0030507: Visualization - introduce AIS_ViewController

ViewerTest_EventManager now inherits AIS_ViewController.
Platform-dependent user input handling within ViewerTest has been revised
to process events in common way through AIS_ViewController.
The mouse navigation has been changed, so that left mouse clicked
without modifers now rotates View.
The rubber-band selection can be activated via Alt+LeftMouseButton.
Selection is now done on mouse unclick and keyboard short-cuts take effect on unclick.

Aspect_Window::SetTitle() - added new method configuring Window title.
Introduced new types Aspect_Touch, Aspect_VKey, Aspect_ScrollDelta
for processing window events in platform-independent way.

src/Aspect/Aspect_ScrollDelta.hxx

@@ -0,0 +1,59 @@
+// Copyright (c) 2019 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#ifndef _Aspect_ScrollDelta_HeaderFile
+#define _Aspect_ScrollDelta_HeaderFile
+
+#include <Aspect_VKeyFlags.hxx>
+#include <NCollection_Vec2.hxx>
+#include <Standard_Real.hxx>
+
+//! Parameters for mouse scroll action.
+struct Aspect_ScrollDelta
+{
+
+  NCollection_Vec2<int> Point; //!< scale position
+  Standard_Real         Delta; //!< delta in pixels
+  Aspect_VKeyFlags      Flags; //!< key flags
+
+  //! Return true if action has point defined.
+  bool HasPoint() const
+  {
+    return Point.x() >= 0
+        && Point.y() >= 0;
+  }
+
+  //! Reset at point.
+  void ResetPoint()
+  {
+    Point.SetValues (-1, -1);
+  }
+
+  //! Empty constructor.
+  Aspect_ScrollDelta()
+  : Point (-1, -1), Delta (0.0), Flags (Aspect_VKeyFlags_NONE) {}
+
+  //! Constructor.
+  Aspect_ScrollDelta (const NCollection_Vec2<int>& thePnt,
+                      Standard_Real theValue,
+                      Aspect_VKeyFlags theFlags = Aspect_VKeyFlags_NONE)
+  : Point (thePnt), Delta (theValue), Flags (theFlags) {}
+
+  //! Constructor with undefined point.
+  Aspect_ScrollDelta (Standard_Real theValue,
+                      Aspect_VKeyFlags theFlags = Aspect_VKeyFlags_NONE)
+  : Point (-1, -1), Delta (theValue), Flags (theFlags) {}
+
+};
+
+#endif // _Aspect_ScrollDelta_HeaderFile