CBaseControlVideo::GetStaticImage

Pure virtual method that derived classes override.

virtual HRESULT GetStaticImage(
  long* pBufferSize,
  long* pDIBImage
) PURE;

Parameters

• pBufferSize
  Size of the output buffer.
• pDIBImage
  Pointer to output buffer.

Return Values

Returns an HRESULT value.

Remarks

Through the IBasicVideo interface, an application can request that it be given a copy of the current image in a memory buffer (some renderers can return E_NOTIMPL to this if they do not support it). The derived class determines how to retrieve the image. When the application calls CBaseControlVideo::GetStaticImage, it calls this pure virtual method that the derived class should override to implement it. This is also called by the CBaseControlVideo::GetCurrentImage member function.

The class provides a helper member function, CBaseControlVideo::CopyImage, that can be given a sample that contains an image, and the member function will copy the relevant section of it (based on the current source rectangle) into the output buffer supplied by the application.

The following example from the video renderer sample, SampVid, demonstrates an implementation of this member function in a derived class. In this example, m_pRenderer holds an object of a class derived from CBaseVideoRenderer.

// Return a copy of the current image in the video renderer

HRESULT CVideoText::GetStaticImage(long *pBufferSize,long *pDIBImage)
{
    // Get any sample the renderer may be holding.

    IMediaSample *pMediaSample = m_pRenderer->GetCurrentSample();
    if (pMediaSample == NULL) {
        return E_UNEXPECTED;
    }

    // Call the base class helper method to do the work.

    HRESULT hr = CopyImage(pMediaSample,          // Buffer containing image
                           &m_pRenderer->m_mtIn,                // Type representing bitmap
                           pBufferSize,                                     // Size of buffer for DIB
                           (BYTE*) pDIBImage);                   // Data buffer for output

    pMediaSample->Release();
    return hr;
}

Requirements

DirectShow applications and DirectShow filters have different include file and link library requirements. See Setting Up the Build Environment for more information.

OS Versions: Windows CE 2.12 and later. Version 2.12 requires DXPAK 1.0 or later.
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Last updated on Wednesday, April 13, 2005

© 2005 Microsoft Corporation. All rights reserved.