Class: Charming::UI::BrailleCanvas

Inherits:
Object
  • Object
show all
Defined in:
lib/charming/presentation/ui/braille_canvas.rb

Overview

BrailleCanvas is a monochrome subpixel drawing surface backed by Unicode braille glyphs (U+2800–U+28FF). Each character cell packs a 2×4 grid of dots, so the canvas addresses width×height pixels while rendering to cols×rows cells — 8× the vertical and 2× the horizontal resolution of plain text. It's pure text (works on every terminal) and composes via row/column/Canvas like any other block. Used by Components::Chart.

Constant Summary collapse

BASE =

The first braille code point; OR-ing dot bits onto it yields the glyph for a cell.

0x2800
DOTS =

Dot bit for each (x%2, y%4) position within a cell, indexed DOTS[y % 4][x % 2].

[[0x01, 0x08], [0x02, 0x10], [0x04, 0x20], [0x40, 0x80]].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(width, height) ⇒ BrailleCanvas

width and height are the drawable area in pixels (dots).



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# File 'lib/charming/presentation/ui/braille_canvas.rb', line 18

def initialize(width, height)
  @width = width
  @height = height
  @cols = (width + 1) / 2
  @rows = (height + 3) / 4
  @cells = Array.new(@rows) { Array.new(@cols, 0) }
end

Instance Attribute Details

#cols ⇒ Object (readonly)

Returns the value of attribute cols.



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# File 'lib/charming/presentation/ui/braille_canvas.rb', line 26

def cols
  @cols
end

#height ⇒ Object (readonly)

Returns the value of attribute height.



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# File 'lib/charming/presentation/ui/braille_canvas.rb', line 26

def height
  @height
end

#rows ⇒ Object (readonly)

Returns the value of attribute rows.



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# File 'lib/charming/presentation/ui/braille_canvas.rb', line 26

def rows
  @rows
end

#width ⇒ Object (readonly)

Returns the value of attribute width.



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# File 'lib/charming/presentation/ui/braille_canvas.rb', line 26

def width
  @width
end

Instance Method Details

#line(x0, y0, x1, y1) ⇒ Object

Draws a straight line between (x0, y0) and (x1, y1) with Bresenham's algorithm. Returns self.



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# File 'lib/charming/presentation/ui/braille_canvas.rb', line 49

def line(x0, y0, x1, y1)
  dx = (x1 - x0).abs
  dy = -(y1 - y0).abs
  sx = (x0 < x1) ? 1 : -1
  sy = (y0 < y1) ? 1 : -1
  err = dx + dy
  x = x0
  y = y0
  loop do
    set(x, y)
    break if x == x1 && y == y1

    e2 = 2 * err
    if e2 >= dy
      err += dy
      x += sx
    end
    if e2 <= dx
      err += dx
      y += sy
    end
  end
  self
end

#set(x, y, on: true) ⇒ Object

Turns the dot at pixel (x, y) on (or off when on: false). Out-of-range points are ignored. Returns self for chaining.



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# File 'lib/charming/presentation/ui/braille_canvas.rb', line 30

def set(x, y, on: true)
  return self unless x.between?(0, @width - 1) && y.between?(0, @height - 1)

  bit = DOTS[y % 4][x % 2]
  if on
    @cells[y / 4][x / 2] |= bit
  else
    @cells[y / 4][x / 2] &= ~bit
  end
  self
end

#to_s ⇒ Object

Renders the canvas as rows lines of cols braille glyphs.



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# File 'lib/charming/presentation/ui/braille_canvas.rb', line 75

def to_s
  @cells.map { |row| row.map { |bits| (BASE + bits).chr(Encoding::UTF_8) }.join }.join("\n")
end

#unset(x, y) ⇒ Object

Turns the dot at pixel (x, y) off. Returns self.



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# File 'lib/charming/presentation/ui/braille_canvas.rb', line 43

def unset(x, y)
  set(x, y, on: false)
end