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

// Copyright 2017 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_TRANSITION_INTERPOLATION_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_ANIMATION_TRANSITION_INTERPOLATION_H_

#include <optional>

#include "base/check_op.h"
#include "third_party/blink/renderer/core/animation/compositor_animations.h"
#include "third_party/blink/renderer/core/animation/interpolation.h"
#include "third_party/blink/renderer/core/animation/interpolation_type.h"
#include "third_party/blink/renderer/core/core_export.h"

namespace blink {

class InterpolationEnvironment;

// See the documentation of Interpolation for general information about this
// class hierarchy.
//
// The primary difference between TransitionInterpolation and other
// Interpolation subclasses is that it must store additional data required for
// retargeting transition effects that were sent to the compositor thread.
// Retargeting a transition involves interrupting an in-progress transition and
// creating a new transition from the current state to the new end state.
//
// The TransitionInterpolation subclass stores the start and end keyframes as
// InterpolationValue objects, with an InterpolationType object that applies to
// both InterpolationValues. It additionally stores CompositorKeyframeValue
// objects corresponding to start and end keyframes as communicated to the
// compositor thread. Together, this is equivalent to representing the start and
// end keyframes as TransitionPropertySpecificKeyframe objects with the added
// constraint that they share an InterpolationType.
// TODO(crbug.com/442163): Store information for communication with the
// compositor without using CompositorKeyframeValue objects.
//
// During the effect application phase of animation computation, the current
// value of the property is applied to the element by calling the Apply
// function.
class CORE_EXPORT TransitionInterpolation : public Interpolation { … };

template <>
struct DowncastTraits<TransitionInterpolation> { … };

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_ANIMATION_TRANSITION_INTERPOLATION_H_