Fix static font generation from variable fonts
This commit is contained in:
jpirnay
@@ -82,7 +82,13 @@ def extract_static_instance(source_path: Path, axes: dict, family_name: str, sty
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print(f" Extracting static instance: {family_name}/{style_name} ({axis_key})")
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font = TTFont(str(source_path))
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instantiateVariableFont(font, axes)
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font = instantiateVariableFont(
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font,
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axes,
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static=True,
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updateFontNames=True,
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optimize=False,
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)
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font.save(str(cached))
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font.close()
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@@ -23,15 +23,22 @@ Usage:
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"""
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import freetype
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import zlib
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import struct
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import sys
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import os
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import math
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import argparse
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import binascii
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from collections import namedtuple
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from fontTools.ttLib import TTFont
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try:
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from PIL import Image
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except ImportError:
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Image = None
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# --- Unicode interval presets ---
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INTERVAL_PRESETS = {
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@@ -137,6 +144,124 @@ def fp4_from_design_units(du, scale):
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return max(-128, min(127, raw))
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def write_png_gray(path, width, height, pixels):
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def png_chunk(chunk_type, data):
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chunk = chunk_type + data
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return struct.pack("!I", len(data)) + chunk + struct.pack("!I", binascii.crc32(chunk) & 0xffffffff)
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ihdr = struct.pack("!IIBBBBB", width, height, 8, 0, 0, 0, 0)
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raw_scanlines = bytearray()
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for y in range(height):
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raw_scanlines.append(0)
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raw_scanlines.extend(pixels[y * width:(y + 1) * width])
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with open(path, "wb") as f:
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f.write(b"\x89PNG\r\n\x1a\n")
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f.write(png_chunk(b"IHDR", ihdr))
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f.write(png_chunk(b"IDAT", zlib.compress(bytes(raw_scanlines), level=9)))
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f.write(png_chunk(b"IEND", b""))
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STYLE_LABELS = {0: "regular", 1: "bold", 2: "italic", 3: "bolditalic"}
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def expand_processed_bitmap(width, height, packed, bits):
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raw = bytearray(width * height)
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pixels_per_byte = 8 // bits
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mask = (1 << bits) - 1
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for idx in range(width * height):
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byte = packed[idx // pixels_per_byte]
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shift = (pixels_per_byte - 1 - (idx % pixels_per_byte)) * bits
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raw[idx] = (byte >> shift) & mask
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return raw
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def pack_2bit_bitmap(width, height, pixels):
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packed = bytearray(((width * height) + 3) // 4)
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for idx, value in enumerate(pixels):
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shift = (3 - (idx % 4)) * 2
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packed[idx // 4] |= (value & 3) << shift
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return bytes(packed)
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def dilate_2bit_bitmap(width, height, pixels):
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out = bytearray(len(pixels))
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for y in range(height):
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for x in range(width):
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maxv = 0
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for dy in (-1, 0, 1):
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ny = y + dy
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if ny < 0 or ny >= height:
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continue
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for dx in (-1, 0, 1):
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nx = x + dx
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if nx < 0 or nx >= width:
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continue
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maxv = max(maxv, pixels[ny * width + nx])
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out[y * width + x] = maxv
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return out
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def glyph_pixels_2bit(entry):
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glyph, packed = entry
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return expand_processed_bitmap(glyph.width, glyph.height, packed, 2)
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def glyph_entries_by_codepoint(sd, code_point):
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return (entry for entry in sd.all_glyphs if entry[0].code_point == code_point)
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def style_uses_synthetic_bold(base_sd, target_sd):
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base_entry = next(glyph_entries_by_codepoint(base_sd, ord('A')), None)
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target_entry = next(glyph_entries_by_codepoint(target_sd, ord('A')), None)
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if base_entry is None or target_entry is None:
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return False
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base_glyph, base_packed = base_entry
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target_glyph, target_packed = target_entry
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if base_glyph.width != target_glyph.width or base_glyph.height != target_glyph.height:
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return False
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base_pixels = expand_processed_bitmap(base_glyph.width, base_glyph.height, base_packed, 2)
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target_pixels = expand_processed_bitmap(target_glyph.width, target_glyph.height, target_packed, 2)
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return base_pixels == target_pixels
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def apply_synthetic_bold(sd, style_label):
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print(f" Debug: synthetic bold applied for style {style_label}", file=sys.stderr)
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for idx, (glyph, packed) in enumerate(sd.all_glyphs):
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if glyph.width == 0 or glyph.height == 0:
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continue
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pixels = expand_processed_bitmap(glyph.width, glyph.height, packed, 2)
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bold_pixels = dilate_2bit_bitmap(glyph.width, glyph.height, pixels)
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sd.all_glyphs[idx] = (glyph, pack_2bit_bitmap(glyph.width, glyph.height, bold_pixels))
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def save_debug_glyph_image(output_path, raster_data):
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base = os.path.splitext(output_path)[0]
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found = False
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for style_id, sd in raster_data.items():
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style_label = STYLE_LABELS.get(style_id, str(style_id))
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png_path = f"{base}_A_{style_label}.png"
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glyph_entry = next(((g, p) for g, p in sd.all_glyphs if g.code_point == ord('A')), None)
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if glyph_entry is None:
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print(f" Debug: letter 'A' not found for style {style_label}", file=sys.stderr)
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continue
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glyph, packed = glyph_entry
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if glyph.width == 0 or glyph.height == 0:
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print(f" Debug: letter 'A' has empty bitmap for style {style_label}", file=sys.stderr)
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continue
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unpacked = expand_processed_bitmap(glyph.width, glyph.height, packed, 2)
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img_pixels = bytes(255 - p * 85 for p in unpacked)
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if Image:
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img = Image.frombytes("L", (glyph.width, glyph.height), img_pixels)
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img.save(png_path)
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else:
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write_png_gray(png_path, glyph.width, glyph.height, img_pixels)
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print(f" Debug: saved letter 'A' bitmap to {png_path}", file=sys.stderr)
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found = True
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if not found:
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print(f" Debug: no letter 'A' glyphs were saved for {output_path}", file=sys.stderr)
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# Standard Unicode ligature codepoints for known input sequences.
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# Used as a fallback when the GSUB substitute glyph has no cmap entry.
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STANDARD_LIGATURE_MAP = {
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@@ -665,7 +790,8 @@ def style_sections_total_size(sections):
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# --- File writers ---
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def generate_cpfont_multistyle(style_fonts, size, intervals, output_path,
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force_autohint=False):
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force_autohint=False, synthetic_bold=False,
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debug_images=False):
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"""Generate a multi-style v4 .cpfont file.
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style_fonts: dict of {style_id: fontfile_path} e.g. {0: "Regular.ttf", 2: "Italic.ttf"}
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@@ -686,6 +812,24 @@ def generate_cpfont_multistyle(style_fonts, size, intervals, output_path,
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fontfile, size, intervals, style_id=style_id,
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force_autohint=force_autohint)
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if synthetic_bold:
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# If a bold-style output is identical to its base style, apply a synthetic
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# bold bitmap transformation so the style still appears heavier.
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regular_sd = raster_data.get(0)
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italic_sd = raster_data.get(2)
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if regular_sd is not None and 1 in raster_data:
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style_label = STYLE_LABELS.get(1, "1")
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if style_uses_synthetic_bold(regular_sd, raster_data[1]):
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apply_synthetic_bold(raster_data[1], style_label)
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if italic_sd is not None and 3 in raster_data:
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style_label = STYLE_LABELS.get(3, "3")
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if style_uses_synthetic_bold(italic_sd, raster_data[3]):
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apply_synthetic_bold(raster_data[3], style_label)
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elif regular_sd is not None and 3 in raster_data:
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style_label = STYLE_LABELS.get(3, "3")
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if style_uses_synthetic_bold(regular_sd, raster_data[3]):
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apply_synthetic_bold(raster_data[3], style_label)
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# Pack binary sections for each style
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packed_sections = {} # style_id -> tuple of section bytearrays
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for style_id, sd in raster_data.items():
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@@ -753,6 +897,8 @@ def generate_cpfont_multistyle(style_fonts, size, intervals, output_path,
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print(f" {sname}: {len(sd.all_glyphs)} glyphs, {len(sd.intervals)} intervals, "
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f"{ssize} bytes", file=sys.stderr)
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print(f" Total: {total_file_size} bytes ({total_file_size / 1024 / 1024:.2f} MB)", file=sys.stderr)
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if debug_images:
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save_debug_glyph_image(output_path, raster_data)
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return total_file_size
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@@ -779,6 +925,10 @@ def main():
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help="Font family name for output filenames (default: derived from font filename).")
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parser.add_argument("--force-autohint", dest="force_autohint", action="store_true",
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help="Force FreeType auto-hinter instead of native font hinting.")
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parser.add_argument("--synthetic-bold", dest="synthetic_bold", action="store_true",
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help="Apply synthetic boldening when bold style equals its source style.")
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parser.add_argument("--debug-images", dest="debug_images", action="store_true",
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help="Save debug A glyph PNGs for each generated style.")
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parser.add_argument("-o", "--output", dest="output",
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help="Output file path (for single-size mode).")
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parser.add_argument("--output-dir", dest="output_dir",
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@@ -883,7 +1033,9 @@ def main():
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print(f"Generating {output_path} (size {sz}, {len(style_fonts)} style(s), v4)...", file=sys.stderr)
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total_size += generate_cpfont_multistyle(
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style_fonts, sz, intervals, output_path,
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force_autohint=args.force_autohint)
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force_autohint=args.force_autohint,
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synthetic_bold=args.synthetic_bold,
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debug_images=args.debug_images)
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print(f"\nTotal: {len(sizes)} files, {total_size / 1024 / 1024:.2f} MB", file=sys.stderr)
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