Week 2 recap GSoC 2025 - searching c++ and creating floating toolbar

Tuesday, 29 July 2025  |  Ross Rosales (rossr)

Intro

Apart from setting up a new open source project, it is important to understand how the application works in order to make the changes you need. In this blog I will go over how I find code, understand the application, and my progress so far with the Selection Action Bar.

Searching code

One Stop Shop for Searching

Command Line

grep -rn "<string_to_search>"

QTCreator

ctrl + f
crtl + shift + f

Debug in C++ code

qDebug() << "[Debug] <string_to_display_for_debugger> << <additional_parameters>;

Krita's codebase is massive, so don't expect to understand everything in one day. What is important is knowing how to find code you need to make the improvements you want. Above are some tools I use when looking for code. I would use the command line or QTCreator search functionality to reverse search strings that are displayed in Krita. This helps me find buttons, dropdowns, and tools. When I want to understand the functionality of the application, I will add qDebug in the code. This allows me to perform an action when Krtia is running and display debug information about the functions I added qDebug to.

Progress

Through the use of the the useful tools above, I was able to make the base UI of the floating toolbar in Krita by identifying QPainter class that created the Assistant Tool. I wanted to use Assistant tool as a reference and recreate a similar UI look. For quick learning purposes and proof of concept, when an Assistant Tool widget is active, the floating toolbar is also generated on screen.

Below is a proof of concept for the Selection Action Bar. I used QPainter to 'draw' onto the KisCanvas2 class. This is like using a paintbrush (QPainter) and painting on a canvas (KisCanvas2). There will still need to be some more UI clean up, however I wanted to present my learnings so far.

Conclusion

Making changes in Krita can be challenging, but by using a few simple tools it can make hours turn into minutes for searching what you need. Again, "the hardest part is finding the resources to be successful". I hope this blog post helps whoever is in need of searching Krita or any C++ codebase.

Contact

To anyone reading this, please feel free to reach out to me. I’m always open to suggestions and thoughts on how to improve as a developer and as a person.
Email: ross.erosales@gmail.com
Matrix: @rossr:matrix.org