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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 "SkottyPriv.h"
#include "SkottyProperties.h"
#include "SkTArray.h"
#include "SkTypes.h"
#include <functional>
#include <memory>
namespace skotty {
class AnimatorBase : public SkNoncopyable {
public:
virtual ~AnimatorBase() = default;
virtual void tick(SkMSec) = 0;
protected:
AnimatorBase() = default;
};
// Describes a keyframe interpolation interval (v0@t0) -> (v1@t1).
// TODO: add interpolation params.
template <typename T>
struct KeyframeInterval {
T fV0,
fV1;
float fT0 = 0,
fT1 = 0;
void lerp(float t, T*) const;
};
// Binds an animated/keyframed property to a node attribute.
template <typename ValT, typename AttrT, typename NodeT>
class Animator : public AnimatorBase {
public:
static std::unique_ptr<Animator> Make(const Json::Value& frames, sk_sp<NodeT> node,
std::function<void(const sk_sp<NodeT>&, const AttrT&)> applyFunc);
void tick(SkMSec t) override {
const auto& frame = this->findInterval(t);
const auto rel_t = (t - frame.fT0) / (frame.fT1 - frame.fT0);
ValT val;
frame.lerp(SkTPin<float>(rel_t, 0, 1), &val);
fFunc(fTarget, val.template as<AttrT>());
}
private:
Animator(SkTArray<KeyframeInterval<ValT>>&& intervals, sk_sp<NodeT> node,
std::function<void(const sk_sp<NodeT>&, const AttrT&)> 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;
std::function<void(const sk_sp<NodeT>&, const AttrT&)> 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, std::function<void(const sk_sp<NodeT>&, const AttrT&)> applyFunc) {
if (!frames.isArray())
return nullptr;
SkTArray<KeyframeInterval<ValT>> intervals;
for (const auto& frame : frames) {
if (!frame.isObject())
return nullptr;
const auto t = ParseScalar(frame["t"], SK_ScalarMin);
if (t == SK_ScalarMin)
break;
auto* prev_interval = intervals.empty() ? nullptr : &intervals.back();
if (prev_interval) {
if (prev_interval->fT0 >= t) {
LOG("!! Ignoring out-of-order key frame (t: %f < t: %f)\n", t, prev_interval->fT0);
continue;
}
// Back-fill the prev interval t1.
prev_interval->fT1 = t;
}
auto& curr_interval = intervals.push_back();
if (!ValT::Parse(frame["s"], &curr_interval.fV0) ||
!ValT::Parse(frame["e"], &curr_interval.fV1) ||
curr_interval.fV0.cardinality() != curr_interval.fV1.cardinality() ||
(prev_interval &&
curr_interval.fV0.cardinality() != prev_interval->fV0.cardinality())) {
// Invalid frame, or "t"-only frame.
intervals.pop_back();
continue;
}
curr_interval.fT0 = curr_interval.fT1 = t;
}
// If we couldn't determine a t1 for the last interval, discard it.
if (!intervals.empty() && intervals.back().fT0 == intervals.back().fT1) {
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->fT0 < f0->fT1);
SkASSERT(f1->fT0 < f1->fT1);
if (t < f0->fT0) {
return *f0;
}
if (t > f1->fT1) {
return *f1;
}
while (f0 != f1) {
SkASSERT(f0 < f1);
SkASSERT(t >= f0->fT0 && t <= f1->fT1);
const auto f = f0 + (f1 - f0) / 2;
SkASSERT(f->fT0 < f->fT1);
if (t > f->fT1) {
f0 = f + 1;
} else {
f1 = f;
}
}
SkASSERT(f0 == f1);
SkASSERT(t >= f0->fT0 && t <= f1->fT1);
return *f0;
}
} // namespace skotty
#endif // SkottyAnimator_DEFINED
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