canvas_ity VS skrift

I have a small TTF implementation that's in the neighborhood of that size and is open source. It's part of my canvas_ity single-header library [0] that's around 2300 LOC / 36 KB object size and implements a C++ version of most of the 2D HTML5 canvas spec [1].

The core implementation of the TTF parsing and drawing is in L1526-L1846 with another small bit at L3205-L3274 of src/canvas_ity.hpp.

It's something of a toy implementation that only supports western left-to-right text, and doesn't do any hinting at all, nor kerning, nor shaping. But it's enough to draw a basic "Hello world!" using any typical TTF file.

The test suite in test/test.cpp L84-304 embeds a few custom Base64-encoded TTF files. They're small and only have a few glyphs but they do exercise a number of interesting edge cases in the OpenType TTF spec [2]. Have a look at the HTML5 port of the test suite at test/test.html in different browsers to see how their canvas implementations render those fonts.

[0] https://github.com/a-e-k/canvas_ity

[1] https://www.w3.org/TR/2015/REC-2dcontext-20151119/

[2] https://standards.iso.org/ittf/PubliclyAvailableStandards/c0...

Agreed, that sort of documentation is pure gold when done well.

It's something I always try to pay forward by doing in my own code. For example, one of my own solo projects was an STB-style single-header -like rasterizer library for C++. I started the implementation half of the library with a short outline of the rendering pipeline's dataflow and the top-level functions responsible for each stage:

https://github.com/a-e-k/canvas_ity/blob/f32fbb37e2fe7c0fcae...

https://github.com/a-e-k/canvas_ity

This is an STB-style single-header C++ library with no dependencies beyond the standard C++ library. In about 2300 lines of 78-column code (not counting blanks or comments), or 1300 semicolons, it implements an API based on the basic W3C specification to draw 2D vector graphics into an image buffer:

- Strokes and fills (with antialiasing and gamma-correct blending)

- Linear and radial gradients

- Patterns (with repeat modes and bi-cubic resampling)

- Line caps and line joins (handling high curvature)

- Dash patterns and dash offsets

- Transforms

- Lines, quadratic and cubic Beziers, arcs, and rectangles

- Text (very basic, but does its own TTF font file parsing!)

- Raster images (i.e., sprites)

- Clipping (via masking)

- Compositing modes (Porter-Duff)

- Drop shadows with Gaussian blurs

I also uncovered a number of interesting browser quirks along the way with the HTML5 port of my testing suite.

Repository: https://github.com/a-e-k/canvas_ity

https://github.com/vidarh/skrift

Libschrift is very readable.

I did my Ruby rewrite basically just top to bottom before reorganizing it. Mine is... readable if you're well versed in Ruby, but still has some warts where it's less than idiomatic Ruby because I stuck closely to the original.

Basically TTF has a crufty binary format, but the basic font data if you're willing to ignore ligatures, hinting, OpenType support and emoticons, is fairly simple (it's basically a bunch of polygons consisting of quadratic beziers and lines, and quadratic beziers are easy to tesselate into lines if you don't want to do a more complex curve renderer), just error-prone to figure out.

If you want/need OpenType you need to support cubic beziers on top of that, which isn't that bad. If you want to support emoticons you need to support a subset of SVG (!)...

So TTF without those bits is pretty much the halfway point.

Also do look at the Canvas C++ header implementation linked in this comment[1]. It's readable, and more featureful than libschrift or my Ruby rewrite, and it's still small while packing a full rendering library in there not just the font renderer. I intend to pillage it (with credits) for ideas ;)

[1] https://news.ycombinator.com/item?id=38839114

I've put plenty of half-baked stuff out there over the years, so that doesn't really worry me. More that at the moment if you try to copy any of it the github repos are all at different stages of not quite up to date, and APIs are in flux, and you're just really likely to have a bad time trying to get anything to work.

I think the real starting point for me is going to be to clean up PureX11 a bit more so the API is at least somewhat cohesive, and then push the WM as it's working enough that it's been my only wm for a few weeks (it does have significant quirks still, but with somewhat minor cleanups it's a decent starting point to play with), and then the terminal as it's fairly freestanding, then some of the file management tools, toolbar, popup menu etc., then lastly my editor. The editor has by far changed most from the version on Github and is also most likely to cause problems for others, so that might take a bit of time, not least because I'm in the middle of a fairly significant overhaul of the way the views and models works.

Here's some of what is out there, though:

* Skrift: This is a Ruby port of libschrift, a TTF font renderer. It's heavily cut down, and currently stands at about 680 lines of code. I intended to tidy up the API as it's still a bit messy after my rewrite: https://github.com/vidarh/skrift

* X11 bindings for Skrift: https://github.com/vidarh/skrift-x11 - these are messy, and I have significant updates to them (including basic fontset support and a mechanism for pixel-perfect boxdrawing characters at any reasonable scale) that have not yet been pushed: https://github.com/vidarh/skrift-x11

* Pure-X11: This is a form and significant overhaul of pure X11 client bindings for Ruby (as in not Xlib or XCB needed): https://github.com/vidarh/ruby-x11 - it's not terribly out of date, but it's a bit in flux as I don't like the initial mechanism, used for the protocol and so I'm thinking about how to trim it down and make it easier to use.

* This is the starting point for my terminal. My terminal is nothing like that any more, but this is the repo that will get all the updates, eventually: https://github.com/vidarh/rubyterm - this initial prototype used a C extension and server-side fonts, while the current version uses Pure-X11 and Skrift

* This was the very first version of my WM I used, a few hours into the switch (from bspwm). It's a straight port from TinyWM. My current one has tiling and some EWMH support and multiple desktops and adds about 700 lines of code - it'll start appearing on Github soon: https://gist.github.com/vidarh/1cdbfcdf3cfd8d25a247243963e55...

* This is a script I used to feed into a 9menu style popup menu script from my file manager to generate folder-contextual actions based on the folder contents: https://gist.github.com/vidarh/323204137de5293bfe216ec751646... -- the current version is quite a bit slicker and will eventually show up

* This is a very dated and broken version of my editor, and odds are you'll struggle to get it to work at all, as it depends on various helper scripts that are not yet packaged up, as have been massive updated since that version; I'm hoping to maybe bring the repo a bit more up to date over the holidays: https://github.com/vidarh/re

* This is a gem that handles the input processing: https://github.com/vidarh/termcontroller

* This does keyboard mapping from symbols from termcontroller to higher level user-defined sequences:

No current version, but I'm preparing it. But actually, to see a really ridiculously minimalist start, this was my starting point, which used a tiny X extension to do the X rendering (though it optimistically included a dummy class intended to be the start for the Ruby X backend). It's awfully limited, and awfully broken, but it shows how little it takes to be able to start writing:

https://github.com/vidarh/rubyterm

It's totally useless for anything other that testing or expanding on, but it was the starting point for the terminal I now run every day, and I'll be updating that repo as I clean up my current version at some point.

The current version uses this for a pure Ruby (no Xlib) X11 client implementation:

https://github.com/vidarh/ruby-x11

And this pure-Ruby TrueType font renderer (I did the Ruby conversion; the C code it's based on was not mine, and is a beautiful example of compact C - look up libschrift):

https://github.com/vidarh/skrift