使用 IFilter 实现一个 TextReader 支持各种文件内容代码,CSharp代码库,德仔网

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【CSharp】使用 IFilter 实现一个 TextReader 支持各种文件内容

作者:Dezai.CN / 发布于2011/2/15/ 470

while (true)
{
if (remaining <= _topSize)
return;
bool useBuffer = !forceDirectlyWrite && remaining < BufferSize;
var size = BufferSize;
if (useBuffer)
size -= _topSize;
else
{
if (remaining < BufferSize)
size = (uint)remaining;
}
if (size < ResBufSize)
size = ResBufSize;
var handle = GCHandle.Alloc(useBuffer ? _buffer : array,
GCHandleType.Pinned);
var ptr = Marshal.UnsafeAddrOfPinnedArrayElement(
useBuffer ? _buffer : array, useBuffer ? (int)_topSize : offset);
IFilterReturnCodes returnCode;
try
{
#if DEBUG
Trace.Write(size);
#endif
returnCode = _filter.GetText(ref size, ptr);
#if DEBUG
Trace.WriteLine("->"+size);
#endif
}
finally
{
handle.Free();
}
if(returnCode != IFilterReturnCodes.FILTER_E_NO_TEXT)
{
if (useBuffer)
_topSize += size;
else
{
offset += (int)size;
remaining -= (int)size;
}
if(_topSize > BufferSize)
{
_resTopSize = _topSize - BufferSize;
_topSize = BufferSize;
}
}
if (returnCode == IFilterReturnCodes.FILTER_S_LAST_TEXT ||
returnCode == IFilterReturnCodes.FILTER_E_NO_MORE_TEXT ||
(returnCode == IFilterReturnCodes.FILTER_E_NO_TEXT && size != 0) ||
(null == FileName && IgnoreError && returnCode ==
IFilterReturnCodes.E_INVALIDARG))
{
_endOfCurrChunk = true;
if (remaining <= _topSize)
return;
break;
}
if(returnCode != IFilterReturnCodes.S_OK)
{
throw new Exception(
"a error occur when getting text by current filter",
new Exception(returnCode.ToString()));
}
}

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