mirror of https://github.com/qpdf/qpdf.git
79 lines
3.0 KiB
C++
79 lines
3.0 KiB
C++
// Copyright (c) 2005-2022 Jay Berkenbilt
|
|
//
|
|
// This file is part of qpdf.
|
|
//
|
|
// 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.
|
|
//
|
|
// Versions of qpdf prior to version 7 were released under the terms
|
|
// of version 2.0 of the Artistic License. At your option, you may
|
|
// continue to consider qpdf to be licensed under those terms. Please
|
|
// see the manual for additional information.
|
|
|
|
#ifndef QPDFSTREAMFILTER_HH
|
|
#define QPDFSTREAMFILTER_HH
|
|
|
|
#include <qpdf/DLL.h>
|
|
#include <qpdf/QPDFObjectHandle.hh>
|
|
#include <qpdf/Pipeline.hh>
|
|
|
|
class QPDF_DLL_CLASS QPDFStreamFilter
|
|
{
|
|
public:
|
|
QPDF_DLL
|
|
QPDFStreamFilter() = default;
|
|
|
|
QPDF_DLL
|
|
virtual ~QPDFStreamFilter() = default;
|
|
|
|
// A QPDFStreamFilter class must implement, at a minimum,
|
|
// setDecodeParms() and getDecodePipeline(). QPDF will always call
|
|
// setDecodeParms() before calling getDecodePipeline(). It is
|
|
// expected that you will store any needed information from
|
|
// decode_parms (or the decode_parms object itself) in your
|
|
// instance so that it can be used to construct the decode
|
|
// pipeline.
|
|
|
|
// Return a boolean indicating whether your filter can proceed
|
|
// with the given /DecodeParms. The default implementation accepts
|
|
// a null object and rejects everything else.
|
|
QPDF_DLL
|
|
virtual bool setDecodeParms(QPDFObjectHandle decode_parms);
|
|
|
|
// Return a pipeline that will decode data encoded with your
|
|
// filter. Your implementation must ensure that the pipeline is
|
|
// deleted when the instance of your class is destroyed.
|
|
QPDF_DLL
|
|
virtual Pipeline* getDecodePipeline(Pipeline* next) = 0;
|
|
|
|
// If your filter implements "specialized" compression or lossy
|
|
// compression, override one or both of these methods. The default
|
|
// implementations return false. See comments in QPDFWriter for
|
|
// details. QPDF defines specialized compression as non-lossy
|
|
// compression not intended for general-purpose data. qpdf, by
|
|
// default, doesn't mess with streams that are compressed with
|
|
// specialized compression, the idea being that the decision to
|
|
// use that compression scheme would fall outside of what
|
|
// QPDFWriter would know anything about, so any attempt to decode
|
|
// and re-encode would probably be undesirable.
|
|
QPDF_DLL
|
|
virtual bool isSpecializedCompression();
|
|
QPDF_DLL
|
|
virtual bool isLossyCompression();
|
|
|
|
private:
|
|
QPDFStreamFilter(QPDFStreamFilter const&) = delete;
|
|
QPDFStreamFilter& operator=(QPDFStreamFilter const&) = delete;
|
|
};
|
|
|
|
#endif // QPDFSTREAMFILTER_HH
|