1/*
2 * Copyright (C) 2017 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
17package android.support.transition;
18
19import android.content.Context;
20import android.graphics.Path;
21import android.util.AttributeSet;
22
23/**
24 * This base class can be extended to provide motion along a Path to Transitions.
25 *
26 * <p>
27 * Transitions such as {@link android.transition.ChangeBounds} move Views, typically
28 * in a straight path between the start and end positions. Applications that desire to
29 * have these motions move in a curve can change how Views interpolate in two dimensions
30 * by extending PathMotion and implementing {@link #getPath(float, float, float, float)}.
31 * </p>
32 * <p>This may be used in XML as an element inside a transition.</p>
33 * <pre>
34 * {@code
35 * <changeBounds>
36 *     <pathMotion class="my.app.transition.MyPathMotion"/>
37 * </changeBounds>
38 * }
39 * </pre>
40 */
41public abstract class PathMotion {
42
43    public PathMotion() {
44    }
45
46    public PathMotion(Context context, AttributeSet attrs) {
47    }
48
49    /**
50     * Provide a Path to interpolate between two points <code>(startX, startY)</code> and
51     * <code>(endX, endY)</code>. This allows controlled curved motion along two dimensions.
52     *
53     * @param startX The x coordinate of the starting point.
54     * @param startY The y coordinate of the starting point.
55     * @param endX   The x coordinate of the ending point.
56     * @param endY   The y coordinate of the ending point.
57     * @return A Path along which the points should be interpolated. The returned Path
58     * must start at point <code>(startX, startY)</code>, typically using
59     * {@link android.graphics.Path#moveTo(float, float)} and end at <code>(endX, endY)</code>.
60     */
61    public abstract Path getPath(float startX, float startY, float endX, float endY);
62}
63