BackgroundHelper.java revision 99ec8b0cb375f7e5577ea3ec9f09e6ff7a95de0d 
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.v17.leanback.widget.BackgroundHelperKitkat;
21import android.view.View;
22
23
24/**
25 * Helper for view backgrounds.
26 * @hide
27 */
28public final class BackgroundHelper {
29
30    final static BackgroundHelperVersionImpl sImpl;
31
32    static interface BackgroundHelperVersionImpl {
33        public void setBackgroundPreservingAlpha(View view, Drawable drawable);
34    }
35
36    private static final class BackgroundHelperStubImpl implements BackgroundHelperVersionImpl {
37        BackgroundHelperStubImpl() {
38        }
39
40        @Override
41        public void setBackgroundPreservingAlpha(View view, Drawable drawable) {
42            // Cannot query drawable alpha
43            view.setBackground(drawable);
44        }
45    }
46
47    private static final class BackgroundHelperKitkatImpl implements BackgroundHelperVersionImpl {
48        BackgroundHelperKitkatImpl() {
49        }
50
51        @Override
52        public void setBackgroundPreservingAlpha(View view, Drawable drawable) {
53            BackgroundHelperKitkat.setBackgroundPreservingAlpha(view, drawable);
54        }
55    }
56
57    private BackgroundHelper() {
58    }
59
60    static {
61        if (Build.VERSION.SDK_INT >= 19) {
62            sImpl = new BackgroundHelperKitkatImpl();
63        } else {
64            sImpl = new BackgroundHelperStubImpl();
65        }
66    }
67
68    public static void setBackgroundPreservingAlpha(View view, Drawable drawable) {
69        sImpl.setBackgroundPreservingAlpha(view, drawable);
70    }
71}
72