Layout.hpp

//
// TGUI - Texus' Graphical User Interface
// Copyright (C) 2012-2026 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_LAYOUT_HPP
#define TGUI_LAYOUT_HPP
 
#include <TGUI/Config.hpp>
 
#include <TGUI/AbsoluteOrRelativeValue.hpp>
#include <TGUI/Vector2.hpp>
 
#include <functional>
#include <memory>
#include <type_traits>

 
namespace tgui
{
    class BackendGui;
    class Widget;
    class Container;

    enum class Orientation
    {
        Vertical,  
        Horizontal 
    };

    enum class HorizontalAlignment
    {
        Left,   
        Center, 
        Right   
    };

    enum class VerticalAlignment
    {
        Top,    
        Center, 
        Bottom  
    };

    enum class AutoLayout
    {
        Manual, 
        Top, 
        Left, 
        Right, 
        Bottom, 
        Leftmost, 
        Rightmost, 
        Fill 
    };

    class TGUI_API Layout
    {
    public:
        enum class Operation
        {
            Value,
            Plus,
            Minus,
            Multiplies,
            Divides,
            Minimum,
            Maximum,
            BindingPosX, // X position, same as BindingLeft if widget origin isn't changed
            BindingPosY, // Y position, same as BindingTop if widget origin isn't changed
            BindingLeft,
            BindingTop,
            BindingWidth,
            BindingHeight,
            BindingInnerWidth,
            BindingInnerHeight,
            BindingString
        };

 
    public:
        Layout() = default;

        template <typename T, typename = typename std::enable_if_t<std::is_arithmetic_v<T>, T>>
        Layout(T constant) :
            m_value{static_cast<float>(constant)}
        {
        }

        Layout(RelativeValue ratio);

        Layout(const char* expression) :
            Layout{String{expression}}
        {
        }

        Layout(String expression);

        explicit Layout(Operation operation, Widget* boundWidget);

        explicit Layout(Operation operation, std::unique_ptr<Layout> leftOperand, std::unique_ptr<Layout> rightOperand);

        Layout(const Layout& other);

        Layout(Layout&& other) noexcept;

        Layout& operator=(const Layout& other);

        Layout& operator=(Layout&& other) noexcept;

        ~Layout();

        void replaceValue(const Layout& value);

        [[nodiscard]] float getValue() const
        {
            return m_value;
        }

        [[nodiscard]] bool isConstant() const
        {
            return m_operation == Operation::Value;
        }

        [[nodiscard]] String toString() const;

        void connectWidget(Widget* widget, bool xAxis, std::function<void()> valueChangedCallbackHandler);

        void unbindWidget();

        void recalculateValue();

        [[nodiscard]] Layout* getLeftOperand() const;

        [[nodiscard]] Layout* getRightOperand() const;

 
    private:
        // If a widget is bound, inform it that the layout no longer binds it
        void unbindLayout();

        // Resets the parent pointers of the left and right operands if they exist and tell the bound widget that this layout
        // requires information about changes to its position or size when the operation requires a widget to be bound.
        void resetPointers();

        // Check whether sublayouts contain a string that refers to a widget which should be bound.
        void parseBindingStringRecursive(Widget* widget, bool xAxis);

        // Find the widget corresponding to the given name and bind it if found
        void parseBindingString(const String& expression, Widget* widget, bool xAxis);

 
    private:
        float m_value = 0;
        Layout* m_parent = nullptr;
        Operation m_operation = Operation::Value;
        std::unique_ptr<Layout> m_leftOperand = nullptr; // The left operand of the operation in case the operation is a math operation
        std::unique_ptr<Layout> m_rightOperand = nullptr; // The left operand of the operation in case the operation is a math operation
        Widget* m_boundWidget = nullptr; // The widget on which this layout depends in case the operation is a binding
        String m_boundString; // String referring to a widget on which this layout depends in case the layout was created from a string and contains a binding operation
        std::function<void()> m_connectedWidgetCallback = nullptr; // Function to call when the value of the layout changes in case the layout and sublayouts are not all constants
        int m_callingCallbackCount = 0; // Used to detect that connectWidget is called in an infinity loop if certain layouts depend on each other

    };

    class TGUI_API Layout2d
    {
    public:
        Layout2d(Vector2f constant = {0, 0}) :
            x{constant.x},
            y{constant.y}
        {
        }

        Layout2d(Layout layoutX, Layout layoutY) :
            x{std::move(layoutX)},
            y{std::move(layoutY)}
        {
        }

        Layout2d(const char* expression) :
            x{expression},
            y{expression}
        {
        }

        Layout2d(const String& expression) :
            x{expression},
            y{expression}
        {
        }

        [[nodiscard]] Vector2f getValue() const
        {
            return {x.getValue(), y.getValue()};
        }

        [[nodiscard]] String toString() const
        {
            return U"(" + x.toString() + U", " + y.toString() + U")";
        }

 
    public:
        Layout x;
        Layout y;
    };

    [[nodiscard]] TGUI_API Layout operator-(Layout right);

    [[nodiscard]] TGUI_API Layout operator+(Layout left, Layout right);

    [[nodiscard]] TGUI_API Layout operator-(Layout left, Layout right);

    [[nodiscard]] TGUI_API Layout operator*(Layout left, Layout right);

    [[nodiscard]] TGUI_API Layout operator/(Layout left, Layout right);

    [[nodiscard]] TGUI_API Layout2d operator-(Layout2d right);

    [[nodiscard]] TGUI_API Layout2d operator+(Layout2d left, Layout2d right);

    [[nodiscard]] TGUI_API Layout2d operator-(Layout2d left, Layout2d right);

    [[nodiscard]] TGUI_API Layout2d operator*(Layout2d left, const Layout& right);

    [[nodiscard]] TGUI_API Layout2d operator*(const Layout& left, Layout2d right);

    [[nodiscard]] TGUI_API Layout2d operator/(Layout2d left, const Layout& right);

 
    inline namespace bind_functions
    {
        [[nodiscard]] TGUI_API Layout bindPosX(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout bindPosY(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout bindLeft(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout bindTop(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout bindWidth(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout bindHeight(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout bindInnerWidth(const std::shared_ptr<Container>& container);

        [[nodiscard]] TGUI_API Layout bindInnerHeight(const std::shared_ptr<Container>& container);

        [[nodiscard]] TGUI_API Layout bindRight(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout bindBottom(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout2d bindPosition(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout2d bindSize(const std::shared_ptr<Widget>& widget);

        [[nodiscard]] TGUI_API Layout2d bindInnerSize(const std::shared_ptr<Container>& container);

        [[nodiscard]] TGUI_API Layout bindWidth(const BackendGui& gui);

        [[nodiscard]] TGUI_API Layout bindHeight(const BackendGui& gui);

        [[nodiscard]] TGUI_API Layout2d bindSize(const BackendGui& gui);

        [[nodiscard]] TGUI_API Layout bindMin(const Layout& value1, const Layout& value2);

        [[nodiscard]] TGUI_API Layout bindMax(const Layout& value1, const Layout& value2);
    } // namespace bind_functions
} // namespace tgui
 
#endif // TGUI_LAYOUT_HPP