countCharsCoverage
Returns the number of characters from text that exists in the Font
If the font contains all the characters the returned value will be the length of text
LIMITATIONS:
This will work only of the associated {font_name}.json file exists within the application resources. If the json file could not be found the method will return -1
Return
the number of characters from text that exists in the Font or -1 if the font json file is missing
Parameters
text
the text to be checked