Better Game Selection Menu

Published on 2022-06-29 in PewPew LCD.

The original PewPew FeatherWing and PewPew Standalone only have 8x8 LED displays, so the menu for selecting games amounted to the name of the currently chosen game scrolling on that display horizontally, while up and down buttons would switch to the previous or next game on the list, with a nifty animation. I initially used the same program as the menu for the PewPew LCD, but there is a huge problem with it: that LCD screen is not made for fast scrolling:

All you get is a smudge, because the pixels don’t change fast enough to support this animation. But not a problem, after all with all those pixels we can have a proper menu, similar to that on the PewPew M4 — with multiple items displayed, and an arrow to choose one of them.

I’ve been meaning to write that menu program for a while now, but my day job and life in general kept getting in the way. Today I finally decided to just sit down and do it, and I’m pretty happy with the result so far:

There are several tricks in here. I used the terminalio library of CircuitPython to use the same text terminal as the REPL uses, but I re-created the TileGrid and the root group to make it all two times bigger — the tiny font is good for printing the errors, because the whole traceback fits on the screen, but it was really too small to comfortably select a game title. For now I’m just using text “>>” for the arrow, but since I re-created the root group, there is nothing stopping me from adding a sprite of a pointing hand in there. I also still need to add scrolling, for the case when there are more than six items to choose from, and perhaps some kind of display for the battery voltage would be nice? In any case, I have the basics functional, so that’s a start.

Oh, and the code is not complex at all:

import os
import pew
import supervisor
import board
import displayio
import terminalio


def wait_keys():
    try:
        while True:
            keys = pew.keys()
            if keys:
                break
        for i in range(5):
            if not pew.keys():
                break
            pew.tick(0.0625)
        else:
            keys = pew.keys()
    except pew.GameOver:
        keys = 0
    return keys


def menu(terminal, items):
    terminal.write("\x1b[2J")
    for item in items[:6]:
        terminal.write("  %s\r\n" % item[:10])
    selected = 0
    total = min(6, len(items)) - 1
    while True:
        terminal.write("\x1b[%d;1H>>" % (selected + 1))
        pew.tick(0.125)
        keys = wait_keys()
        terminal.write("\x1b[%d;1H  " % (selected + 1))
        if keys & pew.K_UP and selected > 0:
            selected -= 1
        if keys & pew.K_DOWN and selected < total:
            selected += 1
        if keys & pew.K_O:
            terminal.write("\x1b[2J")
            return items[selected]

pew.init()
grid = board.DISPLAY.root_group[0]
grid = displayio.TileGrid(grid.bitmap, pixel_shader=grid.pixel_shader,
    tile_width = grid.tile_width, tile_height=grid.tile_height,
    width = 12, height = 6)
screen = displayio.Group()
screen.scale = 2
screen.append(grid)
board.DISPLAY.show(screen)
terminal = terminalio.Terminal(grid, terminalio.FONT)
files = [name[:-3] for name in os.listdir()
         if name.endswith('.py') and name != 'main.py']
game = menu(terminal, files)
supervisor.set_next_code_file("%s.py" % game, reload_on_success=True)
supervisor.reload()