www.pudn.com > ShellExtGuide3_demo.zip > TxtInfoShlExt.cpp

// TxtInfoShlExt.cpp : Implementation of CTxtInfoShlExt 
#include "stdafx.h" 
#include "TxtInfo.h" 
#include "TxtInfoShlExt.h" 
 
#include  
 
///////////////////////////////////////////////////////////////////////////// 
// CTxtInfoShlExt 
 
HRESULT CTxtInfoShlExt::Load ( LPCOLESTR wszFilename, DWORD dwMode ) 
{ 
    AFX_MANAGE_STATE(AfxGetStaticModuleState());    // init MFC 
    UNREFERENCED_PARAMETER(dwMode); 
 
    // Let CString convert the filename to ANSI if necessary. 
    m_sFilename = wszFilename; 
 
    return S_OK; 
} 
 
HRESULT CTxtInfoShlExt::GetInfoTip ( DWORD dwFlags, LPWSTR* ppwszTip ) 
{ 
    AFX_MANAGE_STATE(AfxGetStaticModuleState());    // init MFC 
 
LPMALLOC   pMalloc; 
CStdioFile file; 
DWORD      dwFileSize; 
CString    sFirstLine; 
BOOL       bReadLine; 
CString    sTooltip; 
 
    UNREFERENCED_PARAMETER(dwFlags); 
    USES_CONVERSION; 
 
    // Try to open the file. 
    if ( !file.Open ( m_sFilename , CFile::modeRead | CFile::shareDenyWrite )) 
        return E_FAIL; 
 
    // Get an IMalloc interface from the shell. 
    if ( FAILED( SHGetMalloc ( &pMalloc ))) 
        return E_FAIL; 
 
    // Get the size of the file. 
    dwFileSize = file.GetLength(); 
 
    // Read in the first line from the file. 
    bReadLine = file.ReadString ( sFirstLine ); 
 
    sTooltip.Format ( _T("File size: %lu"), dwFileSize ); 
 
    // If we were able to read in the first line, add it to the tooltip. 
    if ( bReadLine ) 
        { 
        sTooltip += _T("\n"); 
        sTooltip += sFirstLine; 
        } 
 
    // Allocate a buffer for Explorer.  Note that the must pass the string  
    // back as a Unicode string, so the string length is multiplied by the  
    // size of a Unicode character. 
    *ppwszTip = (LPWSTR) pMalloc->Alloc ( (1 + lstrlen(sTooltip)) * sizeof(wchar_t) ); 
 
    // Release the IMalloc interface now that we're done using it. 
    pMalloc->Release(); 
 
    if ( NULL == *ppwszTip ) 
        { 
        return E_OUTOFMEMORY; 
        } 
 
    // Use the Unicode string copy function to put the tooltip text in the buffer. 
    wcscpy ( *ppwszTip, T2COLE((LPCTSTR) sTooltip) ); 
 
    return S_OK; 
}