Class: Fatty::Viewport

Inherits:
Object
  • Object
show all
Defined in:
lib/fatty/viewport.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(top: 0, height:) ⇒ Viewport

Returns a new instance of Viewport.



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# File 'lib/fatty/viewport.rb', line 8

def initialize(top: 0, height:)
  @top    = top
  @height = height
end

Instance Attribute Details

#height ⇒ Object

Returns the value of attribute height.



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# File 'lib/fatty/viewport.rb', line 6

def height
  @height
end

#top ⇒ Object

Returns the value of attribute top.



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# File 'lib/fatty/viewport.rb', line 5

def top
  @top
end

Instance Method Details

#adjust_for_trim(n) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 13

def adjust_for_trim(n)
  @top = [@top - n, 0].max
end

#at_bottom?(total_lines = nil) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/fatty/viewport.rb', line 17

def at_bottom?(total_lines = nil)
  return false unless total_lines

  @top >= max_top(total_lines)
end

#at_top? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/fatty/viewport.rb', line 23

def at_top?
  @top <= 0
end

#bottom_index(total_lines) ⇒ Object

1-based index of the last visible line (clamped), or 0 if no lines.



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# File 'lib/fatty/viewport.rb', line 28

def bottom_index(total_lines)
  return 0 if total_lines <= 0

  [@top + @height, total_lines].min
end

#clamp!(lines) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 50

def clamp!(lines)
  @top = @top.clamp(0, max_top(lines.size))
end

#max_top(total_lines) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 46

def max_top(total_lines)
  [total_lines - @height, 0].max
end

#page_bottom(lines) ⇒ Object

Jump to the very bottom.



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# File 'lib/fatty/viewport.rb', line 82

def page_bottom(lines)
  @top = max_top(lines.size)
end

#page_down(lines) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 72

def page_down(lines)
  scroll_down(lines, @height)
end

#page_top ⇒ Object

Jump to the very top.



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# File 'lib/fatty/viewport.rb', line 77

def page_top
  @top = 0
end

#page_up(lines) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 68

def page_up(lines)
  scroll_up(lines, @height)
end

#position_percent(total_lines) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 34

def position_percent(total_lines)
  return 100 if total_lines <= 0

  b = bottom_index(total_lines)
  pct = (b.to_f / total_lines.to_f) * 100.0
  pct.round
end

#reset ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 86

def reset
  @top = 0
end

#scroll_down(lines, n = 1) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 59

def scroll_down(lines, n = 1)
  @top += n
  clamp!(lines)
end

#scroll_to_bottom(lines) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 64

def scroll_to_bottom(lines)
  @top = max_top(lines.size)
end

#scroll_up(lines, n = 1) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 54

def scroll_up(lines, n = 1)
  @top -= n
  clamp!(lines)
end

#slice(lines) ⇒ Object 



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# File 'lib/fatty/viewport.rb', line 42

def slice(lines)
  lines[@top, @height] || []
end