1/*
2 * Copyright 2018 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 androidx.core.graphics;
18
19import android.graphics.Path;
20import android.graphics.PointF;
21
22import androidx.annotation.FloatRange;
23import androidx.annotation.NonNull;
24import androidx.annotation.RequiresApi;
25
26import java.util.ArrayList;
27import java.util.Collection;
28import java.util.List;
29
30/** A set of path-related utility methods. */
31public final class PathUtils {
32    /**
33     * Flattens (or approximate) a {@link Path} with a series of line segments using a 0.5 pixel
34     * error.
35     *
36     * <em>Note:</em> This method requires API 26 or newer.
37     *
38     * @see #flatten(Path, float)
39     */
40    @RequiresApi(26)
41    @NonNull
42    public static Collection<PathSegment> flatten(@NonNull Path path) {
43        return flatten(path, 0.5f);
44    }
45
46    /**
47     * Flattens (or approximate) a {@link Path} with a series of line segments.
48     *
49     * <em>Note:</em> This method requires API 26 or newer.
50     *
51     * @param error The acceptable error for a line on the Path. Typically this would be
52     *              0.5 so that the error is less than half a pixel.
53     *
54     * @see Path#approximate
55     */
56    @RequiresApi(26)
57    @NonNull
58    public static Collection<PathSegment> flatten(@NonNull final Path path,
59            @FloatRange(from = 0) final float error) {
60        float[] pathData = path.approximate(error);
61        int pointCount = pathData.length / 3;
62        List<PathSegment> segments = new ArrayList<>(pointCount);
63        for (int i = 1; i < pointCount; i++) {
64            int index = i * 3;
65            int prevIndex = (i - 1) * 3;
66
67            float d = pathData[index];
68            float x = pathData[index + 1];
69            float y = pathData[index + 2];
70
71            float pd = pathData[prevIndex];
72            float px = pathData[prevIndex + 1];
73            float py = pathData[prevIndex + 2];
74
75            if (d != pd && (x != px || y != py)) {
76                segments.add(new PathSegment(new PointF(px, py), pd, new PointF(x, y), d));
77            }
78        }
79        return segments;
80    }
81
82    private PathUtils() {
83    }
84}
85