IWMDMOperation::GetObjectTotalSize method (mswmdm.h)

Article
02/22/2024

Windows Media Device Manager calls GetObjectTotalSize before a file is written to the device in order to retrieve the total size of the object, in bytes.

Syntax

HRESULT GetObjectTotalSize(
  [out] DWORD *pdwSize,
  [out] DWORD *pdwSizeHigh
);

Parameters

[out] pdwSize

Pointer to a DWORD that, on return, specifies the low-order bits of the object size in bytes.

[out] pdwSizeHigh

Pointer to a DWORD that, on return, specifies the high-order bits of the object size in bytes.

Return value

The application should return one of the following HRESULT values.

Return code	Description
S_OK	The read operation should continue.
WMDM_E_USER_CANCELLED	The read operation should be cancelled without finishing.
E_FAIL	An unspecified error occurred, and the read operation should be cancelled without finishing.

Remarks

This method is called after the GetObjectAttributes method has been called. When transferring, the object implementing this interface is passed the total size of the content being sent.

Examples

The following C++ code implements GetObjectTotalSize. It uses the Win32 function GetFileInformationByHandle to retrieve the file size of the file about to be written to the device (m_File), and returns the values.


// About to start writing to the device.
HRESULT GetObjectTotalSize(DWORD*  pdwSize,    DWORD*  pdwSizeHigh)
{
    BY_HANDLE_FILE_INFORMATION fileInfo;
    GetFileInformationByHandle(
        m_File,
        &fileInfo);

    *pdwSize = fileInfo.nFileSizeLow;
    *pdwSizeHigh = fileInfo.nFileSizeHigh;
    // TODO: Display the message: "IWMDMOperation event--GetObjectTotalSize."
    return S_OK;
}

Requirements

Requirement	Value
Target Platform	Windows
Header	mswmdm.h
Library	Mssachlp.lib