The FreeType project has successfully participated at Google Summer of Code. Here is our ideas list for future years – if you have another one, please write to our mailing list so that we can discuss your suggestions, eventually adding them to this page.
Before contacting us, however, you should get really acquainted with the topic you would like to start with – in particular, search the mailing list archive and/or do some googling! We don't want to answer questions like “I'm interested in your project, I want to contribute, please tell me what to do!” again and again…
Right now, FreeType's rendering results of the current development version are not systematically compared to a baseline version, using continuous integration (CI) or something similar. This is problematic, since rendering regressions can be very easily missed due to subtle differences.
The idea is to select a representative set of reference fonts from font corpora (which already exist mainly for fuzzing). The fonts are used to produce glyph images for various sizes and rendering modes (anti-aliased, B/W, native hinting, auto-hinting, etc.). FreeType can already produce MD5 checksums of glyph images as part of its debugging output; these values should be compared against a baseline version of rendering results. If there are differences, HTML pages should be generated that contain comparison images of the baseline's and the current development version's rendering result, ideally indicating how large the differences between the images are by using some yet to be defined measure.
Difficulty: medium. Requirements: C, Unix build tools. Potential mentors: Werner Lemberg, Alexei Podtelezhnikov, Toshiya Suzuki (FreeType).
Due to historical reasons, FreeType's build systems
are strange to newcomers. The default one is based
support. Alternatives are generic build files
together with special support files
and some even more exotic, old platforms.
This project is intended to update the build systems. Here is a preliminary list of tasks.
cmakesupport, there are a bunch of issues in Freetype's bug tracker that should be taken care of.
Difficulty: medium. Requirements:
Various Unix and Windows build tools, in
cmake. Potential mentors:
Werner Lemberg, Alexei Podtelezhnikov, Toshiya Suzuki
fontduerendering engine to FreeType
Raph Levien has
an experimental font renderer written in
describes some of its features in more detail; of
particular interest is that it is much faster than
FreeType's anti-aliasing rendering module.
The gist of this project would be to port the Rust code to C and to integrate it into FreeType, providing it as an alternative rendering engine that eventually might replace the old one. It would be necessary to investigate how this can be done, and whether it is feasible at all. In case a port doesn't make sense (for whatever reasons) it should be investigated whether the ideas of the code can be used to re-implement the rasterizer in C.
Difficulty: medium (if porting) to high (if reimplementing). Requirements: Rust, C, Unix build tools. Potential mentors: Werner Lemberg, Alexei Podtelezhnikov, Toshiya Suzuki (FreeType), Raph Levien (Google).
Right now, FreeType comes with a suite of small graphic tools to test the library, most notably ‘ftview’ and ‘ftgrid’. The used graphics library, while working more or less, is very archaic, not having any comfort that modern GUIs are providing.
To improve this, a new demo program called ‘ftinspect’ was started, based on the Qt GUI toolkit. However, the development is currently stalled, mainly for lack of time.
The idea is to finish ftinspect, handling all aspects of the other demo programs. Currently, it only provides the functionality of ‘ftgrid’.
If the student prefers, the Qt toolkit could be replaced with GTK.
Difficulty: medium. Requirements: C, C++, Qt, Unix build tools. Potential mentor: Werner Lemberg (FreeType).
FreeType extensively uses a home-brewed tracing
solution that mainly relies on the C preprocessor
fprintf function printing to
for documentation). However, this simplistic approach
is not adequate for all platforms,
stderr is not always easily
Many freely available tracing and logging libraries exist. It would be necessary to test and check which one meets FreeType's requirements. A few requirements have already been discussed in the mailing list. Note that this discussion is by no means exhaustive.
As a rough guideline, the project could be structured as follows.
Difficulty: medium. Requirements: C, C++, Unix and Windows build tools. Potential mentors: Werner Lemberg, Alexei Podtelezhnikov, Toshiya Suzuki (FreeType), Armin Hasitzka.
At smaller sizes, usually in the range 12ppem to 20ppem, it can happen that separate outlines of glyphs touch each other (mainly caused by rounding issues), making glyphs illegible. A typical example is glyph ‘i’, where the vertical space between the i-dot and the body must have a certain size to let the reader's eye separate the two parts. [Note that the auto-hinter's capability to hint glyphs smaller than 12ppem is very limited in general and thus not part of this project description.]
Another example is the tilde accent, ‘~’, used in languages like Spanish: Even at smaller sizes the wiggle of the accent shape must be prevented, otherwise it can happen that a character like ‘ã’ looks like ‘ā’.
There are numerous other cases where some knowledge of the shape of a given glyph might help the auto-hinter improve the hinting, irrespective of the font shape or family – the i-dot and its body must be separate for virtually all available fonts.
The project consists of the following parts.
Difficulty: medium to high. Requirements: C, and ideally some basic font hinting and rasterization knowledge. Potential mentors: Werner Lemberg, Alexei Podtelezhnikov (FreeType).
Do you have more ideas? Please write to our mailing list so that we can discuss your suggestions, eventually adding them to the list!
Last update: 6-Sept-2020