pebble-misc/tools/scale_bdf.py

#!/usr/bin/env python3
import sys


def scale_bitmap_rows(rows, bbx_width, factor):
    new_width = bbx_width * factor
    new_bytes = (new_width + 7) // 8
    new_bits = new_bytes * 8

    old_bytes = (bbx_width + 7) // 8
    old_bits = old_bytes * 8

    result = []
    for row_hex in rows:
        hex_val = int(row_hex, 16)

        # Extract bits MSB-first — BDF pixels are left-aligned within
        # ceil(width/8) bytes, MSB of first byte = leftmost pixel.
        bits = []
        for bit_idx in range(bbx_width):
            bit = (hex_val >> (old_bits - 1 - bit_idx)) & 1
            bits.append(bit)

        # Expand horizontally: each bit repeated `factor` times
        expanded = []
        for b in bits:
            expanded.extend([b] * factor)

        # Pack back into MSB-first, left-aligned hex
        packed = 0
        for idx, b in enumerate(expanded):
            if b:
                packed |= 1 << (new_bits - 1 - idx)

        hex_str = format(packed, f'0{new_bytes * 2}X')

        # Expand vertically: duplicate the row `factor` times
        for _ in range(factor):
            result.append(hex_str)

    return result


def scale_bdf(input_path, output_path, factor):
    if factor < 1 or not isinstance(factor, int):
        print(f"Error: scale factor must be a positive integer, got {factor}")
        sys.exit(1)

    with open(input_path) as f:
        lines = f.readlines()

    out = []
    in_bitmap = False
    bitmap_rows = []
    current_bbx_w = 0
    current_bbx_h = 0
    current_bbx_x = 0
    current_bbx_y = 0

    for line in lines:
        line = line.rstrip('\n')

        if in_bitmap:
            if line == 'ENDCHAR':
                scaled_rows = scale_bitmap_rows(bitmap_rows, current_bbx_w, factor)
                out.extend(scaled_rows)
                out.append('ENDCHAR')
                in_bitmap = False
                bitmap_rows = []
            else:
                bitmap_rows.append(line)
            continue

        if line == 'STARTCHAR':
            in_bitmap = False
            out.append(line)
        elif line == 'BITMAP':
            in_bitmap = True
            out.append('BITMAP')
        elif line.startswith('FONT '):
            out.append(scale_font_line(line, factor))
        elif line.startswith('SIZE '):
            parts = line.split()
            out.append(
                f'SIZE {int(parts[1]) * factor} {parts[2]} {parts[3]}'
            )
        elif line.startswith('FONTBOUNDINGBOX '):
            parts = line.split()
            out.append(
                f'FONTBOUNDINGBOX {int(parts[1]) * factor} '
                f'{int(parts[2]) * factor} '
                f'{int(parts[3]) * factor} '
                f'{int(parts[4]) * factor}'
            )
        elif line.startswith('BBX '):
            parts = line.split()
            current_bbx_w = int(parts[1])
            current_bbx_h = int(parts[2])
            current_bbx_x = int(parts[3])
            current_bbx_y = int(parts[4])
            out.append(
                f'BBX {current_bbx_w * factor} '
                f'{current_bbx_h * factor} '
                f'{current_bbx_x * factor} '
                f'{current_bbx_y * factor}'
            )
        elif line.startswith('PIXEL_SIZE '):
            parts = line.split()
            out.append(f'PIXEL_SIZE {int(parts[1]) * factor}')
        elif line.startswith('POINT_SIZE '):
            parts = line.split()
            out.append(f'POINT_SIZE {int(parts[1]) * factor}')
        elif line.startswith('FONT_ASCENT '):
            parts = line.split()
            out.append(f'FONT_ASCENT {int(parts[1]) * factor}')
        elif line.startswith('FONT_DESCENT '):
            parts = line.split()
            out.append(f'FONT_DESCENT {int(parts[1]) * factor}')
        elif line.startswith('CAP_HEIGHT '):
            parts = line.split()
            val = int(parts[1])
            if val > 0:
                out.append(f'CAP_HEIGHT {val * factor}')
            else:
                out.append(line)
        elif line.startswith('X_HEIGHT '):
            parts = line.split()
            val = int(parts[1])
            if val > 0:
                out.append(f'X_HEIGHT {val * factor}')
            else:
                out.append(line)
        elif line.startswith('AVERAGE_WIDTH '):
            parts = line.split()
            out.append(f'AVERAGE_WIDTH {int(parts[1]) * factor}')
        elif line.startswith('DWIDTH '):
            parts = line.split()
            out.append(f'DWIDTH {int(parts[1]) * factor} {parts[2]}')
        elif line.startswith('SWIDTH '):
            parts = line.split()
            out.append(f'SWIDTH {int(parts[1]) * factor} {parts[2]}')
        elif line.startswith('BITED_DWIDTH '):
            parts = line.split()
            out.append(f'BITED_DWIDTH {int(parts[1]) * factor}')
        elif line.startswith('METRICSSET '):
            pass  # skip Apple metrics, they'll be regenerated
        else:
            out.append(line)

    with open(output_path, 'w') as f:
        f.write('\n'.join(out) + '\n')

    print(f'Scaled {input_path} by {factor}x → {output_path}')


def scale_font_line(line, factor):
    """Scale the XLFD FONT line."""
    # FONT -foundry-family-weight-slant-setwidth-addstyle-pixel-point-resx-resy...
    # Fields are dash-separated
    parts = line.split('-')
    # parts[0] = 'FONT '
    # parts[7] = pixel size (should be int)
    # parts[8] = point size (decipoints)
    try:
        pixel_size = int(parts[7])
        parts[7] = str(pixel_size * factor)
    except (ValueError, IndexError):
        pass
    try:
        point_size = int(parts[8])
        parts[8] = str(point_size * factor)
    except (ValueError, IndexError):
        pass
    return '-'.join(parts)


if __name__ == '__main__':
    if len(sys.argv) != 4:
        print(f'Usage: {sys.argv[0]} <input.bdf> <output.bdf> <scale_factor>')
        print(f'Example: {sys.argv[0]} lecoishmono.bdf lecoishmono_18.bdf 2')
        sys.exit(1)
    scale_bdf(sys.argv[1], sys.argv[2], int(sys.argv[3]))