regenerate previews

analyze.py

@@ -250,6 +250,8 @@ WIDTH_CLASS_RATIOS = {
 }
 
 SCHEMA_VERSION = 3
+PREVIEW_HEIGHT = 96
+PREVIEW_RENDER_SIZE = 256
 
 GOOGLE_METADATA_URL = "https://fonts.google.com/metadata/fonts"
 
@@ -1848,27 +1850,29 @@ def missing_characters(font_path: Path, text: str) -> list[dict[str, str]]:
             if ord(character) not in cmap
         ]
 
-def load_fitted_font(font_path: Path, text: str, width: int, height: int) -> tuple[ImageFont.FreeTypeFont, tuple[int, int, int, int]]:
-    maximum_width = width - 120
-    maximum_height = height - 72
-    size = min(190, maximum_height)
-    for _ in range(5):
-        font = ImageFont.truetype(str(font_path), size=size)
-        box = font.getbbox(text)
-        text_width = max(1, box[2] - box[0])
-        text_height = max(1, box[3] - box[1])
-        scale = min(maximum_width / text_width, maximum_height / text_height, 1.0)
-        if scale >= 0.995 or size <= 12:
-            return font, box
-        size = max(12, int(size * scale * 0.97))
-    return font, box
+def tightly_rendered_text(
+    font_path: Path, text: str, height: int = PREVIEW_HEIGHT
+) -> Image.Image:
+    font = ImageFont.truetype(str(font_path), size=PREVIEW_RENDER_SIZE)
+    box = font.getbbox(text)
+    source_width = box[2] - box[0]
+    source_height = box[3] - box[1]
+    if source_width <= 0 or source_height <= 0:
+        raise ValueError("family name has an empty render bounding box")
+    source = Image.new("RGBA", (source_width, source_height), (0, 0, 0, 0))
+    draw = ImageDraw.Draw(source)
+    draw.text((-box[0], -box[1]), text, fill=(22, 22, 24, 255), font=font)
+    alpha_bounds = source.getchannel("A").getbbox()
+    if alpha_bounds is None:
+        raise ValueError("family name produced no visible pixels")
+    tight = source.crop(alpha_bounds)
+    output_width = max(1, round(tight.width * height / tight.height))
+    return tight.resize((output_width, height), Image.Resampling.LANCZOS)
 
 def render_preview(
     root: str,
     staging: str,
     job: dict[str, str],
-    width: int,
-    height: int,
 ) -> dict[str, Any]:
     root_path = Path(root)
     staging_path = Path(staging)
@@ -1883,27 +1887,23 @@ def render_preview(
     except Exception as error:  # noqa: BLE001 - isolate individual legacy fonts.
         coverage_error = f"{type(error).__name__}: {error}"
 
-    image = Image.new("RGB", (width, height), (248, 248, 246))
-    draw = ImageDraw.Draw(image)
     try:
-        font, box = load_fitted_font(
-            font_path, job["family_name"], width=width, height=height
-        )
-        text_width = box[2] - box[0]
-        text_height = box[3] - box[1]
-        x = (width - text_width) / 2 - box[0]
-        y = (height - text_height) / 2 - box[1]
-        draw.text((x, y), job["family_name"], fill=(22, 22, 24), font=font)
+        image = tightly_rendered_text(font_path, job["family_name"])
     except Exception as error:  # noqa: BLE001 - still emit a placeholder WebP.
         render_error = f"{type(error).__name__}: {error}"
-        fallback = ImageFont.load_default(size=28)
+        fallback = ImageFont.load_default(size=PREVIEW_RENDER_SIZE)
         message = "Preview unavailable"
         box = fallback.getbbox(message)
-        draw.text(
-            ((width - (box[2] - box[0])) / 2, (height - (box[3] - box[1])) / 2),
-            message,
-            fill=(150, 25, 25),
-            font=fallback,
+        source = Image.new(
+            "RGBA", (box[2] - box[0], box[3] - box[1]), (0, 0, 0, 0)
+        )
+        ImageDraw.Draw(source).text(
+            (-box[0], -box[1]), message, fill=(150, 25, 25, 255), font=fallback
+        )
+        tight = source.crop(source.getchannel("A").getbbox())
+        fallback_width = max(1, round(tight.width * PREVIEW_HEIGHT / tight.height))
+        image = tight.resize(
+            (fallback_width, PREVIEW_HEIGHT), Image.Resampling.LANCZOS
         )
     image.save(output_path, format="WEBP", lossless=True, method=4, exact=True)
     digest = hashlib.sha256(output_path.read_bytes()).hexdigest()
@@ -1913,6 +1913,8 @@ def render_preview(
         "family_name": job["family_name"],
         "preview_file": f"previews/{output_name}",
         "preview_sha256": digest,
+        "preview_width": image.width,
+        "preview_height": image.height,
         "family_name_coverage_complete": not missing and coverage_error is None,
         "missing_characters": missing,
         "coverage_error": coverage_error,
@@ -1943,8 +1945,6 @@ def parse_arguments() -> argparse.Namespace:
     parser.add_argument(
         "--skip-previews", action="store_true", help="Build the index without WebP previews."
     )
-    parser.add_argument("--preview-width", type=int, default=1600)
-    parser.add_argument("--preview-height", type=int, default=320)
     return parser.parse_args()
 
 
@@ -1965,12 +1965,8 @@ def build_previews(
     root: Path,
     index_path: Path,
     workers: int,
-    width: int,
-    height: int,
 ) -> dict[str, Any]:
     output_dir = root / "previews"
-    if width < 320 or height < 120:
-        raise SystemExit("preview dimensions are too small")
     with index_path.open(encoding="utf-8") as stream:
         index = json.load(stream)
     if int(index.get("schema_version", 0)) < 3:
@@ -2001,8 +1997,6 @@ def build_previews(
                     str(root),
                     str(staging),
                     job,
-                    width,
-                    height,
                 ): job
                 for job in jobs
             }
@@ -2040,6 +2034,8 @@ def build_previews(
                         "file": result["preview_file"],
                         "sha256": result["preview_sha256"],
                         "text": result["family_name"],
+                        "width": result["preview_width"],
+                        "height": result["preview_height"],
                         "family_name_coverage_complete": result[
                             "family_name_coverage_complete"
                         ],
@@ -2054,8 +2050,10 @@ def build_previews(
         summary = {
             "generated_at": datetime.now(timezone.utc).isoformat(),
             "format": "webp",
-            "width": width,
-            "height": height,
+            "height": PREVIEW_HEIGHT,
+            "width_mode": "content",
+            "background": "transparent",
+            "padding": 0,
             "directory": "previews",
             "preview_count": len(results),
             "complete_family_name_coverage_count": len(results) - len(incomplete),
@@ -2099,8 +2097,6 @@ def main() -> int:
             root,
             output,
             arguments.workers,
-            arguments.preview_width,
-            arguments.preview_height,
         )
     return 0