ValueError: Font must be horizontally mapped.

[wumfi]

As per issue #10, I too am getting the above error with any ttf I find online.

Is there something specific I should be searching for to find horizontally mapped fonts?

Each file that I run through font_to_py.py produces a file where the hmap function is returning False.

EDIT: This is using the standard Micropython installed on a Raspberry Pi Pico. I'm running the font_to_py.py script on my Mac (Python3.9).

[peterhinch]

You need to run font_to_py with the -x argument to produce a horizontally mapped Python font.

Run

$ font_to_py --help

for a list of args.

[easytarget]

This should be properly and prominently documented. The default for your tool is that it produces results that are incompatible with the example Writer class provided. edit: sorry for shouting

[peterhinch]

The correct mapping depends on your display hardware. Vertically mapped fonts are compatible with Writer and display correctly on hardware which uses vertical mapping.

[lerouxb]

The correct mapping depends on your display hardware. Vertically mapped fonts are compatible with Writer and display correctly on hardware which uses vertical mapping.

Is this true? Reading the code there's if font.hmap() and then in else it throws. Immediately after that it has a hardcoded print that states that the orientation is horizontal: https://github.com/peterhinch/micropython-font-to-py/blob/c37e4acabd2e43eaae468c0f1854f35be86c27bd/writer/writer.py#L72-L77

[peterhinch]

Apologies, you are right. A hazard of old age - you forget how your own code actually works...

The reason for the -x flag is historical. I started work on font-to-py nearly ten years ago for an early (now obsolete) e-paper display which was vertically mapped. I therefore made vertical mapping the default. (Note that framebuf has some support for vertical mapping). Alas horizontal mapping seems to be universal in modern displays.

While it would make sense to make horizontal the defualt in font-to-py - and also to scrap binary fonts, another relic - I'm reluctant to make breaking changes. There is always someone who pops up, howling in anguish.

Perhaps the way forward is for font_to_py.py to issue a warning message if a font is created without the -x arg?

[lerouxb]

No need to apologize. I'm much younger and have to find a team member to explain to me my own diffs from weeks ago on a surprisingly regular basis :)

I think maybe just a notice / paragraph added to the markdown file should be fine.

A side-note: I misinterpreted the phrasing there for some reason. I couldn't tell if the flag meant "This .bdf file IS horizontally mapped" or "map this horizontally when writing the .py file" and went on a detour looking into the specs of how the files work 😆

It also didn't help that I was trying out a font that has a configure and make step, but the source is also .bdf and then I pointed font_to_py at the source files.. So I was getting garbage even after I mapped it horizontally. Eventually noticed that the glyph positions are clearly offset and then it clicked.

[peterhinch]

I have now pushed an update. The default mapping is horizontal. The -x arg still exists but has no effect. There is a new -y or --ymap arg that specifies vertical mapping.

The docs further clarify that mappings refer to the output file and display hardware. They also state that vertical mapping is incompatible with Writer classes.

[easytarget]

Sorry for shouting in my earlier comment, and thank you for fixing this. .. I should probably apologise for necro-posting a closed issue too ;-)