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.transition;
17
18import android.content.Context;
19import android.content.res.TypedArray;
20import android.graphics.Matrix;
21import android.graphics.Path;
22import android.graphics.PathMeasure;
23import android.util.AttributeSet;
24import android.util.PathParser;
25
26import com.android.internal.R;
27
28/**
29 * A PathMotion that takes a Path pattern and applies it to the separation between two points.
30 * The starting point of the Path will be moved to the origin and the end point will be scaled
31 * and rotated so that it matches with the target end point.
32 * <p>This may be used in XML as an element inside a transition.</p>
33 * <pre>{@code
34 * <changeBounds>
35 *     <patternPathMotion android:patternPathData="M0 0 L0 100 L100 100"/>
36 * </changeBounds>}
37 * </pre>
38 */
39public class PatternPathMotion extends PathMotion {
40
41    private Path mOriginalPatternPath;
42
43    private final Path mPatternPath = new Path();
44
45    private final Matrix mTempMatrix = new Matrix();
46
47    /**
48     * Constructs a PatternPathMotion with a straight-line pattern.
49     */
50    public PatternPathMotion() {
51        mPatternPath.lineTo(1, 0);
52        mOriginalPatternPath = mPatternPath;
53    }
54
55    public PatternPathMotion(Context context, AttributeSet attrs) {
56        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.PatternPathMotion);
57        try {
58            String pathData = a.getString(R.styleable.PatternPathMotion_patternPathData);
59            if (pathData == null) {
60                throw new RuntimeException("pathData must be supplied for patternPathMotion");
61            }
62            Path pattern = PathParser.createPathFromPathData(pathData);
63            setPatternPath(pattern);
64        } finally {
65            a.recycle();
66        }
67
68    }
69
70    /**
71     * Creates a PatternPathMotion with the Path defining a pattern of motion between two
72     * coordinates. The pattern will be translated, rotated, and scaled to fit between the start
73     * and end points. The pattern must not be empty and must have the end point differ from the
74     * start point.
75     *
76     * @param patternPath A Path to be used as a pattern for two-dimensional motion.
77     */
78    public PatternPathMotion(Path patternPath) {
79        setPatternPath(patternPath);
80    }
81
82    /**
83     * Returns the Path defining a pattern of motion between two coordinates.
84     * The pattern will be translated, rotated, and scaled to fit between the start and end points.
85     * The pattern must not be empty and must have the end point differ from the start point.
86     *
87     * @return the Path defining a pattern of motion between two coordinates.
88     * @attr ref android.R.styleable#PatternPathMotion_patternPathData
89     */
90    public Path getPatternPath() {
91        return mOriginalPatternPath;
92    }
93
94    /**
95     * Sets the Path defining a pattern of motion between two coordinates.
96     * The pattern will be translated, rotated, and scaled to fit between the start and end points.
97     * The pattern must not be empty and must have the end point differ from the start point.
98     *
99     * @param patternPath A Path to be used as a pattern for two-dimensional motion.
100     * @attr ref android.R.styleable#PatternPathMotion_patternPathData
101     */
102    public void setPatternPath(Path patternPath) {
103        PathMeasure pathMeasure = new PathMeasure(patternPath, false);
104        float length = pathMeasure.getLength();
105        float[] pos = new float[2];
106        pathMeasure.getPosTan(length, pos, null);
107        float endX = pos[0];
108        float endY = pos[1];
109        pathMeasure.getPosTan(0, pos, null);
110        float startX = pos[0];
111        float startY = pos[1];
112
113        if (startX == endX && startY == endY) {
114            throw new IllegalArgumentException("pattern must not end at the starting point");
115        }
116
117        mTempMatrix.setTranslate(-startX, -startY);
118        float dx = endX - startX;
119        float dy = endY - startY;
120        float distance = (float) Math.hypot(dx, dy);
121        float scale = 1 / distance;
122        mTempMatrix.postScale(scale, scale);
123        double angle = Math.atan2(dy, dx);
124        mTempMatrix.postRotate((float) Math.toDegrees(-angle));
125        patternPath.transform(mTempMatrix, mPatternPath);
126        mOriginalPatternPath = patternPath;
127    }
128
129    @Override
130    public Path getPath(float startX, float startY, float endX, float endY) {
131        double dx = endX - startX;
132        double dy = endY - startY;
133        float length = (float) Math.hypot(dx, dy);
134        double angle = Math.atan2(dy, dx);
135
136        mTempMatrix.setScale(length, length);
137        mTempMatrix.postRotate((float) Math.toDegrees(angle));
138        mTempMatrix.postTranslate(startX, startY);
139        Path path = new Path();
140        mPatternPath.transform(mTempMatrix, path);
141        return path;
142    }
143
144}
145