diff options
| author | Jay Berkenbilt <ejb@ql.org> | 2020-12-22 21:19:18 +0100 |
|---|---|---|
| committer | Jay Berkenbilt <ejb@ql.org> | 2020-12-26 14:48:20 +0100 |
| commit | 0675a3f61a465f282eba8e1f54bdda3920257959 (patch) | |
| tree | 9b3545baae79933df6bbbc237bdd6b8bdbbfb263 /include | |
| parent | cc8895078a1d64928e8ee335f1e8c7d6928de1b3 (diff) | |
| download | qpdf-0675a3f61a465f282eba8e1f54bdda3920257959.tar.zst | |
Decide not to allow stream data providers to modify dictionary
Diffstat (limited to 'include')
| -rw-r--r-- | include/qpdf/QPDFObjectHandle.hh | 29 |
1 files changed, 22 insertions, 7 deletions
diff --git a/include/qpdf/QPDFObjectHandle.hh b/include/qpdf/QPDFObjectHandle.hh index c6534b17..0cd10569 100644 --- a/include/qpdf/QPDFObjectHandle.hh +++ b/include/qpdf/QPDFObjectHandle.hh @@ -70,13 +70,28 @@ class QPDFObjectHandle // QPDFWriter may, in some cases, add compression, but if it // does, it will update the filters as needed. Every call to // provideStreamData for a given stream must write the same - // data. The object ID and generation passed to this method - // are those that belong to the stream on behalf of which the - // provider is called. They may be ignored or used by the - // implementation for indexing or other purposes. This - // information is made available just to make it more - // convenient to use a single StreamDataProvider object to - // provide data for multiple streams. + // data. Note that, when writing linearized files, qpdf will + // call your provideStreamData twice, and if it generates + // different output, you risk generating invalid output or + // having qpdf throw an exception. The object ID and + // generation passed to this method are those that belong to + // the stream on behalf of which the provider is called. They + // may be ignored or used by the implementation for indexing + // or other purposes. This information is made available just + // to make it more convenient to use a single + // StreamDataProvider object to provide data for multiple + // streams. + + // A few things to keep in mind: + // + // * Stream data providers must not modify any objects since + // they may be called after some parts of the file have + // already been written. + // + // * Since qpdf may call provideStreamData multiple times when + // writing linearized files, if the work done by your stream + // data provider is slow or computationally intensive, you + // might want to implement your own cache. // Prior to qpdf 10.0.0, it was not possible to handle errors // the way pipeStreamData does or to pass back success. |