qtmultimedia/src/plugins/wmf/mfstream.cpp

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#include "mfstream.h"
#include <QtCore/qcoreapplication.h>

//MFStream is added for supporting QIODevice type of media source.
//It is used to delegate invocations from media foundation(through IMFByteStream) to QIODevice.

MFStream::MFStream(QIODevice *stream, bool ownStream)
    : m_cRef(1)
    , m_stream(stream)
    , m_ownStream(ownStream)
    , m_currentReadResult(0)
{
    //Move to the thread of the stream object
    //to make sure invocations on stream
    //are happened in the same thread of stream object
    this->moveToThread(stream->thread());
    connect(stream, SIGNAL(readyRead()), this, SLOT(handleReadyRead()));
}

MFStream::~MFStream()
{
    if (m_currentReadResult)
        m_currentReadResult->Release();
    if (m_ownStream)
        m_stream->deleteLater();
}

//from IUnknown
STDMETHODIMP MFStream::QueryInterface(REFIID riid, LPVOID *ppvObject)
{
    if (!ppvObject)
        return E_POINTER;
    if (riid == IID_IMFByteStream) {
        *ppvObject = static_cast<IMFByteStream*>(this);
    } else if (riid == IID_IUnknown) {
        *ppvObject = static_cast<IUnknown*>(this);
    } else {
        *ppvObject =  NULL;
        return E_NOINTERFACE;
    }
    AddRef();
    return S_OK;
}

STDMETHODIMP_(ULONG) MFStream::AddRef(void)
{
    return InterlockedIncrement(&m_cRef);
}

STDMETHODIMP_(ULONG) MFStream::Release(void)
{
    LONG cRef = InterlockedDecrement(&m_cRef);
    if (cRef == 0) {
        this->deleteLater();
    }
    return cRef;
}


//from IMFByteStream
STDMETHODIMP MFStream::GetCapabilities(DWORD *pdwCapabilities)
{
    if (!pdwCapabilities)
        return E_INVALIDARG;
    *pdwCapabilities = MFBYTESTREAM_IS_READABLE;
    if (!m_stream->isSequential())
        *pdwCapabilities |= MFBYTESTREAM_IS_SEEKABLE;
    return S_OK;
}

STDMETHODIMP MFStream::GetLength(QWORD *pqwLength)
{
    if (!pqwLength)
        return E_INVALIDARG;
    QMutexLocker locker(&m_mutex);
    *pqwLength = QWORD(m_stream->size());
    return S_OK;
}

STDMETHODIMP MFStream::SetLength(QWORD)
{
    return E_NOTIMPL;
}

STDMETHODIMP MFStream::GetCurrentPosition(QWORD *pqwPosition)
{
    if (!pqwPosition)
        return E_INVALIDARG;
    QMutexLocker locker(&m_mutex);
    *pqwPosition = m_stream->pos();
    return S_OK;
}

STDMETHODIMP MFStream::SetCurrentPosition(QWORD qwPosition)
{
    QMutexLocker locker(&m_mutex);
    //SetCurrentPosition may happend during the BeginRead/EndRead pair,
    //refusing to execute SetCurrentPosition during that time seems to be
    //the simplest workable solution
    if (m_currentReadResult)
        return S_FALSE;

    bool seekOK = m_stream->seek(qint64(qwPosition));
    if (seekOK)
        return S_OK;
    else
        return S_FALSE;
}

STDMETHODIMP MFStream::IsEndOfStream(BOOL *pfEndOfStream)
{
    if (!pfEndOfStream)
        return E_INVALIDARG;
    QMutexLocker locker(&m_mutex);
    *pfEndOfStream = m_stream->atEnd() ? TRUE : FALSE;
    return S_OK;
}

STDMETHODIMP MFStream::Read(BYTE *pb, ULONG cb, ULONG *pcbRead)
{
    QMutexLocker locker(&m_mutex);
    qint64 read = m_stream->read((char*)(pb), qint64(cb));
    if (pcbRead)
        *pcbRead = ULONG(read);
    return S_OK;
}

STDMETHODIMP MFStream::BeginRead(BYTE *pb, ULONG cb, IMFAsyncCallback *pCallback,
                       IUnknown *punkState)
{
    if (!pCallback || !pb)
        return E_INVALIDARG;

    Q_ASSERT(m_currentReadResult == NULL);

    AsyncReadState *state = new (std::nothrow) AsyncReadState(pb, cb);
    if (state == NULL)
        return E_OUTOFMEMORY;

    HRESULT hr = MFCreateAsyncResult(state, pCallback, punkState, &m_currentReadResult);
    state->Release();
    if (FAILED(hr))
        return hr;

    QCoreApplication::postEvent(this, new QEvent(QEvent::User));
    return hr;
}

STDMETHODIMP MFStream::EndRead(IMFAsyncResult* pResult, ULONG *pcbRead)
{
    if (!pcbRead)
        return E_INVALIDARG;
    IUnknown *pUnk;
    pResult->GetObject(&pUnk);
    AsyncReadState *state = static_cast<AsyncReadState*>(pUnk);
    *pcbRead = state->bytesRead();
    pUnk->Release();

    m_currentReadResult->Release();
    m_currentReadResult = NULL;

    return S_OK;
}

STDMETHODIMP MFStream::Write(const BYTE *, ULONG, ULONG *)
{
    return E_NOTIMPL;
}

STDMETHODIMP MFStream::BeginWrite(const BYTE *, ULONG ,
                        IMFAsyncCallback *,
                        IUnknown *)
{
    return E_NOTIMPL;
}

STDMETHODIMP MFStream::EndWrite(IMFAsyncResult *,
                      ULONG *)
{
    return E_NOTIMPL;
}

STDMETHODIMP MFStream::Seek(
    MFBYTESTREAM_SEEK_ORIGIN SeekOrigin,
    LONGLONG llSeekOffset,
    DWORD,
    QWORD *pqwCurrentPosition)
{
    QMutexLocker locker(&m_mutex);
    if (m_currentReadResult)
        return S_FALSE;

    qint64 pos = qint64(llSeekOffset);
    switch (SeekOrigin) {
    case msoCurrent:
        pos += m_stream->pos();
        break;
    }
    bool seekOK = m_stream->seek(pos);
    if (*pqwCurrentPosition)
        *pqwCurrentPosition = pos;
    if (seekOK)
        return S_OK;
    else
        return S_FALSE;
}

STDMETHODIMP MFStream::Flush()
{
    return E_NOTIMPL;
}

STDMETHODIMP MFStream::Close()
{
    QMutexLocker locker(&m_mutex);
    if (m_ownStream)
        m_stream->close();
    return S_OK;
}

void MFStream::doRead()
{
    bool readDone = true;
    IUnknown *pUnk = NULL;
    HRESULT    hr = m_currentReadResult->GetObject(&pUnk);
    if (SUCCEEDED(hr)) {
        //do actual read
        AsyncReadState *state =  static_cast<AsyncReadState*>(pUnk);
        ULONG cbRead;
        Read(state->pb(), state->cb() - state->bytesRead(), &cbRead);
        pUnk->Release();

        state->setBytesRead(cbRead + state->bytesRead());
        if (state->cb() > state->bytesRead() && !m_stream->atEnd()) {
            readDone = false;
        }
    }

    if (readDone) {
        //now inform the original caller
        m_currentReadResult->SetStatus(hr);
        MFInvokeCallback(m_currentReadResult);
    }
}


void MFStream::handleReadyRead()
{
    doRead();
}

void MFStream::customEvent(QEvent *event)
{
    if (event->type() != QEvent::User) {
        QObject::customEvent(event);
        return;
    }
    doRead();
}

//AsyncReadState is a helper class used in BeginRead for asynchronous operation
//to record some BeginRead parameters, so these parameters could be
//used later when actually executing the read operation in another thread.
MFStream::AsyncReadState::AsyncReadState(BYTE *pb, ULONG cb)
    : m_cRef(1)
    , m_pb(pb)
    , m_cb(cb)
    , m_cbRead(0)
{
}

//from IUnknown
STDMETHODIMP MFStream::AsyncReadState::QueryInterface(REFIID riid, LPVOID *ppvObject)
{
    if (!ppvObject)
        return E_POINTER;

    if (riid == IID_IUnknown) {
        *ppvObject = static_cast<IUnknown*>(this);
    } else {
        *ppvObject =  NULL;
        return E_NOINTERFACE;
    }
    AddRef();
    return S_OK;
}

STDMETHODIMP_(ULONG) MFStream::AsyncReadState::AddRef(void)
{
    return InterlockedIncrement(&m_cRef);
}

STDMETHODIMP_(ULONG) MFStream::AsyncReadState::Release(void)
{
    LONG cRef = InterlockedDecrement(&m_cRef);
    if (cRef == 0)
        delete this;
    // For thread safety, return a temporary variable.
    return cRef;
}

BYTE* MFStream::AsyncReadState::pb() const
{
    return m_pb;
}

ULONG MFStream::AsyncReadState::cb() const
{
    return m_cb;
}

ULONG MFStream::AsyncReadState::bytesRead() const
{
    return m_cbRead;
}

void MFStream::AsyncReadState::setBytesRead(ULONG cbRead)
{
    m_cbRead = cbRead;
}