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 @Override 38 public void setBackgroundPreservingAlpha(View view, Drawable drawable) { 39 // Cannot query drawable alpha 40 view.setBackground(drawable); 41 } 42 } 43 44 private static final class BackgroundHelperKitkatImpl implements BackgroundHelperVersionImpl { 45 @Override 46 public void setBackgroundPreservingAlpha(View view, Drawable drawable) { 47 BackgroundHelperKitkat.setBackgroundPreservingAlpha(view, drawable); 48 } 49 } 50 51 private BackgroundHelper() { 52 } 53 54 static { 55 if (Build.VERSION.SDK_INT >= 19) { 56 sImpl = new BackgroundHelperKitkatImpl(); 57 } else { 58 sImpl = new BackgroundHelperStubImpl(); 59 } 60 } 61 62 public static void setBackgroundPreservingAlpha(View view, Drawable drawable) { 63 sImpl.setBackgroundPreservingAlpha(view, drawable); 64 } 65} 66