////////////////////////////////////////////////////////////////////////////////
//
//  Licensed to the Apache Software Foundation (ASF) under one or more
//  contributor license agreements.  See the NOTICE file distributed with
//  this work for additional information regarding copyright ownership.
//  The ASF licenses this file to You under the Apache License, Version 2.0
//  (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.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
//
////////////////////////////////////////////////////////////////////////////////

package mx.effects.easing
{

/**
 *  The Spark effects provided as of Flex 4 use classes which implement the 
 *  IEaser interface instead of the easing functions in classes like Linear for 
 *  the earlier Flex 3 effects. To achieve the same functionality of the old
 *  Linear class, create a new instance of spark.effects.easing.Linear or call
 *  spark.effects.easing.Linear.getInstance() to get a singleton instance.
 */
[Alternative(replacement="spark.effects.easing.Linear", since="4.0")]

/**
 *  The Linear class defines easing functions to implement 
 *  linear motion with Flex effect classes. 
 *
 *  For more information, see http://www.robertpenner.com/profmx.
 *  
 *  @langversion 3.0
 *  @playerversion Flash 9
 *  @playerversion AIR 1.1
 *  @productversion Flex 3
 */  
public class Linear
{
    include "../../core/Version.as";

    //--------------------------------------------------------------------------
    //
    //  Class methods
    //
    //--------------------------------------------------------------------------
    
    /**
     *  The <code>easeNone()</code> method defines a constant motion, 
     *  with no acceleration. 
     *
     *  @param t Specifies time.
     *
     *  @param b Specifies the initial position of a component.
     *
     *  @param c Specifies the total change in position of the component.
     *
     *  @param d Specifies the duration of the effect, in milliseconds.
     *
     *  @return Number corresponding to the position of the component.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion Flex 3
     */  
    public static function easeNone(t:Number, b:Number,
                                    c:Number, d:Number):Number
    {
        return c * t / d + b;
    }

    /**
     *  The <code>easeIn()</code> method starts motion from zero velocity, 
     *  and then accelerates motion as it executes. 
     *
     *  @param t Specifies time.
     *
     *  @param b Specifies the initial position of a component.
     *
     *  @param c Specifies the total change in position of the component.
     *
     *  @param d Specifies the duration of the effect, in milliseconds.
     *
     *  @return Number corresponding to the position of the component.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion Flex 3
     */  
    public static function easeIn(t:Number, b:Number,
                                  c:Number, d:Number):Number
    {
        return c * t / d + b;
    }

    /**
     *  The <code>easeOut()</code> method starts motion fast, 
     *  and then decelerates motion to a zero velocity as it executes. 
     *
     *  @param t Specifies time.
     *
     *  @param b Specifies the initial position of a component.
     *
     *  @param c Specifies the total change in position of the component.
     *
     *  @param d Specifies the duration of the effect, in milliseconds.
     *
     *  @return Number corresponding to the position of the component.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion Flex 3
     */  
    public static function easeOut(t:Number, b:Number,
                                   c:Number, d:Number):Number
    {
        return c * t / d + b;
    }

    /**
     *  The <code>easeInOut()</code> method combines the motion 
     *  of the <code>easeIn()</code> and <code>easeOut()</code> methods
     *  to start the motion from zero velocity, accelerate motion, 
     *  then decelerate back to zero velocity. 
     *
     *  @param t Specifies time.
     *
     *  @param b Specifies the initial position of a component.
     *
     *  @param c Specifies the total change in position of the component.
     *
     *  @param d Specifies the duration of the effect, in milliseconds.
     *
     *  @return Number corresponding to the position of the component.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion Flex 3
     */  
    public static function easeInOut(t:Number, b:Number,
                                     c:Number, d:Number):Number
    {
        return c * t / d + b;
    }
}

}