Add CBDT to maximum_color

README.md

@@ -36,6 +36,9 @@ can be generated:
 ```shell
 # Adds COLR to a font with SVG and vice versa
 maxmium_color my_colr_font.ttf
+
+# Adds COLR to a font with SVG and vice versa, and generates a CBDT table
+maxmium_color --bitmaps my_colr_font.ttf
 ```
 
 The intended result is a font that will Just Work in any modern browser:
@@ -44,7 +47,7 @@ The intended result is a font that will Just Work in any modern browser:
 | --- | --- | --- |
 | COLR | Chrome 98+ | https://developer.chrome.com/blog/colrv1-fonts/ |
 | SVG | Firefox, Safari | |
-| CBDT | Chrome <98 | |
+| CBDT | Chrome <98 | Only generated if you pass `--bitmaps` to `maximum_color`|
 
 Note that at time of writing Chrome 98+ prefers CBDT to COLR. Also CBDT is
 huge. So ... maybe take the resulting font and subset it per-browser if at

src/nanoemoji/bitmap_tables.py

@@ -39,7 +39,6 @@
     Sequence,
     Tuple,
 )
-import statistics
 import sys
 
 
@@ -275,11 +274,27 @@ def _make_cbdt_strike(
     return strike, data
 
 
+def raise_if_too_big_for_cbdt(color_glyphs: Sequence[ColorGlyph]):
+    too_big = sorted(
+        (c for c in color_glyphs if max(c.bitmap.size) not in _UINT8_RANGE),
+        key=lambda c: c.bitmap_filename,
+    )
+    if not too_big:
+        return
+    raise ValueError(
+        "Bitmap is too big for CBDT, try lowering bitmap_resolution: "
+        + ",".join(c.bitmap_filename for c in too_big)
+    )
+
+
 def make_cbdt_table(
     config: FontConfig,
     ttfont: ttLib.TTFont,
     color_glyphs: Sequence[ColorGlyph],
 ):
+    # CBDT is a wee bit limited in pixel size
+    raise_if_too_big_for_cbdt(color_glyphs)
+
     # bitmap tables don't like it when we're out of order
     color_glyphs = sorted(color_glyphs, key=lambda c: c.glyph_id)
 

src/nanoemoji/colr_to_svg.py

@@ -51,6 +51,7 @@
 from fontTools.ttLib.tables import otTables
 
 
+_FOREGROUND_COLOR_INDEX = 0xFFFF
 _GRADIENT_PAINT_FORMATS = (PaintLinearGradient.format, PaintRadialGradient.format)
 _COLR_TO_SVG_TEMPLATE = r'<svg viewBox="TBD" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><defs/></svg>'
 
@@ -95,7 +96,12 @@ def _draw_svg_path(
 
 
 def _color(ttfont: ttLib.TTFont, palette_index, alpha=1.0) -> colors.Color:
-    cpal_color = ttfont["CPAL"].palettes[0][palette_index]
+    palette = ttfont["CPAL"].palettes[0]
+    if palette_index == _FOREGROUND_COLOR_INDEX:
+        return colors.Color.fromstring("black")  # as good a guess as any
+    if palette_index >= len(palette):
+        raise IndexError(f"{palette_index} illegal in palette of {len(palette)}")
+    cpal_color = palette[palette_index]
     return colors.Color(
         red=cpal_color.red,
         green=cpal_color.green,
@@ -296,10 +302,13 @@ def glyph_region(ttfont: ttLib.TTFont, glyph_name: str) -> Rect:
     """The area occupied by the glyph, NOT factoring in that Y flips.
 
     map_font_space_to_viewbox handles font +y goes up => svg +y goes down."""
+    width = ttfont["hmtx"][glyph_name][0]
+    if width == 0:
+        width = ttfont["glyf"][glyph_name].xMax
     return Rect(
         0,
         -ttfont["OS/2"].sTypoAscender,
-        ttfont["hmtx"][glyph_name][0],
+        width,
         ttfont["OS/2"].sTypoAscender - ttfont["OS/2"].sTypoDescender,
     )
 
@@ -309,7 +318,12 @@ def _view_box_and_transform(
 ) -> Tuple[Rect, Affine2D]:
 
     view_box = view_box_callback(glyph_name)
-    font_to_vbox = map_font_space_to_viewbox(view_box, glyph_region(ttfont, glyph_name))
+    assert view_box.w > 0, f"0-width viewBox for {glyph_name}?!"
+
+    region = glyph_region(ttfont, glyph_name)
+    assert region.w > 0, f"0-width region for {glyph_name}?!"
+
+    font_to_vbox = map_font_space_to_viewbox(view_box, region)
 
     return (view_box, font_to_vbox)
 

src/nanoemoji/copy.py

@@ -0,0 +1,32 @@
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from absl import app
+from pathlib import Path
+import shutil
+
+
+def main(argv):
+    assert len(argv) == 3, "Expected 2 args, input font and output"
+
+    input_file = Path(argv[1])
+    assert input_file.is_file(), f"No file {input_file}"
+    output_file = Path(argv[2])
+    assert input_file.resolve() != output_file.resolve()
+
+    shutil.copyfile(input_file, output_file)
+
+
+if __name__ == "__main__":
+    app.run(main)

src/nanoemoji/generate_svgs_from_colr.py

@@ -37,7 +37,9 @@
 
 def _view_box(font: ttLib.TTFont, glyph_name: str) -> Rect:
     # we want a viewbox that results in no scaling when translating from font-space
-    return glyph_region(font, glyph_name)
+    region = glyph_region(font, glyph_name)
+    assert region.w > 0, f"0-width region for {glyph_name}"
+    return region
 
 
 def main(argv):

src/nanoemoji/glue_together.py

@@ -118,9 +118,12 @@ def _copy_cbdt(target: ttLib.TTFont, donor: ttLib.TTFont):
     # other than glyph names so we can just construct a new
     # order that matches that of target
     donor_order = list(cbdt_glyph_info.keys())
+    only_in_donor = set(donor_order) - set(target.getGlyphOrder())
     # confirm our core assumption that we successfully held glyph names stable
-    if not set(donor_order) <= set(target.getGlyphOrder()):
-        raise ValueError("Donor glyph names do not exist in target")
+    if only_in_donor:
+        raise ValueError(
+            f"Donor glyph names do not exist in target: {sorted(only_in_donor)}"
+        )
     new_order = sorted(donor_order, key=target.getGlyphID)
 
     # now we know the desired order, reshard into runs
@@ -154,7 +157,7 @@ def _copy_cbdt(target: ttLib.TTFont, donor: ttLib.TTFont):
         strike.bitmapSizeTable.min_gid = min_gid
         strike.bitmapSizeTable.max_gid = max_gid
 
-        max_width = max(cbdt_glyph_info[gn].data.metrics.width for gn in glyph_run)
+        max_width = max(cbdt_glyph_info[gn].data.metrics.Advance for gn in glyph_run)
         strike.bitmapSizeTable.hori.widthMax = max_width
         strike.bitmapSizeTable.vert.widthMax = max_width
 
@@ -179,11 +182,12 @@ def main(argv):
     target = load_fully(Path(FLAGS.target_font))
     donor = load_fully(Path(FLAGS.donor_font))
 
-    if FLAGS.color_table == "COLR":
+    donation = FLAGS.color_table.lower().strip()
+    if donation == "colr":
         _copy_colr(target, donor)
-    elif FLAGS.color_table == "SVG":
+    elif donation == "svg":
         _copy_svg(target, donor)
-    elif FLAGS.color_table == "CBDT":
+    elif donation == "cbdt":
         _copy_cbdt(target, donor)
     else:
         raise ValueError(f"Unsupported color table '{FLAGS.color_table}'")

src/nanoemoji/keep_glyph_names.py

@@ -0,0 +1,61 @@
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Update post to keep glyph names."""
+from absl import app
+from absl import flags
+from absl import logging
+from fontTools import ttLib
+from pathlib import Path
+
+
+FLAGS = flags.FLAGS
+
+
+flags.DEFINE_string(
+    "log_level",
+    "INFO",
+    "The threshold for what messages will be logged. One of DEBUG, INFO, WARN, "
+    "ERROR, or FATAL.",
+)
+
+
+def keep_glyph_names(font: ttLib.TTFont):
+    # ref https://github.com/googlefonts/ufo2ft/blob/ad28eea062e0dd48678309bd9ef86dfcc85fa85a/Lib/ufo2ft/postProcessor.py#L281-L285
+    if "post" not in font:
+        raise ValueError(f"No post table")
+    post = font["post"]
+    post.formatType = 2.0
+    post.extraNames = []
+    post.mapping = {}
+
+
+def main(argv):
+    logging.set_verbosity(FLAGS.log_level)
+
+    assert len(argv) == 3, "Expected 2 args, input font and output font"
+
+    input_file = Path(argv[1])
+    assert input_file.is_file(), f"No file {input_file}"
+    output_file = Path(argv[2])
+    assert input_file.resolve() != output_file.resolve()
+
+    font = ttLib.TTFont(input_file)
+    keep_glyph_names(font)
+
+    font.save(output_file)
+
+
+if __name__ == "__main__":
+    app.run(main)