text: //
  // Copyright (c) 2017 the Cross project.
  //
  // 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.
  //
  #pragma once
  
  
  #include "../../Core/Object.h"
  #include "../../Math/StringHash.h"
  #include "../../Container/HashMap.h"
  #include "../../Graphics/VertexBuffer.h"
  #include "../../Graphics/IndexBuffer.h"
  #include "../../Math/Matrix4.h"
  #include "../../Graphics/Texture2D.h"
  #include "../../UI/SystemUI/SystemUIEvents.h"
  
  #include <imgui.h>
  
  
  namespace Cross
  {
  
  class SystemUI
          : public Cross::Object
  {
  CROSS_OBJECT(SystemUI, Cross::Object);
  public:
      SystemUI(Cross::Context* context);
      ~SystemUI();
  
      //! Get ui scale.
      //! \return scale of ui.
      float GetScale() const { return uiScale_; };
      //! Set ui scale.
      //! \param scale of ui.
      void SetScale(float scale);
      //! Add font to imgui subsystem.
      /*!
        \param font_path a string pointing to TTF font resource.
        \param size a font size. If 0 then size of last font is used.
        \param ranges optional ranges of font that should be used. Parameter is array of {start1, stop1, ..., startN, stopN, 0}.
        \param merge set to true if new font should be merged to last active font.
        \return ImFont instance that may be used for setting current font when drawing GUI.
      */
      ImFont* AddFont(const Cross::String& font_path, float size = 0, const unsigned short* ranges = 0,
                      bool merge = false);
      //! Add font to imgui subsystem.
      /*!
        \param font_path a string pointing to TTF font resource.
        \param size a font size. If 0 then size of last font is used.
        \param ranges optional ranges of font that should be used. Parameter is std::initializer_list of {start1, stop1, ..., startN, stopN, 0}.
        \param merge set to true if new font should be merged to last active font.
        \return ImFont instance that may be used for setting current font when drawing GUI.
      */
      ImFont* AddFont(
              const Cross::String& font_path, float size = 0,
              const std::initializer_list<unsigned short>& ranges = {}, bool merge = false);
  
  protected:
      float uiScale_ = 1.f;
      Cross::Matrix4 projection_;
      Cross::VertexBuffer vertexBuffer_;
      Cross::IndexBuffer indexBuffer_;
      Cross::SharedPtr<Texture2D> fontTexture_;
  
      void ReallocateFontTexture();
      void UpdateProjectionMatrix();
      void OnEndRendering(Cross::VariantMap& args);
      void OnRenderDrawLists(ImDrawData* data);
      void OnRawEvent(VariantMap& args);
  };
  
  }
  