Micropython support for Display

[dwalton76]

Take a look at what David did here: https://github.com/dlech/micropython-ev3dev/blob/ev3dev-stetch/src/uev3dev/display.py

and see if we can bring that in to add Display support for micropython

[dwalton76]

@WasabiFan I am going to experiment with David’s Micropython Display code. Maybe this will be like the buttons where we can add this without a ton of effort :)

[WasabiFan]

The major issue I see here is that most of our current display API is really just exposing the PILlow drawing object. I think we do still have wrapper methods around it though, so maybe we can fill in some holes there and then have the PIL object only available on CPython.

[dwalton76]

I think if we could get just text to the display working that would be worth committing. Drawing shapes, etc could all come later if needed.

Am doing my work here if you want to give it a try. I can't actually get anything to display though (using Display.text_pixels)...not sure why yet https://github.com/dwalton76/ev3dev-lang-python/tree/micropython-display

[dwalton76]

Hmm this looks interesting https://docs.micropython.org/en/latest/library/framebuf.html

import framebuf

# FrameBuffer needs 2 bytes for every RGB565 pixel
fbuf = FrameBuffer(bytearray(10 * 100 * 2), 10, 100, framebuf.RGB565)

fbuf.fill(0)
fbuf.text('MicroPython!', 0, 0, 0xffff)
fbuf.hline(0, 10, 96, 0xffff)

[dwalton76]

oh wait David's code was already using that...doh!!

[bpmerkel]

Okay. Just in case anyone is watching this space... You can display and position text on the LCD screen using escape code sequences supported by the EV3DEV console driver (appears to support the VT100 sequences). Here are some code snippets that'll get you started:

def set_cursor(on=False):
    # use escape code to turn cursor on or off
    if on:
        print("\x1b[?25h", end='')
    else:
        print("\x1b[?25l", end='')


def clear_screen():
    print("\x1b[2J\x1b[H", end='')
    set_cursor(False)


def text_at(row, col, text='', reverse=False):
    if reverse:
        text = "\x1b[7m%s\x1b[m" % (text)

    print("\x1b[%d;%dH%s" % (row, col, text), end='')


def enable_big_text(font="Lat15-TerminusBold24x12"):
    """
    Set the LCD console font larger so we can SEE IT!
    `font` the name of the font to use
    """
    # Font choices:
    # Lat15-Terminus12x6 Lat15-Terminus14 Lat15-Terminus16 Lat15-Terminus20x10 Lat15-Terminus22x11 Lat15-Terminus24x12 Lat15-Terminus28x14 Lat15-Terminus32x16
    # Lat15-TerminusBold12x6 Lat15-TerminusBold14 Lat15-TerminusBold16 Lat15-TerminusBold20x10 Lat15-TerminusBold22x11 Lat15-TerminusBold24x12 Lat15-TerminusBold28x14 Lat15-TerminusBold32x16
    # Lat15-Courier13 Lat15-Courier14 Lat15-Courier15 Lat15-Courier16
    # Lat15-CourierBold13 Lat15-CourierBold14 Lat15-CourierBold15
    # Lat15-Fixed13 Lat15-Fixed14 Lat15-Fixed15 Lat15-Fixed16 Lat15-Fixed18 Lat15-Fixed24x12
    # Lat15-FixedBold13 Lat15-FixedBold14 Lat15-FixedBold15 Lat15-FixedBold16 Lat15-FixedBold18 Lat15-FixedBold24x12
    # Lat15-Lucid12 Lat15-Lucid13 Lat15-Lucid15 Lat15-Lucid16 Lat15-Lucid22x12 Lat15-Lucid29x16
    # Lat15-LucidBold11 Lat15-LucidBold13 Lat15-LucidBold15 Lat15-LucidBold16 Lat15-LucidBold22x12 Lat15-LucidBold29x16
    os.system("setfont %s" % (font))
    clear_screen()

[dwalton76]

@bpmerkel that is awesome, nice work!! :) Would you be interested in taking on this ticket? Basically just take what you have above and stick it in a Display class that is only used when is_micropython() is True, else use the Display class that we have today.

[bpmerkel]

Looking at the Display() class, it's pretty embedded with the FrameBuffer-based logic (it subclasses FbMem). Instead of spaghetti if is_micopython() paths, what do you think about creating a new Console() class within display.py, that simply offers the VT helper functions for the LCD panel console/tty (and would work in both python3 and micropython)?

[dwalton76]

We've tried to keep the API the same for the python vs micropython equivalents of the same class so even though it is a little if/else spaghettish it does make it easier to take a program and jump back and forth between python/micropython. For the micropython implementation of Display text_grid() would be the only method you would really implement, for all of the others I would just have the log a "not supported in micropython" message.

[dlech]

I think it makes sense to have a distinct text and graphics modes for the display. Startup time of programs could be greatly improved if they don't want to use graphics mode and just display text.

[WasabiFan]

I agree with David here — I think the text mode functionality would be best suited for its own class and API. It's useful, but it isn't a replacement for true drawing and isn't used in the same way.

[bpmerkel]

Okay. Plan B. I submitted a PR for Display() with is_micropython and layered the ANSI code logic into the Display() API as best it could (minus the Image and text_pixels functionality). Let me make another fork and build a Console() class (for both Python and micropython). I'll submit a second PR and let the keepers review for applicability. :-)

[WasabiFan]

That sounds excellent. Thanks!

Apologies for being slow to respond; my internet connection is two tin cans and some string at the moment so I'm not checking GitHub very often.

[dwalton76]

A separate Console class sounds cool to me. Will take a look at PR this evening.

[dwalton76]

@WasabiFan any objections to closing this now that we have the Console class? Pulling off Display in micropython doesn’t feel like it would add enough given the amount of work it would take.

[WasabiFan]

I think we should leave it open even though it's deprioritized. This is always available if someone wants to take it on and is useful to reference what is/isn't implemented.