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