AbsoluteOrRelativeValue.hpp

 
//
// TGUI - Texus' Graphical User Interface
// Copyright (C) 2012-2020 Bruno Van de Velde (vdv_b@tgui.eu)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
//    you must not claim that you wrote the original software.
//    If you use this software in a product, an acknowledgment
//    in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
//    and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
 
 
#ifndef TGUI_ABSOLUTE_OR_RELATIVE_VALUE_HPP
#define TGUI_ABSOLUTE_OR_RELATIVE_VALUE_HPP
 
#include <TGUI/Global.hpp>
#include <TGUI/to_string.hpp>
#include <type_traits>
#include <string>
 
 
namespace tgui
{
    class TGUI_API AbsoluteOrRelativeValue
    {
    public:
 
        TGUI_CONSTEXPR AbsoluteOrRelativeValue()
        {
            // Constructor isn't defined as "= default" because this leads to an IntelliSense error
        }
 
 
        template <typename T, typename = typename std::enable_if<std::is_arithmetic<T>::value, T>::type>
        TGUI_CONSTEXPR AbsoluteOrRelativeValue(T constant) :
            m_constant    {true},
            m_value       {static_cast<float>(constant)}
        {
        }
 
 
        AbsoluteOrRelativeValue(const char* expression) :
            AbsoluteOrRelativeValue{std::string{expression}}
        {
        }
 
 
        AbsoluteOrRelativeValue(const std::string& expression)
        {
            if (!expression.empty() && (expression.back() == '%'))
            {
                m_constant = false;
                m_ratio    = strToFloat(expression.substr(0, expression.length()-1)) / 100.f;
            }
            else
            {
                m_constant = true;
                m_value    = strToFloat(expression.substr(0, expression.length()));
            }
        }
 
 
        TGUI_CONSTEXPR float getValue() const
        {
            return m_value;
        }
 
 
        TGUI_CONSTEXPR float getRatio() const
        {
            return m_ratio;
        }
 
 
        TGUI_CONSTEXPR bool isConstant() const
        {
            return m_constant;
        }
 
 
        void updateParentSize(float newParentSize)
        {
            if (!m_constant)
            {
                m_parentValue = newParentSize;
                m_value = m_ratio * newParentSize;
            }
        }
 
 
        std::string toString() const
        {
            if (m_constant)
                return to_string(m_value);
            else
                return to_string(m_ratio * 100) + '%';
        }
 
 
    protected:
 
        bool  m_constant     = true;
        float m_value        = 0;
        float m_ratio        = 0;
        float m_parentValue  = 0;
    };
 
 
    struct TGUI_API RelativeValue : AbsoluteOrRelativeValue
    {
        explicit TGUI_CONSTEXPR RelativeValue(float ratio)
        {
            m_constant = false;
            m_ratio    = ratio;
        }
    };
 
}
 
 
#endif // TGUI_ABSOLUTE_OR_RELATIVE_VALUE_HPP