BackgroundHelper.java revision c39d9c75590eca86a5e7e32a8824ba04a0d42e9b 
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.graphics.drawable.Drawable;
19import android.os.Build;
20import android.support.annotation.RestrictTo;
21import android.support.v17.leanback.widget.BackgroundHelperKitkat;
22import android.view.View;
23
24import static android.support.annotation.RestrictTo.Scope.GROUP_ID;
25
26
27/**
28 * Helper for view backgrounds.
29 * @hide
30 */
31@RestrictTo(GROUP_ID)
32public final class BackgroundHelper {
33
34    final static BackgroundHelperVersionImpl sImpl;
35
36    interface BackgroundHelperVersionImpl {
37        void setBackgroundPreservingAlpha(View view, Drawable drawable);
38    }
39
40    private static final class BackgroundHelperStubImpl implements BackgroundHelperVersionImpl {
41        BackgroundHelperStubImpl() {
42        }
43
44        @Override
45        public void setBackgroundPreservingAlpha(View view, Drawable drawable) {
46            // Cannot query drawable alpha
47            view.setBackground(drawable);
48        }
49    }
50
51    private static final class BackgroundHelperKitkatImpl implements BackgroundHelperVersionImpl {
52        BackgroundHelperKitkatImpl() {
53        }
54
55        @Override
56        public void setBackgroundPreservingAlpha(View view, Drawable drawable) {
57            BackgroundHelperKitkat.setBackgroundPreservingAlpha(view, drawable);
58        }
59    }
60
61    private BackgroundHelper() {
62    }
63
64    static {
65        if (Build.VERSION.SDK_INT >= 19) {
66            sImpl = new BackgroundHelperKitkatImpl();
67        } else {
68            sImpl = new BackgroundHelperStubImpl();
69        }
70    }
71
72    public static void setBackgroundPreservingAlpha(View view, Drawable drawable) {
73        sImpl.setBackgroundPreservingAlpha(view, drawable);
74    }
75}
76