Test for Usable Characters

Adafruit_framebuf.py on Line 567 line = struct.unpack("B", self._font.read(1))[0] randomly causing
struct.error: ('unpack requires a buffer of 1 byte')

from my code

LineBuf =(x.text.strip()[0:60])
pixel_framebuf.text(LineBuf, i, 4, 0x0000FF)

It appears the web text randomly contained Unicode Decimal 8217 RIGHT SINGLE QUOTATION MARK which I'm guessing is not part of font5x8.bin and thus generates the error? When I replace with Unicode Decimal 39 APOSTROPHE all is good.

Of course they look pretty identical so it was difficult to understand the problem.

Is it possible to include a check for Usable Characters ?

Start at Adafruit_framebuf.py line 567 and reproduce the failure with the supplied LineBuf example containing Unicode U+2019, then compare it with the ASCII apostrophe case. Determine the expected handling for characters not represented by font5x8.bin; done should include coverage showing that such input no longer raises the reported struct.error.

Written by the indexing model from the issue text.