juce_AnimatedPositionBehaviours.h

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 /*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   By using JUCE, you agree to the terms of both the JUCE 7 End-User License
   Agreement and JUCE Privacy Policy.
 
   End User License Agreement: www.juce.com/juce-7-licence
   Privacy Policy: www.juce.com/juce-privacy-policy
 
   Or: You may also use this code under the terms of the GPL v3 (see
   www.gnu.org/licenses).
 
   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.
 
  ==============================================================================
*/
 
//==============================================================================
namespace juce::AnimatedPositionBehaviours
{
 
    struct ContinuousWithMomentum
    {
        ContinuousWithMomentum() = default;
 
        void setFriction (double newFriction) noexcept
        {
            damping = 1.0 - newFriction;
        }
 
        void setMinimumVelocity (double newMinimumVelocityToUse) noexcept
        {
            minimumVelocity = newMinimumVelocityToUse;
        }
 
        void releasedWithVelocity (double /*position*/, double releaseVelocity) noexcept
        {
            velocity = releaseVelocity;
        }
 
        double getNextPosition (double oldPos, double elapsedSeconds) noexcept
        {
            velocity *= damping;
 
            if (std::abs (velocity) < minimumVelocity)
                velocity = 0;
 
            return oldPos + velocity * elapsedSeconds;
        }
 
        bool isStopped (double /*position*/) const noexcept
        {
            return approximatelyEqual (velocity, 0.0);
        }
 
    private:
        double velocity = 0, damping = 0.92, minimumVelocity = 0.05;
    };
 
    //==============================================================================
    struct SnapToPageBoundaries
    {
        SnapToPageBoundaries() = default;
 
        void releasedWithVelocity (double position, double releaseVelocity) noexcept
        {
            targetSnapPosition = std::floor (position + 0.5);
 
            if (releaseVelocity >  1.0 && targetSnapPosition < position)  ++targetSnapPosition;
            if (releaseVelocity < -1.0 && targetSnapPosition > position)  --targetSnapPosition;
        }
 
        double getNextPosition (double oldPos, double elapsedSeconds) const noexcept
        {
            if (isStopped (oldPos))
                return targetSnapPosition;
 
            const double snapSpeed = 10.0;
            const double velocity = (targetSnapPosition - oldPos) * snapSpeed;
            const double newPos = oldPos + velocity * elapsedSeconds;
 
            return isStopped (newPos) ? targetSnapPosition : newPos;
        }
 
        bool isStopped (double position) const noexcept
        {
            return std::abs (targetSnapPosition - position) < 0.001;
        }
 
    private:
        double targetSnapPosition = 0.0;
    };
 
} // namespace juce::AnimatedPositionBehaviours