buchstabensuppe

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at least better than PIL.ImageFont

toy font rendering for low pixelcount high contrast displays, i. e. openlab's flipdot display.

features

supports text shaping via harfbuzz
per grapheme cluster font fallback
grayscale and binary b/w support

building

requirements:

redo-c
Optionally make for install script and such
utf8proc
harfbuzz
libschrift == 0.10.1

# run inside nix-shell if you have nix!

# static library
$ redo libbuchstabensuppe.a

# demo binary
$ redo bs-renderflipdot.exe

# tests
$ redo test.exe && ./test.exe

alternatively you can just run nix-build

demo

if you want to play around with the font rendering in binary mode you can use the dry run mode of the supplied ./bs-renderflipdot.exe (or ./result/bin/bs-renderflipdot if you use nix) binary.

Run ./bs-renderflipdot.exe -? for usage instructions and don't forget -n for dry running!

$ ./bs-renderflipdot.exe -f fonts/unifont.ttf -f fonts/unifont_upper.ttf -n "Greetings ❣️" 2>/dev/null
                                                                                            
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flipdot interaction

the picture above shows buchstabensuppe being used to render text onto a simulated flipdot display. take notice especially of the following:

fallback fonts are supported: the emoji is not found in unifont.ttf, but rendered from unifont_upper.ttf
correct text shaping is supported (as far as the font supports it): g̈ which consists of two codepoints is rendered as a combined cluster consisting of two glyphs.

bs-renderflipdot.c is a simple example showing how to interact with a flipdot display. mainly it involves:

rendering a string to a bitmap using bs_render_utf8_string
making sure that the dimensions of the display and the image match with bs_bitmap_extend
processing the resulting bitmap using bs_bitmap_map
rendering the resulting bitmap on the display using bs_flipdot_render.
dealing with bitmaps too big for the display using bs_scroll_next_view and bs_page_next_view.

you can also play around with its cli: the following command renders “Hello World” black on white using GNU Unifont onto a flipdot display (or simulator) running on localhost:2323. See bs-renderflipdot(1) for more usage details.

./bs-renderflipdot.exe -f /path/to/unifont.ttf -f /path/to/unifont_upper.ttf -i "Hello World"

caveats