StaticShadowHelper.java revision f4acd3cf076435ce836a6d4a9027b73ec3050def 
1/*
2 * Copyright (C) 2015 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.support.v17.leanback.widget;
17
18import android.os.Build;
19import android.view.View;
20import android.view.ViewGroup;
21
22
23/**
24 * Helper for static (nine patch) shadows.
25 */
26final class StaticShadowHelper {
27
28    final static StaticShadowHelper sInstance = new StaticShadowHelper();
29    boolean mSupportsShadow;
30    ShadowHelperVersionImpl mImpl;
31
32    /**
33     * Interface implemented by classes that support Shadow.
34     */
35    static interface ShadowHelperVersionImpl {
36        public void prepareParent(ViewGroup parent);
37        public Object addStaticShadow(ViewGroup shadowContainer, boolean roundedCorners);
38        public void setShadowFocusLevel(Object impl, float level);
39    }
40
41    /**
42     * Interface used when we do not support Shadow animations.
43     */
44    private static final class ShadowHelperStubImpl implements ShadowHelperVersionImpl {
45        @Override
46        public void prepareParent(ViewGroup parent) {
47            // do nothing
48        }
49
50        @Override
51        public Object addStaticShadow(ViewGroup shadowContainer, boolean roundedCorners) {
52            // do nothing
53            return null;
54        }
55
56        @Override
57        public void setShadowFocusLevel(Object impl, float level) {
58            // do nothing
59        }
60    }
61
62    /**
63     * Implementation used on JBMR2 (and above).
64     */
65    private static final class ShadowHelperJbmr2Impl implements ShadowHelperVersionImpl {
66        @Override
67        public void prepareParent(ViewGroup parent) {
68            ShadowHelperJbmr2.prepareParent(parent);
69        }
70
71        @Override
72        public Object addStaticShadow(ViewGroup shadowContainer, boolean roundedCorners) {
73            // Static shadows are always rounded
74            return ShadowHelperJbmr2.addShadow(shadowContainer);
75        }
76
77        @Override
78        public void setShadowFocusLevel(Object impl, float level) {
79            ShadowHelperJbmr2.setShadowFocusLevel(impl, level);
80        }
81    }
82
83    /**
84     * Returns the StaticShadowHelper.
85     */
86    private StaticShadowHelper() {
87        if (Build.VERSION.SDK_INT >= 18) {
88            mSupportsShadow = true;
89            mImpl = new ShadowHelperJbmr2Impl();
90        } else {
91            mSupportsShadow = false;
92            mImpl = new ShadowHelperStubImpl();
93        }
94    }
95
96    public static StaticShadowHelper getInstance() {
97        return sInstance;
98    }
99
100    public boolean supportsShadow() {
101        return mSupportsShadow;
102    }
103
104    public void prepareParent(ViewGroup parent) {
105        mImpl.prepareParent(parent);
106    }
107
108    public Object addStaticShadow(ViewGroup shadowContainer, boolean roundedCorners) {
109        return mImpl.addStaticShadow(shadowContainer, roundedCorners);
110    }
111
112    public void setShadowFocusLevel(Object impl, float level) {
113        mImpl.setShadowFocusLevel(impl, level);
114    }
115}
116