为什么我的 IExtractIcon 处理程序没有被调用？

Question

我正在尝试根据示例在 C++ 中实现图标处理程序：

The Complete Idiot's Guide to Writing Shell Extensions - Part IX

使用示例项目让示例运行没有问题，但是当我尝试在我的 QT 项目中构建它时，我的处理程序从未被调用。

安装我的 DLL 后，'ShellExtView' 将其显示为“图标处理程序”，据我所知，注册表中的一切看起来都正常。

我使用了这里的注册码并用它来注册示例 shell 扩展并且它有效，所以我认为我注册 [=35= 的方式没有问题] 扩展。

这是我的代码：

头文件：

#include <Windows.h>
// ATL
#include <atlbase.h>
extern CComModule _Module;
#include <atlcom.h>
#include <atlconv.h>

// Win32
#include <comdef.h>
#include <ShlObj.h>

#define MAX_SUFFIX (32)

#define MY_ID "{E94EFFAC-DBD6-40EF-92FC-460FDEB3684A}"
#define TARGET_ICON_HANDLER_CLASS "txtfile"
const CLSID my_id = {0xE94EFFAC, 0xDBD6, 0x40EF, {0x92, 0XF, 0X46, 0X0F, 0XDE, 0XB3, 0X68, 0X4A}};
const CLSID myLib_id = {0xE94EFFAD, 0xDBD6, 0x40EF, {0x92, 0XF, 0X46, 0X0F, 0XDE, 0XB3, 0X68, 0X4A}};



class CIconShlExt :
        public CComObjectRootEx<CComSingleThreadModel>,
        public CComCoClass<CIconShlExt, &my_id>,
        public IPersistFile,
        public IExtractIcon
{
public:
     CIconShlExt() : m_haveSuffix(false) { }

    BEGIN_COM_MAP(CIconShlExt)
         COM_INTERFACE_ENTRY(IPersistFile)
         COM_INTERFACE_ENTRY(IExtractIcon)
     END_COM_MAP()

    DECLARE_NO_REGISTRY()

    // IPersistFile
    STDMETHODIMP GetClassID( CLSID* pClsId)  { return E_NOTIMPL; }
    STDMETHODIMP IsDirty() { return E_NOTIMPL; }
    STDMETHODIMP Save( LPCOLESTR, BOOL ) { return E_NOTIMPL; }
    STDMETHODIMP SaveCompleted( LPCOLESTR ) { return E_NOTIMPL; }
    STDMETHODIMP GetCurFile( LPOLESTR* ) { return E_NOTIMPL; }

     STDMETHODIMP Load( LPCOLESTR wszFile, DWORD );

     // IExtractIcon
     STDMETHODIMP GetIconLocation( UINT uFlags, LPTSTR szIconFile, UINT cchMax,
                                   int* piIndex, UINT* pwFlags );
     STDMETHODIMP Extract( LPCTSTR pszFile, UINT nIconIndex, HICON* phiconLarge,
                           HICON* phiconSmall, UINT nIconSize );

     WCHAR m_suffix[MAX_SUFFIX];
     bool  m_haveSuffix;

};

IPersistFile 和 IExtractIcon 方法（从不调用）：

#pragma region IPersistFile
STDMETHODIMP CIconShlExt::Load(LPCOLESTR wszFile, DWORD)
{
    // I never get here!
    return S_OK;
}
#pragma endregion


#pragma region IExtractIcon

STDMETHODIMP CIconShlExt::GetIconLocation(UINT /*uFlags*/, LPTSTR szIconFile, UINT cchMax, int* piIndex, UINT* pwFlags )
{
    // I never get here!

    // Give it a strange icon so I know it did something
    *piIndex = -218;
    lstrcpyn(szIconFile, "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\msenvico.dll", cchMax);
    *pwFlags = GIL_PERINSTANCE; // GIL_NOTFILENAME;

    return S_OK;
}

STDMETHODIMP CIconShlExt::Extract( LPCTSTR , UINT , HICON*, HICON* , UINT)
{
    return S_FALSE;
}

#pragma endregion

主DLL文件：

static DWORD SetRegistryKeyAndValue(HKEY root, const char *key, const char *value, const char *name)
{
    HKEY hKey = NULL;
    DWORD err;

    err = RegCreateKeyEx(root, key, 0, NULL, REG_OPTION_NON_VOLATILE, KEY_WRITE, NULL, &hKey, NULL);

    if (err == ERROR_SUCCESS) {
        if (name != NULL) {
            // Set the specified value of the key.
            DWORD cbData = lstrlen(name) * sizeof(*name) +1;
            err = RegSetValueEx(hKey, value, 0, REG_SZ, reinterpret_cast<const BYTE *>(name), cbData);

        }
        RegCloseKey(hKey);
    }

    return err;
}

static void unregisterHandler()
{
    RegDeleteTree(HKEY_CLASSES_ROOT, "CLSID\" MY_ID);

    RegDeleteKey(HKEY_LOCAL_MACHINE, "Software\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved\" MY_ID);
    RegDeleteTree(HKEY_CLASSES_ROOT, TARGET_ICON_HANDLER_CLASS "\ShellEx\IconHandler");
}

static DWORD registerHandler(const char *dll)
{
DWORD err;

    if ((err = SetRegistryKeyAndValue(HKEY_CLASSES_ROOT, "CLSID\" MY_ID, nullptr, "My icon extension")) != ERROR_SUCCESS)
        goto error;

    if ((err = SetRegistryKeyAndValue(HKEY_CLASSES_ROOT, "CLSID\" MY_ID"\InprocServer32", NULL, dll)) != ERROR_SUCCESS)
        goto error;

    if ((err = SetRegistryKeyAndValue(HKEY_CLASSES_ROOT, "CLSID\" MY_ID"\InprocServer32", "ThreadingModel", "Apartment")) != ERROR_SUCCESS)
        goto error;

    if ((err = SetRegistryKeyAndValue(HKEY_LOCAL_MACHINE, "Software\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved", MY_ID, "My icon extension")) != ERROR_SUCCESS)
        goto error;

    if ((err = SetRegistryKeyAndValue(HKEY_CLASSES_ROOT, TARGET_ICON_HANDLER_CLASS "\ShellEx\IconHandler", nullptr, MY_ID)) != ERROR_SUCCESS)
        goto error;

    if ((err = SetRegistryKeyAndValue(HKEY_CLASSES_ROOT, TARGET_ICON_HANDLER_CLASS "\DefaultIcon", nullptr, "%1")) != ERROR_SUCCESS)
        goto error;

    return err;

error:
    unregisterHandler();
    return err;
}


BEGIN_OBJECT_MAP(ObjectMap)
OBJECT_ENTRY(my_id, CIconShlExt)
END_OBJECT_MAP()

CComModule _Module;

extern "C"
BOOL WINAPI DllMain(HINSTANCE hInstance, DWORD dwReason, LPVOID /*lpReserved*/)
{
    if (dwReason == DLL_PROCESS_ATTACH)
    {
        _Module.Init(ObjectMap, hInstance, &myLib_id);
        DisableThreadLibraryCalls(hInstance);
    }
    else if (dwReason == DLL_PROCESS_DETACH)
        _Module.Term();
    return TRUE;    // ok
}

/////////////////////////////////////////////////////////////////////////////
// Used to determine whether the DLL can be unloaded by OLE

STDAPI DllCanUnloadNow()
{
    return (_Module.GetLockCount()==0) ? S_OK : S_FALSE;
}

/////////////////////////////////////////////////////////////////////////////
// Returns a class factory to create an object of the requested type

STDAPI DllGetClassObject(REFCLSID rclsid, REFIID riid, LPVOID* ppv)
{
    return _Module.GetClassObject(rclsid, riid, ppv);
}

STDAPI DllRegisterServer()
{
    char dllPath[MAX_PATH];
    if (GetModuleFileName(_Module.m_hInst, dllPath, ARRAYSIZE(dllPath)) == 0)
    {
        HRESULT hr = HRESULT_FROM_WIN32(GetLastError());
        return hr;
    }
    DWORD rtc = registerHandler(dllPath);
    if (rtc != ERROR_SUCCESS)
        return HRESULT_FROM_WIN32(rtc);

    return _Module.RegisterServer(false);
}

STDAPI  DllUnregisterServer(void)
{   
    unregisterHandler();
    return _Module.UnregisterServer(false);
}

Answer 1

无法保证 .txt 文件扩展名的 ProgID 在每个系统上都是 txtfile。许多应用为了自己的目的劫持 .txt。您应该从 HKEY_CLASSES_ROOT\.txt 键中读取实际的 ProgID，然后为该 ProgID 注册您的处理程序。

但是，更重要的是，您真的不应该直接修改 HKEY_CLASSES_ROOT 子项，而是修改 HKEY_CURRENT_USER\Software\Classes 和 HKEY_LOCAL_MACHINE\Software\Classes 下的相应子项。 This is documented 在 MSDN 上：

Class registration and file name extension information is stored under both the HKEY_LOCAL_MACHINE and HKEY_CURRENT_USER keys. The HKEY_LOCAL_MACHINE\Software\Classes key contains default settings that can apply to all users on the local computer. The HKEY_CURRENT_USER\Software\Classes key contains settings that apply only to the interactive user. The HKEY_CLASSES_ROOT key provides a view of the registry that merges the information from these two sources. HKEY_CLASSES_ROOT also provides this merged view for applications designed for previous versions of Windows.

The user-specific settings have priority over the default settings. For example, the default setting might specify a particular application to handle .doc files. But a user can override this setting by specifying a different application in the registry.

Registry functions such as RegOpenKeyEx or RegQueryValueEx allow you to specify the HKEY_CLASSES_ROOT key. When you call these functions from a process running in the interactive user account, the system merges the default settings in HKEY_LOCAL_MACHINE\Software\Classes with the interactive user's settings at HKEY_CURRENT_USER\Software\Classes. For more information on how these settings are merged, see Merged View of HKEY_CLASSES_ROOT.

To change the settings for the interactive user, store the changes under HKEY_CURRENT_USER\Software\Classes rather than HKEY_CLASSES_ROOT.

To change the default settings, store the changes under HKEY_LOCAL_MACHINE\Software\Classes. If you write keys to a key under HKEY_CLASSES_ROOT, the system stores the information under HKEY_LOCAL_MACHINE\Software\Classes. If you write values to a key under HKEY_CLASSES_ROOT, and the key already exists under HKEY_CURRENT_USER\Software\Classes, the system will store the information there instead of under HKEY_LOCAL_MACHINE\Software\Classes.

Answer 2

我发现了问题：

我在将 GUID 字符串转换为 CLSID 时出错。

转换错误：

#define MY_ID "{E94EFFAC-DBD6-40EF-92FC-460FDEB3684A}"
const CLSID my_id = {0xE94EFFAC, 0xDBD6, 0x40EF, {0x92, 0XF, 0X46, 0X0F, 0XDE, 0XB3, 0X68, 0X4A}};

正确转换：

#define MY_ID "{E94EFFAC-DBD6-40EF-92FC-460FDEB3684A}"
const CLSID my_id = {0xE94EFFAC, 0xDBD6, 0x40EF, {0x92, 0XFC, 0X46, 0X0F, 0XDE, 0XB3, 0X68, 0X4A}};

为什么我的 IExtractIcon 处理程序没有被调用？

Why doesn't my IExtractIcon Handler get called?

c++

atl

shell-extensions