Can't draw on LCD screen

[obo]

I'm trying to draw the smiley-frowney demo mentioned in #194 on the LCD screen of my EV3.

• ev3dev version: 4.14.35-ev3dev-2.0.0-ev3
• ev3dev-lang-python version: (don't know how to get, I'm rather new to python)

The demo code I used is this:

#!/usr/bin/env python3
# from https://github.com/ev3dev/ev3dev-lang-python/issues/194

from time import sleep
import ev3dev.auto as ev3

screen = ev3.Screen()

smile = True

while True:
    screen.clear()

    # Screen.draw returns a PIL.ImageDraw handle
    screen.draw.ellipse(( 20, 20,  60, 60))
    screen.draw.ellipse((118, 20, 158, 60))

    if smile:
        screen.draw.arc((20, 80, 158, 100), 0, 180)
    else:
        screen.draw.arc((20, 80, 158, 100), 180, 360)

    smile = not smile

    # Update lcd display
    screen.update()

    sleep(1)

I can run this from ssh using this trick:

sudo openvt -s -w -- sudo --user robot -- ./draw-smiley-frowney.py

The LCD goes blank, then quickly shows a tiny error message and I get Brickman again.

When I run the demo from Brickman, the error log is collected, so I can read the message:

robot@ev3dev:~/lego/random-bits$ cat draw-smiley-frowney.py.err.logTraceback (most recent call last):
  File "/home/robot/lego/random-bits/draw-smiley-frowney.py", line 26, in <module>
    screen.update()
  File "/usr/lib/python3/dist-packages/ev3dev/core.py", line 3325, in update
    raise Exception("Not supported")

(The simpler demo http://www.ev3dev.org/docs/tutorials/using-ev3-lcd/ behaves similarly, screen goes blank, debug prints get printed, no error is reported but nothing is drawn on screen.)

[obo]

Just tested also your photo-booth:
https://github.com/dlech/ev3dev-photo-booth

The picture is taken and stored in the file but nothing appears on the LCD, not even the Smile! string.

The only error message I get is this:

** (brickrun:1826): CRITICAL **: brickrun.vala:100: Failed to send signal: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method 'SignalGroup'

[dlech]

Duplicate of #455

sudo openvt -s -w -- sudo --user robot -- ./draw-smiley-frowney.py

Better "trick":

brickrun ./draw-smiley-frowney.py

The only error message I get is this:

upgrade your packages

# make sure EV3 is connected to Internet
sudo apt update
sudo apt upgrade

[dlech]

Should be fixed in v1.2.0

ev3dev-lang-python version: (don't know how to get, I'm rather new to python)

dpkg -s python3-ev3dev | grep Version

[dlech]

Also, you can now use grayscale 😄

#!/usr/bin/env python3

from time import sleep

import ev3dev.auto as ev3

screen = ev3.Screen()

smile = True

while True:
    screen.clear()

    screen.draw.ellipse((20, 20, 60, 60))
    screen.draw.ellipse((30, 30, 50, 50), fill=128)
    screen.draw.ellipse((118, 20, 158, 60))
    screen.draw.ellipse((128, 30, 148, 50), fill=128)

    if smile:
        screen.draw.arc((20, 80, 158, 100), 0, 180)
    else:
        screen.draw.arc((20, 80, 158, 100), 180, 360)

    smile = not smile

    screen.update()

    sleep(1)

[dlech]

ev3dev-lang-python version: (don't know how to get, I'm rather new to python)

Also:

python3 -c 'import ev3dev.version; print(ev3dev.version.__version__)'

[obo]

Yes, works with:

python3 -c 'import ev3dev.version; print(ev3dev.version.__version__)'
1.2.0

(At the first attempt of brickrun, the screen remained blank, but the second and subsequent attempts worked well.)

Wonderful grayscale!

[dlech]

At the first attempt of brickrun, the screen remained blank

Please open a new issue at https://github.com/ev3dev/ev3dev/issues if this continues to be a problem.