kernMap.py

'''
Simple map to illustrate kerning topography.

By default, the output is an interactive html `canvas`, for exploration of the
kerning map. Use `pixel` or `svg` formats to obtain a fingerprint of the
kerning data.

An optional glyph list can be supplied (one glyph name per line), which will
influence the size of the kerning map, and override the built-in glyph order.

'''


import argparse
import colorsys

from defcon import Font
from fontTools.ttLib import TTFont
from pathlib import Path
from string import Template
from PIL import Image, ImageDraw

from dumpkerning import extractKerning


def get_args():
    parser = argparse.ArgumentParser(
        description=__doc__,
        formatter_class=argparse.ArgumentDefaultsHelpFormatter
    )
    parser.add_argument(
        'input_file',
        help='input file',
        action='store',
    )
    parser.add_argument(
        '-f', '--format',
        help='output format',
        choices=['canvas', 'pixel', 'svg'],
        default='canvas',
        action='store',
    )
    parser.add_argument(
        '-c', '--cell_size',
        help='cell size',
        default=5,
        action='store',
        type=int,
    )
    parser.add_argument(
        '-g', '--glyph_list',
        help='supply optional glyph list file',
        default=False,
        action='store',
    )
    return parser.parse_args()


def float_to_hex(rgb_tuple):
    '''
    convert a RGB tuple into a hex string
    '''
    hex_string = '#'

    for value in rgb_tuple:
        hex_value = hex(int(round(value * 255)))
        hex_string += hex_value[2:].zfill(2)

    return hex_string


def kern_color(k_value, min_value, max_value, hex_values=False):
    '''
    assign a color based on kerning intensity
    '''
    # saturation is at least 50%, otherwise hard to see
    sat = 0.5
    val = 1
    if k_value == 0:
        hue = 0
        sat = 0
    elif k_value < 0:
        hue = (1 / 360) * 0
        # increase saturation by up to 50%
        sat += k_value / min_value / 2
    else:
        hue = (1 / 360) * 180
        sat += k_value / max_value / 2

    r, g, b = colorsys.hsv_to_rgb(hue, sat, val)

    if hex_values:
        return float_to_hex((r, g, b))
    else:
        return r, g, b


def get_glyph_order(input_path):
    '''
    Depending on the input file, the approach for getting to the glyph order
    may differ.

    '''
    if input_path.suffix == '.ufo':
        f = Font(input_path)
        return f.glyphOrder
    elif input_path.suffix in ['.otf', '.ttf']:
        f = TTFont(input_path)
        return f.getGlyphOrder()
    else:
        # fea files don’t imply a glyph order, so this is just sorting all the
        # used glyphs alphabetically
        from getKerningPairsFromFEA import FEAKernReader
        fkr = FEAKernReader(input_path)
        found_pairs = fkr.flatKerningPairs.keys()
        all_glyphs = set([glyph for pair in found_pairs for glyph in pair])
        return sorted(all_glyphs)


def read_glyph_list(glyph_list_file):
    with open(glyph_list_file, 'r') as blob:
        glyph_list = blob.read().splitlines()
    return glyph_list


def make_kern_map(input_file, cell_size=5, glyph_list=None, format=None):

    input_path = Path(input_file)
    kerning = extractKerning(input_path)

    if glyph_list:
        glyph_order = read_glyph_list(glyph_list)
        all_kerned_pairs = {
            pair: value for pair, value in kerning.items() if
            set(pair) < set(glyph_order)}
    else:
        glyph_order = get_glyph_order(input_path)
        all_kerned_pairs = kerning

    basename = input_path.stem
    kern_values = list(all_kerned_pairs.values())
    k_min = min(kern_values)
    k_max = max(kern_values)

    if format == 'pixel':

        size_in_px = len(glyph_order) * cell_size
        img = Image.new('RGB', (size_in_px, size_in_px), '#fff')

        for row_index, g_name_a in enumerate(glyph_order):
            for col_index, g_name_b in enumerate(glyph_order):
                kv = all_kerned_pairs.get((g_name_a, g_name_b), None)
                x = row_index * cell_size
                y = col_index * cell_size
                rect = [(x, y), (x + cell_size, y + cell_size)]
                if kv is not None:
                    kc = kern_color(kv, k_min, k_max, hex_values=True)
                    img_dummy = ImageDraw.Draw(img)
                    img_dummy.rectangle(rect, fill=kc)

        output_path = Path(f'~/Desktop/{basename}_kernmap.png').expanduser()
        print(output_path)
        img.save(output_path)

    elif format == 'canvas':

        # A canvas can have a maxium area of 268 435 456 pixels.
        # Since we are dealing with hidpi canvas, the actual useable pixels
        # are 268 435 456 / 4 = 67 108 864
        canvas_area = (len(glyph_order) * cell_size) ** 2 * 4
        if canvas_area > 128 ** 4:
            print(
                'The canvas is too large and may not render.\n'
                'Try decreasing the cell size (option -c).'
            )

        with open('kernMap templates/canvas_prologue.html', 'r') as html_pro:
            canvas_prologue = Template(html_pro.read())
        with open('kernMap templates/canvas_epilogue.html', 'r') as html_epi:
            canvas_epilogue = html_epi.read()
        canvas = []

        sorted_pairs = sorted(
            all_kerned_pairs.keys(),
            key=lambda x: (glyph_order.index(x[0]), glyph_order.index(x[1])))
        neg_kerned_pairs = [
            p for p in sorted_pairs if all_kerned_pairs.get(p) <= 0]
        pos_kerned_pairs = [
            p for p in sorted_pairs if all_kerned_pairs.get(p) > 0]

        canvas.append(
            '                context.fillStyle = "#f00";')
        for left, right in neg_kerned_pairs:
            pair_index_l = glyph_order.index(left)
            pair_index_r = glyph_order.index(right)
            canvas.append(
                '                context.fillRect('
                f'{pair_index_l} * STEP, '
                f'{pair_index_r} * STEP, STEP, STEP)')

        canvas.append(
            '                context.fillStyle = "#0f0";')
        for left, right in pos_kerned_pairs:
            pair_index_l = glyph_order.index(left)
            pair_index_r = glyph_order.index(right)
            canvas.append(
                '                context.fillRect('
                f'{pair_index_l} * STEP, '
                f'{pair_index_r} * STEP, STEP, STEP)')

        # XXX this is a bit janky (and writes a lot of data into the html) --
        # but it works for now.
        flat_kern_items = [
            f'"{" ".join(p)}": {v},' for (p, v) in all_kerned_pairs.items()]

        header_content = {
            'base_name': basename,
            'glyph_order': ' '.join(glyph_order),
            'cell_size': cell_size,
            'kerning_data': ' '.join(flat_kern_items),
        }

        full_html = (
            canvas_prologue.safe_substitute(header_content) +
            '\n'.join(canvas) +
            canvas_epilogue
        )
        output_path = Path(f'~/Desktop/{basename}_kernmap.html').expanduser()
        print(output_path)
        with open(output_path, 'w') as o:
            o.write(full_html)

    elif format == 'svg':
        rect_size = cell_size

        svg_prologue = (
            '<svg version="1.1" width="{0}" height="{0}" '
            'xmlns="http://www.w3.org/2000/svg">\n'.format(
                len(glyph_order) * rect_size)
        )
        svg_epilogue = (
            '</svg>\n'
        )
        svg_path = (
            '<path style="fill:{}" d="M{} {} H{} V{} H{} z"/>'
        )

        svg = []
        for row_index, g_name_a in enumerate(glyph_order):
            for col_index, g_name_b in enumerate(glyph_order):
                x, y = row_index * rect_size, col_index * rect_size
                # pair = f'{g_name_a} {g_name_b}'
                kv = all_kerned_pairs.get((g_name_a, g_name_b), None)
                if kv is not None:
                    fill = kern_color(kv, k_min, k_max, hex_values=True)
                    svg.append(svg_path.format(
                        fill, x, y, x + rect_size, y + rect_size, x))

        full_svg = svg_prologue + '\n'.join(svg) + svg_epilogue
        output_path = Path(f'~/Desktop/{basename}_kernmap.svg').expanduser()
        print(output_path)
        with open(output_path, 'w') as o:
            o.write(full_svg)


if __name__ == '__main__':
    args = get_args()
    make_kern_map(args.input_file, args.cell_size, args.glyph_list, args.format)