Visual Basic 6 Black Book
(Publisher: The Coriolis Group)
Author(s): Steven Holzner
ISBN: 1576102831
Publication Date: 08/01/98

Making The Multimedia Control Wait

The Aesthetic Design Department is calling again. Users are flipping through your program too fast, not even waiting until the company’s theme song finishes playing. Can’t you do something about that?

You can set a multimedia control’s Wait property to True (the default is False) if you want to make that control finish its current operation before continuing on to another. Note that this property is not available at design time.

Let’s see an example; here, we open a file, C:\windows\media\canyon.mid, with a multimedia control, MMControl1, and set its Wait property to True:

Private Sub Form_Load()
    MMControl1.FileName = "c:\windows\media\canyon.mid"
    MMControl1.Command = "Open"
    MMControl1.Wait = True
End Sub

Now when the user performs an operation with the control, such as playing the file, the control will wait until that operation is complete before letting the user select another operation.

Multimedia Without Multimedia Controls

The Testing Department is calling again. The multimedia control in your program takes up more than 100K—can’t you use something else? Hmm, you say, I’ll look into it.

If you just want to play sounds, you can use the Windows API function PlaySound. Using this built-in function instead of a multimedia control can save you a lot of memory space. Let’s see an example. Here, we’ll play the Windows c:\windows\media\Tada.wav file (which comes with Windows) using PlaySound. First, we declare the PlaySound function in a program; here’s how you use PlaySound:

Declare Function PlaySound Lib "winmm.dll" Alias "PlaySoundA" (ByVal _
   lpszName As String, ByVal hModule As Long, ByVal dwFlags As Long) _
   As Long

Declaring this function as a Private function lets us declare this in the (General) section of a form (without the Private keyword, we’d have to declare this function in a module):

Private Declare Function PlaySound Lib "winmm.dll" Alias _
    "PlaySoundA" (ByVal lpszName As String, ByVal hModule As Long, _
    ByVal dwFlags As Long) As Long

Now we can call PlaySound directly when the user clicks a command button, Command1; here, we pass it a value of &H20000 to indicate that we’re reading the sound from a file and ignore the function’s return value this way:

Private Sub Command1_Click()
    retVal = PlaySound("c:\windows\media\Tada.wav", 0&, &H20000)
End Sub

Here are the flags you can use in the dwFlags parameter of the PlaySound function:

•  SND_SYNC—&H0 (the default); play the sound synchronously

•  SND_ASYNC—&H1; play the sound asynchronously

•  SND_NODEFAULT—&H2; silence is not the default, if sound is not found

•  SND_MEMORY—&H4; lpszName points to a memory file

•  SND_ALIAS—&H10000; name is a win.ini [sounds] entry

•  SND_FILENAME—&H20000; name is a file name

•  SND_RESOURCE—&H40004; name is a resource name or atom

•  SND_ALIAS_ID—&H110000; name is a win.ini [sounds] entry identifier

•  SND_ALIAS_START—0; must be > 4096 to keep strings in same section of resource file

•  SND_LOOP—&H8; loop the sound until next PlaySound

•  SND_NOSTOP—&H10; don’t stop any currently playing sound

•  SND_NOWAIT—&H2000; don’t wait if the driver is busy

And that’s it—now we’re playing sounds without multimedia controls.

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TIP:  For lots more information on interfacing directly to the Windows API, see the next chapter.

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