modules/skottie/src/animator/TextKeyframeAnimator.cpp

/*
 * Copyright 2020 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "modules/skottie/src/SkottieJson.h"
#include "modules/skottie/src/SkottieValue.h"
#include "modules/skottie/src/animator/KeyframeAnimator.h"
#include "modules/skottie/src/text/TextValue.h"

namespace skottie::internal {

namespace  {
class TextKeyframeAnimator final : public KeyframeAnimator {
public:
    TextKeyframeAnimator(std::vector<Keyframe> kfs, std::vector<SkCubicMap> cms,
                         std::vector<TextValue> vs, TextValue* target_value)
        : INHERITED(std::move(kfs), std::move(cms))
        , fValues(std::move(vs))
        , fTarget(target_value) {}

private:
    StateChanged onSeek(float t) override {
        const auto& lerp_info = this->getLERPInfo(t);

        // Text value keyframes are treated as selectors, not as interpolated values.
        if (*fTarget != fValues[SkToSizeT(lerp_info.vrec0.idx)]) {
            *fTarget = fValues[SkToSizeT(lerp_info.vrec0.idx)];
            return true;
        }

        return false;
    }

    const std::vector<TextValue> fValues;
    TextValue*                   fTarget;

    using INHERITED = KeyframeAnimator;
};

class TextExpressionAnimator final : public Animator {
public:
    TextExpressionAnimator(sk_sp<ExpressionEvaluator<SkString>> expression_evaluator,
        TextValue* target_value)
        : fExpressionEvaluator(std::move(expression_evaluator))
        , fTarget(target_value) {}

private:

    StateChanged onSeek(float t) override {
        SkString old_value = fTarget->fText;

        fTarget->fText = fExpressionEvaluator->evaluate(t);

        return fTarget->fText != old_value;
    }

    sk_sp<ExpressionEvaluator<SkString>> fExpressionEvaluator;
    TextValue* fTarget;
};

class TextAnimatorBuilder final : public AnimatorBuilder {
public:
    explicit TextAnimatorBuilder(TextValue* target)
        : INHERITED(Keyframe::Value::Type::kIndex)
        , fTarget(target) {}

    sk_sp<KeyframeAnimator> makeFromKeyframes(const AnimationBuilder& abuilder,
                                    const skjson::ArrayValue& jkfs) override {
        SkASSERT(jkfs.size() > 0);

        fValues.reserve(jkfs.size());
        if (!this->parseKeyframes(abuilder, jkfs)) {
            return nullptr;
        }
        fValues.shrink_to_fit();

        return sk_sp<TextKeyframeAnimator>(
                    new TextKeyframeAnimator(std::move(fKFs),
                                                std::move(fCMs),
                                                std::move(fValues),
                                                fTarget));
    }

    sk_sp<Animator> makeFromExpression(ExpressionManager& em, const char* expr) override {
         sk_sp<ExpressionEvaluator<SkString>> expression_evaluator =
                em.createStringExpressionEvaluator(expr);
            return sk_make_sp<TextExpressionAnimator>(expression_evaluator, fTarget);
    }

    bool parseValue(const AnimationBuilder& abuilder, const skjson::Value& jv) const override {
        return Parse(jv, abuilder, fTarget);
    }

private:
    bool parseKFValue(const AnimationBuilder& abuilder,
                        const skjson::ObjectValue&,
                        const skjson::Value& jv,
                        Keyframe::Value* v) override {
        TextValue val;
        if (!Parse(jv, abuilder, &val)) {
            return false;
        }

        // TODO: full deduping?
        if (fValues.empty() || val != fValues.back()) {
            fValues.push_back(std::move(val));
        }

        v->idx = SkToU32(fValues.size() - 1);

        return true;
    }

    std::vector<TextValue> fValues;
    TextValue*             fTarget;

    using INHERITED = AnimatorBuilder;
};

} // namespace

template <>
bool AnimatablePropertyContainer::bind<TextValue>(const AnimationBuilder& abuilder,
                                                  const skjson::ObjectValue* jprop,
                                                  TextValue* v) {
    TextAnimatorBuilder builder(v);
    return this->bindImpl(abuilder, jprop, builder);
}

} // namespace skottie::internal