise to the reader.<\/span><\/span><\/p>\n

            <\/span>End<\/span> If<\/span><\/span><\/p>\n

        <\/span>End<\/span> If<\/span><\/span><\/p>\n

 <\/span><\/p>\n

    <\/span>End<\/span> Sub<\/span><\/span><\/p>\n

 <\/span><\/p>\n

That all should look rather familiar from my last post.  <\/span>Note that I\u2019ve used two new methods called \u201cInsert\u201d to do the actual insertion.  <\/span>One takes just a media item and is used when dealing with non-arc songs, and the other also takes a place value and is used for arcs, since we want to keep songs in the arcs together (i.e., if the first song of an arc goes to position 7, the next song must go to position 8 \u2013 there\u2019s no randomness needed for that case).  <\/span>The Insert() methods look like this:<\/font><\/p>\n

    <\/span>Public<\/span> Sub<\/span> Insert(ByVal<\/span> mediaItem As<\/span> WMPLib.IWMPMedia)<\/span><\/p>\n

        <\/span>Dim<\/span> place As<\/span> Integer<\/span> = FindInsertionLocation()<\/span><\/p>\n

        <\/span>Insert(place, mediaItem)<\/span><\/p>\n

    <\/span>End<\/span> Sub<\/span><\/span><\/p>\n

 <\/font><\/span><\/p>\n

    <\/span>Public<\/span> Sub<\/span> Insert(ByVal<\/span> place As<\/span> Integer<\/span>, ByVal<\/span> mediaItem As<\/span> WMPLib.IWMPMedia)<\/span><\/p>\n

        <\/span>If<\/span> place = newplaylist.count Then<\/span><\/span><\/p>\n

            <\/span>‘ Insert at the end of the list<\/span><\/span><\/p>\n

            <\/span>newplaylist.appendItem(mediaItem)<\/span><\/p>\n

        <\/span>Else<\/span><\/span><\/p>\n

            <\/span>‘ Insert exactly at the index indicated, moving other items down<\/span><\/span><\/p>\n

            <\/span>newplaylist.insertItem(place, mediaItem)<\/span><\/p>\n

        <\/span>End<\/span> If<\/span><\/span><\/p>\n

        <\/span>Me<\/span>.SavePlaylistBtn.Enabled = True<\/span> ‘ We have something in the playlist<\/span><\/span><\/p>\n

    <\/span>End<\/span> Sub<\/span><\/span><\/p>\n

 <\/span><\/p>\n

Finally, we need to define the FindInsertionLocation() method used by the Insert() and MergePlaylist() methods.  <\/span>Basically, this just involves getting a random number.  <\/span>However, if that resulting random number points to a location within an arc, we need to crawl backward to the beginning of the arc, since we don\u2019t want to interrupt it.  <\/span>Furthermore, the random number should be based on the number of songs already in the list plus one<\/b>, since you can always append after the existing songs as well as inserting in front of them.   <\/span>Here\u2019s the code:<\/font><\/p>\n

    <\/span>Public<\/span> Function<\/span> FindInsertionLocation() As<\/span> Integer<\/span><\/span><\/p>\n

        <\/span>If<\/span> newplaylist.count = 0 Then<\/span><\/span><\/p>\n

            <\/span>‘ List is empty, so media will go at position 0.<\/span><\/span><\/p>\n

            <\/span>Return<\/span> 0<\/span><\/p>\n

        <\/span>Else<\/span><\/span><\/p>\n

            <\/span>‘ Get a random location from 0 to n, where n is the current number of songs in the playlist<\/span><\/span><\/p>\n

            <\/span>‘ (*not* 0 to n-1, because given x existing songs,there are x+1 places to insert a new song<\/span><\/span><\/p>\n

            <\/span>‘ — in front of any existing song, plus after them all).<\/span><\/span><\/p>\n

            <\/span>Dim<\/span> placeToInsert As<\/span> Integer<\/span> = Math.Truncate(Microsoft.VisualBasic.Rnd() * (newplaylist.count + 1))<\/span><\/p>\n

            <\/span>If<\/span> placeToInsert = newplaylist.count Then<\/span> Return<\/span> placeToInsert ‘ Insert at end<\/span><\/span><\/p>\n

 <\/span><\/p>\n

            <\/span>Dim<\/span> mediaItem As<\/span> WMPLib.IWMPMedia = newplaylist.Item(placeToInsert)<\/span><\/p>\n

            <\/span>‘ Check the “Part of set” attribute — see http:\/\/msdn2.microsoft.com\/en-us\/library\/bb248408.aspx<\/span><\/span><\/p>\n

            <\/span>‘ for a list of attributes for different media types.<\/span><\/span><\/p>\n

            <\/span>Dim<\/span> sPartOfSet As<\/span> String<\/span> = mediaItem.getItemInfo(“WM\/PartOfSet”<\/span>)<\/span><\/p>\n

            <\/span>‘ See if the value is a number.<\/span><\/span><\/p>\n

            <\/span>If<\/span> sPartOfSet <> “”<\/span> AndAlso<\/span> IsNumeric(sPartOfSet) Then<\/span><\/span><\/p>\n

                <\/span>‘ It’s a number.  <\/span>We may have an arc of songs here.  <\/span><\/span><\/span><\/p>\n

                <\/span>‘ Get the number and rewind to the first one.<\/span><\/span><\/p>\n

                <\/span>‘ If we run into anything unexpected then just do a normal copy.<\/span><\/span><\/p>\n

                <\/span>Dim<\/span> iPartOfSet As<\/span> Integer<\/span> = sPartOfSet<\/span><\/p>\n

    <\/span>            <\/span>‘ Make sure we don’t go past the beginning of the list!<\/span><\/span><\/p>\n

                <\/span>If<\/span> placeToInsert – (iPartOfSet – 1) >= 0 Then<\/span><\/span><\/p>\n

                    <\/span>‘ Rewind to what should be the beginning of the arc and get the song.<\/span><\/span><\/p>\n

                    <\/span>‘ (Hopefully, they\u2019re all there, but I\u2019m not going to count on them being all<\/span><\/span><\/p>\n

                    <\/span>‘ all there and initially in the right order.  <\/span>My<\/span><\/span><\/p>\n

                    <\/span>‘ default when confused will be to just copy the <\/span><\/span><\/p>\n

                    <\/span>‘ originally picked song as if it wasn\u2019t part of an arc.)<\/span><\/span><\/p>\n

                    <\/span>Dim<\/span> currentPlaceToInsert As<\/span> Integer<\/span> = placeToInsert – (iPartOfSet – 1)<\/span><\/p>\n

                    <\/span>Dim<\/span> currentMediaItem As<\/span> WMPLib.IWMPMedia = newplaylist.Item(currentPlaceToInsert)<\/span><\/p>\n

                    <\/span>Dim<\/span> sCurrentPartOfSet As<\/span> String<\/span> = currentMediaItem.getItemInfo(“WM\/PartOfSet”<\/span>)<\/span><\/p>\n

 <\/span><\/p>\n

                    <\/span>‘ Do some error checking here — the attribute had better be “1”<\/span><\/span><\/p>\n

                    <\/span>If<\/span> Not<\/span> sCurrentPartOfSet = “1”<\/span> Then<\/span> Return<\/span> placeToInsert ‘ Partial arc — just use the original number<\/span><\/span><\/p>\n

 <\/span><\/p>\n

                    <\/span>‘ Return the beginning of the arc<\/span><\/span><\/p>\n

                    <\/span>Return<\/span> currentPlaceToInsert<\/span><\/p>\n

                <\/span>End<\/span> If<\/span><\/span><\/p>\n

                <\/span>‘ Partial arc exists beginning of list — just use the original number<\/span><\/span><\/p>\n

                <\/span>Return<\/span> placeToInsert<\/span><\/p>\n

            <\/span>End<\/span> If<\/span><\/span><\/p>\n

            <\/span>‘ No interesting information in PartOfSet — just use the original nuber<\/span><\/span><\/p>\n

            <\/span>Return<\/span> placeToInsert<\/span><\/p>\n

        <\/span>End<\/span> If<\/span><\/span><\/p>\n

    <\/span>End<\/span> Function<\/span><\/span><\/p>\n

 <\/span><\/p>\n

And that\u2019s pretty much it.  <\/span>Now, to get the app to work properly when opening it from playlists in File Explorer, there are a couple of ways to proceed:<\/font><\/font><\/p>\n

(1) Register WPL files to your application as the default application instead of Windows Media Player, which you can do from the Tools\\Folder Options\\File Types in Windows XP or the Folders applet in Windows Vista.  <\/span>(Don\u2019t forget to change it back when you\u2019re done playing around.)  This can also be done in a setup project you create for your app — use the File Type editor to modify the registration.  Note that users generally don’t like it when installers quietly change the file type registration, so plan accordingly. <\/span><\/font><\/font><\/p>\n

<\/span>(2) If you\u2019d rather avoid mangling with the default for the file type, you can take a shortcut by simply dragging a set of playlists to your application\u2019s icon, which will force them to be loaded by your app regardless of how the file type is registered on your system.  Running the playlist from the command line will have the same effect, since you’re explicitly specifing your app in that case.<\/span><\/font><\/font><\/p>\n

<\/span>Note that you can even invoke another playlist while your app is already running (via point (1) or (2)) and have that playlist merge into the existing list — very cool indeed. <\/span><\/font><\/font><\/p>\n

The final app is attached below \u2013 enjoy!  (I wrote it using a recent build of VS2008, incidentally, though none of the functionality I used is any different than what’s available in VS2005.)  <\/span>\u2018Til next time\u2026<\/font><\/p>\n

–Matt–*<\/font><\/p>\n

 <\/font><\/p>\n

VBJukebox.zip<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

(This post assumes that you\u2019ve read my previous post on Windows Media at http:\/\/blogs.msdn.com\/vbteam\/archive\/2007\/10\/30\/let-the-music-play-matt-gertz.aspx \u2013 I will be modifying that code in this post.) After posting my media player blog sample a couple of weeks ago, I got a few questions from a reader called Saleem on how to adapt it to take multiple files as […]<\/p>\n","protected":false},"author":258,"featured_media":8818,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[22,195],"tags":[101,165,166],"class_list":["post-5193","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-matt-gertz","category-visual-basic","tag-matt-gertz","tag-vb2005","tag-vb2008"],"acf":[],"blog_post_summary":"

(This post assumes that you\u2019ve read my previous post on Windows Media at http:\/\/blogs.msdn.com\/vbteam\/archive\/2007\/10\/30\/let-the-music-play-matt-gertz.aspx \u2013 I will be modifying that code in this post.) After posting my media player blog sample a couple of weeks ago, I got a few questions from a reader called Saleem on how to adapt it to take multiple files as […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/posts\/5193","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/users\/258"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/comments?post=5193"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/posts\/5193\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/media\/8818"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/media?parent=5193"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/categories?post=5193"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/vbteam\/wp-json\/wp\/v2\/tags?post=5193"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}