0031570: Samples - add Qt samples similar to standard MFC samples

Added Qt sample OCCTOverview providing examples of use of OCCT API with relevant code and demonstration of results in the viewer.

Off-topic: some unused images are removed from dox/introduction/images/

samples/OCCTOverview/code/AdaptorCurve_AIS.h

@@ -0,0 +1,52 @@
+// Copyright (c) 2020 OPEN CASCADE SAS
+//
+// This file is part of the examples of the Open CASCADE Technology software library.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE
+
+#ifndef ADAPTOR_CURVE_AIS_H
+#define ADAPTOR_CURVE_AIS_H
+
+#include <AIS_InteractiveObject.hxx>
+#include <Geom_Curve.hxx>
+
+//! AIS interactive Object for Geom_Curve
+class AdaptorCurve_AIS : public AIS_InteractiveObject
+{
+  DEFINE_STANDARD_RTTI_INLINE(AdaptorCurve_AIS, AIS_InteractiveObject)
+public:
+  AdaptorCurve_AIS (const Handle(Geom_Curve)& theCurve) : myCurve(theCurve) {}
+private:
+
+  //! Return TRUE for supported display modes (modes 0 and 1 are supported).
+  virtual Standard_Boolean AcceptDisplayMode (const Standard_Integer theMode) const Standard_OVERRIDE { return theMode == 0 || theMode == 1; }
+
+  //! Compute presentation.
+  Standard_EXPORT virtual void Compute (const Handle(PrsMgr_PresentationManager3d)& thePrsMgr,
+                                        const Handle(Prs3d_Presentation)& thePrs,
+                                        const Standard_Integer theMode) Standard_OVERRIDE;
+
+  //! Compute selection (not implemented).
+  virtual void ComputeSelection (const Handle(SelectMgr_Selection)&,
+                                 const Standard_Integer) Standard_OVERRIDE {}
+
+private:
+  Handle(Geom_Curve) myCurve;
+};
+
+#endif