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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "nsAlgorithm.h" // For clamped()
#include "nsStyleUtil.h"
namespace mozilla {
void
ComputedTimingFunction::Init(const nsTimingFunction &aFunction)
{
mType = aFunction.mType;
if (nsTimingFunction::IsSplineType(mType)) {
mTimingFunction.Init(aFunction.mFunc.mX1, aFunction.mFunc.mY1,
aFunction.mFunc.mX2, aFunction.mFunc.mY2);
} else {
mSteps = aFunction.mSteps;
}
}
static inline double
StepTiming(uint32_t aSteps,
double aPortion,
ComputedTimingFunction::BeforeFlag aBeforeFlag,
nsTimingFunction::Type aType)
{
MOZ_ASSERT(0.0 <= aPortion && aPortion <= 1.0, "out of range");
MOZ_ASSERT(aType == nsTimingFunction::Type::StepStart ||
aType == nsTimingFunction::Type::StepEnd, "invalid type");
if (aPortion == 1.0) {
return 1.0;
}
// Calculate current step using step-end behavior
uint32_t step = uint32_t(aPortion * aSteps); // floor
// step-start is one step ahead
if (aType == nsTimingFunction::Type::StepStart) {
step++;
}
// If the "before flag" is set and we are at a transition point,
// drop back a step (but only if we are not already at the zero point--
// we do this clamping here since |step| is an unsigned integer)
if (step != 0 &&
aBeforeFlag == ComputedTimingFunction::BeforeFlag::Set &&
fmod(aPortion * aSteps, 1) == 0) {
step--;
}
// Convert to a progress value
return double(step) / double(aSteps);
}
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);
}
// Since we use endpoint-exclusive timing, the output of a steps(start) timing
// function when aPortion = 0.0 is the top of the first step. When aPortion is
// negative, however, we should use the bottom of the first step. We handle
// negative values of aPortion specially here since once we clamp aPortion
// to [0,1] below we will no longer be able to distinguish to the two cases.
if (aPortion < 0.0) {
return 0.0;
}
// Clamp in case of steps(end) and steps(start) for values greater than 1.
aPortion = clamped(aPortion, 0.0, 1.0);
return StepTiming(mSteps, aPortion, aBeforeFlag, mType);
}
int32_t
ComputedTimingFunction::Compare(const ComputedTimingFunction& aRhs) const
{
if (mType != aRhs.mType) {
return int32_t(mType) - int32_t(aRhs.mType);
}
if (mType == nsTimingFunction::Type::CubicBezier) {
int32_t order = mTimingFunction.Compare(aRhs.mTimingFunction);
if (order != 0) {
return order;
}
} else if (mType == nsTimingFunction::Type::StepStart ||
mType == nsTimingFunction::Type::StepEnd) {
if (mSteps != aRhs.mSteps) {
return int32_t(mSteps) - int32_t(aRhs.mSteps);
}
}
return 0;
}
void
ComputedTimingFunction::AppendToString(nsAString& aResult) const
{
switch (mType) {
case nsTimingFunction::Type::CubicBezier:
nsStyleUtil::AppendCubicBezierTimingFunction(mTimingFunction.X1(),
mTimingFunction.Y1(),
mTimingFunction.X2(),
mTimingFunction.Y2(),
aResult);
break;
case nsTimingFunction::Type::StepStart:
case nsTimingFunction::Type::StepEnd:
nsStyleUtil::AppendStepsTimingFunction(mType, mSteps, aResult);
break;
default:
nsStyleUtil::AppendCubicBezierKeywordTimingFunction(mType, aResult);
break;
}
}
/* 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.
nsTimingFunction::Type lhsType = aLhs.isNothing() ?
nsTimingFunction::Type::Linear : aLhs->GetType();
nsTimingFunction::Type rhsType = aRhs.isNothing() ?
nsTimingFunction::Type::Linear : aRhs->GetType();
if (lhsType != rhsType) {
return int32_t(lhsType) - int32_t(rhsType);
}
// Both of them are Nothing().
if (lhsType == nsTimingFunction::Type::Linear) {
return 0;
}
// Other types.
return aLhs->Compare(aRhs.value());
}
} // namespace mozilla
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