// method does nothing but return the same rectangle as we are passed in

    RECT SourceRect = ScaleSourceRect(&m_SourceRect);

    LONG lAdjustedSourceTop = SourceRect.top;
    // if the origin of bitmap is bottom-left, adjust soruce_rect_top
    // to be the bottom-left corner instead of the top-left.
    if (pbmi->biHeight > 0) {
       lAdjustedSourceTop = pbmi->biHeight - SourceRect.bottom;
    }
    // Is the window the same size as the video

    if (m_bStretch == FALSE) {

        // Put the image straight into the window

        SetDIBitsToDevice(
            (HDC) m_hdc,                            // Target device HDC
            m_TargetRect.left,                      // X sink position
            m_TargetRect.top,                       // Y sink position
            m_TargetRect.right - m_TargetRect.left, // Destination width
            m_TargetRect.bottom - m_TargetRect.top, // Destination height
            SourceRect.left,                        // X source position
            lAdjustedSourceTop,                     // Adjusted Y source position
            (UINT) 0,                               // Start scan line
            pbmi->biHeight,                         // Scan lines present
            pImage,                                 // Image data
            (BITMAPINFO *) pbmi,                    // DIB header
            DIB_RGB_COLORS);                        // Type of palette

    } else {

        // Stretch the image when copying to the window

        StretchDIBits(
            (HDC) m_hdc,                            // Target device HDC
            m_TargetRect.left,                      // X sink position
            m_TargetRect.top,                       // Y sink position
            m_TargetRect.right - m_TargetRect.left, // Destination width
            m_TargetRect.bottom - m_TargetRect.top, // Destination height
            SourceRect.left,                        // X source position
            lAdjustedSourceTop,                     // Adjusted Y source position
            SourceRect.right - SourceRect.left,     // Source width
            SourceRect.bottom - SourceRect.top,     // Source height
            pImage,                                 // Image data
            (BITMAPINFO *) pbmi,                    // DIB header
            DIB_RGB_COLORS,                         // Type of palette
            SRCCOPY);                               // Simple image copy
    }

    // This shows the sample reference times over the top of the image which
    // looks a little flickery. I tried using GdiSetBatchLimit and GdiFlush to
    // control the screen updates but it doesn't quite work as expected and
    // only partially reduces the flicker. I also tried using a memory context
    // and combining the two in that before doing a final BitBlt operation to
    // the screen, unfortunately this has considerable performance penalties
    // and also means that this code is not executed when compiled retail

    #ifdef DEBUG
    DisplaySampleTimes(pMediaSample);
    #endif
}


// This is called with an IMediaSample interface on the image to be drawn. We
// decide on the drawing mechanism based on who's allocator we are using. We
// may be called when the window wants an image painted by WM_PAINT messages
// We can't realise the palette here because we have the renderer lock, any
// call to realise may cause an interthread send message to the window thread
// which may in turn be waiting to get the renderer lock before servicing it

BOOL CDrawImage::DrawImage(IMediaSample *pMediaSample)
{
    ASSERT(m_hdc);
    ASSERT(m_MemoryDC);
    NotifyStartDraw();

    // If the output pin used our allocator then the samples passed are in
    // fact CVideoSample objects that contain CreateDIBSection data that we
    // use to do faster image rendering, they may optionally also contain a
    // DirectDraw surface pointer in which case we do not do the drawing

    if (m_bUsingImageAllocator == FALSE) {
        SlowRender(pMediaSample);
        EXECUTE_ASSERT(GdiFlush());
        NotifyEndDraw();
        return TRUE;
    }

    // This is a DIBSECTION buffer

    FastRender(pMediaSample);
    EXECUTE_ASSERT(GdiFlush());
    NotifyEndDraw();
    return TRUE;
}


BOOL CDrawImage::DrawVideoImageHere(
    HDC hdc,
    IMediaSample *pMediaSample,
    LPRECT lprcSrc,
    LPRECT lprcDst
    )
{
    ASSERT(m_pMediaType);
    BITMAPINFOHEADER *pbmi = HEADER(m_pMediaType->Format());
    BYTE *pImage;

    // Get the image data buffer

    HRESULT hr = pMediaSample->GetPointer(&pImage);
    if (FAILED(hr)) {
        return FALSE;
    }

    RECT SourceRect;
    RECT TargetRect;

    if (lprcSrc) {
        SourceRect = *lprcSrc;
    }
    else  SourceRect = ScaleSourceRect(&m_SourceRect);

    if (lprcDst) {
        TargetRect = *lprcDst;
    }
    else  TargetRect = m_TargetRect;

    LONG lAdjustedSourceTop = SourceRect.top;
    // if the origin of bitmap is bottom-left, adjust soruce_rect_top
    // to be the bottom-left corner instead of the top-left.
    if (pbmi->biHeight > 0) {
       lAdjustedSourceTop = pbmi->biHeight - SourceRect.bottom;
    }


    // Stretch the image when copying to the DC

    BOOL bRet = (0 != StretchDIBits(hdc,
                                    TargetRect.left,
                                    TargetRect.top,
                                    TargetRect.right - TargetRect.left,
                                    TargetRect.bottom - TargetRect.top,
                                    SourceRect.left,
                                    lAdjustedSourceTop,
                                    SourceRect.right - SourceRect.left,
                                    SourceRect.bottom - SourceRect.top,
                                    pImage,
                                    (BITMAPINFO *)pbmi,
                                    DIB_RGB_COLORS,
                                    SRCCOPY));
    return bRet;
}


// This is called by the owning window object after it has created the window
// and it's drawing contexts. We are constructed with the base window we'll
// be drawing into so when given the notification we retrive the device HDCs
// to draw with. We cannot call these in our constructor as they are virtual

void CDrawImage::SetDrawContext()
{
    m_MemoryDC = m_pBaseWindow->GetMemoryHDC();
    m_hdc = m_pBaseWindow->GetWindowHDC();
}


// This is called to set the target rectangle in the video window, it will be
// called whenever a WM_SIZE message is retrieved from the message queue. We
// simply store the rectangle and use it later when we do the drawing calls

void CDrawImage::SetTargetRect(RECT *pTargetRect)
{
    ASSERT(pTargetRect);
    m_TargetRect = *pTargetRect;
    SetStretchMode();
}


// Return the current target rectangle

void CDrawImage::GetTargetRect(RECT *pTargetRect)
{
    ASSERT(pTargetRect);
    *pTargetRect = m_TargetRect;
}


// This is called when we want to change the section of the image to draw. We
// use this information in the drawing operation calls later on. We must also
// see if the source and destination rectangles have the same dimensions. If
// not we must stretch during the drawing rather than a direct pixel copy

void CDrawImage::SetSourceRect(RECT *pSourceRect)
{
    ASSERT(pSourceRect);
    m_SourceRect = *pSourceRect;
    SetStretchMode();
}


// Return the current source rectangle

void CDrawImage::GetSourceRect(RECT *pSourceRect)
{
    ASSERT(pSourceRect);
    *pSourceRect = m_SourceRect;
}


// This is called when either the source or destination rectanges change so we
// can update the stretch flag. If the rectangles don't match we stretch the
// video during the drawing otherwise we call the fast pixel copy functions
// NOTE the source and/or the destination rectangle may be completely empty

void CDrawImage::SetStretchMode()
{
    // Calculate the overall rectangle dimensions

    LONG SourceWidth = m_SourceRect.right - m_SourceRect.left;
    LONG SinkWidth = m_TargetRect.right - m_TargetRect.left;
    LONG SourceHeight = m_SourceRect.bottom - m_SourceRect.top;
    LONG SinkHeight = m_TargetRect.bottom - m_TargetRect.top;

    m_bStretch = TRUE;
    if (SourceWidth == SinkWidth) {
        if (SourceHeight == SinkHeight) {
            m_bStretch = FALSE;
        }
    }
}


// Tell us whose allocator we are using. This should be called with TRUE if
// the filter agrees to use an allocator based around the CImageAllocator
// SDK base class - whose image buffers are made through CreateDIBSection.
// Otherwise this should be called with FALSE and we will draw the images
// using SetDIBitsToDevice and StretchDIBitsToDevice. None of these calls
// can handle buffers which have non zero strides (like DirectDraw uses)

void CDrawImage::NotifyAllocator(BOOL bUsingImageAllocator)
{
    m_bUsingImageAllocator = bUsingImageAllocator;
}


// Are we using the image DIBSECTION allocator

BOOL CDrawImage::UsingImageAllocator()
{
    return m_bUsingImageAllocator;
}


// We need the media type of the connection so that we can get the BITMAPINFO
// from it. We use that in the calls to draw the image such as StretchDIBits
// and also when updating the colour table held in shared memory DIBSECTIONs

void CDrawImage::NotifyMediaType(CMediaType *pMediaType)
{
    m_pMediaType = pMediaType;
}


// We store in this object a cookie maintaining the current palette version.
// Each time a palettised format is changed we increment this value so that
// when we come to draw the images we look at the colour table value they
// have and if less than the current we know to update it. This version is
// only needed and indeed used when working with shared memory DIBSECTIONs

LONG CDrawImage::GetPaletteVersion()
{
    return m_PaletteVersion;
}


// Resets the current palette version number

void CDrawImage::ResetPaletteVersion()
{
    m_PaletteVersion = PALETTE_VERSION;
}


// Increment the current palette version

void CDrawImage::IncrementPaletteVersion()
{
    m_PaletteVersion++;
}


// Constructor must initialise the base allocator. Each sample we create has a
// palette version cookie on board. When the source filter changes the palette
// during streaming the window object increments an internal cookie counter it
// keeps as well. When it comes to render the samples it looks at the cookie
// values and if they don't match then it knows to update the sample's colour
// table. However we always create samples with a cookie of PALETTE_VERSION
// If there have been multiple format changes and we disconnect and reconnect
// thereby causing the samples to be reallocated we will create them with a
// cookie much lower than the current version, this isn't a problem since it
// will be seen by the window object and the versions will then be updated

CImageAllocator::CImageAllocator(CBaseFilter *pFilter,
                                 TCHAR *pName,
                                 HRESULT *phr) :
    CBaseAllocator(pName,NULL,phr,TRUE,TRUE),
    m_pFilter(pFilter)
{
    ASSERT(phr);
    ASSERT(pFilter);
}


// Check our DIB buffers have been released

#ifdef DEBUG
CImageAllocator::~CImageAllocator()
{
    ASSERT(m_bCommitted == FALSE);
}
#endif


// Called from destructor and also from base class to free resources. We work
// our way through the list of media samples deleting the DIBSECTION created
// for each. All samples should be back in our list so there is no chance a
// filter is still using one to write on the display or hold on a pending list

void CImageAllocator::Free()
{
    ASSERT(m_lAllocated == m_lFree.GetCount());
    EXECUTE_ASSERT(GdiFlush());
    CImageSample *pSample;
    DIBDATA *pDibData;

    while (m_lFree.GetCount() != 0) {
        pSample = (CImageSample *) m_lFree.RemoveHead();
        pDibData = pSample->GetDIBData();
        EXECUTE_ASSERT(DeleteObject(pDibData->hBitmap));
        EXECUTE_ASSERT(CloseHandle(pDibData->hMapping));
        delete pSample;
    }

    m_lAllocated = 0;
}


// Prepare the allocator by checking all the input parameters

STDMETHODIMP CImageAllocator::CheckSizes(ALLOCATOR_PROPERTIES *pRequest)
{
    // Check we have a valid connection

    if (m_pMediaType == NULL) {
        return VFW_E_NOT_CONNECTED;
    }

    // NOTE We always create a DIB section with the source format type which
    // may contain a source palette. When we do the BitBlt drawing operation
    // the target display device may contain a different palette (we may not
    // have the focus) in which case GDI will do after the palette mapping

    VIDEOINFOHEADER *pVideoInfo = (VIDEOINFOHEADER *) m_pMediaType->Format();

    // When we call CreateDIBSection it implicitly maps only enough memory
    // for the image as defined by thee BITMAPINFOHEADER. If the user asks
    // for an image smaller than this then we reject the call, if they ask
    // for an image larger than this then we return what they can have

    if ((DWORD) pRequest->cbBuffer < pVideoInfo->bmiHeader.biSizeImage) {
        return E_INVALIDARG;
    }

    // Reject buffer prefixes