class BBS::Cursor

Where the cursor of a session is, as far as the code drawing on it knows, and the escape sequences that move it from there: the drawing primitives BBS::Field and BBS::Editor share.

Moves are relative, from the position the cursor was last moved to or written up to, so a C64 never gets HOME. On a PETSCII line the cursor goes down with RETURN rather than cursor down: what is drawn works the same through the C64’s screen editor and through a terminal program that handles the control codes itself.

The methods return the bytes to write rather than writing them, so a caller sends a whole screen update at once.

Attributes

col [R]

The column of the cursor, 1-based (relative to where counting began).

row [R]

The row of the cursor, 1-based (relative to where counting began).

Public Class Methods

new (session, row: 1, col: 1)

Source

# File lib/bbs/cursor.rb, line 23
def initialize(session, row: 1, col: 1)
  @session = session
  @petscii = session.respond_to?(:petscii?) && session.petscii?
  @row     = row
  @col     = col
end

Starts counting at row, col on the screen of session.

Public Instance Methods

cells (text)

Source

# File lib/bbs/cursor.rb, line 74
def cells(text)
  @petscii ? text.each_char.map { |c| Petscii.cell(c) }.join : text
end

text as the screen shows it, one cell a character: on a C64 a character with no single PETSCII glyph becomes ? (see BBS::Petscii.cell), so the columns stay where they are counted.

clear ()

Source

# File lib/bbs/cursor.rb, line 44
def clear
  @row = 1
  @col = 1
  @petscii ? "#{Ansi::RESET}#{Ansi::CLEAR_SCREEN}" : "#{Ansi::RESET}#{Ansi::CLEAR}"
end

Returns the bytes that reset the colours, clear the screen and home the cursor (on a C64 CLR homes it by itself), and counts from 1, 1.

key ()

Source

# File lib/bbs/cursor.rb, line 35
def key
  key = @session.readkey
  raise IOError, 'the caller hung up' if key.nil?

  key
end

Reads a key from the session (see BBS::Telnet#readkey). Raises IOError when the caller hangs up.

move (row, col)

Source

# File lib/bbs/cursor.rb, line 51
def move(row, col)
  out = +''
  if row > @row && @petscii
    out << (Ansi::CRLF * (row - @row))
    @col = 1
  elsif row != @row
    out << (row > @row ? "#{Ansi::CSI}#{row - @row}B" : "#{Ansi::CSI}#{@row - row}A")
  end
  out << (col > @col ? "#{Ansi::CSI}#{col - @col}C" : "#{Ansi::CSI}#{@col - col}D") unless col == @col
  @row = row
  @col = col
  out
end

Returns the bytes that move the cursor to row, col.

petscii? ()

Source

# File lib/bbs/cursor.rb, line 31
def petscii? = @petscii

True when the session is a PETSCII line (a C64).

wrote (count)

Source

# File lib/bbs/cursor.rb, line 67
def wrote(count)
  @col += count
end

Counts count characters written at the cursor: it is that many columns further right.