gecko-dev/content/smil/nsSMILKeySpline.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the Mozilla SMIL module.
*
* The Initial Developer of the Original Code is Brian Birtles.
* Portions created by the Initial Developer are Copyright (C) 2005
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Brian Birtles <birtles@gmail.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef NS_SMILKEYSPLINE_H_
#define NS_SMILKEYSPLINE_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);
}
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;
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_