Scroll text on the Adafruit IS31FL3741 13x9 RGB Matrix with a Frame Buffer

code.py

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-FileCopyrightText: 2023 Neradoc https://neradoc.me
# SPDX-License-Identifier: MIT
"""
A somewhat hacky attempt at scrolling text on the IS31FL3741 13x9 Matrix
https://www.adafruit.com/product/5201
"""
import time
import board
from rainbowio import colorwheel
from adafruit_is31fl3741.adafruit_rgbmatrixqt import Adafruit_RGBMatrixQT
import adafruit_is31fl3741
from is31matrixqt_framebuf import IS31FrameBuffer

# i2c = board.I2C()
i2c = board.STEMMA_I2C()

is31 = Adafruit_RGBMatrixQT(i2c, allocate=adafruit_is31fl3741.PREFER_BUFFER)
is31.set_led_scaling(0xFF)
is31.global_current = 0xFF
is31.enable = True

fbuff = IS31FrameBuffer(is31)

def scroll(text, color):
    for x in range(-13, 7 * len(text)):
        is31.fill(0)
        fbuff.text(text, -x, 1, color)
        is31.show()

while True:
    scroll("Hello world!", 0x00FF80)

is31matrixqt_framebuf.py

# SPDX-FileCopyrightText: 2023 Neradoc https://neradoc.me
# SPDX-License-Identifier: MIT
"""
"""
import adafruit_framebuf
from adafruit_is31fl3741.adafruit_rgbmatrixqt import Adafruit_RGBMatrixQT

def rgb_matrix_qt_mapping():
    mapping = [0] * (13*9*3)
    i = 0
    for y in range(9):
        for x in range(13):
            (b, g, r) = Adafruit_RGBMatrixQT.pixel_addrs(x,y)
            for z in (r, g, b):
                mapping[i] = z
                i = i + 1
    return mapping

class IS31Buffer:
    def __init__(self, is31, mapping):
        self.is31 = is31
        self.mapping = mapping

    def __len__(self):
        return len(self.is31)

    def __setitem__(self, index, val):
        if isinstance(index, slice):
            start, stop, step = index.indices(13*9*3)
            for val_i, in_i in enumerate(range(start, stop, step)):
                self.is31[self.mapping[in_i]] = val[val_i]
        else:
            self.is31[self.mapping[index]] = val

def IS31FrameBuffer(is31):
    is31_buffer = IS31Buffer(is31, rgb_matrix_qt_mapping())
    return adafruit_framebuf.FrameBuffer(
        is31_buffer, 13, 9,
        adafruit_framebuf.RGB888
    )