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