TwoFingerScrollDetect.hpp

//
// TGUI - Texus' Graphical User Interface
// Copyright (C) 2012-2025 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.
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// 3. This notice may not be removed or altered from any source distribution.
//
 
#ifndef TGUI_TWO_FINGER_SCROLL_DETECT_HPP
#define TGUI_TWO_FINGER_SCROLL_DETECT_HPP
 
#include <TGUI/Vector2.hpp>
 
#if !TGUI_EXPERIMENTAL_USE_STD_MODULE
    #include <cstdint>
    #include <unordered_map>
#endif

 
TGUI_MODULE_EXPORT namespace tgui
{
    class TGUI_API TwoFingerScrollDetect
    {
    public:

        void reportFingerDown(std::intptr_t fingerId, float x, float y);

        void reportFingerUp(std::intptr_t fingerId);

        void reportFingerMotion(std::intptr_t fingerId, float x, float y);

        bool isScrolling() const;

        Vector2f getTouchPosition() const;

        float getDelta(float scale);

    private:

        Vector2f calculateFingerCentroid();

    private:
 
        std::unordered_map<std::intptr_t, Vector2f> m_fingerPositions;
        Vector2f m_initialCentroidPosition;
        Vector2f m_lastCentroidPosition;
        bool m_trackingActive = true; // When three fingers touch, we stop trying to detect scrolling until all fingers are released again
    };
}
 
#endif // TGUI_TWO_FINGER_SCROLL_DETECT_HPP