89 lines
2.5 KiB
Java
89 lines
2.5 KiB
Java
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/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.server;
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/**
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* A specialized list of window information objects backed by an array.
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*
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* This class is part of an InputManager optimization to avoid allocating objects and arrays
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* unnecessarily. Internally, it keeps an array full of demand-allocated objects that it
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* recycles each time the list is cleared. The used portion of the array is padded with a null.
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*
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* The contents of the list are intended to be Z-ordered from top to bottom.
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*
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* @hide
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*/
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public final class InputWindowList {
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private InputWindow[] mArray;
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private int mCount;
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/**
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* Creates an empty list.
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*/
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public InputWindowList() {
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mArray = new InputWindow[8];
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}
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/**
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* Clears the list.
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*/
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public void clear() {
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if (mCount == 0) {
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return;
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}
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int count = mCount;
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mCount = 0;
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mArray[count] = mArray[0];
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while (count > 0) {
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count -= 1;
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mArray[count].recycle();
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}
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mArray[0] = null;
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}
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/**
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* Adds an uninitialized input window object to the list and returns it.
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*/
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public InputWindow add() {
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if (mCount + 1 == mArray.length) {
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InputWindow[] oldArray = mArray;
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mArray = new InputWindow[oldArray.length * 2];
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System.arraycopy(oldArray, 0, mArray, 0, mCount);
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}
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// Grab object from tail (after used section) if available.
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InputWindow item = mArray[mCount + 1];
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if (item == null) {
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item = new InputWindow();
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}
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mArray[mCount] = item;
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mCount += 1;
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mArray[mCount] = null;
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return item;
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}
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/**
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* Gets the input window objects as a null-terminated array.
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* @return The input window array.
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*/
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public InputWindow[] toNullTerminatedArray() {
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return mArray;
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}
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}
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