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<h1><a href="index.html">FreeType</a> & GSoC</h1>
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<p>The FreeType project has successfully participated at
<a href="https://developers.google.com/open-source/gsoc/">Google
Summer of Code</a>. Here is our ideas list for future
years – if you have another one, please write to
our <a href="mailto:freetype-devel@nongnu.org">mailing
list</a> so that we can discuss your suggestions,
eventually adding them to this page.</p>
<p>If you are interested to participate as a student, please
also contact us via
the <a href="mailto:freetype-devel@nongnu.org">mailing
list</a>. It's probably best if
you <a href="https://lists.nongnu.org/mailman/listinfo/freetype-devel">subscribe</a>
to it.</p>
<p class="warning">Before contacting us, however, you should
get <em>really</em> acquainted with the topic you would
like to start with – in particular, search
the <a href="https://lists.nongnu.org/archive/html/freetype-devel/">mailing
list archive</a> 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…</p>
<dl>
<dt>Develop a test framework for checking FreeType's
rendering output</dt>
<dd>
<p>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.</p>
<p>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.</p>
<p><em>Difficulty:</em> medium. <em>Requirements:</em>
C, Unix build tools. <em>Potential mentors:</em>
Werner Lemberg, Alexei Podtelezhnikov, Toshiya Suzuki
(FreeType).</p>
</dd>
</dl>
<dl>
<dt>Update FreeType's build systems</dt>
<dd>
<p>Due to historical reasons, FreeType's build systems
are strange to newcomers. The default one is based
on <a href="https://www.gnu.org/software/make/"><code>GNU
make</code></a>, also
integrating <a href="https://www.gnu.org/software/autoconf/"><code>autoconf</code></a>
support. Alternatives are generic build files
for <a href="https://cmake.org/"><code>cmake</code></a>
and <a href="https://www.freetype.org/jam/"><code>ftjam</code></a>,
together with special support files
for <a href="https://visualstudio.microsoft.com">MS
Visual
Studio</a>, <a href="https://en.wikipedia.org/wiki/OpenVMS">OpenVMS</a>,
and some even more exotic, old platforms.</p>
<p>This project is intended to update the build systems.
Here is a preliminary list of tasks.</p>
<ul>
<li>Investigate which build systems should be
retained, modified, added, removed, etc.,
approaching the project with a conservative point of
view. This needs intensive contact with the mailing
list(s) to identify the needs of users and the
preferences of developers.</li>
<li>Check software distributions for different
platforms and analyze how FreeType's build systems
are modified for integration. This might give
further hints on necessary changes or
adaptations.</li>
<li>Especially for <code>cmake</code> support, there
are a bunch of issues
in <a href="https://savannah.nongnu.org/bugs/?group=freetype">Freetype's
bug tracker</a> that should be taken care of.</li>
<li>Modernize and update the build system based on the
outcome of the previous items. This might also
include changes in the directory structure of the
source files if necessary and useful.</li>
</ul>
<p><em>Difficulty:</em> medium. <em>Requirements:</em>
Various Unix and Windows build tools, in
particular <code>GNU make</code>
and <code>cmake</code>. <em>Potential mentors:</em>
Werner Lemberg, Alexei Podtelezhnikov, Toshiya Suzuki
(FreeType).</p>
</dd>
</dl>
<dl>
<dt>Port the <code>font-rs</code>/<code>fontdue</code>
rendering engine to FreeType</dt>
<dd>
<p>Raph Levien has
developed <a href="https://github.com/raphlinus/font-rs"><code>font-rs</code></a>,
an experimental font renderer written in
the <a href="https://www.rust-lang.org/">Rust
programming language</a>.
A <a href="https://medium.com/@raphlinus/inside-the-fastest-font-renderer-in-the-world-75ae5270c445">blogpost</a>
describes some of its features in more detail; of
particular interest is that it is much faster than
FreeType's anti-aliasing rendering module.</p>
<p>Note that
the <a href="https://crates.io/crates/fontdue"><code>fontdue</code></a>
Rust package is another rendering engine based
on <code>font-rs</code>, and it claims to be even
faster.
<p>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.</p>
<p><em>Difficulty:</em> medium (if porting) to high (if
reimplementing). <em>Requirements:</em> Rust, C, Unix
build tools. <em>Potential mentors:</em> Werner
Lemberg, Alexei Podtelezhnikov, Toshiya Suzuki
(FreeType), Raph Levien (Google).</p>
</dd>
</dl>
<dl>
<dt>Improve the ‘ftinspect’ demo program
(started as a GSoC 2019 project, unfinished)</dt>
<dd>
<p>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.</p>
<p>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.</p>
<p>The idea is to finish ftinspect,
handling <em>all</em> aspects of the other demo
programs. Currently, it only provides the
functionality of ‘ftgrid’.</p>
<p>If the student prefers, the Qt toolkit could be
replaced with GTK.<p>
<p><em>Difficulty:</em> medium. <em>Requirements:</em>
C, C++, Qt, Unix build tools. <em>Potential
mentor:</em> Werner Lemberg (FreeType).</p>
</dd>
</dl>
<dl>
<dt>Replace FreeType's tracing and debugging facilities
with an external logging library</dt>
<dd>
<p>FreeType extensively uses a home-brewed tracing
solution that mainly relies on the C preprocessor
and the <code>fprintf</code> function printing to
<code>stderr</code> (see
file <a href="https://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/docs/DEBUG"><code>docs/DEBUG</code></a>
for documentation). However, this simplistic approach
is not adequate for all platforms,
where <code>stderr</code> is not always easily
accessible.</p>
<p>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
<a href="http://lists.nongnu.org/archive/html/freetype-devel/2019-01/msg00023.html">discussed
in the mailing list</a>. Note that this discussion
is by no means exhaustive.</p>
<p>As a rough guideline, the project could be structured
as follows.</p>
<ul>
<li>Get accustomed to FreeType's current
tracer/logger, all its current features, and how it
is currently being used. Extract a few
representative samples from FreeType to help with
the next step.</li>
<li>Evaluate, compare, and discuss freely available
tracing and logging libraries in respect to
FreeType's current tracer/logger.</li>
<li>Replace the old tracer/logger with the new one
within FreeType.</li>
<li>Write a brief but precise ‘how-to’
article for FreeType's website about using the new
tracer/logger which is aimed at FreeType's
developers.</li>
</ul>
<p><em>Difficulty:</em> medium. <em>Requirements:</em>
C, C++, Unix and Windows build tools. <em>Potential
mentors:</em> Werner Lemberg, Alexei Podtelezhnikov,
Toshiya Suzuki (FreeType), Armin Hasitzka.</p>
</dd>
</dl>
<dl>
<dt>Add a ‘capability database’ to FreeType's
auto-hinter</dt>
<dd>
<p>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.]</p>
<p>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’.</p>
<p>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.</p>
<p>The project consists of the following parts.</p>
<ul>
<li>Identify hinting problems of the auto-hinter
related to shape distortion and accent positioning.
A good starting point is
the <a href="https://savannah.nongnu.org/bugs/?group=freetype">FreeType
bug database.</a></li>
<li>Collect necessary adjustments. For the above two
examples, it would be necessary (a) to tell the
auto-hinter that there must be a certain vertical
distance between the body and its accent, and (b) to
distort some glyph shapes intentionally so that
rasterization at small ppem values gives decent
results.</li>
<li>Invent a database format (to be compiled into the
library) that describes the necessary actions.
Basically, this would be a key-value table, where
the key is the Unicode character code of the
affected glyph, and the value is a list of necessary
actions.</li>
<li>Add a mechanism to the auto-hinter to read the
database, and to apply the action (shift, distort,
whatever) to the affected glyph outlines if
necessary. This last feature is the non-trivial
part of this project.</li>
</ul>
<p><em>Difficulty:</em> medium to
high. <em>Requirements:</em> C, and ideally some
basic font hinting and rasterization
knowledge. <em>Potential mentors:</em> Werner
Lemberg, Alexei Podtelezhnikov (FreeType).</p>
</dd>
</dl>
<p>Do you have more ideas? Please write to
our <a href="mailto:freetype-devel@nongnu.org">mailing
list</a> so that we can discuss your suggestions,
eventually adding them to the list!</p>
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<div class="updated">
<p>Last update: 16-May-2020</p>
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