/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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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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using System.IO;
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using System;
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using System.Collections;
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using HH.WMS.Utils.NPOI.Util;
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namespace HH.WMS.Utils.NPOI.POIFS.NIO
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{
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/// <summary>
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/// A POIFS <see cref="T:HH.WMS.Utils.NPOI.POIFS.NIO.DataSource"/> backed by a byte array.
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/// </summary>
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public class ByteArrayBackedDataSource : DataSource
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{
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private byte[] buffer;
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private long size;
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public ByteArrayBackedDataSource(byte[] data, int size)
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{
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this.buffer = data;
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this.size = size;
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}
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public ByteArrayBackedDataSource(byte[] data)
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: this(data, data.Length)
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{
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}
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public override ByteBuffer Read(int length, long position)
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{
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if (position >= size)
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{
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throw new IndexOutOfRangeException(
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"Unable to read " + length + " bytes from " +
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position + " in stream of length " + size
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);
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}
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int toRead = (int)Math.Min(length, size - position);
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return ByteBuffer.CreateBuffer(buffer, (int)position, toRead);
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}
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public override void Write(ByteBuffer src, long position)
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{
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long endPosition = position + src.Length;
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if (endPosition > buffer.Length)
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{
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Extend(endPosition);
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}
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// Now copy
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src.Read(buffer, (int)position, src.Length);
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// Update size if needed
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if (endPosition > size)
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{
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size = endPosition;
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}
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}
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private void Extend(long length)
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{
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// Consider extending by a bit more than requested
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long difference = length - buffer.Length;
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if (difference < buffer.Length * 0.25)
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{
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difference = (long)(buffer.Length * 0.25);
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}
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if (difference < 4096)
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{
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difference = 4096;
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}
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byte[] nb = new byte[(int)(difference + buffer.Length)];
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Array.Copy(buffer, 0, nb, 0, (int)size);
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buffer = nb;
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}
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public override void CopyTo(Stream stream)
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{
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stream.Write(buffer, 0, (int)size);
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}
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public override long Size
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{
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get
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{
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return size;
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}
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}
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public override void Close()
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{
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buffer = null;
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size = -1;
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}
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}
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}
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