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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 package android.animation;
     17 
     18 import java.util.List;
     19 
     20 /**
     21  * This interface abstracts a collection of Keyframe objects and is called by
     22  * ValueAnimator to calculate values between those keyframes for a given animation.
     23  * @hide
     24  */
     25 public interface Keyframes extends Cloneable {
     26 
     27     /**
     28      * Sets the TypeEvaluator to be used when calculating animated values. This object
     29      * is required only for Keyframes that are not either IntKeyframes or FloatKeyframes,
     30      * both of which assume their own evaluator to speed up calculations with those primitive
     31      * types.
     32      *
     33      * @param evaluator The TypeEvaluator to be used to calculate animated values.
     34      */
     35     void setEvaluator(TypeEvaluator evaluator);
     36 
     37     /**
     38      * @return The value type contained by the contained Keyframes.
     39      */
     40     Class getType();
     41 
     42     /**
     43      * Gets the animated value, given the elapsed fraction of the animation (interpolated by the
     44      * animation's interpolator) and the evaluator used to calculate in-between values. This
     45      * function maps the input fraction to the appropriate keyframe interval and a fraction
     46      * between them and returns the interpolated value. Note that the input fraction may fall
     47      * outside the [0-1] bounds, if the animation's interpolator made that happen (e.g., a
     48      * spring interpolation that might send the fraction past 1.0). We handle this situation by
     49      * just using the two keyframes at the appropriate end when the value is outside those bounds.
     50      *
     51      * @param fraction The elapsed fraction of the animation
     52      * @return The animated value.
     53      */
     54     Object getValue(float fraction);
     55 
     56     /**
     57      * @return A list of all Keyframes contained by this. This may return null if this is
     58      * not made up of Keyframes.
     59      */
     60     List<Keyframe> getKeyframes();
     61 
     62     Keyframes clone();
     63 
     64     /**
     65      * A specialization of Keyframes that has integer primitive value calculation.
     66      */
     67     public interface IntKeyframes extends Keyframes {
     68 
     69         /**
     70          * Works like {@link #getValue(float)}, but returning a primitive.
     71          * @param fraction The elapsed fraction of the animation
     72          * @return The animated value.
     73          */
     74         int getIntValue(float fraction);
     75     }
     76 
     77     /**
     78      * A specialization of Keyframes that has float primitive value calculation.
     79      */
     80     public interface FloatKeyframes extends Keyframes {
     81 
     82         /**
     83          * Works like {@link #getValue(float)}, but returning a primitive.
     84          * @param fraction The elapsed fraction of the animation
     85          * @return The animated value.
     86          */
     87         float getFloatValue(float fraction);
     88     }
     89 }
     90