src/PageState.hpp

   1 /*
   2 Copyright_License {
   3
   4   XCSoar Glide Computer - http://www.xcsoar.org/
   5   Copyright (C) 2000-2013 The XCSoar Project
   6   A detailed list of copyright holders can be found in the file "AUTHORS".
   7
   8   This program is free software; you can redistribute it and/or
   9   modify it under the terms of the GNU General Public License
  10   as published by the Free Software Foundation; either version 2
  11   of the License, or (at your option) any later version.
  12
  13   This program is distributed in the hope that it will be useful,
  14   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16   GNU General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with this program; if not, write to the Free Software
  20   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21 }
  22 */
  23
  24 #ifndef XCSOAR_PAGE_STATE_HPP
  25 #define XCSOAR_PAGE_STATE_HPP
  26
  27 #include "PageSettings.hpp"
  28 #include "Math/fixed.hpp"
  29
  30 #include <array>
  31 #include <type_traits>
  32
  33 /**
  34  * The state of one configured page.
  35  */
  36 struct PageState {
  37   /**
  38    * The last map scale on this page.  Negative means it's undefined.
  39    * This attribute is only used if PageSettings::distinct_zoom is
  40    * enabled.
  41    */
  42   fixed map_scale;
  43
  44   void Clear() {
  45     map_scale = fixed(-1);
  46   }
  47 };
  48
  49 /**
  50  * Keeps track of the state of the "pages" subsystem.
  51  */
  52 struct PagesState {
  53   static constexpr unsigned MAX_PAGES = PageSettings::MAX_PAGES;
  54
  55   /**
  56    * The index of the current page in the list of configured pages,
  57    * see #PageSettings.
  58    *
  59    * This setting is only active if #special_page is not defined.
  60    * Otherwise, it is the page that we will return to after the user
  61    * decides to leave the #special_page.
  62    */
  63   unsigned current_index;
  64
  65   /**
  66    * If this attribute is defined (see PageLayout::IsDefined()), then
  67    * the current page is not the one in #PageSettings, specified by
  68    * #page_index, but a page that was created automatically.  For
  69    * example, it could be a page that was created by clicking on the
  70    * FLARM radar.  Pressing left/right will return to the last
  71    * configured page.
  72    */
  73   PageLayout special_page;
  74
  75   std::array<PageState, MAX_PAGES> pages;
  76
  77   void Clear();
  78 };
  79
  80 static_assert(std::is_trivial<PagesState>::value, "type is not trivial");
  81
  82 #endif