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77 lines
3.0 KiB
C++
77 lines
3.0 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef DOM_SMIL_SMILMILESTONE_H_
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#define DOM_SMIL_SMILMILESTONE_H_
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#include "mozilla/SMILTypes.h"
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namespace mozilla {
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/*
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* A significant moment in an SMILTimedElement's lifetime where a sample is
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* required.
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*
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* Animations register the next milestone in their lifetime with the time
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* container that they belong to. When the animation controller goes to run
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* a sample it first visits all the animations that have a registered milestone
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* in order of their milestone times. This allows interdependencies between
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* animations to be correctly resolved and events to fire in the proper order.
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*
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* A distinction is made between a milestone representing the end of an interval
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* and any other milestone. This is because if animation A ends at time t, and
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* animation B begins at the same time t (or has some other significant moment
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* such as firing a repeat event), SMIL's endpoint-exclusive timing model
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* implies that the interval end occurs first. In fact, interval ends can be
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* thought of as ending an infinitesimally small time before t. Therefore,
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* A should be sampled before B.
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*
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* Furthermore, this distinction between sampling the end of an interval and
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* a regular sample is used within the timing model (specifically in
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* SMILTimedElement) to ensure that all intervals ending at time t are sampled
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* before any new intervals are entered so that we have a fully up-to-date set
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* of instance times available before committing to a new interval. Once an
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* interval is entered, the begin time is fixed.
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*/
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class SMILMilestone {
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public:
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constexpr SMILMilestone(SMILTime aTime, bool aIsEnd)
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: mTime(aTime), mIsEnd(aIsEnd) {}
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constexpr SMILMilestone() : mTime(0), mIsEnd(false) {}
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bool operator==(const SMILMilestone& aOther) const {
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return mTime == aOther.mTime && mIsEnd == aOther.mIsEnd;
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}
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bool operator!=(const SMILMilestone& aOther) const {
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return !(*this == aOther);
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}
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bool operator<(const SMILMilestone& aOther) const {
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// Earlier times sort first, and for equal times end milestones sort first
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return mTime < aOther.mTime ||
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(mTime == aOther.mTime && mIsEnd && !aOther.mIsEnd);
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}
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bool operator<=(const SMILMilestone& aOther) const {
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return *this == aOther || *this < aOther;
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}
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bool operator>=(const SMILMilestone& aOther) const {
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return !(*this < aOther);
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}
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SMILTime mTime; // The milestone time. This may be in container time or
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// parent container time depending on where it is used.
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bool mIsEnd; // true if this milestone corresponds to an interval
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// end, false otherwise.
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};
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} // namespace mozilla
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#endif // DOM_SMIL_SMILMILESTONE_H_
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