module BBS::Petscii::Canvas::Output

The bytes that send a Canvas to a C64: the whole screen (frame), a stretch of a row (span), scattered cells (patch), the cursor alone (cursor). Each is raw PETSCII, a binary String for session.write_raw.

Public Instance Methods

cursor (row, col)

Source

# File lib/bbs/petscii/canvas/output.rb, line 54
def cursor(row, col) = moves_to(row, col).pack('C*')

The cursor moves to row, col, with nothing printed: HOME, then down and right. A binary String.

frame ()

Source

# File lib/bbs/petscii/canvas/output.rb, line 13
def frame
  out  = [UPPERCASE, CLEAR]
  pen  = Pen.new
  last = last_visible_row
  (0..last).each do |row|
    len = visible_end(row)
    pen.emit(out, @cells[row].first(len))
    next if len == COLS || row == last

    out << CR
    pen.rvs = false
  end
  out.pack('C*')
end

The whole screen: the graphics set, a clear screen, then the rows, each cut after its last visible cell, as a binary String.

patch (positions)

Source

# File lib/bbs/petscii/canvas/output.rb, line 41
def patch(positions)
  out = [HOME, RVS_OFF]
  pen = Pen.new
  at  = [0, 0]
  nearest_first(positions.uniq).each do |row, col|
    at = step_to(out, at, row, col)
    pen.emit(out, [@cells[row][col]])
  end
  pen.close(out).pack('C*')
end

The cells at positions, [row, col] each, the cursor stepping to the nearest one left instead of from the top left each time: the cheap repaint of a few cells scattered over the screen. A binary String.

span (row, col, width)

Source

# File lib/bbs/petscii/canvas/output.rb, line 30
def span(row, col, width)
  out = moves_to(row, col) << RVS_OFF
  pen = Pen.new
  pen.emit(out, @cells[row][col, width])
  pen.close(out).pack('C*')
end

The cells of row from col, width long, with the cursor moves that put them in place, as a binary String.