include/rive/animation/state_transition.hpp

#ifndef _RIVE_STATE_TRANSITION_HPP_
#define _RIVE_STATE_TRANSITION_HPP_
#include "rive/animation/state_transition_flags.hpp"
#include "rive/generated/animation/state_transition_base.hpp"
#include <stdio.h>
#include <vector>

namespace rive
{
class LayerState;
class StateMachineLayerImporter;
class StateTransitionImporter;
class TransitionCondition;
class StateInstance;
class SMIInput;
class LinearAnimation;
class LinearAnimationInstance;

enum class AllowTransition : unsigned char
{
    no,
    waitingForExit,
    yes
};

class StateTransition : public StateTransitionBase
{
    friend class StateMachineLayerImporter;
    friend class StateTransitionImporter;

private:
    StateTransitionFlags transitionFlags() const
    {
        return static_cast<StateTransitionFlags>(flags());
    }
    LayerState* m_StateTo = nullptr;

    std::vector<TransitionCondition*> m_Conditions;
    void addCondition(TransitionCondition* condition);

public:
    ~StateTransition() override;
    const LayerState* stateTo() const { return m_StateTo; }

    StatusCode onAddedDirty(CoreContext* context) override;
    StatusCode onAddedClean(CoreContext* context) override;

    /// Whether the transition is marked disabled (usually done in the
    /// editor).
    bool isDisabled() const
    {
        return (transitionFlags() & StateTransitionFlags::Disabled) ==
               StateTransitionFlags::Disabled;
    }

    /// Returns AllowTransition::yes when this transition can be taken from
    /// stateFrom with the given inputs.
    AllowTransition allowed(StateInstance* stateFrom,
                            Span<SMIInput*> inputs,
                            bool ignoreTriggers) const;

    /// Whether the animation is held at exit or if it keeps advancing
    /// during mixing.
    bool pauseOnExit() const
    {
        return (transitionFlags() & StateTransitionFlags::PauseOnExit) ==
               StateTransitionFlags::PauseOnExit;
    }

    /// Whether exit time is enabled. All other conditions still apply, the
    /// exit time is effectively an AND with the rest of the conditions.
    bool enableExitTime() const
    {
        return (transitionFlags() & StateTransitionFlags::EnableExitTime) ==
               StateTransitionFlags::EnableExitTime;
    }

    StatusCode import(ImportStack& importStack) override;

    size_t conditionCount() const { return m_Conditions.size(); }
    TransitionCondition* condition(size_t index) const
    {
        if (index < m_Conditions.size())
        {
            return m_Conditions[index];
        }
        return nullptr;
    }

    /// The amount of time to mix the outgoing animation onto the incoming
    /// one when changing state. Only applies when going out from an
    /// AnimationState.
    float mixTime(const LayerState* stateFrom) const;

    /// Computes the exit time in seconds of the stateFrom. Set absolute to
    /// true if you want the returned time to be relative to the entire
    /// animation. Set absolute to false if you want it relative to the work
    /// area.
    float exitTimeSeconds(const LayerState* stateFrom, bool absolute = false) const;

    /// Provide the animation instance to use for computing percentage
    /// durations for exit time.
    virtual const LinearAnimationInstance*
    exitTimeAnimationInstance(const StateInstance* from) const;

    /// Provide the animation to use for computing percentage durations for
    /// exit time.
    virtual const LinearAnimation* exitTimeAnimation(const LayerState* from) const;

    /// Retruns true when we need to hold the exit time, also applies the
    /// correct time to the animation instance in the stateFrom, when
    /// applicable (when it's an AnimationState).
    bool applyExitCondition(StateInstance* stateFrom) const;
};
} // namespace rive

#endif