diff options
author | Jay Berkenbilt <ejb@ql.org> | 2020-12-23 12:12:49 +0100 |
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committer | Jay Berkenbilt <ejb@ql.org> | 2020-12-28 18:58:19 +0100 |
commit | 39bfa0130713defc9abb478a70717ca07377cdab (patch) | |
tree | 18b6370d5f2f7d10a3f1ef09a8f0dd3b9281bd3c /include/qpdf/QPDFStreamFilter.hh | |
parent | 1fb26f08ad91d08f67ac30e2557ddcadd8b9ccac (diff) | |
download | qpdf-39bfa0130713defc9abb478a70717ca07377cdab.tar.zst |
Implement user-provided stream filters
Refactor QPDF_Stream to use stream filter classes to handle supported
stream filters as well.
Diffstat (limited to 'include/qpdf/QPDFStreamFilter.hh')
-rw-r--r-- | include/qpdf/QPDFStreamFilter.hh | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/include/qpdf/QPDFStreamFilter.hh b/include/qpdf/QPDFStreamFilter.hh new file mode 100644 index 00000000..5fdcf5ca --- /dev/null +++ b/include/qpdf/QPDFStreamFilter.hh @@ -0,0 +1,78 @@ +// Copyright (c) 2005-2020 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 iself) 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 |