Implement PCF font loading #32
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A pcf font can be generated from a bdf font using `bdftopcf` from debian/ubuntu package fonts-utils
This font was probably manually trimmed from one with a larger repertoire of code points. This was fine, except that bdftopcf didn't like it.
This will be used by a future version of adafruit_display_text to avoid needing to load glyphs from the font to guess these values.
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this is working great for me, can merge on CI |
ladyada
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Dec 8, 2020
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Dec 9, 2020
Updating https://github.com/adafruit/Adafruit_CircuitPython_SCD30 to 1.0.1 from 1.0.0: > fixed co2=> eCO2 Updating https://github.com/adafruit/Adafruit_CircuitPython_Bitmap_Font to 1.3.0 from 1.2.3: > Merge pull request adafruit/Adafruit_CircuitPython_Bitmap_Font#32 from jepler/pcf Updating https://github.com/adafruit/Adafruit_CircuitPython_Bundle/circuitpython_library_list.md to NA from NA: > Added the following libraries: Adafruit_CircuitPython_SCD30
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PCF is a binary font format historically used in the X11 system. It offers a smaller size for many font files, as well as improved random access to glyph data.
PCF fonts can be created from BDF fonts with
bdftopcf, such asbdftopcf -o Arial16.pcf Arial16.bdf. bdf has many sub-formats. The format I selected is the default (on x86 / x64 systems). This is not quite the most compact format (it pads bitmap rows to a multiple of 32 bits) and it also doesn't match the preferred internal bitmap format of circuitpython. Adding support for other formats is possible.About 50% of the time loading are in the bit-pushing loop,
which is the most optimized version I could devise. A future improvement to the core to allow setting multiple pixels from a buffer (bitmap.blit or slice assignment) could yield further improvements.
On magtag loading the
yasashi24font takes much less time, around 2s instead of 13s to load ASCII plus kana code points.This also