0030619: Draw Harness, ViewerTest - add continuous rendering option to vrepaint command

Aspect_Window::InvalidateContent() - added new virtual method for invalidating window content using platform-specific API.

TKDraw, tkLoop() on Window platform has been changed so that to prevent
continuous input window events blocking terminal input
(e.g. in case if processing events is not fast enough or
if another continuously sends new events).

TKViewerTest, on X11 platform has been fixed a message processing
so that to avoid messages being not processed.
Added aggregation of Exposer and ConfigureNotify events.
Fixed aggregation MotionNotify events.

src/Aspect/Aspect_Window.hxx

@@ -30,6 +30,8 @@
 #include <Aspect_TypeOfResize.hxx>
 #include <Standard_Integer.hxx>
 #include <Aspect_Drawable.hxx>
+
+class Aspect_DisplayConnection;
 class Aspect_WindowDefinitionError;
 class Aspect_WindowError;
 class Aspect_Background;
@@ -107,6 +109,16 @@ public:
   //! Returns native Window FB config (GLXFBConfig on Xlib)
   Standard_EXPORT virtual Aspect_FBConfig NativeFBConfig() const = 0;
 
+  //! Invalidate entire window content.
+  //!
+  //! Implementation is expected to allow calling this method from non-GUI thread,
+  //! e.g. by queuing exposure event into window message queue or in other thread-safe manner.
+  //!
+  //! Optional display argument should be passed when called from non-GUI thread
+  //! on platforms implementing thread-unsafe connections to display.
+  //! NULL can be passed instead otherwise.
+  virtual void InvalidateContent (const Handle(Aspect_DisplayConnection)& theDisp) { (void )theDisp; }
+
   DEFINE_STANDARD_RTTIEXT(Aspect_Window,Standard_Transient)
 
 protected:

src/Cocoa/Cocoa_Window.hxx

@@ -136,6 +136,10 @@ public:
   //! Returns nothing on OS X
   virtual Aspect_FBConfig NativeFBConfig() const Standard_OVERRIDE { return NULL; }
 
+  //! Invalidate entire window content by setting NSView::setNeedsDisplay property.
+  //! Call will be implicitly redirected to the main thread when called from non-GUI thread.
+  Standard_EXPORT virtual void InvalidateContent (const Handle(Aspect_DisplayConnection)& theDisp = NULL) Standard_OVERRIDE;
+
 protected:
 
 #if defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE

src/Cocoa/Cocoa_Window.mm

@@ -66,6 +66,31 @@ static Standard_Integer getScreenBottom()
 }
 #endif
 
+//! Extension for Cocoa_Window::InvalidateContent().
+#if defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE
+  @interface UIView (UIViewOcctAdditions)
+  - (void )invalidateContentOcct: (id )theSender;
+  @end
+  @implementation UIView (UIViewOcctAdditions)
+  - (void )invalidateContentOcct: (id )theSender
+  {
+    (void )theSender;
+    [self setNeedsDisplay];
+  }
+  @end
+#else
+  @interface NSView (NSViewOcctAdditions)
+  - (void )invalidateContentOcct: (id )theSender;
+  @end
+  @implementation NSView (NSViewOcctAdditions)
+  - (void )invalidateContentOcct: (id )theSender
+  {
+    (void )theSender;
+    [self setNeedsDisplay: YES];
+  }
+  @end
+#endif
+
 // =======================================================================
 // function : Cocoa_Window
 // purpose  :
@@ -377,3 +402,30 @@ void Cocoa_Window::Size (Standard_Integer& theWidth,
   theWidth  = (Standard_Integer )aBounds.size.width;
   theHeight = (Standard_Integer )aBounds.size.height;
 }
+
+// =======================================================================
+// function : InvalidateContent
+// purpose  :
+// =======================================================================
+void Cocoa_Window::InvalidateContent (const Handle(Aspect_DisplayConnection)& )
+{
+  if (myHView == NULL)
+  {
+    return;
+  }
+
+  if ([NSThread isMainThread])
+  {
+  #if defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE
+    [myHView setNeedsDisplay];
+  #else
+    [myHView setNeedsDisplay: YES];
+  #endif
+  }
+  else
+  {
+    [myHView performSelectorOnMainThread: @selector(invalidateContentOcct:)
+                              withObject: NULL
+                           waitUntilDone: NO];
+  }
+}

src/Draw/Draw_Window.cxx

@@ -2345,23 +2345,24 @@ static DWORD WINAPI tkLoop(VOID)
   Standard_Boolean toLoop = Standard_True;
   while (toLoop)
   {
-    while(Tcl_DoOneEvent(TCL_ALL_EVENTS | TCL_DONT_WAIT));
+    // The natural way is first flushing events, already put into queue, and then processing custom code in-between.
+    // Unfortunately, Tcl has no API returning the number of queued events like XPending(), and only empty state can be checked.
+    // Since events can be continuously fed from parallel threads, Tcl_DoOneEvent might never return empty state at all.
+    const bool isTclEventQueueEmpty = Tcl_DoOneEvent(TCL_ALL_EVENTS | TCL_DONT_WAIT) == 0;
     if (console_semaphore == HAS_CONSOLE_COMMAND)
     {
-      TCollection_AsciiString aCmdUtf8 (console_command);
+      const TCollection_AsciiString aCmdUtf8 (console_command);
-      if (Draw_Interprete (aCmdUtf8.ToCString()))
+      const bool wasInterpreted = Draw_Interprete (aCmdUtf8.ToCString());
+      if (Draw_IsConsoleSubsystem)
       {
-        if (Draw_IsConsoleSubsystem) Prompt (interp, 0);
+        Prompt (interp, wasInterpreted ? 0 : 1);
-      }
-      else
-      {
-        if (Draw_IsConsoleSubsystem) Prompt (interp, 1);
       }
       console_semaphore = WAIT_CONSOLE_COMMAND;
     }
-    else
+    else if (isTclEventQueueEmpty)
     {
-      Sleep(100);
+      // release CPU while polling
+      Sleep (1);
     }
   #ifdef _TK
     // We should not exit until the Main Tk window is closed

src/ViewerTest/ViewerTest_ViewerCommands.cxx

@@ -59,6 +59,7 @@
 #include <Image_AlienPixMap.hxx>
 #include <Image_VideoRecorder.hxx>
 #include <OpenGl_GraphicDriver.hxx>
+#include <OSD.hxx>
 #include <OSD_Timer.hxx>
 #include <TColStd_HSequenceOfAsciiString.hxx>
 #include <TColStd_SequenceOfInteger.hxx>
@@ -574,6 +575,121 @@ TCollection_AsciiString ViewerTest::GetCurrentViewName ()
 {
   return ViewerTest_myViews.Find2( ViewerTest::CurrentView());
 }
+
+//! Auxiliary tool performing continuous redraws of specified window.
+class ViewerTest_ContinuousRedrawer
+{
+public:
+  //! Return global instance.
+  static ViewerTest_ContinuousRedrawer& Instance()
+  {
+    static ViewerTest_ContinuousRedrawer aRedrawer;
+    return aRedrawer;
+  }
+public:
+
+  //! Destructor.
+  ~ViewerTest_ContinuousRedrawer()
+  {
+    Stop();
+  }
+
+  //! Start thread.
+  void Start (const Handle(Aspect_Window)& theWindow,
+              Standard_Real theTargetFps)
+  {
+    if (myWindow != theWindow
+     || myTargetFps != theTargetFps)
+    {
+      Stop();
+      myWindow = theWindow;
+      myTargetFps = theTargetFps;
+    }
+    if (myThread.GetId() == 0)
+    {
+      myToStop = false;
+      myThread.Run (this);
+    }
+  }
+
+  //! Stop thread.
+  void Stop (const Handle(Aspect_Window)& theWindow = NULL)
+  {
+    if (!theWindow.IsNull()
+      && myWindow != theWindow)
+    {
+      return;
+    }
+
+    {
+      Standard_Mutex::Sentry aLock (myMutex);
+      myToStop = true;
+    }
+    myThread.Wait();
+    myToStop = false;
+    myWindow.Nullify();
+  }
+
+private:
+
+  //! Thread loop.
+  void doThreadLoop()
+  {
+    Handle(Aspect_DisplayConnection) aDisp = new Aspect_DisplayConnection();
+    OSD_Timer aTimer;
+    aTimer.Start();
+    Standard_Real aTimeOld = 0.0;
+    const Standard_Real aTargetDur = myTargetFps > 0.0 ? 1.0 / myTargetFps : -1.0;
+    for (;;)
+    {
+      {
+        Standard_Mutex::Sentry aLock (myMutex);
+        if (myToStop)
+        {
+          return;
+        }
+      }
+      if (myTargetFps > 0.0)
+      {
+        const Standard_Real aTimeNew  = aTimer.ElapsedTime();
+        const Standard_Real aDuration = aTimeNew - aTimeOld;
+        if (aDuration >= aTargetDur)
+        {
+          myWindow->InvalidateContent (aDisp);
+          aTimeOld = aTimeNew;
+        }
+      }
+      else
+      {
+        myWindow->InvalidateContent (aDisp);
+      }
+
+      OSD::MilliSecSleep (1);
+    }
+  }
+
+  //! Thread creation callback.
+  static Standard_Address doThreadWrapper (Standard_Address theData)
+  {
+    ViewerTest_ContinuousRedrawer* aThis = (ViewerTest_ContinuousRedrawer* )theData;
+    aThis->doThreadLoop();
+    return 0;
+  }
+
+  //! Empty constructor.
+  ViewerTest_ContinuousRedrawer()
+  : myThread (doThreadWrapper),
+    myTargetFps (0.0),
+    myToStop (false) {}
+
+private:
+  Handle(Aspect_Window) myWindow;
+  OSD_Thread      myThread;
+  Standard_Mutex  myMutex;
+  Standard_Real   myTargetFps;
+  volatile bool   myToStop;
+};
+
 //==============================================================================
 //function : ViewerInit
 //purpose  : Create the window viewer and initialize all the global variable
@@ -617,15 +733,26 @@ TCollection_AsciiString ViewerTest::ViewerInit (const Standard_Integer thePxLeft
     aPxHeight = thePxHeight;
 
   // Get graphic driver (create it or get from another view)
-  if (!ViewerTest_myDrivers.IsBound1 (aViewNames.GetDriverName()))
+  const bool isNewDriver = !ViewerTest_myDrivers.IsBound1 (aViewNames.GetDriverName());
+  if (isNewDriver)
   {
     // Get connection string
   #if !defined(_WIN32) && (!defined(__APPLE__) || defined(MACOSX_USE_GLX))
-    TCollection_AsciiString aDisplayName(theDisplayName);
+    if (!theDisplayName.IsEmpty())
-    if (!aDisplayName.IsEmpty())
+    {
-      SetDisplayConnection (new Aspect_DisplayConnection ());
+      SetDisplayConnection (new Aspect_DisplayConnection (theDisplayName));
+    }
     else
-      SetDisplayConnection (new Aspect_DisplayConnection (aDisplayName));
+    {
+      ::Display* aDispX = NULL;
+      // create dedicated display connection instead of reusing Tk connection
+      // so that to procede events independently through VProcessEvents()/ViewerMainLoop() callbacks
+      /*Draw_Interpretor& aCommands = Draw::GetInterpretor();
+      Tcl_Interp* aTclInterp = aCommands.Interp();
+      Tk_Window aMainWindow = Tk_MainWindow (aTclInterp);
+      aDispX = aMainWindow != NULL ? Tk_Display (aMainWindow) : NULL;*/
+      SetDisplayConnection (new Aspect_DisplayConnection (aDispX));
+    }
   #else
     (void)theDisplayName; // avoid warning on unused argument
     SetDisplayConnection (new Aspect_DisplayConnection ());
@@ -801,13 +928,11 @@ TCollection_AsciiString ViewerTest::ViewerInit (const Standard_Integer thePxLeft
   }
 
 #if !defined(_WIN32) && (!defined(__APPLE__) || defined(MACOSX_USE_GLX))
-  #if TCL_MAJOR_VERSION  < 8
+  if (isNewDriver)
-  Tk_CreateFileHandler((void*)XConnectionNumber(GetDisplayConnection()->GetDisplay()),
+  {
-      TK_READABLE, VProcessEvents, (ClientData) VT_GetWindow()->XWindow() );
+    ::Display* aDispX = GetDisplayConnection()->GetDisplay();
-  #else
+    Tcl_CreateFileHandler (XConnectionNumber (aDispX), TCL_READABLE, VProcessEvents, (ClientData )aDispX);
-  Tk_CreateFileHandler(XConnectionNumber(GetDisplayConnection()->GetDisplay()),
+  }
-      TK_READABLE, VProcessEvents, (ClientData) VT_GetWindow()->XWindow() );
-  #endif
 #endif
 
   VT_GetWindow()->Map();
@@ -1363,6 +1488,8 @@ void ViewerTest::RemoveView (const TCollection_AsciiString& theViewName, const S
   // Delete view
   Handle(V3d_View) aView = ViewerTest_myViews.Find1(theViewName);
   Handle(AIS_InteractiveContext) aCurrentContext = FindContextByView(aView);
+  ViewerTest_ContinuousRedrawer& aRedrawer = ViewerTest_ContinuousRedrawer::Instance();
+  aRedrawer.Stop (aView->Window());
 
   // Remove view resources
   ViewerTest_myViews.UnBind1(theViewName);
@@ -1399,11 +1526,7 @@ void ViewerTest::RemoveView (const TCollection_AsciiString& theViewName, const S
       {
         ViewerTest_myDrivers.UnBind2 (aCurrentContext->CurrentViewer()->Driver());
       #if !defined(_WIN32) && !defined(__WIN32__) && (!defined(__APPLE__) || defined(MACOSX_USE_GLX))
-        #if TCL_MAJOR_VERSION  < 8
+        Tcl_DeleteFileHandler (XConnectionNumber (aCurrentContext->CurrentViewer()->Driver()->GetDisplayConnection()->GetDisplay()));
-        Tk_DeleteFileHandler((void*)XConnectionNumber(aCurrentContext->CurrentViewer()->Driver()->GetDisplayConnection()->GetDisplay()));
-        #else
-        Tk_DeleteFileHandler(XConnectionNumber(aCurrentContext->CurrentViewer()->Driver()->GetDisplayConnection()->GetDisplay()));
-        #endif
       #endif
       }
 
@@ -2554,24 +2677,26 @@ int max( int a, int b )
 }
 
 int ViewerMainLoop (Standard_Integer argc, const char** argv)
-
 {
   static XEvent aReport;
-  Standard_Boolean pick = argc > 0;
+  const Standard_Boolean toPick = argc > 0;
+  Standard_Boolean toPickMore = toPick;
   Display* aDisplay = GetDisplayConnection()->GetDisplay();
   XNextEvent (aDisplay, &aReport);
 
   // Handle event for the chosen display connection
-  switch (aReport.type) {
+  switch (aReport.type)
+  {
     case ClientMessage:
     {
       if ((Atom)aReport.xclient.data.l[0] == GetDisplayConnection()->GetAtom(Aspect_XA_DELETE_WINDOW))
       {
         // Close the window
         ViewerTest::RemoveView(FindViewIdByWindowHandle (aReport.xclient.window));
+        return toPick ? 0 : 1;
       }
+      break;
     }
-        return 0;
     case FocusIn:
     {
       // Activate inactive view
@@ -2580,49 +2705,67 @@ int ViewerMainLoop(Standard_Integer argc, const char** argv)
       {
         ActivateView (FindViewIdByWindowHandle (aReport.xfocus.window));
       }
-      }
       break;
+    }
     case Expose:
+    {
+      Window anXWindow = GetWindowHandle (VT_GetWindow());
+      if (anXWindow == aReport.xexpose.window)
       {
         VT_ProcessExpose();
       }
+
+      // remove all the ExposureMask and process them at once
+      for (int aNbMaxEvents = XPending (aDisplay); aNbMaxEvents > 0; --aNbMaxEvents)
+      {
+        if (!XCheckWindowEvent (aDisplay, anXWindow, ExposureMask, &aReport))
+        {
           break;
+        }
+      }
+
+      break;
+    }
     case ConfigureNotify:
+    {
+      // remove all the StructureNotifyMask and process them at once
+      Window anXWindow = GetWindowHandle (VT_GetWindow());
+      for (int aNbMaxEvents = XPending (aDisplay); aNbMaxEvents > 0; --aNbMaxEvents)
+      {
+        if (!XCheckWindowEvent (aDisplay, anXWindow, StructureNotifyMask, &aReport))
+        {
+          break;
+        }
+      }
+
+      if (anXWindow == aReport.xconfigure.window)
       {
         VT_ProcessConfigure();
       }
       break;
+    }
     case KeyPress:
     {
-
+      KeySym aKeySym;
-          KeySym ks_ret ;
+      char aKeyBuf[11];
-          char buf_ret[11] ;
-          int ret_len ;
       XComposeStatus status_in_out;
-
+      int aKeyLen = XLookupString ((XKeyEvent* )&aReport, (char* )aKeyBuf, 10, &aKeySym, &status_in_out);
-          ret_len = XLookupString( ( XKeyEvent *)&aReport ,
+      aKeyBuf[aKeyLen] = '\0';
-            (char *) buf_ret , 10 ,
+      if (aKeyLen != 0)
-            &ks_ret , &status_in_out ) ;
-
-
-          buf_ret[ret_len] = '\0' ;
-
-          if (ret_len)
       {
-            VT_ProcessKeyPress (buf_ret);
+        VT_ProcessKeyPress (aKeyBuf);
-          }
       }
       break;
+    }
     case ButtonPress:
     {
       X_ButtonPress = aReport.xbutton.x;
       Y_ButtonPress = aReport.xbutton.y;
-
       if (aReport.xbutton.button == Button1)
       {
         if (aReport.xbutton.state & ControlMask)
         {
-              pick = VT_ProcessButton1Press (argc, argv, pick, (aReport.xbutton.state & ShiftMask));
+          toPickMore = VT_ProcessButton1Press (argc, argv, toPick, (aReport.xbutton.state & ShiftMask) != 0);
         }
         else
         {
@@ -2635,32 +2778,39 @@ int ViewerMainLoop(Standard_Integer argc, const char** argv)
         // Start rotation
         VT_ProcessButton3Press();
       }
-        }
       break;
+    }
     case ButtonRelease:
     {
-          if( IsDragged )
+      if (!IsDragged)
       {
-            if( !DragFirst )
+        VT_ProcessButton3Release();
-            {
+        break;
-              if (ViewerTest::GetAISContext()->IsDisplayed (GetRubberBand()))
-              {
-                ViewerTest::GetAISContext()->Remove (GetRubberBand(), Standard_False);
-                ViewerTest::GetAISContext()->CurrentViewer()->RedrawImmediate();
-              }
       }
 
       Handle(AIS_InteractiveContext) aContext = ViewerTest::GetAISContext();
       if (aContext.IsNull())
       {
-              cout << "The context is null. Please use vinit before createmesh" << endl;
+        std::cout << "Error: No active view.\n";
         return 0;
       }
 
-            Standard_Boolean ShiftPressed = ( aReport.xbutton.state & ShiftMask );
+      if (!DragFirst
-            if( aReport.xbutton.button==1 )
+        && aContext->IsDisplayed (GetRubberBand()))
+      {
+        aContext->Remove (GetRubberBand(), Standard_False);
+        aContext->CurrentViewer()->RedrawImmediate();
+      }
+
+      if (aReport.xbutton.button != Button1)
+      {
+        break;
+      }
+
+      const Standard_Boolean isShiftPressed = (aReport.xbutton.state & ShiftMask) != 0;
       if (DragFirst)
-                if( ShiftPressed )
+      {
+        if (isShiftPressed)
         {
           aContext->ShiftSelect (Standard_True);
         }
@@ -2668,8 +2818,10 @@ int ViewerMainLoop(Standard_Integer argc, const char** argv)
         {
           aContext->Select (Standard_True);
         }
+      }
       else
-                if( ShiftPressed )
+      {
+        if (isShiftPressed)
         {
           aContext->ShiftSelect (Min (X_ButtonPress, X_Motion), Min (Y_ButtonPress, Y_Motion),
                                  Max (X_ButtonPress, X_Motion), Max (Y_ButtonPress, Y_Motion),
@@ -2681,30 +2833,34 @@ int ViewerMainLoop(Standard_Integer argc, const char** argv)
                             Max (X_ButtonPress, X_Motion), Max(Y_ButtonPress, Y_Motion),
                             ViewerTest::CurrentView(), Standard_True);
         }
-            else
+      }
-              VT_ProcessButton3Release();
-
       IsDragged = Standard_False;
-          }
-          else
-            VT_ProcessButton3Release();
-        }
       break;
+    }
     case MotionNotify:
     {
-          if (GetWindowHandle (VT_GetWindow()) != aReport.xmotion.window)
+      Window anXWindow = GetWindowHandle (VT_GetWindow());
+      if (anXWindow != aReport.xmotion.window)
       {
         break;
       }
+
+      // remove all the ButtonMotionMask and process them at once
+      for (int aNbMaxEvents = XPending (aDisplay); aNbMaxEvents > 0; --aNbMaxEvents)
+      {
+        if (!XCheckWindowEvent (aDisplay, anXWindow, ButtonMotionMask | PointerMotionMask, &aReport))
+        {
+          break;
+        }
+      }
+
       if (IsDragged)
       {
-            if( !DragFirst )
+        if (!DragFirst
-            {
+          && ViewerTest::GetAISContext()->IsDisplayed (GetRubberBand()))
-              if (ViewerTest::GetAISContext()->IsDisplayed (GetRubberBand()))
         {
           ViewerTest::GetAISContext()->Remove (GetRubberBand(), Standard_False);
         }
-            }
 
         X_Motion = aReport.xmotion.x;
         Y_Motion = aReport.xmotion.y;
@@ -2723,18 +2879,18 @@ int ViewerMainLoop(Standard_Integer argc, const char** argv)
       {
         X_Motion = aReport.xmotion.x;
         Y_Motion = aReport.xmotion.y;
-
+        if ((aReport.xmotion.state & ControlMask) != 0)
-            // remove all the ButtonMotionMaskr
+        {
-            while( XCheckMaskEvent( aDisplay, ButtonMotionMask, &aReport) ) ;
+          if ((aReport.xmotion.state & Button1Mask) != 0)
-
+          {
-            if ( aReport.xmotion.state & ControlMask ) {
-              if ( aReport.xmotion.state & Button1Mask ) {
             ProcessControlButton1Motion();
           }
-              else if ( aReport.xmotion.state & Button2Mask ) {
+          else if ((aReport.xmotion.state & Button2Mask) != 0)
+          {
             VT_ProcessControlButton2Motion();
           }
-              else if ( aReport.xmotion.state & Button3Mask ) {
+          else if ((aReport.xmotion.state & Button3Mask) != 0)
+          {
             VT_ProcessControlButton3Motion();
           }
         }
@@ -2743,45 +2899,74 @@ int ViewerMainLoop(Standard_Integer argc, const char** argv)
           VT_ProcessMotion();
         }
       }
-        }
       break;
     }
-return pick;
+  }
+  return (!toPick || toPickMore) ? 1 : 0;
 }
 
 //==============================================================================
 //function : VProcessEvents
-//purpose  : call by Tk_CreateFileHandler() to be able to manage the
+//purpose  : manage the event in the Viewer window (see Tcl_CreateFileHandler())
-//       event in the Viewer window
 //==============================================================================
-
+static void VProcessEvents (ClientData theDispX, int)
-static void VProcessEvents(ClientData,int)
 {
-  NCollection_Vector<int> anEventNumbers;
+  Display* aDispX = (Display* )theDispX;
-  // Get number of messages from every display
+  Handle(Aspect_DisplayConnection) aDispConn;
   for (NCollection_DoubleMap<TCollection_AsciiString, Handle(Graphic3d_GraphicDriver)>::Iterator
-       anIter (ViewerTest_myDrivers); anIter.More(); anIter.Next())
+       aDriverIter (ViewerTest_myDrivers); aDriverIter.More(); aDriverIter.Next())
   {
-    anEventNumbers.Append(XPending (anIter.Key2()->GetDisplayConnection()->GetDisplay()));
+    const Handle(Aspect_DisplayConnection)& aDispConnTmp = aDriverIter.Key2()->GetDisplayConnection();
+    if (aDispConnTmp->GetDisplay() == aDispX)
+    {
+      aDispConn = aDispConnTmp;
+      break;
     }
-    // Handle events for every display
+  }
-  int anEventIter = 0;
+  if (aDispConn.IsNull())
-  for (NCollection_DoubleMap <TCollection_AsciiString, Handle(Graphic3d_GraphicDriver)>::Iterator
-       anIter (ViewerTest_myDrivers); anIter.More(); anIter.Next(), anEventIter++)
   {
-    for (int i = 0; i < anEventNumbers.Value(anEventIter) &&
+    std::cerr << "Error: ViewerTest is unable processing messages for unknown X Display\n";
-         XPending (anIter.Key2()->GetDisplayConnection()->GetDisplay()) > 0; ++i)
-    {
-      SetDisplayConnection (anIter.Key2()->GetDisplayConnection());
-      int anEventResult = ViewerMainLoop( 0, NULL);
-      // If window is closed or context was not found finish current event processing loop
-      if (!anEventResult)
     return;
   }
+
+  // process new events in queue
+  SetDisplayConnection (aDispConn);
+  int aNbRemain = 0;
+  for (int aNbEventsMax = XPending (aDispX), anEventIter (0);;)
+  {
+    const int anEventResult = ViewerMainLoop (0, NULL);
+    if (anEventResult == 0)
+    {
+      return;
     }
 
-  SetDisplayConnection (ViewerTest::GetAISContext()->CurrentViewer()->Driver()->GetDisplayConnection());
+    aNbRemain = XPending (aDispX);
+    if (++anEventIter >= aNbEventsMax
+     || aNbRemain <= 0)
+    {
+      break;
+    }
+  }
 
+  // Listening X events through Tcl_CreateFileHandler() callback is fragile,
+  // it is possible that new events will arrive to queue before the end of this callback
+  // so that either this callback should go into an infinite loop (blocking processing of other events)
+  // or to keep unprocessed events till the next queue update (which can arrive not soon).
+  // Sending a dummy event in this case is a simple workaround (still, it is possible that new event will be queued in-between).
+  if (aNbRemain != 0)
+  {
+    XEvent aDummyEvent;
+    memset (&aDummyEvent, 0, sizeof(aDummyEvent));
+    aDummyEvent.type = ClientMessage;
+    aDummyEvent.xclient.format = 32;
+    XSendEvent (aDispX, InputFocus, False, 0, &aDummyEvent);
+    XFlush (aDispX);
+  }
+
+  if (const Handle(AIS_InteractiveContext)& anActiveCtx = ViewerTest::GetAISContext())
+  {
+    SetDisplayConnection (anActiveCtx->CurrentViewer()->Driver()->GetDisplayConnection());
+  }
 }
 #endif
 
@@ -2983,7 +3168,8 @@ static int VRepaint (Draw_Interpretor& , Standard_Integer theArgNb, const char**
   {
     TCollection_AsciiString anArg (theArgVec[anArgIter]);
     anArg.LowerCase();
-    if (anArg == "-immediate")
+    if (anArg == "-immediate"
+     || anArg == "-imm")
     {
       isImmediateUpdate = Standard_True;
       if (anArgIter + 1 < theArgNb
@@ -2992,9 +3178,32 @@ static int VRepaint (Draw_Interpretor& , Standard_Integer theArgNb, const char**
         ++anArgIter;
       }
     }
+    else if (anArg == "-continuous"
+          || anArg == "-cont"
+          || anArg == "-fps"
+          || anArg == "-framerate")
+    {
+      Standard_Real aFps = -1.0;
+      if (anArgIter + 1 < theArgNb
+       && TCollection_AsciiString (theArgVec[anArgIter + 1]).IsRealValue())
+      {
+        aFps = Draw::Atof (theArgVec[++anArgIter]);
+      }
+
+      ViewerTest_ContinuousRedrawer& aRedrawer = ViewerTest_ContinuousRedrawer::Instance();
+      if (Abs (aFps) >= 1.0)
+      {
+        aRedrawer.Start (aView->Window(), aFps);
+      }
+      else
+      {
+        aRedrawer.Stop();
+      }
+    }
     else
     {
       std::cout << "Syntax error at '" << anArg << "'\n";
+      return 1;
     }
   }
 
@@ -12566,8 +12775,13 @@ void ViewerTest::ViewerCommands(Draw_Interpretor& theCommands)
     "   \"scale\" - specifies factor to scale computed z range.\n",
     __FILE__, VZFit, group);
   theCommands.Add("vrepaint",
-            "vrepaint [-immediate]"
+            "vrepaint [-immediate] [-continuous FPS]"
-    "\n\t\t: force redraw",
+    "\n\t\t: force redraw of active View"
+    "\n\t\t:   -immediate  flag performs redraw of immediate layers only;"
+    "\n\t\t:   -continuous activates/deactivates continuous redraw of active View,"
+    "\n\t\t:                0 means no continuous rendering,"
+    "\n\t\t:               -1 means non-stop redraws,"
+    "\n\t\t:               >0 specifies target framerate,",
     __FILE__,VRepaint,group);
   theCommands.Add("vclear",
     "vclear          : vclear"

src/WNT/WNT_Window.cxx

@@ -355,4 +355,16 @@ void WNT_Window::SetPos (const Standard_Integer theX,  const Standard_Integer th
   aYBottom = theY1;
 }
 
+// =======================================================================
+// function : InvalidateContent
+// purpose  :
+// =======================================================================
+void WNT_Window::InvalidateContent (const Handle(Aspect_DisplayConnection)& )
+{
+  if (myHWindow != NULL)
+  {
+    ::InvalidateRect ((HWND )myHWindow, NULL, TRUE);
+  }
+}
+
 #endif // _WIN32

src/WNT/WNT_Window.hxx

@@ -115,6 +115,10 @@ public:
   //! Returns nothing on Windows
   virtual Aspect_FBConfig NativeFBConfig() const Standard_OVERRIDE { return NULL; }
 
+  //! Invalidate entire window content by calling InvalidateRect() WinAPI function, resulting in WM_PAINT event put into window message loop.
+  //! Method can be called from non-window thread, and system will also automatically aggregate multiple events into single one.
+  Standard_EXPORT virtual void InvalidateContent (const Handle(Aspect_DisplayConnection)& theDisp = NULL) Standard_OVERRIDE;
+
   DEFINE_STANDARD_RTTIEXT(WNT_Window,Aspect_Window)
 
 protected:

src/Xw/Xw_Window.cxx

@@ -482,4 +482,26 @@ void Xw_Window::Size (Standard_Integer& theWidth,
   theHeight = aWinAttr.height;
 }
 
+// =======================================================================
+// function : InvalidateContent
+// purpose  :
+// =======================================================================
+void Xw_Window::InvalidateContent (const Handle(Aspect_DisplayConnection)& theDisp)
+{
+  if (myXWindow == 0)
+  {
+    return;
+  }
+
+  const Handle(Aspect_DisplayConnection)& aDisp = !theDisp.IsNull() ? theDisp : myDisplay;
+  Display* aDispX = aDisp->GetDisplay();
+
+  XEvent anEvent;
+  memset (&anEvent, 0, sizeof(anEvent));
+  anEvent.type = Expose;
+  anEvent.xexpose.window = myXWindow;
+  XSendEvent (aDispX, myXWindow, False, ExposureMask, &anEvent);
+  XFlush (aDispX);
+}
+
 #endif //  Win32 or Mac OS X

src/Xw/Xw_Window.hxx

@@ -111,6 +111,13 @@ public:
     return myFBConfig;
   }
 
+  //! Invalidate entire window content through generation of Expose event.
+  //! This method does not aggregate multiple calls into single event - dedicated event will be sent on each call.
+  //! When NULL display connection is specified, the connection specified on window creation will be used.
+  //! Sending exposure messages from non-window thread would require dedicated display connection opened specifically
+  //! for this working thread to avoid race conditions, since Xlib display connection is not thread-safe by default.
+  Standard_EXPORT virtual void InvalidateContent (const Handle(Aspect_DisplayConnection)& theDisp) Standard_OVERRIDE;
+
 protected:
 
   Handle(Aspect_DisplayConnection) myDisplay; //!< X Display connection