Empty text string causes a Label's y-attribute to change

[CedarGroveStudios]

After a single character label with an empty text-attribute is defined, the label's y-attribute is incremented by 7 when the label's text-attribute is loaded with a character (TEST 1). Conversely, if the label is defined with a character in the text-attribute, the y-attribute will decrement by 7 when the text-attributed is emptied (TEST 3). In either case, the y-attribute shouldn't change. Looks like something associated with the anchor point calculation updating the y-attribute.

Adafruit CircuitPython 5.3.1 on 2020-07-13; Adafruit ItsyBitsy M4 Express with samd51g19
CircuitPython 5.x Library Bundle 20210-08-26

Test code:

from   adafruit_display_text.label   import Label

font_0 = terminalio.FONT  # Internal font

print('CircuitPython 5.x Library Bundle 20210-08-26')
address = (12, 14)
print('adress:', address)

print()
print('TEST 0: pre-load Label text, change text later')
test_0 = Label(font_0, text='0', color=0xFFFFFF, max_glyphs=1)
test_0.x, test_0.y = address
print('x =', test_0.x, 'y=', test_0.y)
test_0.text = '1'
print('x =', test_0.x, 'y=', test_0.y)

print()
print('TEST 1: no Label text, change text later')
test_1 = Label(font_0, text='', color=0xFFFFFF, max_glyphs=1)
test_1.x, test_1.y = address
print('x =', test_1.x, 'y=', test_1.y)
test_1.text = '1'
print('x =', test_1.x, 'y=', test_1.y)

print()
print('TEST 2: no Label text, no text in change')
test_2 = Label(font_0, text='', color=0xFFFFFF, max_glyphs=1)
test_2.x, test_2.y = address
print('x =', test_2.x, 'y=', test_2.y)
test_2.text = ''
print('x =', test_2.x, 'y=', test_2.y)

print()
print('TEST 3: pre-load Label text, no text in change')
test_3 = Label(font_0, text='0', color=0xFFFFFF, max_glyphs=1)
test_3.x, test_3.y = address
print('x =', test_3.x, 'y=', test_3.y)
test_3.text = ''
print('x =', test_3.x, 'y=', test_3.y)

REPL output:

>>> 
soft reboot

Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.
code.py output:
CircuitPython 5.x Library Bundle 20210-08-26
adress: (12, 14)

TEST 0: pre-load Label text, change text later
x = 12 y= 14
x = 12 y= 14

TEST 1: no Label text, change text later
x = 12 y= 14
x = 12 y= 21

TEST 2: no Label text, no text in change
x = 12 y= 14
x = 12 y= 14

TEST 3: pre-load Label text, no text in change
x = 12 y= 14
x = 12 y= 7

Press any key to enter the REPL. Use CTRL-D to reload.```

[kmatch98]

Thanks for the detailed description of the issue!

As you suggested, it’s likely an issue with the anchored_position or maybe the bounding_box calculation of a blank string. I will check it out and get back with you.

[kmatch98]

@CedarGroveStudios I tested using the latest version and it works ok for me. I think you are using a slightly older version of the label.

Can you please pull the latest adafruit_display_text\label library and let me know your results? Here is the circuitpython.org page with the latest library bundle.

Here's what I found:

1. I used the 8/26 library bundle that you specified and it worked correctly for me. It worked both for label.mpy from the bundle and label.py from the latest library here.
2. I went back to the 8/11 version of the library bundle and the results match what you showed above. Here is the older library version I used with the label.py file.

1. Results with the 8/26 library bundle - I think this is working right

Here is the output I get from running your code on the latest label.py library. I think this is the result that you should get.

adress: (12, 14)

TEST 0: pre-load Label text, change text later
x = 12 y= 14
x = 12 y= 14

TEST 1: no Label text, change text later
x = 12 y= 14
x = 12 y= 14

TEST 2: no Label text, no text in change
x = 12 y= 14
x = 12 y= 14

TEST 3: pre-load Label text, no text in change
x = 12 y= 14
x = 12 y= 14

2. Results with the 8/11 library bundle specified above - This matches the results you showed

adress: (12, 14)

TEST 0: pre-load Label text, change text later
x = 12 y= 14
x = 12 y= 14

TEST 1: no Label text, change text later
x = 12 y= 14
x = 12 y= 21

TEST 2: no Label text, no text in change
x = 12 y= 14
x = 12 y= 14

TEST 3: pre-load Label text, no text in change
x = 12 y= 14
x = 12 y= 7

The test code I used

Here is the code that I ran. The only change I made was import terminalio at the top:

import terminalio
from adafruit_display_text.label import Label

font_0 = terminalio.FONT  # Internal font

print('CircuitPython 5.x Library Bundle 20210-08-26')
address = (12, 14)
print('adress:', address)

print()
print('TEST 0: pre-load Label text, change text later')
test_0 = Label(font_0, text='0', color=0xFFFFFF, max_glyphs=1)
test_0.x, test_0.y = address
print('x =', test_0.x, 'y=', test_0.y)
test_0.text = '1'
print('x =', test_0.x, 'y=', test_0.y)

print()
print('TEST 1: no Label text, change text later')
test_1 = Label(font_0, text='', color=0xFFFFFF, max_glyphs=1)
test_1.x, test_1.y = address
print('x =', test_1.x, 'y=', test_1.y)
test_1.text = '1'
print('x =', test_1.x, 'y=', test_1.y)

print()
print('TEST 2: no Label text, no text in change')
test_2 = Label(font_0, text='', color=0xFFFFFF, max_glyphs=1)
test_2.x, test_2.y = address
print('x =', test_2.x, 'y=', test_2.y)
test_2.text = ''
print('x =', test_2.x, 'y=', test_2.y)

print()
print('TEST 3: pre-load Label text, no text in change')
test_3 = Label(font_0, text='0', color=0xFFFFFF, max_glyphs=1)
test_3.x, test_3.y = address
print('x =', test_3.x, 'y=', test_3.y)
test_3.text = ''
print('x =', test_3.x, 'y=', test_3.y)

while True:
    pass

[CedarGroveStudios]

Thank you for your speedy response @kmatch98 ! I was able to confirm that 8/26 bundle release had indeed provided the fix. My always reliable automatic library update routine skipped over adafruit_display_text and a couple of other libraries during its latest execution. Sorry about the fire drill.

[kmatch98]

No worries, I’m just glad we pre-emptively solved the issue. Cheers!