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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 list of possible
projects – if you 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 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>Note that starting with 2021 the time available for
students has been halved. Most of our projects are
modular, more or less, allowing students to propose a
subset of the mentioned targets if this appears
appropriate.</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>However,
a <a href="https://github.com/fundies/freetype2/tree/greg-gsoc">GSoC
2020 project</a> now provides a good framework that
can act as a starting point for better integration.
In addition, we are moving to the gitlab instance
of <a href="https://gitlab.freedesktop.org/freetype">freedesktop.org</a>;
this implies that access to
its <a href="https://docs.gitlab.com/ee/ci/">CI
abilities</a> should be straightforward.</p>
<p>The idea is to select a representative set of
reference fonts from font corpora (which already exist
mainly
for <a href="https://github.com/freetype/freetype2-testing/tree/master/fuzzing">fuzzing</a>).
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, HTML, 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://mesonbuild.com/"><code>meson</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. Right now, we tend to
move to <code>meson</code>.</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://gitlab.freedesktop.org/groups/freetype/-/issues">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>,
<code>cmake</code>,
and <code>meson</code>. <em>Potential mentors:</em>
Werner Lemberg, Alexei Podtelezhnikov, Toshiya Suzuki
(FreeType).</p>
</dd>
</dl>
<dl>
<dt>Integrate FreeType with alternative rendering
engines</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. It
claims to be much faster than FreeType's anti-aliasing
rendering module due to SIMD optimizations.</p>
<p>Note that
the <a href="https://github.com/mooman219/fontdue"><code>fontdue</code></a>
Rust package is another rendering engine based on
<code>font-rs</code>, and it claims to be even faster
and is actively developed. You can find some additional
discussion <a href="https://www.reddit.com/r/rust/comments/ilnd41/fontdue_the_fastest_font_renderer_in_the_world">here</a>.
Another project inspired by <code>font-rs</code> is
<a href="https://github.com/servo/pathfinder"><code>Pathfinder</code></a>,
which takes advantages of GPU rendering.</p>
<p>The project is about implementing an
alternative <a href="https://www.freetype.org/freetype2/docs/reference/ft2-module_management.html#ft_renderer"><code>FT_Renderer</code></a>
module in C that can take priority over the
native FreeType rasterizer. It should either wrap the
calls to a linked precompiled object or port the Rust
code to C. It requires in-depth feasibility
analysis of either approach and a good understanding
of FreeType's architectural details.</p>
<p><em>Difficulty:</em> high. <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 FreeType demo programs</dt>
<dd>
<p>Right now, FreeType comes with a suite of small
graphic tools to test and showcase the library, most
notably <a href="https://gitlab.freedesktop.org/freetype/freetype-demos/-/blob/master/src/ftview.c"><code>ftview</code></a>
and <a href="https://gitlab.freedesktop.org/freetype/freetype-demos/-/blob/master/src/ftgrid.c"><code>ftgrid</code></a>.
They natively work
on <a href="https://www.x.org/wiki/">X11</a> and
<a href="https://docs.microsoft.com/en-us/windows/win32/gdi/windows-gdi">Windows
GDI</a> without any additional requirements. One
opportunity is to port them
to <a href="https://wayland.freedesktop.org/">Wayland</a>
and <a href="https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/OSX_Technology_Overview/CocoaApplicationLayer/CocoaApplicationLayer.html">Cocoa/macOS</a>.
This would involve implementing a small, low-level
driver to manage a basic window, together with
associated keyboard and resizing events.</p>
<p>Another opportunity is to work on a modern GUI tool
to showcase and test FreeType capabilities. A first
try to improve the demo program
called <a href="https://gitlab.freedesktop.org/freetype/freetype-demos/-/tree/master/src/ftinspect"><code>ftinspect</code></a>,
which is based on the <a href="https://www.qt.io/">Qt
GUI</a> toolkit, was started as
a <a href="https://gitlab.freedesktop.org/freetype/freetype-demos/-/tree/gsoc-2019-veeki">GSoC
2019 project</a>. However, the development is
currently stalled.</p>
<p>The idea is to finish <code>ftinspect</code>,
handling <em>all</em> aspects of the other demo
programs. Currently, it only provides the
functionality of <code>ftgrid</code>.</p>
<p>If the student prefers, the Qt toolkit could be
replaced
with <a href="https://www.gtk.org/">GTK</a>.<p>
<p><em>Difficulty:</em> medium. <em>Requirements:</em>
C, C++, Qt, Unix build tools. <em>Potential
mentor:</em> Werner Lemberg, Alexei Podtelezhnikov
(FreeType).</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
<a href="https://www.freetype.org/autohinting/hinter.html">auto-hinter</a>
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://gitlab.freedesktop.org/groups/freetype/-/issues">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>
<dl>
<dt>Integrate VFlib's TeX font support into FreeType</dt>
<dd>
<p>A <a href="https://gitlab.freedesktop.org/freetype/freetype/-/tree/GSoC-2018-parth">GSoC
2018 project</a> was a first try to integrate
<a href="http://www-masu.ist.osaka-u.ac.jp/~kakugawa/VFlib/">VFlib</a>
into FreeType. This library contains mature support
for TeX's bitmap formats (in
particular <code>GF</code> and <code>PK</code> fonts,
together with <code>TFM</code> metric files
and <code>VF</code> virtual fonts).</p>
<p>The project would be as follows.</p>
<ul>
<li>Evaluate the existing code to find out whether it
can be used as a starting point to complete the
begun task, this is, to merge VFlib's source code
into FreeType, thus providing new modules to handle
TeX bitmap fonts.</li>
<li>Evaluate different routes if necessary. For
example, it might be easier to provide simple and
small wrapper modules that call VFlib functions. In
other words, this wouldn't integrate the code of
VFlib but have it as an external dependency.</li>
<li>Create modules.</li>
</ul>
<p>The canonic reference of
the <code>PK</code>, <code>GF</code>, <code>TFM</code>,
and <code>VF</code> font formats is the source code of
the TeX
tools <a href="https://www.tug.org/svn/texlive/trunk/Master/texmf-dist/doc/generic/knuth/mfware/gftopk.pdf?view=co">gftopk</a>
(for
<code>PK</code>), <a href="https://www.tug.org/svn/texlive/trunk/Master/texmf-dist/doc/generic/knuth/mfware/gftype.pdf?view=co">gftype</a>
(for
<code>GF</code>), <a href="https://www.tug.org/svn/texlive/trunk/Master/texmf-dist/doc/generic/knuth/texware/tftopl.pdf?view=co">tftopl</a>
(for <code>TFM</code>),
and <a href="https://www.tug.org/svn/texlive/trunk/Master/texmf-dist/doc/generic/knuth/etc/vftovp.pdf?view=co">vftovp</a>
(for <code>VF</code>).</p>
<p><em>Difficulty:</em> medium (hard for VF
support). <em>Requirements:</em> C, Unix build tools,
knowledge of TeX infrastructure
(using <a href="https://www.tug.org/texlive/">TeXLive</a>
is recommended). <em>Potential mentor:</em> Werner
Lemberg (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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<p>Last update: 18-Feb-2021</p>
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