Functions for justifying Unicode text in a monospaced display such as a terminal, based on the display width of characters.
Port of ftfy.formatting. The Python original relies on the wcwidth
library; we reimplement the core single-character width lookup from the same
Unicode tables. The string-width function here is the simple sum of character
widths (it is not grapheme-cluster aware), which matches wcwidth.wcswidth
for ordinary text.
Summary
Functions
The display width of a single character in a monospaced terminal: 0, 1, or 2 for printable characters, and -1 for non-printable/control characters.
Center text within a display width of at least width cells.
Left-justify text to a display width of at least width cells, padding with
fillchar (which must have display width 1). "Left" means toward the start of
the string.
Right-justify text to a display width of at least width cells.
The number of character cells this string is likely to occupy in a monospaced, Unicode-aware terminal. Returns -1 if it contains a non-printable or control character.
Functions
The display width of a single character in a monospaced terminal: 0, 1, or 2 for printable characters, and -1 for non-printable/control characters.
iex> Ftfy.Formatting.character_width("車")
2
iex> Ftfy.Formatting.character_width("A")
1
iex> Ftfy.Formatting.character_width("\n")
-1@spec display_center(binary(), non_neg_integer(), binary()) :: binary()
Center text within a display width of at least width cells.
@spec display_ljust(binary(), non_neg_integer(), binary()) :: binary()
Left-justify text to a display width of at least width cells, padding with
fillchar (which must have display width 1). "Left" means toward the start of
the string.
@spec display_rjust(binary(), non_neg_integer(), binary()) :: binary()
Right-justify text to a display width of at least width cells.
The number of character cells this string is likely to occupy in a monospaced, Unicode-aware terminal. Returns -1 if it contains a non-printable or control character.
iex> Ftfy.Formatting.monospaced_width("ちゃぶ台返し")
12
iex> Ftfy.Formatting.monospaced_width("example" <> <<0x80::utf8>>)
-1