Josh's Brain

E-ink screens show only black and white, but can effectively show grayscale using dithering. Internally the screens use a full color frame buffer, so colors should be specified the same as normal.

Fill the background with white using a single large bitmap

# fill the background with white
background_bitmap = displayio.Bitmap(WIDTH, HEIGHT, 1)
# Map colors in a palette
palette = displayio.Palette(1)
palette[0] = WHITE # 0xffffff
# Create a Tilegrid with the background and put in the displayio group
t = displayio.TileGrid(background_bitmap, pixel_shader=palette)
group.append(t)

Then set the color of labels to be BLACK as 0x000000.

A bitmap is just an empty image. It has a fixed size and number of colors. Pixels can be set directly using x,y coordinates.

import displayio


bitmap = displayio.Bitmap(32,32,2)
palette = displayio.Palette(2)
palette[0] = 0x000000
palette[1] = 0xffffff

# set pixel at x=3, y=4 to color 1
bitmap[3,4] = 1

Bitmaps can only be shown on screen using a tilegrid. To create a tilegrid that shows the bitmap without any repetition, do:

tilegrid = displayio.TileGrid(bitmap, pixel_shader=palette)
display.root_group.append(tilegrid)

convert a PNG to a indexed color bitmap

convert digits.png -colors 64 -type palette -compress None BMP3:digits.bmp

Use a custom font in a label or button

Overview | Custom Fonts for CircuitPython Displays | Adafruit Learning System

Convert truetype font to bitmap

brew install otf2bdf
otf2bdf FontFile.ttf -p pointsize -o FontFile.bdf

convert bitmap ascii to bitmap binary bdftopcf font converter

Use in python code

from adafruit_display_text import label
from adafruit_bitmap_font import bitmap_font

font = bitmap_font.load_font("my_font.bdf")
# draw in red
text_label = label.Label(font, text="Greetings Earthling!", color=0xFF0000)

create a new text label:

from adafruit_display_text import label
 
label = label.Label(
    font=terminalio.FONT,
    text="Greetings Earthlings",
    x=20,
    y=10,
    scale=1
)
display.root_group.append(label)

Everything graphics in CircuitPython is built around the displayio library.

• API docs
• Official Adafruit Tutorial

display graphics

First you need a display object, which is usually preconfigured for your board if it has a built in display, as board.display. It will automatically refresh the screen. The root of the screengraph should already be set to a group, so you can append to it.

display = board.display
display.root_group.append(some_gfx_object)