Save Wintab packets to a local queue as WT_PACKET events arrive or when

handling mouse input. This Wintab to mouse synchronization issues, and
likely prevents queue exhaustion for some Wintab implmenetations.

Signed-off-by: Nicholas Rishel <rishel.nick@gmail.com>

intern/ghost/intern/GHOST_SystemWin32.cpp

@@ -234,6 +234,11 @@ GHOST_SystemWin32::~GHOST_SystemWin32()
   toggleConsole(1);
 }
 
+GHOST_TUns64 GHOST_SystemWin32::millisSinceStart(__int64 ms) const
+{
+  return (GHOST_TUns64)(ms - m_start * 1000 / m_freq);
+}
+
 GHOST_TUns64 GHOST_SystemWin32::performanceCounterToMillis(__int64 perf_ticks) const
 {
   // Calculate the time passed since system initialization.
@@ -1591,6 +1596,9 @@ LRESULT WINAPI GHOST_SystemWin32::s_wndProc(HWND hwnd, UINT msg, WPARAM wParam,
           window->processWintabProximityEvent(inRange);
           break;
         }
+        case WT_PACKET:
+          window->updatePendingWintabEvents();
+          break;
         ////////////////////////////////////////////////////////////////////////
         // Pointer events, processed
         ////////////////////////////////////////////////////////////////////////

intern/ghost/intern/GHOST_SystemWin32.h

@@ -64,6 +64,8 @@ class GHOST_SystemWin32 : public GHOST_System {
    ** Time(r) functionality
    ***************************************************************************************/
 
+  GHOST_TUns64 millisSinceStart(__int64 ms) const;
+
   /**
    * This method converts performance counter measurements into milliseconds since the start of the
    * system process.

intern/ghost/intern/GHOST_WindowWin32.cpp

@@ -1045,6 +1045,7 @@ void GHOST_WindowWin32::initializeWintab()
     lc.lcPktData = PACKETDATA;
     lc.lcPktMode = PACKETMODE;
     lc.lcMoveMask = PACKETDATA;
+    lc.lcOptions |= CXO_MESSAGES;
     // Wacom maps y origin to the tablet's bottom
     // Invert to match Windows y origin mapping to the screen top
     lc.lcOutExtY = -lc.lcOutExtY;
@@ -1298,12 +1299,16 @@ GHOST_TSuccess GHOST_WindowWin32::getWintabInfo(std::vector<GHOST_WintabInfoWin3
 
   GHOST_SystemWin32 *system = (GHOST_SystemWin32 *)GHOST_System::getSystem();
 
-  const int numPackets = m_wintab.packetsGet(
-      m_wintab.context, m_wintab.pkts.size(), m_wintab.pkts.data());
-  outWintabInfo.resize(numPackets);
+  updatePendingWintabEvents();
+
+  auto &pendingEvents = m_wintab.pendingEvents;
+  size_t pendingEventSize = pendingEvents.size();
+  outWintabInfo.resize(pendingEventSize);
+
+  for (int i = 0; i < pendingEventSize; i++) {
+    PACKET pkt = pendingEvents.front();
+    pendingEvents.pop();
 
-  for (int i = 0; i < numPackets; i++) {
-    PACKET pkt = m_wintab.pkts[i];
     GHOST_TabletData tabletData = GHOST_TABLET_DATA_NONE;
     switch (pkt.pkCursor % 3) { /* % 3 for multiple devices ("DualTrack") */
       case 0:
@@ -1390,6 +1395,46 @@ GHOST_TSuccess GHOST_WindowWin32::getWintabInfo(std::vector<GHOST_WintabInfoWin3
   return GHOST_kSuccess;
 }
 
+void GHOST_WindowWin32::updatePendingWintabEvents()
+{
+  if (!(m_wintab.packetsGet && m_wintab.context)) {
+    return;
+  }
+  GHOST_SystemWin32 *system = (GHOST_SystemWin32 *)GHOST_System::getSystem();
+
+  auto &pendingEvents = m_wintab.pendingEvents;
+
+  // Clear outdated events from queue.
+  GHOST_TUns64 currTime = system->getMilliSeconds();
+  GHOST_TUns64 timeout = 300;
+  while (!pendingEvents.empty()) {
+    GHOST_TUns64 pktTime = system->millisSinceStart(pendingEvents.front().pkTime);
+    if (currTime - pktTime > timeout) {
+      pendingEvents.pop();
+    }
+    else {
+      break;
+    }
+  }
+
+  // Get new packets.
+  const int numPackets = m_wintab.packetsGet(
+      m_wintab.context, m_wintab.pkts.size(), m_wintab.pkts.data());
+
+  int i = 0;
+  // Don't queue outdated packets, such events can include packets that occurred before the current
+  // window lost and regained focus.
+  for (; i < numPackets; i++) {
+    GHOST_TUns64 pktTime = system->millisSinceStart(m_wintab.pkts[i].pkTime);
+    if (currTime - pktTime < timeout) {
+      break;
+    }
+  }
+  for (; i < numPackets; i++) {
+    pendingEvents.push(m_wintab.pkts[i]);
+  }
+}
+
 GHOST_TUns16 GHOST_WindowWin32::getDPIHint()
 {
   if (m_user32) {

intern/ghost/intern/GHOST_WindowWin32.h

@@ -35,6 +35,7 @@
 #endif
 
 #include <vector>
+#include <queue>
 
 #include <wintab.h>
 // PACKETDATA and PACKETMODE modify structs in pktdef.h, so make sure they come first
@@ -482,6 +483,10 @@ class GHOST_WindowWin32 : public GHOST_Window {
    */
   GHOST_TSuccess getWintabInfo(std::vector<GHOST_WintabInfoWin32> &outWintabInfo);
 
+  /**
+   */
+  void updatePendingWintabEvents();
+
   GHOST_TSuccess beginFullScreen() const
   {
     return GHOST_kFailure;
@@ -625,6 +630,7 @@ class GHOST_WindowWin32 : public GHOST_Window {
     LONG maxAzimuth = 0, maxAltitude = 0;
     /* Queue size doesn't change once set, so reuse the same buffer */
     std::vector<PACKET> pkts;
+    std::queue<PACKET> pendingEvents;
   } m_wintab;
 
   /**