juce_AnimatedPositionBehaviours.h

Go to the documentation of this file.

/*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2015 - ROLI Ltd.
 
   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3
 
   Details of these licenses can be found at: www.gnu.org/licenses
 
   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 
   ------------------------------------------------------------------------------
 
   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.juce.com for more information.
 
  ==============================================================================
*/
 
#ifndef JUCE_ANIMATEDPOSITIONBEHAVIOURS_H_INCLUDED
#define JUCE_ANIMATEDPOSITIONBEHAVIOURS_H_INCLUDED
 
 
//==============================================================================
namespace AnimatedPositionBehaviours
{
    struct ContinuousWithMomentum
    {
        ContinuousWithMomentum() noexcept
            : velocity (0), damping (0.92)
        {
        }
 
        void setFriction (double newFriction) noexcept
        {
            damping = 1.0 - newFriction;
        }
 
        void releasedWithVelocity (double /*position*/, double releaseVelocity) noexcept
        {
            velocity = releaseVelocity;
        }
 
        double getNextPosition (double oldPos, double elapsedSeconds) noexcept
        {
            velocity *= damping;
 
            if (std::abs (velocity) < 0.05)
                velocity = 0;
 
            return oldPos + velocity * elapsedSeconds;
        }
 
        bool isStopped (double /*position*/) const noexcept
        {
            return velocity == 0;
        }
 
    private:
        double velocity, damping;
    };
 
    //==============================================================================
    struct SnapToPageBoundaries
    {
        SnapToPageBoundaries() noexcept   : targetSnapPosition()
        {
        }
 
        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;
    };
};
 
 
#endif   // JUCE_ANIMATEDPOSITIONBEHAVIOURS_H_INCLUDED