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/qt/OCCTOverview/src/DocumentCommon.h

@@ -0,0 +1,75 @@
+// 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 DOCUMENT_COMMON_OVERVIEW_H
+#define DOCUMENT_COMMON_OVERVIEW_H
+
+#include "CommonSample.h"
+
+#include <Standard_WarningsDisable.hxx>
+#include <QObject>
+#include <QList>
+#include <Standard_WarningsRestore.hxx>
+
+#include <AIS_InteractiveContext.hxx>
+#include <V3d_Viewer.hxx>
+
+class ApplicationCommonWindow;
+
+//! Implements visualization of samples content
+class COMMONSAMPLE_EXPORT DocumentCommon : public QObject
+{
+  Q_OBJECT
+public:
+
+  DocumentCommon(ApplicationCommonWindow* );
+  ~DocumentCommon() { }
+
+  const Handle(AIS_InteractiveContext)& getContext() { return myContext; }
+
+  const Handle(V3d_Viewer)& getViewer() { return myViewer; }
+
+  void setViewer (const Handle(V3d_Viewer)& theViewer) { myViewer = theViewer; }
+
+  void SetObjects(const NCollection_Vector<Handle(AIS_InteractiveObject)>& theObjects,
+                  Standard_Boolean theDisplayShaded = Standard_False);
+  void Clear();
+  bool IsEmpty() const { return myContextIsEmpty; }
+
+signals:
+  void selectionChanged();
+  void sendCloseDocument( DocumentCommon* );
+
+private:
+  Handle(V3d_Viewer) Viewer (const Standard_ExtString theName,
+                             const Standard_CString theDomain,
+                             const Standard_Real theViewSize,
+                             const V3d_TypeOfOrientation theViewProj,
+                             const Standard_Boolean theComputedMode,
+                             const Standard_Boolean theDefaultComputedMode );
+
+private:
+  Handle(V3d_Viewer)             myViewer;
+  Handle(AIS_InteractiveContext) myContext;
+  bool myContextIsEmpty;
+};
+
+#endif