OutlineOnlyWithChildrenFrameLayout.java revision 8e10080c914d1ad0784394fa3026b85535535847 
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.annotation.TargetApi;
22import android.content.Context;
23import android.graphics.Outline;
24import android.support.annotation.RequiresApi;
25import android.support.annotation.RestrictTo;
26import android.util.AttributeSet;
27import android.view.View;
28import android.view.ViewOutlineProvider;
29import android.widget.FrameLayout;
30
31/**
32 * {@link FrameLayout} subclass that provides an outline only when it has children, so that it does
33 * not cast a shadow when empty.
34 *
35 * @hide
36 */
37@RequiresApi(21)
38@TargetApi(21)
39@RestrictTo(LIBRARY_GROUP)
40public class OutlineOnlyWithChildrenFrameLayout extends FrameLayout {
41
42    private ViewOutlineProvider mMagicalOutlineProvider;
43    private ViewOutlineProvider mInnerOutlineProvider;
44
45    public OutlineOnlyWithChildrenFrameLayout(Context context) {
46        super(context);
47    }
48
49    public OutlineOnlyWithChildrenFrameLayout(Context context, AttributeSet attrs) {
50        super(context, attrs);
51    }
52
53    public OutlineOnlyWithChildrenFrameLayout(Context context, AttributeSet attrs,
54            int defStyleAttr) {
55        super(context, attrs, defStyleAttr);
56    }
57
58    public OutlineOnlyWithChildrenFrameLayout(Context context, AttributeSet attrs,
59            int defStyleAttr, int defStyleRes) {
60        super(context, attrs, defStyleAttr, defStyleRes);
61    }
62
63    @Override
64    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
65        super.onLayout(changed, left, top, right, bottom);
66        invalidateOutline();
67    }
68
69    @Override
70    public void setOutlineProvider(ViewOutlineProvider provider) {
71        mInnerOutlineProvider = provider;
72        if (mMagicalOutlineProvider == null) {
73            // Can't initialize this directly because this method is called from the superclass's
74            // constructor.
75            mMagicalOutlineProvider = new ViewOutlineProvider() {
76                @Override
77                public void getOutline(View view, Outline outline) {
78                    if (getChildCount() > 0) {
79                        mInnerOutlineProvider.getOutline(view, outline);
80                    } else {
81                        ViewOutlineProvider.BACKGROUND.getOutline(view, outline);
82                    }
83                }
84            };
85        }
86        super.setOutlineProvider(mMagicalOutlineProvider);
87    }
88}
89