§R6 Braille Sparkline Encoding

§R6.1 Braille Pattern Block

Unicode Braille Patterns occupy U+2800–U+28FF (256 characters). Each character represents a 2×4 dot matrix within one character cell, providing 2× horizontal and 4× vertical sub-cell resolution.

§R6.2 Dot Position → Bit Mapping

Each Braille character’s codepoint is U+2800 + bitmask, where bits map to dot positions:

Position:    Bit:
┌───┬───┐
│ 1 │ 4 │   bit 0 = dot 1 (top-left)
│ 2 │ 5 │   bit 1 = dot 2 (mid-left)
│ 3 │ 6 │   bit 2 = dot 3 (lower-left)
│ 7 │ 8 │   bit 3 = dot 7 (bottom-left)
└───┴───┘   bit 4 = dot 4 (top-right)
            bit 5 = dot 5 (mid-right)
            bit 6 = dot 6 (lower-right)
            bit 7 = dot 8 (bottom-right)

§R6.3 Sparkline Construction Algorithm

To render a sparkline from a sequence of values:

1. Normalize values to a 0–3 range (for single-column sparklines) or 0–7 range (for two-column sparklines using both dot columns).
2. For each character cell in the sparkline, determine which vertical dots to fill based on the normalized value. A value of 0 = no dots; a value of 3 = dots at positions 7, 3, 2 (bottom three on left column).
3. Compute the bitmask by OR-ing the bits for each active dot position.
4. Emit U+2800 + bitmask.

Example — single-column bar chart (left column only):

§R6.4 Progress Bar Using Eighth Blocks

For linear progress bars, use eighth-block characters for smooth fill:

A progress bar of width W cols at P% completion:

filled_cells = floor(W * P / 100)
partial = ((W * P / 100) - filled_cells) * 8   → index into eighth-block table
output = "█" × filled_cells + eighth_block[partial] + " " × remaining