gecko-dev/dom/smil/nsSMILKeySpline.h
Cameron McCormack c2e4c54592 Bug 1198708 - Part 6: Implement KeyframeEffectReadOnly.getFrames(). r=birtles,bzbarsky
Since getFrames() must gather all properties set at a given keyframe
offset time for a given easing function, we need to provide a total
ordering for ComputedTimingFunction objects.  Until the spec defines how
to do this, we sort first by NS_STYLE_TRANSITION_TIMING_FUNCTION_*
value, then second by the four values in a cubic-bezier() function (in
order) or the integer and optional keyword in a steps() function.

Because we don't support automatic spacing of keyframes yet,
ComputedKeyFrame.computedOffset is always the same as Keyframe.offset.

Another assumption made is that the value of easing for a Keyframe
object at 100% should be the same as the value from the previous
Keyframe for the same property.  An alternative would be to leave off
easing from that Keyframe, which would need the default value for that
IDL dictionary member removed (otherwise it would always be set to
"linear").
2015-09-29 12:20:14 +10:00

123 lines
3.0 KiB
C++

/* -*- 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/. */
#ifndef NS_SMILKEYSPLINE_H_
#define NS_SMILKEYSPLINE_H_
#include "mozilla/ArrayUtils.h"
#include "mozilla/PodOperations.h"
/**
* Utility class to provide scaling defined in a keySplines element.
*/
class nsSMILKeySpline
{
public:
nsSMILKeySpline() { /* caller must call Init later */ }
/**
* Creates a new key spline control point description.
*
* aX1, etc. are the x1, y1, x2, y2 cubic Bezier control points as defined by
* SMILANIM 3.2.3. They must each be in the range 0.0 <= x <= 1.0
*/
nsSMILKeySpline(double aX1, double aY1,
double aX2, double aY2)
{
Init(aX1, aY1, aX2, aY2);
}
double X1() const { return mX1; }
double Y1() const { return mY1; }
double X2() const { return mX2; }
double Y2() const { return mY2; }
void Init(double aX1, double aY1,
double aX2, double aY2);
/**
* Gets the output (y) value for an input (x).
*
* @param aX The input x value. A floating-point number between 0 and
* 1 (inclusive).
*/
double GetSplineValue(double aX) const;
void GetSplineDerivativeValues(double aX, double& aDX, double& aDY) const;
bool operator==(const nsSMILKeySpline& aOther) const {
return mX1 == aOther.mX1 &&
mY1 == aOther.mY1 &&
mX2 == aOther.mX2 &&
mY2 == aOther.mY2;
}
bool operator!=(const nsSMILKeySpline& aOther) const {
return !(*this == aOther);
}
int32_t Compare(const nsSMILKeySpline& aRhs) const {
if (mX1 != aRhs.mX1) return mX1 < aRhs.mX1 ? -1 : 1;
if (mY1 != aRhs.mY1) return mY1 < aRhs.mY1 ? -1 : 1;
if (mX2 != aRhs.mX2) return mX2 < aRhs.mX2 ? -1 : 1;
if (mY2 != aRhs.mY2) return mY2 < aRhs.mY2 ? -1 : 1;
return 0;
}
private:
void
CalcSampleValues();
/**
* Returns x(t) given t, x1, and x2, or y(t) given t, y1, and y2.
*/
static double
CalcBezier(double aT, double aA1, double aA2);
/**
* Returns dx/dt given t, x1, and x2, or dy/dt given t, y1, and y2.
*/
static double
GetSlope(double aT, double aA1, double aA2);
double
GetTForX(double aX) const;
double
NewtonRaphsonIterate(double aX, double aGuessT) const;
double
BinarySubdivide(double aX, double aA, double aB) const;
static double
A(double aA1, double aA2)
{
return 1.0 - 3.0 * aA2 + 3.0 * aA1;
}
static double
B(double aA1, double aA2)
{
return 3.0 * aA2 - 6.0 * aA1;
}
static double
C(double aA1)
{
return 3.0 * aA1;
}
double mX1;
double mY1;
double mX2;
double mY2;
enum { kSplineTableSize = 11 };
double mSampleValues[kSplineTableSize];
static const double kSampleStepSize;
};
#endif // NS_SMILKEYSPLINE_H_