WIN fix redraw during window move and resize

During window move and resize, Windows spawns a nested message
loop, blocking our direct processing. In this case we switch to
timer messages for all timeouts.

But if LO is busy with background jobs, the posted 0ms timer
messages will block any system event processing, halting any
updates until we're idle again. So for these cases we switch
to the WM_TIMER based SetTimer timer.

Change-Id: I854f4984d7c75d6829f82cda5cb4479967edce48
Reviewed-on: https://gerrit.libreoffice.org/43350
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>

2 files changed, 43 insertions, 2 deletions

diff --git a/vcl/win/app/salinst.cxx b/vcl/win/app/salinst.cxx
index ade332297fc6..54598a420040 100644
--- a/vcl/win/app/salinst.cxx
+++ b/vcl/win/app/salinst.cxx
@@ -530,6 +530,10 @@ bool ImplSalYield( bool bWait, bool bHandleAllCurrentEvents )
         }
     }
 
+    // we're back in the main loop after resize or move
+    if ( pTimer )
+        pTimer->SetForceRealTimer( false );
+
     return bWasMsg;
 }
 
@@ -665,6 +669,13 @@ LRESULT CALLBACK SalComWndProc( HWND, UINT nMsg, WPARAM wParam, LPARAM lParam, i
             pTimer->ImplHandleTimerEvent( wParam );
             break;
         }
+        case WM_TIMER:
+        {
+            WinSalTimer *const pTimer = static_cast<WinSalTimer*>( ImplGetSVData()->maSchedCtx.mpSalTimer );
+            assert( pTimer != nullptr );
+            pTimer->ImplHandle_WM_TIMER( wParam );
+            break;
+        }
     }
 
     return nRet;
diff --git a/vcl/win/app/saltimer.cxx b/vcl/win/app/saltimer.cxx
index fe22d53db8c8..9d20c70bdb5a 100644
--- a/vcl/win/app/saltimer.cxx
+++ b/vcl/win/app/saltimer.cxx
@@ -41,12 +41,15 @@ void WinSalTimer::ImplStop()
     const WinSalInstance *pInst = pSalData->mpInstance;
     assert( !pInst || pSalData->mnAppThreadId == GetCurrentThreadId() );
 
+    if ( m_bForceRealTimer && m_bDirectTimeout )
+        KillTimer( GetSalData()->mpInstance->mhComWnd, m_aWmTimerId );
+    m_bDirectTimeout = false;
+
     const HANDLE hTimer = m_nTimerId;
     if ( nullptr == hTimer )
         return;
 
     m_nTimerId = nullptr;
-    m_bDirectTimeout = false;
     DeleteTimerQueueTimer( nullptr, hTimer, INVALID_HANDLE_VALUE );
     // Keep InvalidateEvent after DeleteTimerQueueTimer, because the event id
     // is set in SalTimerProc, which DeleteTimerQueueTimer will finish or cancel.
@@ -73,13 +76,21 @@ void WinSalTimer::ImplStart( sal_uLong nMS )
     if ( !m_bDirectTimeout )
         CreateTimerQueueTimer(&m_nTimerId, nullptr, SalTimerProc, this,
                               nMS, 0, WT_EXECUTEINTIMERTHREAD | WT_EXECUTEONLYONCE);
-    // We don't need any wakeup message, as this code can just run in the
+    else if ( m_bForceRealTimer )
+    {
+        // so we don't block the nested message queue in move and resize
+        // with posted 0ms SAL_MSG_TIMER_CALLBACK messages
+        SetTimer( GetSalData()->mpInstance->mhComWnd, m_aWmTimerId,
+                  USER_TIMER_MINIMUM, nullptr );
+    }
+    // we don't need any wakeup message, as this code can just run in the
     // main thread!
 }
 
 WinSalTimer::WinSalTimer()
     : m_nTimerId( nullptr )
     , m_bDirectTimeout( false )
+    , m_bForceRealTimer( false )
 {
 }
 
@@ -156,4 +167,23 @@ void WinSalTimer::ImplHandleTimerEvent( const WPARAM aWPARAM )
     ImplHandleElapsedTimer();
 }
 
+void WinSalTimer::SetForceRealTimer( const bool bVal )
+{
+    if ( m_bForceRealTimer == bVal )
+        return;
+
+    m_bForceRealTimer = bVal;
+
+    // we need a real timer, as m_bDirectTimeout won't be processed
+    if ( bVal && m_bDirectTimeout )
+        Start( 0 );
+}
+
+void WinSalTimer::ImplHandle_WM_TIMER( const WPARAM aWPARAM )
+{
+    assert( m_aWmTimerId == aWPARAM );
+    if ( m_aWmTimerId == aWPARAM && m_bDirectTimeout && m_bForceRealTimer )
+        ImplHandleElapsedTimer();
+}
+
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