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/OcctWindow.h

@@ -0,0 +1,111 @@
+// 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 OcctWindow_H
+#define OcctWindow_H
+
+#include <Aspect_Window.hxx>
+
+#include <Standard_WarningsDisable.hxx>
+#include <QWidget>
+#include <Standard_WarningsRestore.hxx>
+
+//!  OcctWindow class implements Aspect_Window interface using Qt API
+//!  as a platform-independent source of window geometry information.
+//!  A similar class should be used instead of platform-specific OCCT
+//!  classes (WNT_Window, Xw_Window) in any Qt 5 application using OCCT
+//!  3D visualization.
+//!
+//!  With Qt 5, the requirement for a Qt-based application to rely fully
+//!  on Qt public API and stop using platform-specific APIs looks mandatory.
+//!  An example of this is changed QWidget event sequence: when a widget is
+//!  first shown on the screen, a resize event is generated before the
+//!  underlying native window is resized correctly, however the QWidget instance
+//!  already holds correct size information at that moment. The OCCT classes
+//!  acting as a source of window geometry for V3d_View class (WNT_Window, Xw_Window)
+//!  are no longer compatible with changed Qt behavior because they rely on
+//!  platform-specific API that cannot return correct window geometry information
+//!  in some cases. A reasonable solution is to provide a Qt-based implementation
+//!  of Aspect_Window interface at application level.
+class OcctWindow : public Aspect_Window
+{
+  DEFINE_STANDARD_RTTIEXT(OcctWindow,Aspect_Window)
+public:
+
+  //! Constructor
+  OcctWindow( QWidget* theWidget, const Quantity_NameOfColor theBackColor = Quantity_NOC_MATRAGRAY );
+
+  //! Destructor
+  virtual ~OcctWindow()
+  {
+    myWidget = NULL;
+  }
+
+  //! Returns native Window handle
+  virtual Aspect_Drawable NativeHandle() const Standard_OVERRIDE
+  {
+    return (Aspect_Drawable)myWidget->winId();
+  }
+
+  //! Returns parent of native Window handle.
+  virtual Aspect_Drawable NativeParentHandle() const Standard_OVERRIDE;
+
+  //! Applies the resizing to the window <me>
+  virtual Aspect_TypeOfResize DoResize() Standard_OVERRIDE;
+
+  //! Returns True if the window <me> is opened
+  //! and False if the window is closed.
+  virtual Standard_Boolean IsMapped() const Standard_OVERRIDE
+  {
+    return !(myWidget->isMinimized() || myWidget->isHidden());
+  }
+
+  //! Apply the mapping change to the window <me>
+  //! and returns TRUE if the window is mapped at screen.
+  virtual Standard_Boolean DoMapping() const Standard_OVERRIDE { return Standard_True; }
+
+  //! Opens the window <me>.
+  virtual void Map() const Standard_OVERRIDE;
+
+  //! Closes the window <me>.
+  virtual void Unmap() const Standard_OVERRIDE;
+
+  virtual void Position( Standard_Integer& theX1, Standard_Integer& theY1,
+                         Standard_Integer& theX2, Standard_Integer& theY2 ) const Standard_OVERRIDE;
+
+  //! Returns The Window RATIO equal to the physical
+  //! WIDTH/HEIGHT dimensions.
+  virtual Standard_Real Ratio() const Standard_OVERRIDE;
+
+  virtual void Size( Standard_Integer& theWidth, Standard_Integer& theHeight ) const Standard_OVERRIDE;
+
+  virtual Aspect_FBConfig NativeFBConfig() const Standard_OVERRIDE { return NULL; }
+
+protected:
+  Standard_Integer myXLeft;
+  Standard_Integer myYTop;
+  Standard_Integer myXRight;
+  Standard_Integer myYBottom;
+  QWidget* myWidget;
+};
+
+
+#endif // OcctWindow_H