gitk-class-diagram

Extends gitk to show a class diagram based on all files that were modified in a given commit, highlighting any changes.

gitk showing some Java classes from mockito

C may not have classes, but putting together structs, enums, and functions per file can still make a useful diagram (htop)

Python: comparing two minor releases of flake8

Usage

• Whenever you select a commit, a class diagram is created and displayed on the bottom right
• The diagram can also span multiple commits if you compare two revisions
• If you exclude files with gitk's filter, they will not appear in the diagram either

Interaction

• Left-click on a class to scroll to its file in gitk's diff view
• Left-click on any text in the diagram to search for it in gitk's diff view
• Options if the image is too big:
  • Use the mouse wheel to zoom out
  • Hold the left mouse button to move around
  • Right-click and select "Open PNG"

Visual aspects

• Red background indicates a removed file, class, attribute, operation, relationship
• Green background indicates an added file, class, attribute, operation, relationship
• Light blue background indicates a changed operation
• A dashed border indicates that the element is not a real class, but rather the global scope of a file
• If a file contains multiple classes, they are clustered within a dotted border
• A blue border indicates the file that is currently shown in gitk's diff view

Language support

How well a language works depends on its support in universal-ctags. See:

ctags --list-languages
ctags --list-kinds-full=<language>

List of what is recognized in popular languages:

• Python — classes, functions, inheritance, function body changes, references to imported files and classes
• Java — classes, functions, inheritance, function body changes, references to imported classes of other packages
• C — structs, functions, attribute types, function body changes, references to included files
• Ruby — classes, functions
• JavaScript — classes, functions
• C++ — most classes are not recognized (ctags provides tags, but gitk-class-diagram does not handle them well enough)
• Go — structs, functions, attribute types

How to get more associations between classes

Put a file like classref.ctags in $HOME/.ctags.d/ to produce associations based on regular expressions. The example file will instruct ctags to record any words in Java source code starting with an upper-case letter (and containing lower-case letters). These words will automatically be interpreted as references to other classes. This works pretty well with some languages. Of course, it's not as reliable as a parser that understands the language. It's also slower.

How to add your own language

Use ctags' optlib and create the tag kinds class, field and function.

Installation

pip install gitk-class-diagram

Your existing gitk binary remains as it is. Start the extended version with:

gitk-cl

Dependencies

• graphviz
• universal-ctags
• python >= 3.7

If you are on Windows, make sure that graphviz, python and ctags are in your PATH.

Configuration

Open gitk's preferences dialog. At the bottom there is an input field which accepts python code. Copy any settings from config.py in there and change the values.

Unfortunately, due to gitk's saving mechanism, the configuration is lost every time you start the original gitk without the extension.