A Journey Through Font Rendering

January 7, 2024 by Matthew Carlson 8 Comments

In the wide world of programming, there are a few dark corners that many prefer to avoid and instead leverage the well-vetted libraries that are already there. [Phillip Tennen] is not one of those people, and when the urge came to improve font rendering for his hobby OS, axle, he got to work writing a TrueType font renderer.

For almost a decade, the OS used a map table encoding all characters as 8×8 bitmaps. While scaling works fine, nonfractional scaling values are hard to read, and fractional scaling values are jagged and blocky. TrueType and font rendering, in general, are often considered dark magic. Font files (.ttf) are structured similarly to Mach-O (the binary format for macOS), with sections containing tagged tables. The font has the concept of glyphs and characters. Glyphs show up on the screen, and characters are the UTF/Unicode values that get translated into glyphs by the font. Three critical tables are glyf (the set of points forming the shape for each glyph), hmtx (how to space the characters), and cmap (how to turn Unicode code points into glyphs).

Seeing the curtain pulled back from the format itself makes it seem easy. In reality, there are all sorts of gotchas along the way. There are multiple types of glyphs, such as polygons, blanks, or compound glyphs. Sometimes, control points in the glyphs need to be inferred. Curves need to be interpolated. Enclosed parts of the polygon need to be filled in. And this doesn’t even get to the hinting system.

Inside many fonts are tiny programs that run on the TrueType VM. When a font is rendered at low enough resolutions, the default control points will lose their curves and become blobs. E’s become C, and D’s become O’s. So, the hinting system allows the font to nudge the control points to better fit on the grid. Of course, [Phillip] goes into even more quirks and details in a wonderful write-up about his learnings. Ultimately, axle has a much better-looking renderer, we get a great afternoon read, and fonts seem a little less like forbidden magic.

Maybe someday [Phillip] will implement other font rendering techniques, such as SDF-based text renderers. But for now, it’s quite the upgrade. The source code is available on GitHub.

Finally! A Typeface For Hardware People

December 4, 2023 by Jenny List 11 Comments

When it comes to novelty typefaces there is no shortage of weird and wonderful fonts to be found when you have finally tired of Comic Sans. Everything from bananas forming letters to Wild West saloon lettering can be yours, plus of course our favourite, the embossed Dymo label. But there’s a new kid on the novelty typeface block, and for us it sweeps all before it.

Scopin’ Sans is as its creator [Guy Dupont] calls it “A typeface for hardware people”, and its party trick is that it doesn’t produce letters. Instead it forms an oscilloscope trace that displays what it would look like as serial data. Instantly your text jumps straight to 1337, and you win the internet.

We have shamefacedly to admit that we don’t know binary ASCII by sight, so we’ll have to take his word for it. But for the curious there’s a demo from which you can amuse yourself creating traces, and if you can’t recognize serial ASCII then the chances are few of the people around you can either. We take our hats off to [Guy], and it’s something we’re sure we’ll use at some point to delight and confuse our friends. It’s not the first font we’ve brought you, here are some more if you come from the bitmap era.

Modifying Old Fonts In The Name Of Baseball

May 11, 2022 by Kristina Panos 4 Comments

Baseball is in full swing again, and having recently accepted a position with Major League Baseball, [Ty Porter] is warming up with a big contribution to the MLB LED Scoreboard project — modifying 20-some old fonts to support baseball’s ‘ꓘ’ character that indicates a special strikeout with a called third strike (meaning the batter didn’t take a swing).

The problem is that Major League Baseball-the-entity recently deprecated the original data source for the scoreboard project. This called for a huge refactor of the codebase, including previously-patched fonts which were now showing either the font’s default no-character character, or nothing at all.

Fortunately, BDF font files are fairly human-readable and make reference to bitmap, which is an actual bitmap in hex. [Ty] settled on Unicode A4D8 (ꓘ), a character from the Tibeto-Burman language Lisu that certainly looks good enough to this baseball fan. Then it became a matter of mirroring the bitmap for ‘K’. [Ty] tried a few things like reversing the nibbles and looking up each one in a table, but that also mirrors the padding, which is bad news.

Then he tried not reversing the nibbles and just looked them up in a table, but this approach dropped and added bits unintentionally. Finally, he tried reversing the order, looking up the reversed nibble, and shifting each byte until there was no padding. This worked for most of the 20 fonts [Ty] patched. The others fell in line with some manual work.

Not much of a baseball fan? You’re almost guaranteed to like this one, especially if you hate mayo.

Hackaday Links: May 1, 2022

May 1, 2022 by Dan Maloney 18 Comments

We start this week with news from Mars, because, let’s face it, the news from this planet isn’t all that much fun lately. But a couple of milestones were reached on the Red Planet, the first being the arrival of Perseverance at the ancient river delta it was sent there to explore. The rover certainly took the scenic route to get there, having covered 10.6 km over the last 424 sols to move to a position only about 3.5 km straight-line distance from where it landed. Granted, a lot of that extra driving was in support of the unexpectedly successful Ingenuity demonstration, plus taking time for a lot of pit stops along the way at interesting features. But the rover is now in place to examine sedimentary rocks most likely to harbor the fossil remains of ancient aquatic life — as opposed to the mainly igneous rocks it has studied along the crater floor so far. We’re looking forward to seeing what happens.

Continue reading “Hackaday Links: May 1, 2022” →

Can You Identify This Mystery Unicode Glyph?

April 24, 2022 by Jenny List 56 Comments

For anyone old enough to have worked with the hell of multiple incompatible character sets, Unicode has been a liberation; a true One Character Set To Contain Them All. We have so many Unicode characters to play with that there’s a fascinating pursuit in itself in probing at the obscure corners of what can be rendered on screen as a Unicode glyph. With so many disparate character sets having been brought together to make the Unicode standard there are plenty of unusual characters to choose from, and it’s one of them that [Jonathan Chan] has examined in detail.

U+237C ⍼, or the right angle with downwards zigzag arrow, is a mysterious Unicode symbol with no known use and from an unknown origin. XKCD featured it as a spoof “Larry Potter”, but as [Jonathan]’s analysis shows it’s proving impossible to narrow down where it came from. Mystical cult symbol? Or perhaps fiscal growth in an economy in which time runs downwards? Either way, when its lineage has been traced into the early 1990s with no answer to the question it appears that there may be a story behind it.

Hackaday readers never cease to amaze us with the breadth of their knowledge, ingenuity, and experience, so we think it’s not impossible that among you there may be people who will turn and pull a dusty computer manual from the shelf to give us the story behind this elusive glyph. We’d love to hear in the comments below.

Meanwhile if Unicode sparks your interest, we’ve given it a close look in the past.

Thanks [Jonty] for the tip.

Hackaday Links: May 9, 2021

May 9, 2021 by Dan Maloney 17 Comments

Well, that de-escalated quickly. It seems like no sooner than a paper was announced that purported to find photographic evidence of fungi growing on Mars, that the planetary science and exobiology community came down on it like a ton of bricks. As well they should — extraordinary claims require extraordinary evidence, and while the photos that were taken by Curiosity and Opportunity sure seem to show something that looks a lot like a terrestrial puffball fungus, there are a lot of other, more mundane ways to explain these formations. Add to the fact that the lead author of the Martian mushroom paper is a known crackpot who once sued NASA for running over fungi instead of investigating them; the putative shrooms later turned out to be rocks, of course. Luckily, we have a geobiology lab wandering around on Mars right now, so if there is or was life on Mars, we’ll probably find out about it. You know, with evidence.

If you’re a fan of dystopic visions of a future where bloodthirsty robots relentlessly hunt down the last few surviving humans, the news that the New York Police Department decided to stop using their “DigiDog” robot will be a bit of a downer. The move stems from outrage generated by politicians and citizens alike, who dreamt up all sorts of reasons why the NYPD shouldn’t be using this tool. And use it they apparently did — the original Boston Dynamics yellow showing through the many scuffs and dings in the NYPD blue paint job means this little critter has seen some stuff since it hit the streets in late 2020. And to think — that robot dog was only a few weeks away from filing its retirement papers.

Attention, Commodore fans based in Europe: the Commodore Users Europe event is coming soon. June 12, to be precise. As has become traditional, the event is virtual, but it’s free and they’re looking for presenters.

In a bid to continue the grand Big Tech tradition of knowing what’s best for everyone, Microsoft just announced that Calibri would no longer be the default font in Office products. And here’s the fun part: we all get to decide what the new default font will be, at least ostensibly. The font wonks at Microsoft have created five new fonts, and you can vote for your favorite on social media. The font designers all wax eloquent on their candidates, and there are somewhat stylized examples of each new font, but what’s lacking is a simple way to judge what each font would actually look like on a page of English text. Whatever happened to “The quick brown fox” or even a little bit of “Lorem ipsum”?

And finally, why are German ambulances — and apparently, German medics — covered in QR codes? Apparently, it’s a way to fight back against digital rubberneckers. The video below is in German, but the gist is clear: people love to stop and take pictures of accident scenes, and smartphones have made this worse, to the point that emergency personnel have trouble getting through to give aid. And that’s not to mention the invasion of privacy; very few accident victims are really at their best at that moment, and taking pictures of them is beyond rude. Oh, and it’s illegal, punishable by up to two years in jail. The idea with the QR codes is to pop up a website with a warning to the rubbernecker. Our German is a bit rusty, but we’re pretty sure that translates to, “Hey idiot, get back in your frigging car!” Feel free to correct us on that.

[Editor’s note: “Stop. Rubbernecking kills”.]

An Entire Game Inside Of A Font

March 22, 2021 by Kristina Panos 17 Comments

Where’s the last place you’d expect to be able to play a game on your computer? The word processing program? Image editor? How about your text editor? That’s right — you can fight your Fontemons in any program that makes use of fonts, because mad genius [Michael Mulet] has created a game that exists entirely within a single Open Type font file.

[Michael] has harnessed the power of ligatures to create a choose-your-own-adventure-style turn-based game that pokes fun at both Pokemon and various typeface names. You start by choosing between Papyromaniac, Verdanta, and Proggito and face off against enemies like Helvetikhan and Scourier.

This works because there are many ways to draw glyphs on a screen. [Michael] chose Type 2 Charstrings, which is a vector graphics format that Adobe created for PostScript. It can draw pixels with a series of move specifications that tell it to draw up, to the right, and then back down before closing off the pixel with an implicit operator that draws from the starting point to the ending point. [Michael] was able to create two shades of gray by drawing smaller versions of the pixels and making the image by combining white and black pixels.

If you just want to play the game, you can either download the .otf file or just try it out in the browser. You’re supposed to use ‘a’ and ‘b’ to make choices that advance the game, but we soon discovered that spamming other keys like ‘v’ and Enter will lead to strange places. If you play it straight, it takes about 20 minutes, but there are enough secrets built in to make it last five times as long. [Michael] was kind enough to create a tutorial for making font-based games, but if you just want to get going, the game engine is open source.

What other fun things can you do on that locked-down work computer? If it has Excel, you can use it to do animation or just kick back and watch a movie.