Module: Tui::Metrics

Defined in:
lib/tui.rb

Class Method Summary collapse

Class Method Details

.char_width(code) ⇒ Object

Simplified width check - we only use known Unicode in this app



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# File 'lib/tui.rb', line 123

def char_width(code)
  # Zero-width: variation selectors (🗑️ = trash + VS16)
  return 0 if code >= 0xFE00 && code <= 0xFE0F

  # Emoji range (📁🏠🗑📂 etc) = width 2
  return 2 if code >= 0x1F300 && code <= 0x1FAFF

  # Everything else (ASCII, arrows, box drawing, ellipsis) = width 1
  1
end

.truncate(text, max_width, overflow: "…") ⇒ Object 



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# File 'lib/tui.rb', line 146

def truncate(text, max_width, overflow: "…")
  return text if visible_width(text) <= max_width

  overflow_width = visible_width(overflow)
  target = [max_width - overflow_width, 0].max
  truncated = String.new
  width = 0
  in_escape = false
  escape_buf = String.new

  text.each_char do |ch|
    if in_escape
      escape_buf << ch
      if ch.match?(/[A-Za-z]/)
        truncated << escape_buf
        escape_buf = String.new
        in_escape = false
      end
      next
    end

    if ch == "\e"
      in_escape = true
      escape_buf = ch
      next
    end

    cw = char_width(ch.ord)
    break if width + cw > target

    truncated << ch
    width += cw
  end

  truncated.rstrip + overflow
end

.truncate_from_start(text, max_width) ⇒ Object

Truncate from the start, keeping trailing portion (for right-aligned overflow) Preserves leading ANSI escape sequences (like dim/color codes)



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# File 'lib/tui.rb', line 185

def truncate_from_start(text, max_width)
  vis_width = visible_width(text)
  return text if vis_width <= max_width

  # Collect leading escape sequences first
  leading_escapes = String.new
  in_escape = false
  escape_buf = String.new
  text_start = 0

  text.each_char.with_index do |ch, i|
    if in_escape
      escape_buf << ch
      if ch.match?(/[A-Za-z]/)
        leading_escapes << escape_buf
        escape_buf = String.new
        in_escape = false
        text_start = i + 1
      end
    elsif ch == "\e"
      in_escape = true
      escape_buf = ch
    else
      # First non-escape character, stop collecting leading escapes
      break
    end
  end

  # Now skip visible characters to get max_width remaining
  chars_to_skip = vis_width - max_width
  skipped = 0
  result = String.new
  in_escape = false

  text.each_char do |ch|
    if in_escape
      result << ch if skipped >= chars_to_skip
      in_escape = false if ch.match?(/[A-Za-z]/)
      next
    end

    if ch == "\e"
      in_escape = true
      result << ch if skipped >= chars_to_skip
      next
    end

    cw = char_width(ch.ord)
    if skipped < chars_to_skip
      skipped += cw
    else
      result << ch
    end
  end

  # Prepend leading escapes to preserve styling
  leading_escapes + result
end

.visible_width(text) ⇒ Object

Optimized width calculation - avoids per-character method calls



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# File 'lib/tui.rb', line 100

def visible_width(text)
  # Fast path: pure ASCII with no escapes
  if text.bytesize == text.length && !text.include?("\e")
    return text.length
  end

  # Strip ANSI escapes only if present
  stripped = text.include?("\e") ? text.gsub(/\e\[[0-9;]*[A-Za-z]/, '') : text

  # Fast path after stripping: pure ASCII
  if stripped.bytesize == stripped.length
    return stripped.length
  end

  # Slow path: calculate width per codepoint (avoids each_char + ord)
  width = 0
  stripped.each_codepoint do |code|
    width += char_width(code)
  end
  width
end

.wide?(ch) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/tui.rb', line 142

def wide?(ch)
  char_width(ch.ord) == 2
end

.zero_width?(ch) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/tui.rb', line 134

def zero_width?(ch)
  code = ch.ord
  (code >= 0xFE00 && code <= 0xFE0F) ||
  (code >= 0x200B && code <= 0x200D) ||
  (code >= 0x0300 && code <= 0x036F) ||
  (code >= 0xE0100 && code <= 0xE01EF)
end