Module: Line

Included in:
Curses::Geometry
Defined in:
lib/curses/geometry/line.rb

Constant Summary collapse

BOTTOM_LEFT_TO_TOP_RIGHT_GLYPH =

CONSTANTS :

'/'
TOP_LEFT_TO_BOTTOM_RIGHT_GLYPH = 
'\\'
HORIZONTAL_GLYPH = 
'-'
VERTICAL_GLYPH = 
'|'

Instance Method Summary collapse

Instance Method Details

#draw_antialiased_line(x1, y1, x2, y2) ⇒ Object 



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# File 'lib/curses/geometry/line.rb', line 100

def draw_antialiased_line(x1, y1, x2, y2)

  # Set-up of the bresenham algorythm :
  x,   y = x1, y1
  dx, dy = x2 - x1, y2 - y1

  x_increment = dx > 0 ? 1 : -1
  y_increment = dy > 0 ? 1 : -1


  # Edge cases :
  if dy == 0 then   # horizontal line
    previous_stroke_glyph = get_stroke_glyph
    set_stroke_glyph HORIZONTAL_GLYPH
    
    draw_horizontal_line(x1, x2, y1)

    set_stroke_glyph previous_stroke_glyph
    return
  end 

  if dx == 0 then   # vertical line
    previous_stroke_glyph = get_stroke_glyph
    set_stroke_glyph VERTICAL_GLYPH
    
    draw_vertical_line(x1, y1, y2)

    set_stroke_glyph previous_stroke_glyph
    return
  end

  # Chosing the "stepping" glyph :
  if dx > 0 then
    step_glyph = dy > 0 ? TOP_LEFT_TO_BOTTOM_RIGHT_GLYPH : BOTTOM_LEFT_TO_TOP_RIGHT_GLYPH 
  else
    step_glyph = dy > 0 ? BOTTOM_LEFT_TO_TOP_RIGHT_GLYPH : TOP_LEFT_TO_BOTTOM_RIGHT_GLYPH
  end

  # Scanning the line :
  dx, dy = dx.abs, dy.abs
  
  # First Point :
  tan = (dy.to_f / dx).abs
  if ( ( tan > 0.08 ) && ( tan < 5.67 ) ) then
    glyph = step_glyph
  else
    glyph = dx > dy ? HORIZONTAL_GLYPH : VERTICAL_GLYPH
  end

  setpos(y1, x1)
  addch(glyph)

  # Rest of the Line :
  if dx > dy then
    d = dx >> 1
    dx.times do |i|
      x += x_increment
      d += dy

      if d >= dx then
        d -= dx;
        y += y_increment;

        setpos(y, x)
        addch(step_glyph)
      else
        ny = y_increment < 0 ? y : y + 1
        setpos ny, x
        addch(HORIZONTAL_GLYPH)
      end
    end
  else
    d = dy >> 1
    (dy - 1).times do |i|
      y += y_increment
      d += dx

      if d >= dy then
        d -= dy
        x += x_increment

        setpos(y, x)
        addch(glyph)
      else
        setpos(y, x)
        addch(VERTICAL_GLYPH)
      end
    end
 end
end

#draw_horizontal_line(x1, x2, y) ⇒ Object

METHODS :



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# File 'lib/curses/geometry/line.rb', line 11

def draw_horizontal_line(x1, x2, y)
  if x1 < x2 then min_x, max_x = x1, x2
  else            min_x, max_x = x2, x1
  end
  
  glyph = get_graphic_context[:stroke_glyph]
  setpos(y, min_x)
  min_x.upto(max_x) do |x|
    addch(glyph)
  end  
end

#draw_line(x1, y1, x2, y2) ⇒ Object 



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# File 'lib/curses/geometry/line.rb', line 35

def draw_line(x1, y1, x2, y2)

  # Set-up of the bresenham algorythm :
  x,   y = x1, y1
  dx, dy = x2 - x1, y2 - y1

  x_increment = dx > 0 ? 1 : -1
  y_increment = dy > 0 ? 1 : -1


  # Edge cases :
  if dy == 0 then   # horizontal line
    draw_horizontal_line(x1, x2, y1)
    return
  end 

  if dx == 0 then   # vertical line
    draw_vertical_line(x1, y1, y2)
    return
  end

  # Scanning the line :
  dx, dy  = dx.abs, dy.abs
  glyph   = get_graphic_context[:stroke_glyph]
  
  # First Point :
  setpos(y1, x1)
  addch(glyph)

  # Rest of the Line :
  if dx > dy then
    d = dx >> 1
    dx.times do |i|
      x += x_increment
      d += dy

      if d >= dx then
        d -= dx;
        y += y_increment;

        setpos(y, x)
      else
        ny = y_increment < 0 ? y : y + 1
        setpos ny, x
      end

      addch(glyph)
    end
  else
    d = dy >> 1
    dy.times do |i|
      y += y_increment
      d += dx

      if d >= dy then
        d -= dy
        x += x_increment
      end

      setpos(y, x)
      addch(glyph)
    end
 end
end

#draw_vertical_line(x, y1, y2) ⇒ Object 



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# File 'lib/curses/geometry/line.rb', line 23

def draw_vertical_line (x, y1, y2)
  if y1 < y2 then min_y, max_y = y1, y2
  else            min_y, max_y = y2, y1
  end

  glyph = get_graphic_context[:stroke_glyph]
  min_y.upto(max_y) do |y|
    setpos(y,x)
    addch(glyph)
  end
end