Volume.exe: Conjunto de níveis de controlo do volume utilizando o Visual Basic

  Form1.frm    - the main form in the project
  Module1.bas  - the module containing the function and type declarations.
  Project1.vbp - the project file
  Project1.vbw - the project workspace file
  Readme.txt   - you are currently reading this file.

• GlobalAlloc - atribui o número de bytes especificado a partir da pilha.
• GlobalLock - bloqueia um objecto de memória global e devolve um ponteiro ao primeiro byte de bloco de memória do objecto. O bloco de memória associado com um objecto de memória bloqueada não pode ser movido ou eliminado.
• GlobalFree - liberta o objecto de memória global especificado e invalida a respectiva alça.
• mixerClose - fecha o dispositivo de mistura especificado.
• mixerGetControlDetails - obtém detalhes sobre um controlo único associado uma linha de áudio.
• mixerGetDevCaps - consulta um dispositivo de mistura especificado para determinar as respectivas capacidades.
• mixerGetID - obtém o identificador de dispositivo para um dispositivo de mistura associado um identificador de dispositivo especificado.
• mixerGetLineControls - copia um ou mais controlos associados a uma linha de áudio.
• mixerGetLineInfo - obtém informações sobre uma linha específica de um dispositivo de mistura.
• mixerGetNumDevs - obtém o número de dispositivos misturadores presentes no sistema.
• mixerMessage - envia uma mensagem de controlador do misturador personalizado directamente para um controlador do misturador.
• mixerOpen - abre um dispositivo de mistura especificado e assegura que o dispositivo não será removido até que a aplicação é fechada a alça.
• mixerSetControlDetails - define as propriedades de um único controlo associado uma linha de áudio.

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Criar projecto de exemplo

1. Inicie um novo projecto EXE padrão no Visual Basic. É criado o Form1 por predefinição.
2. Adicione dois botões de comando, duas caixas de texto e duas etiquetas ao Form1.
3. Adicione um módulo ao projecto, concluindo os seguintes passos:
   1. No menu Project, clique em Adicionar módulo. Add Module aparece a caixa de diálogo.
   2. O separador novo, escolha ' módulo ' e clique em OK. Um novo módulo é adicionado ao projecto.
4. Copie o seguinte código para a janela Code do Module1:

         Option Explicit
   
         Public Const MMSYSERR_NOERROR = 0
         Public Const MAXPNAMELEN = 32
         Public Const MIXER_LONG_NAME_CHARS = 64
         Public Const MIXER_SHORT_NAME_CHARS = 16
         Public Const MIXER_GETLINEINFOF_COMPONENTTYPE = &H3&
         Public Const MIXER_GETCONTROLDETAILSF_VALUE = &H0&
         Public Const MIXER_GETLINECONTROLSF_ONEBYTYPE = &H2&
         Public Const MIXERLINE_COMPONENTTYPE_DST_FIRST = &H0&
         Public Const MIXERLINE_COMPONENTTYPE_SRC_FIRST = &H1000&
   
         Public Const MIXERLINE_COMPONENTTYPE_DST_SPEAKERS = _
                        (MIXERLINE_COMPONENTTYPE_DST_FIRST + 4)
   
         Public Const MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE = _
                        (MIXERLINE_COMPONENTTYPE_SRC_FIRST + 3)
   
         Public Const MIXERLINE_COMPONENTTYPE_SRC_LINE = _
                        (MIXERLINE_COMPONENTTYPE_SRC_FIRST + 2)
   
         Public Const MIXERCONTROL_CT_CLASS_FADER = &H50000000
         Public Const MIXERCONTROL_CT_UNITS_UNSIGNED = &H30000
   
         Public Const MIXERCONTROL_CONTROLTYPE_FADER = _
                        (MIXERCONTROL_CT_CLASS_FADER Or _
                        MIXERCONTROL_CT_UNITS_UNSIGNED)
   
         Public Const MIXERCONTROL_CONTROLTYPE_VOLUME = _
                        (MIXERCONTROL_CONTROLTYPE_FADER + 1)
   
         Declare Function mixerClose Lib "winmm.dll" _
                        (ByVal hmx As Long) As Long
   
         Declare Function mixerGetControlDetails Lib "winmm.dll" _
                        Alias "mixerGetControlDetailsA" _
                        (ByVal hmxobj As Long, _
                        pmxcd As MIXERCONTROLDETAILS, _
                        ByVal fdwDetails As Long) As Long
   
         Declare Function mixerGetDevCaps Lib "winmm.dll" _
                        Alias "mixerGetDevCapsA" _
                        (ByVal uMxId As Long, _
                        ByVal pmxcaps As MIXERCAPS, _
                        ByVal cbmxcaps As Long) As Long
   
         Declare Function mixerGetID Lib "winmm.dll" _
                        (ByVal hmxobj As Long, _
                        pumxID As Long, _
                        ByVal fdwId As Long) As Long
   
         Declare Function mixerGetLineControls Lib "winmm.dll" _
                        Alias "mixerGetLineControlsA" _
                        (ByVal hmxobj As Long, _
                        pmxlc As MIXERLINECONTROLS, _
                        ByVal fdwControls As Long) As Long
   
         Declare Function mixerGetLineInfo Lib "winmm.dll" _
                        Alias "mixerGetLineInfoA" _
                        (ByVal hmxobj As Long, _
                        pmxl As MIXERLINE, _
                        ByVal fdwInfo As Long) As Long
   
         Declare Function mixerGetNumDevs Lib "winmm.dll" () As Long
   
         Declare Function mixerMessage Lib "winmm.dll" _
                        (ByVal hmx As Long, _
                        ByVal uMsg As Long, _
                        ByVal dwParam1 As Long, _
                        ByVal dwParam2 As Long) As Long
   
         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
   
         Declare Function mixerSetControlDetails Lib "winmm.dll" _
                        (ByVal hmxobj As Long, _
                        pmxcd As MIXERCONTROLDETAILS, _
                        ByVal fdwDetails As Long) As Long
   
         Declare Sub CopyStructFromPtr Lib "kernel32" _
                        Alias "RtlMoveMemory" _
                        (struct As Any, _
                        ByVal ptr As Long, _
                        ByVal cb As Long)
   
         Declare Sub CopyPtrFromStruct Lib "kernel32" _
                        Alias "RtlMoveMemory" _
                        (ByVal ptr As Long, _
                        struct As Any, _
                        ByVal cb As Long)
   
         Declare Function GlobalAlloc Lib "kernel32" _
                        (ByVal wFlags As Long, _
                        ByVal dwBytes As Long) As Long
   
         Declare Function GlobalLock Lib "kernel32" _
                        (ByVal hmem As Long) As Long
   
         Declare Function GlobalFree Lib "kernel32" _
                        (ByVal hmem As Long) As Long
   
         Type MIXERCAPS
            wMid As Integer                   '  manufacturer id
            wPid As Integer                   '  product id
            vDriverVersion As Long            '  version of the driver
            szPname As String * MAXPNAMELEN   '  product name
            fdwSupport As Long                '  misc. support bits
            cDestinations As Long             '  count of destinations
         End Type
   
         Type MIXERCONTROL
            cbStruct As Long           '  size in Byte of MIXERCONTROL
            dwControlID As Long        '  unique control id for mixer device
            dwControlType As Long      '  MIXERCONTROL_CONTROLTYPE_xxx
            fdwControl As Long         '  MIXERCONTROL_CONTROLF_xxx
            cMultipleItems As Long     '  if MIXERCONTROL_CONTROLF_MULTIPLE
                                       '  set
            szShortName As String * MIXER_SHORT_NAME_CHARS  ' short name of
                                                            ' control
            szName As String * MIXER_LONG_NAME_CHARS        ' long name of
                                                            ' control
            lMinimum As Long           '  Minimum value
            lMaximum As Long           '  Maximum value
            reserved(10) As Long       '  reserved structure space
            End Type
   
         Type MIXERCONTROLDETAILS
            cbStruct As Long       '  size in Byte of MIXERCONTROLDETAILS
            dwControlID As Long    '  control id to get/set details on
            cChannels As Long      '  number of channels in paDetails array
            item As Long           '  hwndOwner or cMultipleItems
            cbDetails As Long      '  size of _one_ details_XX struct
            paDetails As Long      '  pointer to array of details_XX structs
         End Type
   
         Type MIXERCONTROLDETAILS_UNSIGNED
            dwValue As Long        '  value of the control
         End Type
   
         Type MIXERLINE
            cbStruct As Long               '  size of MIXERLINE structure
            dwDestination As Long          '  zero based destination index
            dwSource As Long               '  zero based source index (if
                                           '  source)
            dwLineID As Long               '  unique line id for mixer device
            fdwLine As Long                '  state/information about line
            dwUser As Long                 '  driver specific information
            dwComponentType As Long        '  component type line connects to
            cChannels As Long              '  number of channels line supports
            cConnections As Long           '  number of connections (possible)
            cControls As Long              '  number of controls at this line
            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
   
         Type MIXERLINECONTROLS
            cbStruct As Long       '  size in Byte of MIXERLINECONTROLS
            dwLineID As Long       '  line id (from MIXERLINE.dwLineID)
                                   '  MIXER_GETLINECONTROLSF_ONEBYID or
            dwControl As Long      '  MIXER_GETLINECONTROLSF_ONEBYTYPE
            cControls As Long      '  count of controls pmxctrl points to
            cbmxctrl As Long       '  size in Byte of _one_ MIXERCONTROL
            pamxctrl As Long       '  pointer to first MIXERCONTROL array
         End Type
   
         Function GetVolumeControl(ByVal hmixer As Long, _
                                 ByVal componentType As Long, _
                                 ByVal ctrlType As Long, _
                                 ByRef mxc As MIXERCONTROL) As Boolean
   
         ' This function attempts to obtain a mixer control.
         ' Returns True if successful.
            Dim mxlc As MIXERLINECONTROLS
            Dim mxl As MIXERLINE
            Dim hmem As Long
            Dim rc As Long
   
            mxl.cbStruct = Len(mxl)
            mxl.dwComponentType = componentType
   
            ' Obtain a line corresponding to the component type
            rc = mixerGetLineInfo(hmixer, _
                                  mxl, _
                                  MIXER_GETLINEINFOF_COMPONENTTYPE)
   
            If (MMSYSERR_NOERROR = rc) Then
                mxlc.cbStruct = Len(mxlc)
                mxlc.dwLineID = mxl.dwLineID
                mxlc.dwControl = ctrlType
                mxlc.cControls = 1
                mxlc.cbmxctrl = Len(mxc)
   
                ' Allocate a buffer for the control
                hmem = GlobalAlloc(&H40, Len(mxc))
                mxlc.pamxctrl = GlobalLock(hmem)
                mxc.cbStruct = Len(mxc)
   
                ' Get the control
                rc = mixerGetLineControls(hmixer, _
                                          mxlc, _
                                          MIXER_GETLINECONTROLSF_ONEBYTYPE)
   
                If (MMSYSERR_NOERROR = rc) Then
                    GetVolumeControl = True
   
                    ' Copy the control into the destination structure
                    CopyStructFromPtr mxc, mxlc.pamxctrl, Len(mxc)
                Else
                    GetVolumeControl = False
                End If
                GlobalFree (hmem)
                Exit Function
            End If
   
            GetVolumeControl = False
         End Function
   
         Function SetVolumeControl(ByVal hmixer As Long, _
                                 mxc As MIXERCONTROL, _
                                 ByVal volume As Long) As Boolean
         ' This function sets the value for a volume control.
         ' Returns True if successful
   
            Dim mxcd As MIXERCONTROLDETAILS
            Dim vol As MIXERCONTROLDETAILS_UNSIGNED
   
            mxcd.item = 0
            mxcd.dwControlID = mxc.dwControlID
            mxcd.cbStruct = Len(mxcd)
            mxcd.cbDetails = Len(vol)
   
            ' Allocate a buffer for the control value buffer
            hmem = GlobalAlloc(&H40, Len(vol))
            mxcd.paDetails = GlobalLock(hmem)
            mxcd.cChannels = 1
            vol.dwValue = volume
   
            ' Copy the data into the control value buffer
            CopyPtrFromStruct mxcd.paDetails, vol, Len(vol)
   
            ' Set the control value
            rc = mixerSetControlDetails(hmixer, _
                                       mxcd, _
                                       MIXER_SETCONTROLDETAILSF_VALUE)
   
            GlobalFree (hmem)
            If (MMSYSERR_NOERROR = rc) Then
                SetVolumeControl = True
            Else
                SetVolumeControl = False
            End If
         End Function
   

5. Copie o seguinte código para a janela Code do Form1:

         Option Explicit
   
         Dim hmixer As Long          ' mixer handle
         Dim volCtrl As MIXERCONTROL ' waveout volume control
         Dim micCtrl As MIXERCONTROL ' microphone volume control
         Dim rc As Long              ' return code
         Dim ok As Boolean           ' boolean return code
         Dim vol As Long             ' volume  
   
         Private Sub Form_Load()
         ' Open the mixer with deviceID 0.
            rc = mixerOpen(hmixer, 0, 0, 0, 0)
            If ((MMSYSERR_NOERROR <> rc)) Then
                MsgBox "Couldn't open the mixer."
                Exit Sub
                End If
   
            ' Get the waveout volume control
            ok = GetVolumeControl(hmixer, _
                                 MIXERLINE_COMPONENTTYPE_DST_SPEAKERS, _
                                 MIXERCONTROL_CONTROLTYPE_VOLUME, _
                                 volCtrl)
            If (ok = True) Then
                ' If the function successfully gets the volume control,
                ' the maximum and minimum values are specified by
                ' lMaximum and lMinimum
                Label1.Caption = volCtrl.lMinimum _
                                 & " to " _
                                 & volCtrl.lMaximum
                End If
   
            ' Get the microphone volume control
            ok = GetVolumeControl(hmixer, _
                                 MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, _
                                 MIXERCONTROL_CONTROLTYPE_VOLUME, _
                                 micCtrl)
            If (ok = True) Then
                Label2.Caption = micCtrl.lMinimum _
                                 & " to " _
                                 & micCtrl.lMaximum
                End If
         End Sub
   
         Private Sub Command1_Click()
            vol = CLng(Text1.Text)
            SetVolumeControl hmixer, volCtrl, vol
         End Sub
   
         Private Sub Command2_Click()
            vol = CLng(Text2.Text)
            SetVolumeControl hmixer, micCtrl, vol
         End Sub

6. No menu ' Executar ', clique em Iniciar ou prima a tecla F5 para iniciar o programa. Minimize o IDE do Visual Basic para que aparece no ecrã Form1. Maximize o programa de nível de volume na barra de tarefas. Dispor Form1 e o programa de nível de volume para que ambos os programas sejam visíveis.
7. Introduza um valor entre os valores mínimos e máximo mostrados numa ou ambas as caixas de texto e clique dos botões de comando no Form1. Tenha em atenção que o cursor de deslocamento correspondente no programa de nível de volume é ajustada para o nível especificado.

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