# Contributing to darktable

The darktable project welcomes contributions:

* [Code](https://www.darktable.org/development/)
* [Documentation](https://www.darktable.org/resources/)
* Testing (and any backtraces if you happen to crash darktable)
* Translations
* [Camera profiles](https://www.darktable.org/resources/camera-support/).
* Tutorials, screencasts, etc.

See the [darktable development page](https://www.darktable.org/development/) for
more information.

## Code

Before you spend a lot of time working on a new feature, it's always best to
discuss your proposed changes with us first.  The best place to do that is in
our IRC channel on **ircs://irc.oftc.net:6697**, channel **#darktable** or the
development mailing list, [see here for more
information](https://www.darktable.org/contact/).  This will dramatically
improve your chances of having your code merged, especially if we think you'll
hang around to maintain it.

### Coding style

We like our code to be properly formatted. We have a well-defined coding style, 
and [.clang-format](.clang-format) style file represents it fully.
You can enforce your commits to follow it:

1. Install [clang-format](http://clang.llvm.org/docs/ClangFormat.html) clang tool. Probably, any version will be ok, but the newer the better.
2. You'll need to integrate `git` and `clang-format`.
  * For that, you will need to download `git-clang-format` from [here](https://github.com/llvm-mirror/clang/blob/master/tools/clang-format/git-clang-format) or [here](https://llvm.org/svn/llvm-project/cfe/trunk/tools/clang-format/git-clang-format).
  * Read it to check for nastiness.
  * Warning: apparently, it only works with Python2, and does not work with Python3!
  * Put it somewhere in your path (e.g. `~/bin` or `/usr/local/bin`) and ensure that it is executable (`chmod +x`).
3. Now, step into your local clone of repository:
  * `cd darktable/.git/hooks`
  * If you previously did not have a `pre-commit` hook:
    * `cp pre-commit.sample pre-commit && chmod +x pre-commit`
  * Open `pre-commit` with your favourite text editor, and append before the last block, here is how the end should look:
```
# format everything
res=$(git clang-format --diff | wc -l)
if [ $res -ne 1 ]
then
	git clang-format
	echo "Commit did not match clang-format"
	exit 1;
fi

# If there are whitespace errors, print the offending file names and fail.
exec git diff-index --check --cached $against --
```
* Also, there is a [Developer's Guide](https://github.com/darktable-org/darktable/wiki/Developer's-guide) on our GitHub wiki, which includues some [Coding Style](https://github.com/darktable-org/darktable/wiki/Developer's-guide#coding-style) guidelines.
