1/*
2 * Copyright (C) 2016 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 android.support.v17.internal.widget;
18
19import static android.support.annotation.RestrictTo.Scope.LIBRARY_GROUP;
20
21import android.content.Context;
22import android.graphics.Outline;
23import android.support.annotation.RequiresApi;
24import android.support.annotation.RestrictTo;
25import android.util.AttributeSet;
26import android.view.View;
27import android.view.ViewOutlineProvider;
28import android.widget.FrameLayout;
29
30/**
31 * {@link FrameLayout} subclass that provides an outline only when it has children, so that it does
32 * not cast a shadow when empty.
33 *
34 * @hide
35 */
36@RequiresApi(21)
37@RestrictTo(LIBRARY_GROUP)
38public class OutlineOnlyWithChildrenFrameLayout extends FrameLayout {
39
40    private ViewOutlineProvider mMagicalOutlineProvider;
41    private ViewOutlineProvider mInnerOutlineProvider;
42
43    public OutlineOnlyWithChildrenFrameLayout(Context context) {
44        super(context);
45    }
46
47    public OutlineOnlyWithChildrenFrameLayout(Context context, AttributeSet attrs) {
48        super(context, attrs);
49    }
50
51    public OutlineOnlyWithChildrenFrameLayout(Context context, AttributeSet attrs,
52            int defStyleAttr) {
53        super(context, attrs, defStyleAttr);
54    }
55
56    public OutlineOnlyWithChildrenFrameLayout(Context context, AttributeSet attrs,
57            int defStyleAttr, int defStyleRes) {
58        super(context, attrs, defStyleAttr, defStyleRes);
59    }
60
61    @Override
62    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
63        super.onLayout(changed, left, top, right, bottom);
64        invalidateOutline();
65    }
66
67    @Override
68    public void setOutlineProvider(ViewOutlineProvider provider) {
69        mInnerOutlineProvider = provider;
70        if (mMagicalOutlineProvider == null) {
71            // Can't initialize this directly because this method is called from the superclass's
72            // constructor.
73            mMagicalOutlineProvider = new ViewOutlineProvider() {
74                @Override
75                public void getOutline(View view, Outline outline) {
76                    if (getChildCount() > 0) {
77                        mInnerOutlineProvider.getOutline(view, outline);
78                    } else {
79                        ViewOutlineProvider.BACKGROUND.getOutline(view, outline);
80                    }
81                }
82            };
83        }
84        super.setOutlineProvider(mMagicalOutlineProvider);
85    }
86}
87