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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 http://mozilla.org/MPL/2.0/. */
#include "ComputedTimingFunction.h"
#include "mozilla/ServoBindings.h"
#include "nsAlgorithm.h" // For clamped()
namespace mozilla {
void ComputedTimingFunction::Init(const nsTimingFunction& aFunction) {
const StyleComputedTimingFunction& timing = aFunction.mTiming;
switch (timing.tag) {
case StyleComputedTimingFunction::Tag::Keyword: {
mType = static_cast<Type>(static_cast<uint8_t>(timing.keyword._0));
static_assert(
static_cast<uint8_t>(StyleTimingKeyword::Linear) == 0 &&
static_cast<uint8_t>(StyleTimingKeyword::Ease) == 1 &&
static_cast<uint8_t>(StyleTimingKeyword::EaseIn) == 2 &&
static_cast<uint8_t>(StyleTimingKeyword::EaseOut) == 3 &&
static_cast<uint8_t>(StyleTimingKeyword::EaseInOut) == 4,
"transition timing function constants not as expected");
static const float timingFunctionValues[5][4] = {
{0.00f, 0.00f, 1.00f, 1.00f}, // linear
{0.25f, 0.10f, 0.25f, 1.00f}, // ease
{0.42f, 0.00f, 1.00f, 1.00f}, // ease-in
{0.00f, 0.00f, 0.58f, 1.00f}, // ease-out
{0.42f, 0.00f, 0.58f, 1.00f} // ease-in-out
};
const float(&values)[4] = timingFunctionValues[uint8_t(mType)];
mTimingFunction.Init(values[0], values[1], values[2], values[3]);
break;
}
case StyleComputedTimingFunction::Tag::CubicBezier:
mType = Type::CubicBezier;
mTimingFunction.Init(timing.cubic_bezier.x1, timing.cubic_bezier.y1,
timing.cubic_bezier.x2, timing.cubic_bezier.y2);
break;
case StyleComputedTimingFunction::Tag::Steps:
mType = Type::Step;
mSteps.mSteps = static_cast<uint32_t>(timing.steps._0);
mSteps.mPos = timing.steps._1;
break;
}
}
static inline double StepTiming(
const ComputedTimingFunction::StepFunc& aStepFunc, double aPortion,
ComputedTimingFunction::BeforeFlag aBeforeFlag) {
// Use the algorithm defined in the spec:
// https://drafts.csswg.org/css-easing-1/#step-timing-function-algo
// Calculate current step.
int32_t currentStep = floor(aPortion * aStepFunc.mSteps);
// Increment current step if it is jump-start or start.
if (aStepFunc.mPos == StyleStepPosition::Start ||
aStepFunc.mPos == StyleStepPosition::JumpStart ||
aStepFunc.mPos == StyleStepPosition::JumpBoth) {
++currentStep;
}
// If the "before flag" is set and we are at a transition point,
// drop back a step
if (aBeforeFlag == ComputedTimingFunction::BeforeFlag::Set &&
fmod(aPortion * aStepFunc.mSteps, 1) == 0) {
--currentStep;
}
// We should not produce a result outside [0, 1] unless we have an
// input outside that range. This takes care of steps that would otherwise
// occur at boundaries.
if (aPortion >= 0.0 && currentStep < 0) {
currentStep = 0;
}
int32_t jumps = aStepFunc.mSteps;
if (aStepFunc.mPos == StyleStepPosition::JumpBoth) {
++jumps;
} else if (aStepFunc.mPos == StyleStepPosition::JumpNone) {
--jumps;
}
if (aPortion <= 1.0 && currentStep > jumps) {
currentStep = jumps;
}
// Convert to the output progress value.
MOZ_ASSERT(jumps > 0, "`jumps` should be a positive integer");
return double(currentStep) / double(jumps);
}
double ComputedTimingFunction::GetValue(
double aPortion, ComputedTimingFunction::BeforeFlag aBeforeFlag) const {
if (HasSpline()) {
// Check for a linear curve.
// (GetSplineValue(), below, also checks this but doesn't work when
// aPortion is outside the range [0.0, 1.0]).
if (mTimingFunction.X1() == mTimingFunction.Y1() &&
mTimingFunction.X2() == mTimingFunction.Y2()) {
return aPortion;
}
// Ensure that we return 0 or 1 on both edges.
if (aPortion == 0.0) {
return 0.0;
}
if (aPortion == 1.0) {
return 1.0;
}
// For negative values, try to extrapolate with tangent (p1 - p0) or,
// if p1 is coincident with p0, with (p2 - p0).
if (aPortion < 0.0) {
if (mTimingFunction.X1() > 0.0) {
return aPortion * mTimingFunction.Y1() / mTimingFunction.X1();
} else if (mTimingFunction.Y1() == 0 && mTimingFunction.X2() > 0.0) {
return aPortion * mTimingFunction.Y2() / mTimingFunction.X2();
}
// If we can't calculate a sensible tangent, don't extrapolate at all.
return 0.0;
}
// For values greater than 1, try to extrapolate with tangent (p2 - p3) or,
// if p2 is coincident with p3, with (p1 - p3).
if (aPortion > 1.0) {
if (mTimingFunction.X2() < 1.0) {
return 1.0 + (aPortion - 1.0) * (mTimingFunction.Y2() - 1) /
(mTimingFunction.X2() - 1);
} else if (mTimingFunction.Y2() == 1 && mTimingFunction.X1() < 1.0) {
return 1.0 + (aPortion - 1.0) * (mTimingFunction.Y1() - 1) /
(mTimingFunction.X1() - 1);
}
// If we can't calculate a sensible tangent, don't extrapolate at all.
return 1.0;
}
return mTimingFunction.GetSplineValue(aPortion);
}
return StepTiming(mSteps, aPortion, aBeforeFlag);
}
int32_t ComputedTimingFunction::Compare(
const ComputedTimingFunction& aRhs) const {
if (mType != aRhs.mType) {
return int32_t(mType) - int32_t(aRhs.mType);
}
if (mType == Type::CubicBezier) {
int32_t order = mTimingFunction.Compare(aRhs.mTimingFunction);
if (order != 0) {
return order;
}
} else if (mType == Type::Step) {
if (mSteps.mPos != aRhs.mSteps.mPos) {
return int32_t(mSteps.mPos) - int32_t(aRhs.mSteps.mPos);
} else if (mSteps.mSteps != aRhs.mSteps.mSteps) {
return int32_t(mSteps.mSteps) - int32_t(aRhs.mSteps.mSteps);
}
}
return 0;
}
void ComputedTimingFunction::AppendToString(nsACString& aResult) const {
nsTimingFunction timing;
switch (mType) {
case Type::CubicBezier:
timing.mTiming = StyleComputedTimingFunction::CubicBezier(
mTimingFunction.X1(), mTimingFunction.Y1(), mTimingFunction.X2(),
mTimingFunction.Y2());
break;
case Type::Step:
timing.mTiming =
StyleComputedTimingFunction::Steps(mSteps.mSteps, mSteps.mPos);
break;
case Type::Linear:
case Type::Ease:
case Type::EaseIn:
case Type::EaseOut:
case Type::EaseInOut:
timing.mTiming = StyleComputedTimingFunction::Keyword(
static_cast<StyleTimingKeyword>(mType));
break;
default:
MOZ_ASSERT_UNREACHABLE("Unsupported timing type");
}
Servo_SerializeEasing(&timing, &aResult);
}
/* static */
int32_t ComputedTimingFunction::Compare(
const Maybe<ComputedTimingFunction>& aLhs,
const Maybe<ComputedTimingFunction>& aRhs) {
// We can't use |operator<| for const Maybe<>& here because
// 'ease' is prior to 'linear' which is represented by Nothing().
// So we have to convert Nothing() as 'linear' and check it first.
Type lhsType = aLhs.isNothing() ? Type::Linear : aLhs->GetType();
Type rhsType = aRhs.isNothing() ? Type::Linear : aRhs->GetType();
if (lhsType != rhsType) {
return int32_t(lhsType) - int32_t(rhsType);
}
// Both of them are Nothing().
if (lhsType == Type::Linear) {
return 0;
}
// Other types.
return aLhs->Compare(aRhs.value());
}
} // namespace mozilla
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