GSoC'22: New CGAL's design to handle basic viewers

Arrangement_on_surface_2/doc/Arrangement_on_surface_2/CGAL/draw_arrangement_2.h

@@ -17,36 +17,63 @@
 #ifndef CGAL_DRAW_ARRANGEMENT_2_H
 #define CGAL_DRAW_ARRANGEMENT_2_H
 
-#include <CGAL/Qt/Basic_viewer_qt.h>
+#include <CGAL/Qt/Basic_viewer.h>
 
 #ifdef DOXYGEN_RUNNING
 
 namespace CGAL {
 
 /*! \ingroup PkgArrangementOnSurface2Draw
- *
- * opens a new window and draws `arr`, an instance of the `CGAL::Arrangement_2`
- * class template. A call to this function is blocking; that is, the program
- * continues only after the user closes the window. This function requires
- * `CGAL_Qt6`, and is only available if the macro `CGAL_USE_BASIC_VIEWER` is
- * defined.  Linking with the cmake target `CGAL::CGAL_Basic_viewer` will link
- * with `CGAL_Qt6` and add the definition `CGAL_USE_BASIC_VIEWER`.
- *
- * \tparam GeometryTraits_2 a geometry traits type, a model of a 2D arrangement
- * traits concept. At this point it must be an instance of either
- * `CGAL::Arr_segment_traits_2` or `CGAL::Arr_conic_traits_2`.
- *
- * \tparam Dcel the \dcel type, a model of the `ArrangementDcel` concept.
- *
- * \param arr the 2D arrangement to draw.
- * \param title the window title.
- *
- * \sa `ArrangementDcel`
- * \sa `ArrangementTraits_2`
+
+  opens a new window and draws `arr`, an instance of the `CGAL::Arrangement_2` class template. Parameters of the drawing are taken from the optional graphics scene options parameter.
+
+A call to this function blocks the execution of the program until the drawing window is closed. This function requires `CGAL_Qt6`, and is only available if the macro `CGAL_USE_BASIC_VIEWER` is defined.
+Linking with the cmake target `CGAL::CGAL_Basic_viewer` will link with `CGAL_Qt6` and add the definition `CGAL_USE_BASIC_VIEWER`.
+
+
+\tparam GeometryTraits_2 a geometry traits type, a model of a 2D arrangement traits concept. At this point it must be an instance of either `CGAL::Arr_segment_traits_2` or `CGAL::Arr_conic_traits_2`.
+\tparam Dcel the \dcel type, a model of the `ArrangementDcel` concept.
+\tparam GSOptions a model of `GraphicsSceneOptions` concept.
+
+\param arr the 2D arrangement to draw.
+\param gso the graphics scene options parameter.
+
+\sa `ArrangementDcel`
+\sa `ArrangementTraits_2`
+*/
+template <typename GeometryTraits_2, typename Dcel, typename GSOptions>
+void draw(const Arrangement_2<GeometryTraits_2, Dcel>& arr, const GSOptions& gso);
+
+/*! \ingroup PkgArrangementOnSurface2Draw
+
+  A shortcut to `CGAL::draw(arr, Graphics_scene_options{})`.
+*/
+template <typename GeometryTraits_2, typename Dcel>
+void draw(const Arrangement_2<GeometryTraits_2, Dcel>& arr);
+
+/*! \ingroup PkgArrangementOnSurface2Draw
+
+adds the vertices, edges and faces of `arr` into the given graphic scene `gs`. Parameters of the cells are taken from the optional graphics scene options parameter `gso`. Note that `gs` is not cleared before being filled (to enable to draw several data structures in the same basic viewer).
+
+\tparam GeometryTraits_2 a geometry traits type, a model of a 2D arrangement traits concept. At this point it must be an instance of either `CGAL::Arr_segment_traits_2` or `CGAL::Arr_conic_traits_2`.
+\tparam Dcel the \dcel type, a model of the `ArrangementDcel` concept.
+\tparam GSOptions a model of `GraphicsSceneOptions` concept.
+
+\param arr the 2D arrangement to draw.
+\param gs the graphic scene to fill.
+\param gso the graphics scene options parameter.
+ */
+template <typename GeometryTraits_2, typename Dcel, typename GSOptions>
+void add_to_graphics_scene(const Arrangement_2<GeometryTraits_2, Dcel>& arr,
+                           CGAL::Graphics_scene& gs, const GSOptions& gso);
+
+/*! \ingroup PkgArrangementOnSurface2Draw
+
+  A shortcut to `CGAL::add_to_graphics_scene(arr, gs, Graphics_scene_options{})`.
  */
 template <typename GeometryTraits_2, typename Dcel>
-void draw(const Arrangement_2<GeometryTraits_2, Dcel>& arr,
-          const char* title = "2D Arrangement Basic Viewer");
+void add_to_graphics_scene(const Arrangement_2<GeometryTraits_2, Dcel>& arr,
+                           CGAL::Graphics_scene& gs);
 
 } /* namespace CGAL */
 

Arrangement_on_surface_2/examples/Arrangement_on_surface_2/draw_arr.cpp

@@ -100,13 +100,24 @@ int main() {
             << arr.number_of_faces() << std::endl;
 
   std::size_t id(0);
-  CGAL::draw(arr, [&] (Arrangement_2::Face_const_handle) -> CGAL::IO::Color {
-                    float h = 360.0f * id++ / arr.number_of_faces();
-                    float s = 0.5;
-                    float v = 0.5;
-                    auto [r, g, b] = hsv_to_rgb(h, s, v);
-                    return CGAL::IO::Color(r,g,b);
-                  }, "hsv colors", true);
-
-  return EXIT_SUCCESS;
+
+ CGAL::Graphics_scene_options<Arrangement_2,
+                              typename Arrangement_2::Vertex_const_handle,
+                              typename Arrangement_2::Halfedge_const_handle,
+                              typename Arrangement_2::Face_const_handle> gso;
+ gso.colored_face=[](const Arrangement_2&, Arrangement_2::Face_const_handle) -> bool
+ { return true; };
+
+ gso.face_color=[&id](const Arrangement_2& arr, Arrangement_2::Face_const_handle) -> CGAL::IO::Color
+ {
+   float h = 360.0f * id++ / arr.number_of_faces();
+   float s = 0.5;
+   float v = 0.5;
+   auto [r, g, b] = hsv_to_rgb(h, s, v);
+   return CGAL::IO::Color(r,g,b);
+ };
+
+ CGAL::draw(arr, gso, "hsv colors");
+
+ return EXIT_SUCCESS;
 }