blob: 2a7d65b388874fe5dca0c0a6b883311791c5d5b8 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
// Copyright (c) 2005-2024 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/Pipeline.hh>
#include <qpdf/QPDFObjectHandle.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
|
