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PyGitViz

PyGitViz is a small program for visualizing the most important content of a Git repository, primarily commits, trees, blobs and branches. The current state of the project is a proof of concept that works, but is not particularly user friendly. It uses Graphviz to create a PDF of the Git repository layout, and then renders it with any PDF viewer that is available.

Demo

PyGitViz in action

PyGitViz in action in its default mode

A longer screencast of an early version of PyGitViz is available below. It both shows what the tool looks like in action, and explains some of the basics of Git's database objects.

PyGitViz default mode

PyGitViz has two primary modes. The default is to show HEAD, refs, commits, blobs and trees. This is the mode demonstrated in the screencast, and is also shown in the image below.

PyGitViz default mode

This is useful for exploring and demonstrating the internals of Git.

PyGitViz hide content mode

It is also possible to hide trees and blobs with the --hide-content option, which produces a view showing only HEAD, refs and commits.

PyGitViz hide-content mode

This is useful for exploring and demonstrating the concept of branching, without being overwhelmed by details of the internals.

Requirements

PyGitViz requires the following to run.

  • Python 3.7 or higher
  • A PDF viewer
    • The viewer should ideally refresh automatically when a PDF is updated, as PyGitViz will render a new PDF for each change it detects in the repository.
    • For Linux, I highly recommend Evince, which refreshes automatically.
    • For macOS, the PDF Preview application that ships with the OS is used by default, and it kind of works, but you need to refocus on the window by hovering over it with your mouse cursor for it to refresh. For a smoother experience, I recommend Skim.
    • For Windows, I find SumatraPDF to work well.
  • The dot command line tool (part of Graphviz).
  • WSL2 additionaly requires the wslview command from the wslu package. This should be preinstalled, but if it isn't, see their install instructions.
    • wslview opens the PDF with the default PDF viewer installed on Windows. Here I again recommend using something like SumatraPDF.

Install

First install the requirements listed above. Then install PyGitViz directly from this repo. If you're on a Linux-distro, WSL2 or macOS, the following should work:

$ python3 -m pip install --user git+https://github.com/slarse/pygitviz.git

Windows note: You may need to replace python3 with python.

How to use

Install the package as instructed in the Install section, and run PyGitViz in a terminal at the root directory of a Git project (i.e. in the same directory where you find the .git repository). You can show the available command line options by running pygitviz -h:

$ pygitviz -h
usage: PyGitViz [-h] [-g GIT_DIRECTORY] [--hide-content] [-p PDF_VIEWER]
                [-s filepath] [--tb]

Git repository visualizer for education and demonstration purposes

optional arguments:
  -h, --help            show this help message and exit
  -g GIT_DIRECTORY, --git-directory GIT_DIRECTORY
                        Path to a .git directory (default: .git)
  --hide-content        Hide trees and blobs from the representation, so only
                        commits and refs are shown (default: False)
  -p PDF_VIEWER, --pdf-viewer PDF_VIEWER
                        Program to open the resulting PDF file with (default:
                        xdg-open)
  -s filepath, --snapshot filepath
                        Capture a single snapshot and save it to the specified
                        path. Supports .pdf and .png (default: None)
  --tb, --traceback     Show full traceback for critical errors (default:
                        False)

If the command cannot be found, you probably have not added the bin directory in which the script was installed to your path. You should still be able to run PyGitViz explicitly as a Python module.

$ python3 -m pygitviz -h
# ***OUTPUT OMITTED***

If you're in a bash-like shell, add an & at the end of the command to put it in the background.

$ pygitviz &

Important: PyGitViz cannot handle pack files (that are created e.g. when you have very many loose Git objects, or when you push). PyGitViz should be used only with small, fresh projects.

Saving a snapshot

By default, PyGitViz will create a PDF in a temporary directory and open it with a PDF viewer. When the application exits, the temporary directory is removed. With the --snapshot option, you can specify a path to save an image to. Currently, PNG and PDF are the only supported formats, and you choose the file format simply by typing out the corresponding extension.

$ pygitviz --snapshot snap.png # save as a PNG image
$ pygitviz --snapshot snap.pdf # save as a PDF

Selecting the PDF viewer

By default, PyGitViz will use the xdg-open command on Linux-based OSes, start on Windows, and open on macOS. If you want to specify some other PDF viewer, pass it as an argument for the -p option.

Windows note: I find it easiest to simply associate the .pdf file type with the desired viewer, and then run with the default start command.

License

PyGitViz is under the MIT license, please see the LICENSE file for details.