Rhythm Selection & Cleanup

generator/engraving/raster.py

@@ -1,13 +1,17 @@
 from __future__ import annotations
 
+import dataclasses
+import math
+
+import PIL.Image
+import PIL.ImageDraw
 import aggdraw
-from fontTools.pens.basePen import BasePen
-from PIL import Image, ImageDraw
+import fontTools.pens.basePen
 
-from generator.engraving.fonts import Fonts
-from generator.engraving.types import Page
+import generator.engraving.fonts
+import generator.engraving.types
 
-class OutlinePen(BasePen):
+class OutlinePen(fontTools.pens.basePen.BasePen):
   def __init__(self, glyphs, scale: float, x: float, y: float):
     super().__init__(glyphs)
     self.path = aggdraw.Path()
@@ -25,12 +29,15 @@ class OutlinePen(BasePen):
   def _endPath(self):
     pass
 
-def rasterize_page(page: Page, fonts: Fonts) -> Image.Image:
+def rasterize_page(page: generator.engraving.types.Page, fonts: generator.engraving.fonts.Fonts) -> PIL.Image.Image:
+  return rasterize_band(page, page.primitives, 0, page.height, fonts)
+
+def rasterize_band(page: generator.engraving.types.Page, primitives: tuple[generator.engraving.types.Primitive, ...], top: int, bottom: int, fonts: generator.engraving.fonts.Fonts) -> PIL.Image.Image:
   scale = page.supersampling
-  image = Image.new('RGB', (page.width * scale, page.height * scale), 'white')
+  image = PIL.Image.new('RGB', (page.width * scale, (bottom - top) * scale), 'white')
   context = aggdraw.Draw(image)
-  for item in page.primitives:
-    points = [(x * scale, y * scale) for x, y in item.points]
+  for item in primitives:
+    points = [(x * scale, y * scale - top * scale) for x, y in item.points]
     if item.kind == 'text':
       continue
     if item.kind == 'glyph':
@@ -52,8 +59,43 @@ def rasterize_page(page: Page, fonts: Fonts) -> Image.Image:
     else:
       context.path(path, aggdraw.Pen('black', item.thickness * scale))
   context.flush()
-  drawing = ImageDraw.Draw(image)
-  for item in page.primitives:
+  drawing = PIL.ImageDraw.Draw(image)
+  for item in primitives:
     if item.kind == 'text':
-      drawing.text(tuple(v * scale for v in item.points[0]), item.value, font=fonts.text_font(item.size * scale), anchor='ls', fill='black')
-  return image.resize((page.width, page.height), Image.Resampling.LANCZOS)
+      x, y = item.points[0]
+      drawing.text((x * scale, y * scale - top * scale), item.value, font=fonts.text_font(item.size * scale), anchor='ls', fill='black')
+  return image.resize((page.width, bottom - top), PIL.Image.Resampling.LANCZOS)
+
+@dataclasses.dataclass(frozen=True)
+class Band:
+  top: int
+  bottom: int
+  primitives: tuple[generator.engraving.types.Primitive, ...]
+
+def page_bands(page: generator.engraving.types.Page) -> tuple[Band, Band, Band] | None:
+  body = tuple(p for system in page.systems for p in system.primitives)
+  header = tuple(p for p in page.primitives if p.role in ('title', 'subtitle'))
+  footer = tuple(p for p in page.primitives if p.role == 'page-number')
+  if not body or not header or not footer or page.primitives != header + body + footer:
+    return None
+  bands = []
+  for primitives in (header, body, footer):
+    box = generator.engraving.types.bounds(primitives)
+    if not box.finite() or box.left < 4 or box.right > page.width - 4 or box.top < 4 or box.bottom > page.height - 4:
+      return None
+    # Six output pixels cover raster antialiasing and the three-pixel Lanczos
+    # support. Integer crop origins preserve the full-page sampling phase.
+    bands.append(Band(max(0, math.floor(box.top) - 6), min(page.height, math.ceil(box.bottom) + 6), primitives))
+  if bands[0].bottom > bands[1].top or bands[1].bottom > bands[2].top:
+    return None
+  return tuple(bands)
+
+def compose_page(page: generator.engraving.types.Page, fonts: generator.engraving.fonts.Fonts, bands: tuple[Band, Band, Band], body: PIL.Image.Image) -> PIL.Image.Image:
+  image = PIL.Image.new('RGB', (page.width, page.height), 'white')
+  if body.mode != 'RGB' or body.size != (page.width, bands[1].bottom - bands[1].top):
+    raise generator.engraving.types.EngravingError('notation band has incompatible geometry')
+  image.paste(body, (0, bands[1].top))
+  for band in (bands[0], bands[2]):
+    with rasterize_band(page, band.primitives, band.top, band.bottom, fonts) as decoration:
+      image.paste(decoration, (0, band.top))
+  return image