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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#include <utility>
#include "PLDHashTable.h"
#include "SMILTargetIdentifier.h"
#include "mozilla/SMILAnimationFunction.h"
#include "mozilla/SMILCompositorTable.h"
#include "mozilla/UniquePtr.h"
#include "nsCSSPropertyID.h"
#include "nsString.h"
#include "nsTHashtable.h"
namespace mozilla {
class ComputedStyle;
// SMILCompositor
// Performs the composition of the animation sandwich by combining the results
// of a series animation functions according to the rules of SMIL composition
// including prioritising animations.
class SMILCompositor : public PLDHashEntryHdr {
using KeyType = SMILTargetIdentifier;
using KeyTypeRef = const KeyType&;
using KeyTypePointer = const KeyType*;
explicit SMILCompositor(KeyTypePointer aKey)
: mKey(*aKey), mForceCompositing(false) {}
SMILCompositor(SMILCompositor&& toMove) noexcept
: PLDHashEntryHdr(std::move(toMove)),
mForceCompositing(false) {}
// PLDHashEntryHdr methods
KeyTypeRef GetKey() const { return mKey; }
bool KeyEquals(KeyTypePointer aKey) const;
static KeyTypePointer KeyToPointer(KeyTypeRef aKey) { return &aKey; }
static PLDHashNumber HashKey(KeyTypePointer aKey);
enum { ALLOW_MEMMOVE = false };
// Adds the given animation function to this Compositor's list of functions
void AddAnimationFunction(SMILAnimationFunction* aFunc);
// Composes the attribute's current value with the list of animation
// functions, and assigns the resulting value to this compositor's target
// attribute. If a change is made that might produce style updates,
// aMightHavePendingStyleUpdates is set to true. Otherwise it is not modified.
void ComposeAttribute(bool& aMightHavePendingStyleUpdates);
// Clears animation effects on my target attribute
void ClearAnimationEffects();
// Cycle-collection support
void Traverse(nsCycleCollectionTraversalCallback* aCallback);
// Toggles a bit that will force us to composite (bypassing early-return
// optimizations) when we hit ComposeAttribute.
void ToggleForceCompositing() { mForceCompositing = true; }
// Transfers |aOther|'s mCachedBaseValue to |this|
void StealCachedBaseValue(SMILCompositor* aOther) {
mCachedBaseValue = std::move(aOther->mCachedBaseValue);
bool HasSameNumberOfAnimationFunctionsAs(const SMILCompositor& aOther) const {
return mAnimationFunctions.Length() == aOther.mAnimationFunctions.Length();
// Create a SMILAttr for my target, on the heap.
// @param aBaseComputedStyle An optional ComputedStyle which, if set, will be
// used when fetching the base style.
UniquePtr<SMILAttr> CreateSMILAttr(const ComputedStyle* aBaseComputedStyle);
// Returns the CSS property this compositor should animate, or
// eCSSProperty_UNKNOWN if this compositor does not animate a CSS property.
nsCSSPropertyID GetCSSPropertyToAnimate() const;
// Returns true if we might need to refer to base styles (i.e. we are
// targeting a CSS property and have one or more animation functions that
// don't just replace the underlying value).
// This might return true in some cases where we don't actually need the base
// style since it doesn't build up the animation sandwich to check if the
// functions that appear to need the base style are actually replaced by
// a function further up the stack.
bool MightNeedBaseStyle() const;
// Finds the index of the first function that will affect our animation
// sandwich. Also toggles the 'mForceCompositing' flag if it finds that any
// (used) functions have changed.
uint32_t GetFirstFuncToAffectSandwich();
// If the passed-in base value differs from our cached base value, this
// method updates the cached value (and toggles the 'mForceCompositing' flag)
void UpdateCachedBaseValue(const SMILValue& aBaseValue);
// The hash key (tuple of element and attributeName)
KeyType mKey;
// Hash Value: List of animation functions that animate the specified attr
nsTArray<SMILAnimationFunction*> mAnimationFunctions;
// Member data for detecting when we need to force-recompose
// ---------------------------------------------------------
// Flag for tracking whether we need to compose. Initialized to false, but
// gets flipped to true if we detect that something has changed.
bool mForceCompositing;
// Cached base value, so we can detect & force-recompose when it changes
// from one sample to the next. (SMILAnimationController moves this
// forward from the previous sample's compositor by calling
// StealCachedBaseValue.)
SMILValue mCachedBaseValue;
} // namespace mozilla