Exception thrown if text is not set on creation but updated later

[jimbobbennett]

The recent changes in 2.6.0 have introduced an exception if the text is not set on a label when it is created, but is set later.

To reproduce:

import board
import terminalio
from adafruit_display_text import label


text = "Hello world"
text_area = label.Label(terminalio.FONT, max_glyphs=15)
text_area.x = 10
text_area.y = 10
text_area.text = text
board.DISPLAY.show(text_area)
while True:
    pass

This is a version of the SimpleTest example but instead of setting the text in the Label constructor, the text is set later.

Not setting the text parameter causes the _boundingbox property to be initialized to None.

When the text property is set later, the property setter retrieves the anchored_position value:

@text.setter
def text(self, new_text):
    current_anchored_position = self.anchored_position

This in turn uses the bounding box and assumes that it has a value rather than being None:

@property
def anchored_position(self):
    """Position relative to the anchor_point. Tuple containing x,y
       pixel coordinates."""
    return (
        int(
            self.x
            + self._boundingbox[0]
            + self._anchor_point[0] * self._boundingbox[2]
        ),
        int(
            self.y
            + self._boundingbox[1]
            + self._anchor_point[1] * self._boundingbox[3]
        ),
    )

This raises an exception:

Traceback (most recent call last):
  File "code.py", line 109, in <module>
  File "adafruit_display_text/label.py", line 241, in text
  File "adafruit_display_text/label.py", line 281, in anchored_position
TypeError: 'NoneType' object is not subscriptable

The workaround is to always set the text in the constructor. A quick fix could be to change the default value from None to "", that way the bounding box is always created.

[FoamyGuy]

fixed with #46