module BBS::Petscii::Canvas::Lookup

The class methods of a Canvas that look codes up: the code of a character (Canvas.code), whether the set has a glyph for it (Canvas.glyph?), the code of a colour (Canvas.color) and the nearest C64 colour to an RGB one (Canvas.nearest).

Public Instance Methods

code (ch)

Source

# File lib/bbs/petscii/canvas/lookup.rb, line 14
def code(ch)
  return [GLYPHS_REVERSED[ch], true] if GLYPHS_REVERSED.key?(ch)
  return [GLYPHS[ch], false] if GLYPHS.key?(ch)

  o = ch.upcase.ord
  o.between?(0x20, 0x5d) ? [o, false] : ['?'.ord, false]
end

The PETSCII code of ch in the uppercase set, and whether it is a reversed glyph (GLYPHS_REVERSED): [code, reversed]. A character the set does not have is '?'.

color (color)

Source

# File lib/bbs/petscii/canvas/lookup.rb, line 36
def color(color)
  return nil if color.nil?
  return color if color.is_a?(Integer) && RGB.key?(color)
  return Petscii.color_code(color) if color.to_s.start_with?(Ansi::ESC)

  name = color.to_s.downcase.tr(' -', '__').sub('gray', 'grey').to_sym
  COLOR_NAMES.fetch(name) { raise ArgumentError, "not a C64 colour: #{color.inspect}" }
end

The colour code of color: a code as it is (a key of RGB), an SGR colour of the palette (BBS::Petscii::Colors), a name of COLOR_NAMES as a Symbol or String ('light grey', :dark_gray and 'LIGHT-BLUE' all work), or nil. Raises ArgumentError for anything else.

glyph? (ch)

Source

# File lib/bbs/petscii/canvas/lookup.rb, line 25
def glyph?(ch)
  return true if GLYPHS.key?(ch) || GLYPHS_REVERSED.key?(ch)

  ch.length == 1 && ASCII_SHOWN.include?(ch.upcase.ord)
end

Whether the uppercase set shows ch as what it is: a glyph of GLYPHS or GLYPHS_REVERSED, or printable ASCII but the backslash (a lowercase letter shows as its capital).

nearest (rgb)

Source

# File lib/bbs/petscii/canvas/lookup.rb, line 46
def nearest(rgb) = RGB.min_by { |_, c| c.zip(rgb).sum { |a, b| (a - b)**2 } }.first

The code of the C64 colour nearest to rgb, [red, green, blue].