Регулятор громкости

Const MMSYSERR_NOERROR = 0
Const MAXPNAMELEN = 32
Const MIXER_LONG_NAME_CHARS = 64
Const MIXER_SHORT_NAME_CHARS = 16
Const MIXER_GETLINEINFOF_COMPONENTTYPE = &H3&
Const MIXER_GETLINECONTROLSF_ONEBYTYPE = &H2&
Const MIXER_SETCONTROLDETAILSF_VALUE = &H0&
Const MIXERLINE_COMPONENTTYPE_DST_FIRST = &H0&
Const MIXERLINE_COMPONENTTYPE_DST_SPEAKERS = &H4
Const MIXERCONTROL_CONTROLTYPE_VOLUME = &H50030001

Private Declare Function mixerOpen Lib "winmm.dll" _
(phmx As Long, ByVal uMxId As Long, ByVal dwCallback As Long, _
ByVal dwinstance As Long, ByVal fdwOpen As Long) As Long

Private Declare Function mixerGetLineInfo Lib "winmm.dll" _
Alias "mixerGetLineInfoA" (ByVal hmxobj As Long, pmxl As MIXERLINE, _
ByVal fdwinfo As Long) As Long

Private Declare Function mixerGetLineControls Lib "winmm.dll" Alias _
"mixerGetLineControlsA" (ByVal hmxobj As Long, _
pmxic As MIXERLINECONTROLS, ByVal fdwControls As Long) As Long

Private Declare Function mixerSetControlDetails Lib "winmm.dll" _
(ByVal hmxobj As Long, pmxcd As MIXERCONTROLDETAILS, ByVal fdwDetails As Long) As Long

Private Declare Function mixerClose Lib "winmm.dll" (ByVal hmx As Long) As Long

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
(Destination As Any, Source As Any, ByVal Length As Long)

Private Declare Function GlobalAlloc Lib "kernel32" _
(ByVal wFlags As Long, ByVal dwBytes As Long) As Long

Private Declare Function GlobalLock Lib "kernel32" (ByVal hmem As Long) As Long

Private Declare Function GlobalFree Lib "kernel32" (ByVal hmem As Long) As Long

Private Type MIXERCONTROL
cbStruct As Long
dwControlID As Long
dwControlType As Long
fdwControl As Long
cMultipleItems As Long
szShortName As String * MIXER_SHORT_NAME_CHARS
szName As String * MIXER_LONG_NAME_CHARS
IMinimum As Long
IMaximum As Long
reserved(10) As Long
End Type

Private Type MIXERCONTROLDETAILS
cbStruct As Long
dwControlID As Long
cChannels As Long
item As Long
cbDetails As Long
paDetails As Long
End Type

Private Type MIXERCONTROLDETAILS_UNSIGNED
dwValue As Long
End Type

Private Type MIXERLINE
cbStruct As Long
dwDestination As Long
dwSource As Long
dwLineID As Long
fdwLine As Long
dwUser As Long
dwComponentType As Long
cChannels As Long
cConnections As Long
cControls As Long
szShortName As String * MIXER_SHORT_NAME_CHARS
szName As String * MIXER_LONG_NAME_CHARS
dwType As Long
dwDeviceID As Long
wMid As Integer
wPid As Integer
vDriverVersion As Long
szPname As String * MAXPNAMELEN
End Type

Private Type MIXERLINECONTROLS
cbStruct As Long
dwLineID As Long
dwControl As Long
cControls As Long
cbmxctrl As Long
pamxctrl As Long
End Type

' Set the master volume level.
' VolumeLevel is the level value in percentage (0 = min, 100 ∙∙= max)
' Returns True if successful

Function SetVolume(VolumeLevel As Long) As Boolean
Dim hmx As Long
Dim uMixerLine As MIXERLINE
Dim uMixerControl As MIXERCONTROL
Dim uMixerLineControls As MIXERLINECONTROLS
Dim uDetails As MIXERCONTROLDETAILS
Dim uUnsigned As MIXERCONTROLDETAILS_UNSIGNED
Dim RetValue As Long
Dim hmem As Long

' VolumeLevel value must be between 0 and 100

If VolumeLevel < 0 Or VolumeLevel > 100 Then GoTo error
' Open the mixer

RetValue = mixerOpen(hmx, 0, 0, 0, 0)

If RetValue <> MMSYSERR_NOERROR Then GoTo error

' Initialize MIXERLINE structure and call mixerGetLineInfo

uMixerLine.cbStruct = Len(uMixerLine)

uMixerLine.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS
RetValue = mixerGetLineInfo(hmx, uMixerLine, MIXER_GETLINEINFOF_COMPONENTTYPE)
If RetValue <> MMSYSERR_NOERROR Then GoTo error

' Initialize MIXERLINECONTROLS strucure and ' call mixerGetLineCdntrols

uMixerLineControls.cbStruct = Len(uMixerLineControls)
uMixerLineControls.dwLineID = uMixerLine.dwLineID
uMixerLineControls.dwControl = MIXERCONTROL_CONTROLTYPE_VOLUME
uMixerLineControls.cControls = 1
uMixerLineControls.cbmxctrl = Len(uMixerControl)

' Allocate a buffer to receive the properties of the master volume control ' and put his address into uMixerLineControls.pamxctrl

hmem = GlobalAlloc(&H40, Len(uMixerControl))
uMixerLineControls.pamxctrl = GlobalLock(hmem)
uMixerControl.cbStruct = Len(uMixerControl)
RetValue = mixerGetLineControls(hmx, uMixerLineControls, _
MIXER_GETLINECONTROLSF_ONEBYTYPE)
If RetValue <> MMSYSERR_NOERROR Then GoTo error

' Copy data buffer into the uMixerControl structure

Call CopyMemory(uMixerControl, ByVal uMixerLineControls.pamxctrl, Len(uMixerControl))
GlobalFree hmem
hmem = 0
uDetails.item = 0
uDetails.dwControlID = uMixerControl.dwControlID
uDetails.cbStruct = Len(uDetails)
uDetails.cbDetails = Len(uUnsigned)

' Allocate a buffer in which properties for the volume control are set ' and put his address into uDetails.paDetails

hmem = GlobalAlloc(&H40, Len(uUnsigned))
uDetails.paDetails = GlobalLock(hmem)
uDetails.cChannels = 1
uUnsigned.dwValue = CLng((VolumeLevel * uMixerControl.IMaximum) / 100)
CopyMemory ByVal uDetails.paDetails, uUnsigned, Len(uUnsigned)

' Set new volume level

RetValue = mixerSetControlDetails(hmx, uDetails, MIXER_SETCONTROLDETAILSF_VALUE)
GlobalFree hmem
hmem = 0
If RetValue <> MMSYSERR_NOERROR Then GoTo error

mixerClose hmx
' signal success

SetVolume = True
Exit Function

error:

' An error occurred ' Release resources

If hmx <> 0 Then mixerClose hmx
If hmem Then GlobalFree hmem
' signal failure

SetVolume = False
End Function