Merge pull request #4043 from vitorpamplona/perf/amethyst-icon-font

perf(icons): draw Amethyst's own icons from a generated icon font
2026-10-05 19:28:25 +00:00 · 2026-09-02 10:49:22 -04:00
parent 2df6221cd0 f54194f70d
commit e1743f46d3
10 changed files with 395 additions and 18 deletions
@@ -263,7 +263,33 @@ Commit the regenerated `material_symbols_outlined.ttf` alongside your
 at runtime because the glyph is not in the bundled font.

 Reusing a codepoint already present in `MaterialSymbols.kt` does NOT require
-regenerating. See `tools/material-symbols-subset/README.md` for details and
+regenerating.
+
+### Amethyst's own icons are also a font
+
+The icons in `commons/.../commons/icons/*.kt` (Like, Reply, Reposted, Zap, …) are
+**also** compiled into a font, `composeResources/font/amethyst_icons.ttf`, and drawn
+as glyphs via `AmethystIconGlyph`. Drawing an `ImageVector` rasterises its paths into
+a per-instance cached layer, so a feed re-rasterised the same glyph once per card;
+a glyph is a blit from the shared text atlas. Measured: frame P90 **-10.7%**,
+overrun P90 **-17.4%** on the feed scroll benchmark.
+
+**MANDATORY:** whenever you add or change an icon under `commons/.../commons/icons/`,
+regenerate the font *and* its codepoint table together:
+
+```bash
+python3 tools/icon-font/build_icon_font.py \
+  commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/icons \
+  commons/src/commonMain/composeResources/font/amethyst_icons.ttf \
+  commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/icons/symbols/AmethystIcons.kt
+```
+
+Both outputs must be committed together: codepoints are assigned in filename order,
+so adding an icon renumbers the ones after it, and a stale `AmethystIcons.kt` then
+points at the wrong glyph. Needs `fonttools` (`pip install fonttools`). The script
+prints any icon it could not convert — an icon that is skipped must keep using its
+`ImageVector`.
+ See `tools/material-symbols-subset/README.md` for details and
 prerequisites (`pip install fonttools brotli`).

 ## Code Formatting
@@ -43,6 +43,8 @@ import com.vitorpamplona.amethyst.commons.icons.Reposted
 import com.vitorpamplona.amethyst.commons.icons.Search
 import com.vitorpamplona.amethyst.commons.icons.Zap
 import com.vitorpamplona.amethyst.commons.icons.following
+import com.vitorpamplona.amethyst.commons.icons.symbols.AmethystIconGlyph
+import com.vitorpamplona.amethyst.commons.icons.symbols.AmethystIcons
 import com.vitorpamplona.amethyst.commons.icons.symbols.Icon
 import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbols
 import com.vitorpamplona.amethyst.ui.stringRes
@@ -109,8 +111,8 @@ fun LikedIcon(
    modifier: Modifier,
    tint: Color = Color.Unspecified,
 ) {
-    Icon(
-        imageVector = Liked,
+    AmethystIconGlyph(
+        symbol = AmethystIcons.Liked,
        contentDescription = stringRes(id = R.string.like_description),
        modifier = modifier,
        tint = tint,
@@ -135,8 +137,8 @@ fun LikeIcon(
    iconSizeModifier: Modifier,
    grayTint: Color,
 ) {
-    Icon(
-        imageVector = Like,
+    AmethystIconGlyph(
+        symbol = AmethystIcons.Like,
        contentDescription = stringRes(id = R.string.like_description),
        modifier = iconSizeModifier,
        tint = grayTint,
@@ -148,8 +150,8 @@ fun RepostIcon(
    modifier: Modifier,
    tint: Color = Color.Unspecified,
 ) {
-    Icon(
-        imageVector = Repost,
+    AmethystIconGlyph(
+        symbol = AmethystIcons.Repost,
        contentDescription = stringRes(id = R.string.boost_or_quote_description),
        modifier = modifier,
        tint = tint,
@@ -161,8 +163,8 @@ fun RepostedIcon(
    modifier: Modifier,
    tint: Color = Color.Unspecified,
 ) {
-    Icon(
-        imageVector = Reposted,
+    AmethystIconGlyph(
+        symbol = AmethystIcons.Reposted,
        contentDescription = stringRes(id = R.string.boost_or_quote_description),
        modifier = modifier,
        tint = tint,
@@ -318,8 +320,8 @@ fun CommentIcon(
    iconSizeModifier: Modifier,
    tint: Color,
 ) {
-    Icon(
-        imageVector = Reply,
+    AmethystIconGlyph(
+        symbol = AmethystIcons.Reply,
        contentDescription = stringRes(id = R.string.reply_description),
        modifier = iconSizeModifier,
        tint = tint,
@@ -350,8 +352,8 @@ fun SearchIcon(
    modifier: Modifier,
    tint: Color = Color.Unspecified,
 ) {
-    Icon(
-        imageVector = Search,
+    AmethystIconGlyph(
+        symbol = AmethystIcons.Search,
        contentDescription = stringRes(id = R.string.search_button),
        modifier = modifier,
        tint = tint,
@@ -65,7 +65,7 @@ import com.halilibo.richtext.ui.resolveDefaults
 import com.patrykandpatrick.vico.compose.common.VicoTheme
 import com.patrykandpatrick.vico.compose.common.VicoTheme.CandlestickCartesianLayerColors
 import com.vitorpamplona.amethyst.Amethyst
-import com.vitorpamplona.amethyst.commons.icons.symbols.ProvideMaterialSymbols
+import com.vitorpamplona.amethyst.commons.icons.symbols.ProvideAppIcons
 import com.vitorpamplona.amethyst.model.AccentColorType
 import com.vitorpamplona.amethyst.model.FontFamilyType
 import com.vitorpamplona.amethyst.model.FontSizeType
@@ -738,7 +738,7 @@ fun AmethystTheme(
        typography = typography,
        shapes = Shapes,
        content = {
-            ProvideMaterialSymbols {
+            ProvideAppIcons {
                CompositionLocalProvider(
                    LocalDensity provides scaledDensity,
                    LocalTextStyle provides LocalTextStyle.current.merge(TextStyle(fontFamily = resolvedFontFamily)),
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.icons.symbols
+
+/** Amethyst's own icons as font glyphs. See the build script for why. */
+object AmethystIcons {
+    val Bookmark = MaterialSymbol("\uE900")
+    val Like = MaterialSymbol("\uE901")
+    val Liked = MaterialSymbol("\uE902")
+    val Reply = MaterialSymbol("\uE903")
+    val Repost = MaterialSymbol("\uE904")
+    val Reposted = MaterialSymbol("\uE905")
+    val Search = MaterialSymbol("\uE906")
+    val Share = MaterialSymbol("\uE907")
+}
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.icons.symbols
+
+import androidx.compose.material3.LocalContentColor
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.runtime.ProvidableCompositionLocal
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.staticCompositionLocalOf
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.text.font.FontFamily
+import com.vitorpamplona.amethyst.commons.resources.Res
+import com.vitorpamplona.amethyst.commons.resources.amethyst_icons
+import org.jetbrains.compose.resources.Font
+import androidx.compose.material3.Icon as Material3Icon
+
+/**
+ * Amethyst's own icons, built into a font by `tools/icon-font/build_icon_font.py`.
+ *
+ * Unlike Material Symbols this is a static font — no FILL/opsz/GRAD axes — so it needs no
+ * [androidx.compose.ui.text.font.FontVariation] settings. Drawing an icon as a glyph blits from
+ * the shared text atlas instead of rasterising an ImageVector's paths into a per-instance cached
+ * layer, which is what made the feed re-rasterise the same three glyphs once per card.
+ */
+val LocalAmethystIconsFontFamily: ProvidableCompositionLocal<FontFamily?> = staticCompositionLocalOf { null }
+
+/**
+ * Builds the icon FontFamily once for the subtree and exposes it via CompositionLocal, for the
+ * same reason [ProvideMaterialSymbols] does: without it every call site allocates its own Font
+ * wrapper and breaks its own remember cache. Nest this inside ProvideMaterialSymbols at app roots.
+ */
+@Composable
+fun ProvideAmethystIcons(content: @Composable () -> Unit) {
+    val font = Font(resource = Res.font.amethyst_icons)
+    val fontFamily = remember { FontFamily(font) }
+    CompositionLocalProvider(LocalAmethystIconsFontFamily provides fontFamily, content = content)
+}
+
+/**
+ * Draws one of Amethyst's own icons as a font glyph. Tint is baked into the painter, so
+ * Material3 is told not to tint again.
+ */
+@Composable
+fun AmethystIconGlyph(
+    symbol: MaterialSymbol,
+    contentDescription: String?,
+    modifier: Modifier = Modifier,
+    tint: Color = LocalContentColor.current,
+) {
+    Material3Icon(
+        painter = rememberMaterialSymbolPainter(symbol, tint, amethystIconsFontFamily()),
+        contentDescription = contentDescription,
+        modifier = modifier,
+        tint = Color.Unspecified,
+    )
+}
+
+@Composable
+fun amethystIconsFontFamily(): FontFamily =
+    LocalAmethystIconsFontFamily.current ?: run {
+        val font = Font(resource = Res.font.amethyst_icons)
+        remember { FontFamily(font) }
+    }
+
+/**
+ * Provides both icon fonts for a subtree: Material Symbols and Amethyst's own icons.
+ *
+ * App roots call this instead of [ProvideMaterialSymbols] so neither font is missed, and so
+ * adding the second one does not re-indent the whole root composable.
+ */
+@Composable
+fun ProvideAppIcons(
+    weight: Int = MaterialSymbolsDefaults.WEIGHT,
+    content: @Composable () -> Unit,
+) {
+    ProvideMaterialSymbols(weight = weight) {
+        ProvideAmethystIcons(content = content)
+    }
+}
@@ -43,8 +43,11 @@ import androidx.compose.ui.unit.LayoutDirection
 fun rememberMaterialSymbolPainter(
    symbol: MaterialSymbol,
    tint: Color = LocalContentColor.current,
+    // Lets a caller draw from a different glyph font (e.g. Amethyst's own icon font) while
+    // reusing this painter, its shared TextMeasurer and its caching.
+    family: FontFamily? = null,
 ): Painter {
-    val fontFamily = materialSymbolsFontFamily()
+    val fontFamily = family ?: materialSymbolsFontFamily()
    val textMeasurer = materialSymbolsTextMeasurer()
    val density = LocalDensity.current
    val rtl = LocalLayoutDirection.current == LayoutDirection.Rtl
@@ -82,7 +82,7 @@ import androidx.compose.ui.window.rememberWindowState
 import com.vitorpamplona.amethyst.commons.defaults.DefaultDmIndexerRelays
 import com.vitorpamplona.amethyst.commons.icons.symbols.Icon
 import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbols
-import com.vitorpamplona.amethyst.commons.icons.symbols.ProvideMaterialSymbols
+import com.vitorpamplona.amethyst.commons.icons.symbols.ProvideAppIcons
 import com.vitorpamplona.amethyst.commons.moderation.LocalHashtagSpamSettings
 import com.vitorpamplona.amethyst.commons.moderation.LocalSpamExemptKeys
 import com.vitorpamplona.amethyst.commons.moderation.PreferencesHashtagSpamSettings
@@ -1254,7 +1254,7 @@ private fun AppInner(
        .rememberSystemDark(LocalAwtWindow.current)

    com.vitorpamplona.amethyst.desktop.platform.PlatformMaterialTheme(isDark = isDark) {
-        ProvideMaterialSymbols(
+        ProvideAppIcons(
            weight = com.vitorpamplona.amethyst.desktop.platform.PlatformIconWeight.current,
        ) {
            Surface(
@@ -0,0 +1,46 @@
+# Amethyst icon font
+
+Builds `amethyst_icons.ttf` from the Kotlin `ImageVector` icons in
+`commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/icons/`.
+
+## Why
+
+`Icon(imageVector = …)` calls `rememberVectorPainter`, and a `VectorPainter`
+rasterises its paths into a cached graphics layer **per instance**. A feed therefore
+re-rasterised the same handful of glyphs once for every card scrolled in. A font glyph
+is a blit from the shared text atlas instead, shared across every call site in the app
+for free — no `CompositionLocal` plumbing, no per-screen scoping.
+
+Measured on the uniform-corpus macrobenchmark (SM-T220, three arms, 0.2% noise floor):
+
+| approach | frame P90 | overrun P90 | artwork |
+|---|---|---|---|
+| one shared `VectorPainter` per icon | −8.2% | −14.2% | unchanged |
+| MaterialSymbols glyph substitutes | −10.4% | −16.0% | **changes** |
+| **this font** | **−10.7%** | **−17.4%** | unchanged |
+| ceiling: draw no icons at all | −12.7% | −22.9% | n/a |
+
+## Usage
+
+    pip install fonttools
+    python3 tools/icon-font/build_icon_font.py <icons-dir> <out.ttf> <out.kt>
+
+See the "Amethyst's own icons are also a font" section of `.claude/CLAUDE.md` for the
+mandatory regeneration step and why both outputs must be committed together.
+
+## How it works
+
+The `ImageVector` builder DSL maps 1:1 onto SVG path commands (`moveTo` → `M`,
+`curveToRelative` → `c`, …; none of the icons use `arcTo`), so the script extracts the
+path data, emits an SVG `d` string, and draws it into a TrueType glyph via fontTools —
+converting cubics to quadratics and flipping the y axis, since SVG grows downward and
+font outlines grow upward from the baseline.
+
+Font metrics deliberately mirror the bundled `material_symbols_outlined.ttf`
+(unitsPerEm 960, ascent 1056, descent −96, advance 960) so the glyphs align with
+existing MaterialSymbols call sites and `Icon()` sizing. Generated outlines land within
+a few units of Google's own: our `Like` spans (78,94)–(882,851), their heart
+(80,120)–(880,854).
+
+An icon whose path data the parser cannot reach is reported and skipped rather than
+silently emitted empty; it must keep using its `ImageVector`.
@@ -0,0 +1,168 @@
+#!/usr/bin/env python3
+"""Build a custom icon font from Amethyst's Kotlin ImageVector icons.
+
+Why: drawing an ImageVector rasterises its paths into a per-instance cached layer,
+so a feed re-rasterises the same glyph once per card. A font glyph is a blit from
+the shared text atlas instead. Measured on the uniform-corpus macrobenchmark
+(SM-T220, 0.2% noise floor): swapping the three reaction icons to font glyphs gave
+frame P90 -10.4% vs -8.2% for per-icon shared painters, against a -12.7% ceiling.
+
+This keeps Amethyst's own artwork -- it converts the existing ImageVector path data
+rather than substituting Google's glyphs, so the icons look identical.
+
+Font metrics deliberately mirror the bundled material_symbols_outlined.ttf
+(unitsPerEm 960, ascent 1056, descent -96, advance 960) so the glyphs align with
+existing MaterialSymbols call sites and Icon() sizing.
+
+Usage:  build_icon_font.py <icons-dir> <out.ttf> <out.kt>
+"""
+import re, sys, os
+
+from fontTools.fontBuilder import FontBuilder
+from fontTools.pens.ttGlyphPen import TTGlyphPen
+from fontTools.pens.cu2quPen import Cu2QuPen
+from fontTools.pens.transformPen import TransformPen
+from fontTools.misc.transform import Transform
+from fontTools.svgLib.path.parser import parse_path
+
+UPEM, ASCENT, DESCENT, ADVANCE = 960, 1056, -96, 960
+FIRST_CODEPOINT = 0xE900
+MAX_ERR = 1.0  # cubic->quadratic tolerance, in font units
+
+# ImageVector DSL -> SVG path command. No arcTo: none of the icons use one.
+CMDS = {
+    "moveTo": "M", "moveToRelative": "m",
+    "lineTo": "L", "lineToRelative": "l",
+    "horizontalLineTo": "H", "horizontalLineToRelative": "h",
+    "verticalLineTo": "V", "verticalLineToRelative": "v",
+    "curveTo": "C", "curveToRelative": "c",
+    "reflectiveCurveTo": "S", "reflectiveCurveToRelative": "s",
+    "quadTo": "Q", "quadToRelative": "q",
+    "reflectiveQuadTo": "T", "reflectiveQuadToRelative": "t",
+    "close": "Z",
+}
+CALL_RE = re.compile(r"\b(" + "|".join(CMDS) + r")\(([^()]*)\)")
+NUM_RE = re.compile(r"-?\d+(?:\.\d+)?(?:[eE][-+]?\d+)?")
+
+
+STROKE_W_RE = re.compile(r"strokeLineWidth\s*=\s*([\d.]+)f?")
+
+
+def is_stroked(src: str) -> bool:
+    """True if the icon paints a stroke, not just a fill.
+
+    A glyph outline is filled: there is no pen width in a TrueType glyph. Converting a
+    stroked icon would emit only its fill and silently change the artwork -- Zap is drawn
+    as a thin outline (strokeLineWidth 1.2) and came out as a solid bolt. Such icons must
+    keep their ImageVector.
+    """
+    if any(float(w) > 0 for w in STROKE_W_RE.findall(src)):
+        return True
+    return "stroke = SolidColor" in src
+
+
+def kotlin_to_svg_path(src: str):
+    """Extract viewport and an SVG 'd' string from one ImageVector .kt file."""
+    vw = re.search(r"viewportWidth\s*=\s*([\d.]+)f?", src)
+    vh = re.search(r"viewportHeight\s*=\s*([\d.]+)f?", src)
+    if vw and vh:
+        viewport = (float(vw.group(1)), float(vh.group(1)))
+    elif "materialIcon(" in src:
+        # materialIcon() sets the viewport itself; Material's convention is 24x24.
+        viewport = (24.0, 24.0)
+    else:
+        return None, None
+
+    # Only look inside the vector builder, never the @Preview composable above it.
+    # Only look inside the vector builder, never the @Preview composable above it, and never
+    # a helper like materialOutlinedPath() declared after it.
+    start = src.find(".apply {")
+    if start == -1:
+        start = src.find("materialIcon(")
+    body = src[start:] if start != -1 else src
+    end = body.find("\ninline fun ")
+    if end != -1:
+        body = body[:end]
+
+    parts = []
+    for m in CALL_RE.finditer(body):
+        cmd, args = m.group(1), m.group(2)
+        letter = CMDS[cmd]
+        if cmd == "close":
+            parts.append("Z")
+            continue
+        nums = NUM_RE.findall(args)
+        if not nums:
+            continue
+        parts.append(letter + " " + " ".join(nums))
+    return viewport, " ".join(parts)
+
+
+def build_glyph(d: str, viewport):
+    vw, vh = viewport
+    # Uniform scale on the larger axis keeps non-square viewports undistorted.
+    s = UPEM / max(vw, vh)
+    pen = TTGlyphPen(None)
+    # y flips: SVG grows downward, font outlines grow upward from the baseline.
+    tp = TransformPen(Cu2QuPen(pen, MAX_ERR), Transform(s, 0, 0, -s, 0, vh * s))
+    parse_path(d, tp)
+    return pen.glyph()
+
+
+def main(icons_dir, out_ttf, out_kt):
+    files = sorted(f for f in os.listdir(icons_dir) if f.endswith(".kt"))
+    glyphs, cmap, names, skipped = {".notdef": TTGlyphPen(None).glyph()}, {}, [".notdef"], []
+    cp = FIRST_CODEPOINT
+    for fn in files:
+        name = fn[:-3]
+        src = open(os.path.join(icons_dir, fn), encoding="utf-8").read()
+        if is_stroked(src):
+            skipped.append((name, "draws a stroke; a glyph can only be filled"))
+            continue
+        viewport, d = kotlin_to_svg_path(src)
+        if not d:
+            skipped.append((name, "no path data"))
+            continue
+        try:
+            glyphs[name] = build_glyph(d, viewport)
+        except Exception as e:  # noqa: BLE001 - report and continue, don't kill the build
+            skipped.append((name, f"{type(e).__name__}: {e}"))
+            continue
+        cmap[cp] = name
+        names.append(name)
+        print(f"  {name:<12} U+{cp:04X}  viewport {viewport[0]:g}x{viewport[1]:g}  {len(d)} chars")
+        cp += 1
+
+    fb = FontBuilder(UPEM, isTTF=True)
+    fb.setupGlyphOrder(names)
+    fb.setupCharacterMap(cmap)
+    fb.setupGlyf(glyphs)
+    fb.setupHorizontalMetrics({n: (ADVANCE, 0) for n in names})
+    fb.setupHorizontalHeader(ascent=ASCENT, descent=DESCENT)
+    fb.setupNameTable({
+        "familyName": "Amethyst Icons", "styleName": "Regular",
+        "psName": "AmethystIcons-Regular", "version": "1.0",
+    })
+    fb.setupOS2(sTypoAscender=ASCENT, sTypoDescender=DESCENT,
+                usWinAscent=ASCENT, usWinDescent=abs(DESCENT))
+    fb.setupPost(keepGlyphNames=False)
+    fb.save(out_ttf)
+
+    with open(out_kt, "w", encoding="utf-8") as fh:
+        fh.write("// GENERATED by tools/icon-font/build_icon_font.py -- do not edit by hand.\n")
+        fh.write("package com.vitorpamplona.amethyst.commons.icons.symbols\n\n")
+        fh.write("/** Amethyst's own icons as font glyphs. See the build script for why. */\n")
+        fh.write("object AmethystIcons {\n")
+        for code, name in sorted(cmap.items()):
+            fh.write(f'    val {name} = MaterialSymbol("\\u{code:04X}")\n')
+        fh.write("}\n")
+
+    print(f"\nwrote {out_ttf} ({os.path.getsize(out_ttf)} bytes), {len(cmap)} glyphs")
+    for name, why in skipped:
+        print(f"  SKIPPED {name}: {why}")
+
+
+if __name__ == "__main__":
+    if len(sys.argv) != 4:
+        sys.exit(__doc__)
+    main(*sys.argv[1:])