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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkottyAnimator_DEFINED
#define SkottyAnimator_DEFINED
#include "SkCubicMap.h"
#include "SkMakeUnique.h"
#include "SkottyPriv.h"
#include "SkottyProperties.h"
#include "SkTArray.h"
#include "SkTypes.h"
#include <memory>
namespace skotty {
class AnimatorBase : public SkNoncopyable {
public:
virtual ~AnimatorBase() = default;
virtual void tick(float) = 0;
protected:
AnimatorBase() = default;
};
class KeyframeIntervalBase : public SkNoncopyable {
public:
KeyframeIntervalBase() = default;
KeyframeIntervalBase(KeyframeIntervalBase&&) = default;
KeyframeIntervalBase& operator=(KeyframeIntervalBase&&) = default;
float t0() const { return fT0; }
float t1() const { return fT1; }
bool isValid() const { return fT0 < fT1; }
bool contains(float t) const { return t >= fT0 && t <= fT1; }
protected:
// Parse the current interval AND back-fill prev interval t1.
bool parse(const Json::Value&, KeyframeIntervalBase* prev);
// Computes a "local" t (relative to [fT0..fT1]), and mapped
// through the cubic (if applicable).
float localT(float t) const;
private:
// Initialized for non-linear interpolation.
std::unique_ptr<SkCubicMap> fCubicMap;
// Start/end times.
float fT0 = 0,
fT1 = 0;
};
// Describes a keyframe interpolation interval (v0@t0) -> (v1@t1).
template <typename T>
class KeyframeInterval final : public KeyframeIntervalBase {
public:
// Parse the current interval AND back-fill prev interval t1.
bool parse(const Json::Value& k, KeyframeInterval* prev) {
SkASSERT(k.isObject());
return this->INHERITED::parse(k, prev) &&
ValueTraits<T>::Parse(k["s"], &fV0) &&
ValueTraits<T>::Parse(k["e"], &fV1) &&
ValueTraits<T>::Cardinality(fV0) == ValueTraits<T>::Cardinality(fV1) &&
(!prev || ValueTraits<T>::Cardinality(fV0) == ValueTraits<T>::Cardinality(prev->fV0));
}
void lerp(float t, T*) const;
private:
// Start/end values.
T fV0,
fV1;
using INHERITED = KeyframeIntervalBase;
};
// Binds an animated/keyframed property to a node attribute.
template <typename ValT, typename AttrT, typename NodeT>
class Animator : public AnimatorBase {
public:
using ApplyFuncT = void(*)(const sk_sp<NodeT>&, const AttrT&);
static std::unique_ptr<Animator> Make(const Json::Value& frames, sk_sp<NodeT> node,
ApplyFuncT&& applyFunc);
void tick(float t) override {
const auto& frame = this->findInterval(t);
ValT val;
frame.lerp(t, &val);
fFunc(fTarget, ValueTraits<ValT>::template As<AttrT>(val));
}
private:
Animator(SkTArray<KeyframeInterval<ValT>>&& intervals, sk_sp<NodeT> node,
ApplyFuncT&& applyFunc)
: fIntervals(std::move(intervals))
, fTarget(std::move(node))
, fFunc(std::move(applyFunc)) {}
const KeyframeInterval<ValT>& findInterval(float t) const;
const SkTArray<KeyframeInterval<ValT>> fIntervals;
sk_sp<NodeT> fTarget;
ApplyFuncT fFunc;
};
template <typename ValT, typename AttrT, typename NodeT>
std::unique_ptr<Animator<ValT, AttrT, NodeT>>
Animator<ValT, AttrT, NodeT>::Make(const Json::Value& frames, sk_sp<NodeT> node,
ApplyFuncT&& applyFunc) {
if (!frames.isArray())
return nullptr;
SkTArray<KeyframeInterval<ValT>> intervals;
intervals.reserve(frames.size());
KeyframeInterval<ValT>* prev_interval = nullptr;
for (const auto& frame : frames) {
if (!frame.isObject())
return nullptr;
KeyframeInterval<ValT> curr_interval;
if (curr_interval.parse(frame, prev_interval)) {
intervals.push_back(std::move(curr_interval));
prev_interval = &intervals.back();
}
}
// If we couldn't determine a t1 for the last interval, discard it.
if (!intervals.empty() && !intervals.back().isValid()) {
intervals.pop_back();
}
if (intervals.empty()) {
return nullptr;
}
return std::unique_ptr<Animator>(
new Animator(std::move(intervals), node, std::move(applyFunc)));
}
template <typename ValT, typename AttrT, typename NodeT>
const KeyframeInterval<ValT>& Animator<ValT, AttrT, NodeT>::findInterval(float t) const {
SkASSERT(!fIntervals.empty());
// TODO: cache last/current frame?
auto f0 = fIntervals.begin(),
f1 = fIntervals.end() - 1;
SkASSERT(f0->isValid());
SkASSERT(f1->isValid());
if (t < f0->t0()) {
return *f0;
}
if (t > f1->t1()) {
return *f1;
}
while (f0 != f1) {
SkASSERT(f0 < f1);
SkASSERT(t >= f0->t0() && t <= f1->t1());
const auto f = f0 + (f1 - f0) / 2;
SkASSERT(f->isValid());
if (t > f->t1()) {
f0 = f + 1;
} else {
f1 = f;
}
}
SkASSERT(f0 == f1);
SkASSERT(f0->contains(t));
return *f0;
}
} // namespace skotty
#endif // SkottyAnimator_DEFINED
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