怎么样在VC中使用COM接口？

1.在“stdafx.h”中，在

#include <afxwin.h> // MFC 核心和标准组件

#include <afxext.h> // MFC 扩展

#include <afxdisp.h> // MFC 自动化类

前面加上

#include <afx.h>

#include <wininet.h>

这两个头文件顺序不可颠倒

即：

#include <afx.h>

#include <wininet.h>

#include <afxwin.h> // MFC 核心和标准组件

#include <afxext.h> // MFC 扩展

#include <afxdisp.h> // MFC 自动化类

2.使用 CoInitialize(NULL) 和 CoUninitialize() 初始化和终止 COM 使用环境。

3.在使用了 ATL COM 接口的源文件头部，包含声明该 ATL COM 接口的头文件即可。

IActiveDesktop ＝》#include <shlobj.h>

一个使用 ATL COM 的例子：

BOOL CSystemSet::SetWallPaper(CString strImaglePath, DWORD dwStyle)

{

CoInitialize(NULL);

BOOL bRet = FALSE;

HRESULT hr = S_FALSE;

IActiveDesktop* pIAD = NULL;

hr = CoCreateInstance(CLSID_ActiveDesktop, NULL, CLSCTX_INPROC_SERVER,

IID_IActiveDesktop, (void**) &pIAD );

if (SUCCEEDED(hr))

{

BOOL bActiveDesktop = FALSE;

COMPONENTSOPT co;

co.dwSize= sizeof(co);

if (SUCCEEDED(pIAD->GetDesktopItemOptions(&co, 0)))

{

if (!co.fActiveDesktop || !co.fEnableComponents)

{

co.fActiveDesktop = TRUE;

co.fEnableComponents = TRUE;

if (SUCCEEDED(pIAD->SetDesktopItemOptions(&co, 0)))

bActiveDesktop = TRUE;

}

else

bActiveDesktop = TRUE;

}

if (bActiveDesktop)

{

WCHAR wszWallpaper [MAX_PATH];

ZeroMemory(wszWallpaper, sizeof(wszWallpaper));

#if defined(_UNICODE)

CopyMemory(wszWallpaper, strImaglePath.GetBuffer(0),

min(MAX_PATH * sizeof(TCHAR), (strImaglePath.GetLength() + 1) * sizeof(TCHAR)));

#else

MultiByteToWideChar(CP_ACP, 0, strImaglePath, -1, wszWallpaper, MAX_PATH);

#endif

WALLPAPEROPT wpo;

wpo.dwSize = sizeof(wpo);

wpo.dwStyle = dwStyle;

if (SUCCEEDED(hr = pIAD->SetWallpaper(wszWallpaper, 0)) &&

SUCCEEDED(hr = pIAD->SetWallpaperOptions(&wpo, 0)) &&

SUCCEEDED(hr = pIAD->ApplyChanges(AD_APPLY_ALL)) &&

SUCCEEDED(hr = pIAD->GetWallpaper(wszWallpaper, MAX_PATH, 0)))

{

bRet = TRUE;

}

}

pIAD->Release();

}

CoUninitialize();

return bRet;

}

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