96 lines
5.0 KiB
Markdown
96 lines
5.0 KiB
Markdown
Contributing to libjpeg-turbo
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=============================
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libjpeg-turbo is a stable and mature product with a worldwide reach, it is an
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ISO/ITU-T reference implementation of the JPEG standard, and its maintainer
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does not earn a salary for maintaining it. Thus, not every code contribution
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can or will be accepted into the libjpeg-turbo code base. In order to maximize
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the chances that a code contribution is acceptable, please adhere to the
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following guidelines:
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1. If the code contribution is a bug fix, then please ensure that enough
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information is provided so that the maintainer can readily reproduce and
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document the bug. That information should include:
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- A clear and concise description of the bug
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- The steps and (if applicable) images necessary to reproduce the bug
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- The compilers, operating systems, and CPUs with which the bug was
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observed
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- The versions of libjpeg-turbo with which the bug was observed
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- If the bug is a regression, the specific commit that introduced the bug
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(use `git bisect` to determine this)
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2. If the code contribution will implement a major new feature, then please
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contact the project maintainer (through a
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[GitHub issue](https://github.com/libjpeg-turbo/libjpeg-turbo/issues/new),
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[direct e-mail](https://libjpeg-turbo.org/About/Contact), or the
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[libjpeg-turbo-devel mailing list](https://libjpeg-turbo.org/About/MailingLists))
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prior to implementing the feature. In general, major new features that are
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potentially disruptive to the quality of libjpeg-turbo are unlikely to be
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accepted unless:
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- The new feature is within the existing scope of libjpeg-turbo.
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- The new feature has been thoroughly regression tested and benchmarked on
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all of the supported platforms that are potentially affected by it.
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- The new feature has been documented clearly and concisely in the change
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log and (if applicable) the libjpeg and TurboJPEG API documentation and
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man pages.
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- The code implementing the new feature is formatted consistently with the
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rest of the libjpeg-turbo code base (use
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[checkstyle](https://github.com/libjpeg-turbo/checkstyle) to validate
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this.)
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- The new feature does not introduce new members into the exposed libjpeg
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API structures (doing so would break backward ABI compatibility.)
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- The new feature does not alter existing libjpeg-turbo usage or
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development workflows.
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- The code implementing the new feature is elegant, easily maintainable,
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and causes the least possible amount of disruption to the libjpeg-turbo
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code base.
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- The new feature is based on the dev branch of the libjpeg-turbo
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repository.
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... OR ...
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- Your organization is prepared to pay for the labor necessary to ensure
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all of the above. Even the most well-written patches can still require
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a significant amount of labor to clean up, test, and integrate. (See
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above RE: the maintainer not earning a salary.)
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Specific types of features that *will not* be accepted:
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- Features that extend the scope of libjpeg-turbo to support image formats
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other than DCT-based JPEG and JFIF
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- Features that extend the scope of libjpeg-turbo to support image
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processing algorithms that are not necessary for JPEG compression or
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decompression
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- Extensions to the JPEG format that have not been approved by the
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appropriate standards bodies
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- Non-trivial performance enhancements that have less than a 5% overall
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impact on performance
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3. If the code contribution is a build system enhancement, then please be
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prepared to justify the enhancement. In general, build system enhancements
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are unlikely to be accepted unless:
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- The enhancement is potentially beneficial to a significant number of
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upstream libjpeg-turbo users/developers. (If the enhancement is only
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beneficial to a downstream project, then it does not belong here.)
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- The enhancement has been tested with the following CMake versions:
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- The earliest version of CMake that libjpeg-turbo currently supports
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(refer to CMakeLists.txt)
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- The most recent major version of CMake
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- (if applicable) The earliest version of CMake with which the
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enhancement can be used
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- The enhancement has been tested on all of the major platforms (Mac,
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Linux, Windows/Visual C++, Windows/MinGW) that are potentially affected
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by it.
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- The enhancement does not introduce new build system requirements or CMake
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variables unless absolutely necessary.
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- The enhancement does not alter existing libjpeg-turbo development
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workflows.
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Specific types of build system enhancements that *will not* be accepted:
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- Enhancements that allow libjpeg-turbo to be built from a subdirectory
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of a downstream repository. These enhancements are not maintainable in
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the upstream libjpeg-turbo build system. Use the CMake
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`ExternalProject_Add()` function instead.
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- Enhancements that introduce new (non-CMake-based) build systems
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