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 com.android.systemui.recents.views;
18
19import android.content.Context;
20import android.graphics.Rect;
21import android.util.AttributeSet;
22import android.widget.FrameLayout;
23
24/**
25 * This is an optimized FrameLayout whose layout is completely directed by its parent, and as a
26 * result, does not propagate <code>requestLayout()</code> up the view hierarchy. Instead, it will
27 * relayout its children with the last known layout bounds when a layout is requested from a child
28 * view.
29 */
30public class FixedSizeFrameLayout extends FrameLayout {
31
32    private final Rect mLayoutBounds = new Rect();
33
34    public FixedSizeFrameLayout(Context context) {
35        super(context);
36    }
37
38    public FixedSizeFrameLayout(Context context, AttributeSet attrs) {
39        super(context, attrs);
40    }
41
42    public FixedSizeFrameLayout(Context context, AttributeSet attrs, int defStyleAttr) {
43        super(context, attrs, defStyleAttr);
44    }
45
46    public FixedSizeFrameLayout(Context context, AttributeSet attrs, int defStyleAttr,
47            int defStyleRes) {
48        super(context, attrs, defStyleAttr, defStyleRes);
49    }
50
51    @Override
52    protected final void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
53        measureContents(MeasureSpec.getSize(widthMeasureSpec),
54                MeasureSpec.getSize(heightMeasureSpec));
55    }
56
57    @Override
58    protected final void onLayout(boolean changed, int left, int top, int right, int bottom) {
59        mLayoutBounds.set(left, top, right, bottom);
60        layoutContents(mLayoutBounds, changed);
61    }
62
63    @Override
64    public final void requestLayout() {
65        // The base ViewGroup constructor attempts to call requestLayout() before this class's
66        // members are initialized so we should just propagate in that case
67        if (mLayoutBounds == null || mLayoutBounds.isEmpty()) {
68            super.requestLayout();
69        } else {
70            // If we are already laid out, then just reuse the same bounds to layout the children
71            // (but not itself)
72            // TODO: Investigate whether we should coalesce these to the next frame if needed
73            measureContents(getMeasuredWidth(), getMeasuredHeight());
74            layoutContents(mLayoutBounds, false);
75        }
76    }
77
78    /**
79     * Measures the contents of this fixed layout.
80     */
81    protected void measureContents(int width, int height) {
82        super.onMeasure(MeasureSpec.makeMeasureSpec(width, MeasureSpec.AT_MOST),
83                MeasureSpec.makeMeasureSpec(height, MeasureSpec.AT_MOST));
84    }
85
86    /**
87     * Lays out the contents of this fixed layout.
88     */
89    protected void layoutContents(Rect bounds, boolean changed) {
90        super.onLayout(changed, bounds.left, bounds.top, bounds.right, bounds.bottom);
91
92        int width = getMeasuredWidth();
93        int height = getMeasuredHeight();
94        onSizeChanged(width, height, width, height);
95    }
96
97}
98