Win: implement Clipboard Format Listener instead of obsolete Viewer

https://docs.microsoft.com/en-us/windows/desktop/dataxchg/using-the-clipboard
discusses the techniques to monitor clipboard contents on Windows, and
recommends Clipboard Format Listener for Vista+.

https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-setclipboardviewer
further mentions that using the current "Clipboard Viewer Window" approach,
"The clipboard viewer chain can be broken by an application that fails to
handle the clipboard chain messages properly".

This change reimplements our listener to use recommended way; this
should make our clipboard handling more robust, avoiding the need to
handle the chain with other applications' windows.

Change-Id: Ib33b27a57d7a6af2ab7e3e59d030aa55329694f9
Reviewed-on: https://gerrit.libreoffice.org/62909Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
Tested-by: Mike Kaganski <mike.kaganski@collabora.com>

dtrans/source/win32/clipb/MtaOleClipb.cxx

@@ -161,7 +161,6 @@ CMtaOleClipboard::CMtaOleClipboard( ) :
     m_hEvtThrdReady( nullptr ),
     m_hwndMtaOleReqWnd( nullptr ),
     m_MtaOleReqWndClassAtom( 0 ),
-    m_hwndNextClipViewer( nullptr ),
     m_pfncClipViewerCallback( nullptr ),
     m_bRunClipboardNotifierThread( true ),
     m_hClipboardChangedEvent( m_hClipboardChangedNotifierEvents[0] ),
@@ -238,8 +237,7 @@ CMtaOleClipboard::~CMtaOleClipboard( )
     if ( m_MtaOleReqWndClassAtom )
         UnregisterClassW( g_szWndClsName, nullptr );
 
-    OSL_ENSURE( ( nullptr == m_pfncClipViewerCallback ) &&
-                !IsWindow( m_hwndNextClipViewer ),
+    OSL_ENSURE( ( nullptr == m_pfncClipViewerCallback ),
                 "Clipboard viewer not properly unregistered" );
 }
 
@@ -354,7 +352,7 @@ bool CMtaOleClipboard::registerClipViewer( LPFNC_CLIPVIEWER_CALLBACK_t pfncClipV
 
 bool CMtaOleClipboard::onRegisterClipViewer( LPFNC_CLIPVIEWER_CALLBACK_t pfncClipViewerCallback )
 {
-    bool bRet = true;
+    bool bRet = false;
 
     // we need exclusive access because the clipboard changed notifier
     // thread also accesses this variable
@@ -366,13 +364,9 @@ bool CMtaOleClipboard::onRegisterClipViewer( LPFNC_CLIPVIEWER_CALLBACK_t pfncCli
         // SetClipboardViewer sends a WM_DRAWCLIPBOARD message we ignore
         // this message if we register ourself as clip viewer
         m_bInRegisterClipViewer = true;
-        m_hwndNextClipViewer = SetClipboardViewer( m_hwndMtaOleReqWnd );
+        bRet = AddClipboardFormatListener(m_hwndMtaOleReqWnd);
         m_bInRegisterClipViewer = false;
 
-        // if there is no other cb-viewer the
-        // return value is NULL!!!
-        bRet = IsWindow( m_hwndNextClipViewer );
-
         // save the new callback function
         m_pfncClipViewerCallback = pfncClipViewerCallback;
     }
@@ -382,8 +376,7 @@ bool CMtaOleClipboard::onRegisterClipViewer( LPFNC_CLIPVIEWER_CALLBACK_t pfncCli
 
         // unregister if input parameter is NULL and we previously registered
         // as clipboard viewer
-        ChangeClipboardChain( m_hwndMtaOleReqWnd, m_hwndNextClipViewer );
-        m_hwndNextClipViewer = nullptr;
+        bRet = RemoveClipboardFormatListener(m_hwndMtaOleReqWnd);
     }
 
     return bRet;
@@ -417,32 +410,9 @@ LRESULT CMtaOleClipboard::onFlushClipboard( )
     return static_cast<LRESULT>( OleFlushClipboard( ) );
 }
 
-// handle clipboard chain change event
+// handle clipboard update event
 
-LRESULT CMtaOleClipboard::onChangeCBChain( HWND hWndRemove, HWND hWndNext )
-{
-    if ( hWndRemove == m_hwndNextClipViewer )
-        m_hwndNextClipViewer = hWndNext;
-    else if ( IsWindow( m_hwndNextClipViewer ) )
-    {
-        // forward the message to the next one
-        DWORD_PTR dwpResult;
-        SendMessageTimeoutW(
-            m_hwndNextClipViewer,
-            WM_CHANGECBCHAIN,
-            reinterpret_cast<WPARAM>(hWndRemove),
-            reinterpret_cast<LPARAM>(hWndNext),
-            SMTO_BLOCK,
-            MAX_CLIPEVENT_PROCESSING_TIME,
-            &dwpResult );
-    }
-
-    return 0;
-}
-
-// handle draw clipboard event
-
-LRESULT CMtaOleClipboard::onDrawClipboard( )
+LRESULT CMtaOleClipboard::onClipboardUpdate()
 {
     // we don't send a notification if we are
     // registering ourself as clipboard
@@ -456,20 +426,6 @@ LRESULT CMtaOleClipboard::onDrawClipboard( )
         aGuard.clear( );
     }
 
-    // forward the message to the next viewer in the chain
-    if ( IsWindow( m_hwndNextClipViewer ) )
-    {
-        DWORD_PTR dwpResult;
-        SendMessageTimeoutW(
-            m_hwndNextClipViewer,
-            WM_DRAWCLIPBOARD,
-            static_cast< WPARAM >( 0 ),
-            static_cast< LPARAM >( 0 ),
-            SMTO_BLOCK,
-            MAX_CLIPEVENT_PROCESSING_TIME,
-            &dwpResult );
-    }
-
     return 0;
 }
 
@@ -543,13 +499,8 @@ LRESULT CALLBACK CMtaOleClipboard::mtaOleReqWndProc( HWND hWnd, UINT uMsg, WPARA
             reinterpret_cast<CMtaOleClipboard::LPFNC_CLIPVIEWER_CALLBACK_t>(wParam));
         break;
 
-    case WM_CHANGECBCHAIN:
-        lResult = pImpl->onChangeCBChain(
-            reinterpret_cast< HWND >( wParam ), reinterpret_cast< HWND >( lParam ) );
-        break;
-
-    case WM_DRAWCLIPBOARD:
-        lResult = pImpl->onDrawClipboard( );
+    case WM_CLIPBOARDUPDATE:
+        lResult = pImpl->onClipboardUpdate();
         break;
 
     case MSG_SHUTDOWN:

dtrans/source/win32/clipb/MtaOleClipb.hxx

@@ -72,9 +72,8 @@ private:
     static LRESULT onFlushClipboard( );
     bool     onRegisterClipViewer( LPFNC_CLIPVIEWER_CALLBACK_t pfncClipViewerCallback );
 
-    // win32 clipboard-viewer support
-    LRESULT onChangeCBChain( HWND hWndRemove, HWND hWndNext );
-    LRESULT onDrawClipboard( );
+    // win32 clipboard listener support
+    LRESULT onClipboardUpdate();
 
     static LRESULT CALLBACK mtaOleReqWndProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam );
     static unsigned int WINAPI oleThreadProc( LPVOID pParam );
@@ -89,7 +88,6 @@ private:
     HANDLE                      m_hEvtThrdReady;
     HWND                        m_hwndMtaOleReqWnd;
     ATOM                        m_MtaOleReqWndClassAtom;
-    HWND                        m_hwndNextClipViewer;
     LPFNC_CLIPVIEWER_CALLBACK_t m_pfncClipViewerCallback;
     bool                        m_bInRegisterClipViewer;