q4.cpp

class CGuiWidget
{
    ...
 
public:
    void Render();
    virtual void RenderInternal();
 
    CRect<uint64> ConvertToBounds( CRect<uint64> Frame ) 
        { ... }
 
    CRect<uint64> GetBounds() const 
        { return ConvertToBounds(m_Frame); }
 
    bool ClipsToBounds() const 
        { return m_ClipsToBounds; }
 
private:
    CGuiWidget* m_Parent;
    std::list<CGuiWidget *> m_Children;
 
    bool m_isHidden = false; 
    CRect<uint64> m_Frame;            // Local coordinates in Parent
    bool m_ClipsToBounds = true;
};
 
void Render()
{
    CRect<uint64> Bounds = this->GetBounds(Frame);
 
    if ( m_Parent && m_Parent->ClipsToBounds() &&
         m_Parent->GetBounds().Intersects( Bounds ) == false )
    {
        return;
    }
 
    if ( m_isHidden )
    {
        return;
    }
 
    RenderInternal();
 
    for (auto const& child : m_Children) 
    {
        child->Render();
    }
}