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/Viewer2dSamples.h

@@ -0,0 +1,76 @@
+// 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 VIEWER2DSAMPLES_H
+#define VIEWER2DSAMPLES_H
+
+#include "BaseSample.h"
+
+#include <AIS_InteractiveContext.hxx>
+#include <V3d_View.hxx>
+
+//! Implements viewer 2D samples.
+class Viewer2dSamples : public BaseSample
+{
+  DEFINE_STANDARD_RTTI_INLINE(Viewer2dSamples, BaseSample)
+public:
+
+  Viewer2dSamples(const TCollection_AsciiString& theSampleSourcePath,
+                  const Handle(V3d_View)& theView,
+                  const Handle(V3d_Viewer)& theViewer,
+                  const Handle(AIS_InteractiveContext)& theContext)
+  : BaseSample (theSampleSourcePath, theContext),
+    myView (theView),
+    myViewer (theViewer)
+  {}
+
+  void SetFileName (const TCollection_AsciiString& theFileName) { myFileName = theFileName; }
+  void ClearExtra();
+
+  static Standard_Boolean IsFileSample  (const TCollection_AsciiString& theSampleName) { return theSampleName == "BackgroungImage2dSample"; }
+  static Standard_Boolean IsShadedSample(const TCollection_AsciiString& theSampleName) { return theSampleName == "BackgroungImage2dSample"; }
+
+protected:
+  virtual void ExecuteSample (const TCollection_AsciiString& theSampleName) Standard_OVERRIDE;
+
+private:
+
+  // One function for every sample
+  void TextView2dSample();
+  void MarkerView2dSample();
+  void FillAreaView2dSample();
+  void LoopOnFaceView2dSample();
+  void RectagularLineGrid2dSample();
+  void RectagularPointGrid2dSample();
+  void CircularLineGrid2dSample();
+  void CircularPointGrid2dSample();
+  void ClearGrid2dSample();
+  void BackgroungImage2dSample();
+
+private:
+
+  TCollection_AsciiString myFileName;
+  Handle(V3d_View)        myView;
+  Handle(V3d_Viewer)      myViewer;
+
+};
+
+#endif // VIEWER2DSAMPLES_H