chromium/third_party/blink/renderer/core/animation/keyframe.h

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_ANIMATION_KEYFRAME_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_ANIMATION_KEYFRAME_H_

#include <optional>

#include "base/memory/scoped_refptr.h"
#include "third_party/blink/renderer/core/animation/effect_model.h"
#include "third_party/blink/renderer/core/animation/property_handle.h"
#include "third_party/blink/renderer/core/animation/timeline_offset.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/platform/animation/timing_function.h"
#include "third_party/blink/renderer/platform/bindings/script_state.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/forward.h"
#include "third_party/blink/renderer/platform/wtf/hash_set.h"

namespace blink {

PropertyHandleSet;

class Element;
class ComputedStyle;
class CompositorKeyframeValue;
class TimelineRange;
class V8ObjectBuilder;

// A base class representing an animation keyframe.
//
// Generically a keyframe is a set of (property, value) pairs. In the
// web-animations spec keyframes have a few additional properties:
//
//   * A possibly-null keyframe offset, which represents the keyframe's position
//     relative to other keyframes in the same effect.
//   * A non-null timing function, which applies to the period of time between
//     this keyframe and the next keyframe in the same effect and influences
//     the interpolation between them.
//   * An keyframe-specific composite operation, which specifies a specific
//     composite operation used to combine values in this keyframe with an
//     underlying value. If this is 'auto', the keyframe effect composite
//     operation is used instead.
//
// For spec details, refer to: https://w3.org/TR/web-animations-1/#keyframe
//
// Implementation-wise the base Keyframe class captures the offset, composite
// operation, and timing function. It is left to subclasses to define and store
// the set of (property, value) pairs.
//
// === PropertySpecificKeyframes ===
//
// When calculating the effect value of a keyframe effect, the web-animations
// spec requires that a set of 'property-specific' keyframes are created.
// Property-specific keyframes resolve any unspecified offsets in the keyframes,
// calculate computed values for the specified properties, convert shorthand
// properties to multiple longhand properties, and resolve any conflicting
// shorthand properties.
//
// In this implementation property-specific keyframes are created only once and
// cached for subsequent calls, rather than re-computing them for every sample
// from the keyframe effect. See KeyframeEffectModelBase::EnsureKeyframeGroups.
//
// FIXME: Make Keyframe immutable
class CORE_EXPORT Keyframe : public GarbageCollected<Keyframe> { … };

PropertySpecificKeyframe;

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_ANIMATION_KEYFRAME_H_