streamingsound.cpp

这是书上的代码

// StreamingSound.cpp: implementation of the CStreamingSound class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "StreamingSound.h"
#include "dxerr8.h"
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CStreamingSound::CStreamingSound( LPDIRECTSOUNDBUFFER pDSBuffer, DWORD dwDSBufferSize, 
                                  CWaveFile* pWaveFile, DWORD dwNotifySize ) 
                : CSound( &pDSBuffer, dwDSBufferSize, 1, pWaveFile )           
{
    m_dwLastPlayPos     = 0;
    m_dwPlayProgress    = 0;
    m_dwNotifySize      = dwNotifySize;
    m_dwNextWriteOffset = 0;
    m_bFillNextNotificationWithSilence = FALSE;
}




//-----------------------------------------------------------------------------
// Name: CStreamingSound::~CStreamingSound()
// Desc: Destroys the class
//-----------------------------------------------------------------------------
CStreamingSound::~CStreamingSound()
{
}



//-----------------------------------------------------------------------------
// Name: CStreamingSound::HandleWaveStreamNotification()
// Desc: Handle the notification that tell us to put more wav data in the 
//       circular buffer
//-----------------------------------------------------------------------------
HRESULT CStreamingSound::HandleWaveStreamNotification( BOOL bLoopedPlay )
{
    HRESULT hr;
    DWORD   dwCurrentPlayPos;
    DWORD   dwPlayDelta;
    DWORD   dwBytesWrittenToBuffer;
    VOID*   pDSLockedBuffer = NULL;
    VOID*   pDSLockedBuffer2 = NULL;
    DWORD   dwDSLockedBufferSize;
    DWORD   dwDSLockedBufferSize2;

    if( m_apDSBuffer == NULL || m_pWaveFile == NULL )
        return CO_E_NOTINITIALIZED;

    // Restore the buffer if it was lost
    BOOL bRestored;
    if( FAILED( hr = RestoreBuffer( m_apDSBuffer[0], &bRestored ) ) )
        return DXTRACE_ERR( TEXT("RestoreBuffer"), hr );

    if( bRestored )
    {
        // The buffer was restored, so we need to fill it with new data
        if( FAILED( hr = FillBufferWithSound( m_apDSBuffer[0], FALSE ) ) )
            return DXTRACE_ERR( TEXT("FillBufferWithSound"), hr );
        return S_OK;
    }

    // Lock the DirectSound buffer
    if( FAILED( hr = m_apDSBuffer[0]->Lock( m_dwNextWriteOffset, m_dwNotifySize, 
                                            &pDSLockedBuffer, &dwDSLockedBufferSize, 
                                            &pDSLockedBuffer2, &dwDSLockedBufferSize2, 0L ) ) )
        return DXTRACE_ERR( TEXT("Lock"), hr );

    // m_dwDSBufferSize and m_dwNextWriteOffset are both multiples of m_dwNotifySize, 
    // it should the second buffer should never be valid
    if( pDSLockedBuffer2 != NULL )
        return E_UNEXPECTED; 

    if( !m_bFillNextNotificationWithSilence )
    {
        // Fill the DirectSound buffer with wav data
        if( FAILED( hr = m_pWaveFile->Read( (BYTE*) pDSLockedBuffer, 
                                                  dwDSLockedBufferSize, 
                                                  &dwBytesWrittenToBuffer ) ) )           
            return DXTRACE_ERR( TEXT("Read"), hr );
    }
    else
    {
        // Fill the DirectSound buffer with silence
        FillMemory( pDSLockedBuffer, dwDSLockedBufferSize, 
                    (BYTE)( m_pWaveFile->m_pwfx->wBitsPerSample == 8 ? 128 : 0 ) );
        dwBytesWrittenToBuffer = dwDSLockedBufferSize;
    }

    // If the number of bytes written is less than the 
    // amount we requested, we have a short file.
    if( dwBytesWrittenToBuffer < dwDSLockedBufferSize )
    {
        if( !bLoopedPlay ) 
        {
            // Fill in silence for the rest of the buffer.
            FillMemory( (BYTE*) pDSLockedBuffer + dwBytesWrittenToBuffer, 
                        dwDSLockedBufferSize - dwBytesWrittenToBuffer, 
                        (BYTE)(m_pWaveFile->m_pwfx->wBitsPerSample == 8 ? 128 : 0 ) );

            // Any future notifications should just fill the buffer with silence
            m_bFillNextNotificationWithSilence = TRUE;
        }
        else
        {
            // We are looping, so reset the file and fill the buffer with wav data
            DWORD dwReadSoFar = dwBytesWrittenToBuffer;    // From previous call above.
            while( dwReadSoFar < dwDSLockedBufferSize )
            {  
                // This will keep reading in until the buffer is full (for very short files).
                if( FAILED( hr = m_pWaveFile->ResetFile() ) )
                    return DXTRACE_ERR( TEXT("ResetFile"), hr );

                if( FAILED( hr = m_pWaveFile->Read( (BYTE*)pDSLockedBuffer + dwReadSoFar,
                                                          dwDSLockedBufferSize - dwReadSoFar,
                                                          &dwBytesWrittenToBuffer ) ) )
                    return DXTRACE_ERR( TEXT("Read"), hr );

                dwReadSoFar += dwBytesWrittenToBuffer;
            } 
        } 
    }

    // Unlock the DirectSound buffer
    m_apDSBuffer[0]->Unlock( pDSLockedBuffer, dwDSLockedBufferSize, NULL, 0 );

    // Figure out how much data has been played so far.  When we have played
    // passed the end of the file, we will either need to start filling the
    // buffer with silence or starting reading from the beginning of the file, 
    // depending if the user wants to loop the sound
    if( FAILED( hr = m_apDSBuffer[0]->GetCurrentPosition( &dwCurrentPlayPos, NULL ) ) )
        return DXTRACE_ERR( TEXT("GetCurrentPosition"), hr );

    // Check to see if the position counter looped
    if( dwCurrentPlayPos < m_dwLastPlayPos )
        dwPlayDelta = ( m_dwDSBufferSize - m_dwLastPlayPos ) + dwCurrentPlayPos;
    else
        dwPlayDelta = dwCurrentPlayPos - m_dwLastPlayPos;

    m_dwPlayProgress += dwPlayDelta;
    m_dwLastPlayPos = dwCurrentPlayPos;

    // If we are now filling the buffer with silence, then we have found the end so 
    // check to see if the entire sound has played, if it has then stop the buffer.
    if( m_bFillNextNotificationWithSilence )
    {
        // We don't want to cut off the sound before it's done playing.
        if( m_dwPlayProgress >= m_pWaveFile->GetSize() )
        {
            m_apDSBuffer[0]->Stop();
        }
    }

    // Update where the buffer will lock (for next time)
    m_dwNextWriteOffset += dwDSLockedBufferSize; 
    m_dwNextWriteOffset %= m_dwDSBufferSize; // Circular buffer

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: CStreamingSound::Reset()
// Desc: Resets the sound so it will begin playing at the beginning
//-----------------------------------------------------------------------------
HRESULT CStreamingSound::Reset()
{
    HRESULT hr;

    if( m_apDSBuffer[0] == NULL || m_pWaveFile == NULL )
        return CO_E_NOTINITIALIZED;

    m_dwLastPlayPos     = 0;
    m_dwPlayProgress    = 0;
    m_dwNextWriteOffset = 0;
    m_bFillNextNotificationWithSilence = FALSE;

    // Restore the buffer if it was lost
    BOOL bRestored;
    if( FAILED( hr = RestoreBuffer( m_apDSBuffer[0], &bRestored ) ) )
        return DXTRACE_ERR( TEXT("RestoreBuffer"), hr );

    if( bRestored )
    {
        // The buffer was restored, so we need to fill it with new data
        if( FAILED( hr = FillBufferWithSound( m_apDSBuffer[0], FALSE ) ) )
            return DXTRACE_ERR( TEXT("FillBufferWithSound"), hr );
    }

    m_pWaveFile->ResetFile();

    return m_apDSBuffer[0]->SetCurrentPosition( 0L );  
}