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 */
16package android.animation;
17
18import java.util.ArrayList;
19import java.util.List;
20
21/**
22 * This interface abstracts a collection of Keyframe objects and is called by
23 * ValueAnimator to calculate values between those keyframes for a given animation.
24 */
25interface 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     * If subclass has variables that it calculates based on the Keyframes, it should reset them
58     * when this method is called because Keyframe contents might have changed.
59     */
60    void invalidateCache();
61
62    /**
63     * @return A list of all Keyframes contained by this. This may return null if this is
64     * not made up of Keyframes.
65     */
66    List<Keyframe> getKeyframes();
67
68    Keyframes clone();
69
70    /**
71     * A specialization of Keyframes that has integer primitive value calculation.
72     */
73    public interface IntKeyframes extends Keyframes {
74
75        /**
76         * Works like {@link #getValue(float)}, but returning a primitive.
77         * @param fraction The elapsed fraction of the animation
78         * @return The animated value.
79         */
80        int getIntValue(float fraction);
81    }
82
83    /**
84     * A specialization of Keyframes that has float primitive value calculation.
85     */
86    public interface FloatKeyframes extends Keyframes {
87
88        /**
89         * Works like {@link #getValue(float)}, but returning a primitive.
90         * @param fraction The elapsed fraction of the animation
91         * @return The animated value.
92         */
93        float getFloatValue(float fraction);
94    }
95}
96