initial commit

tests/fixtures/pdf/generate_comments.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+"""Generate synthetic read-only comment keyboard fixtures, without dependencies."""
+from pathlib import Path
+
+objects = [
+    b'<< /Type /Catalog /Pages 2 0 R >>',
+    b'<< /Type /Pages /Kids [3 0 R] /Count 1 >>',
+    b'<< /Type /Page /Parent 2 0 R /MediaBox [0 0 240 260] /CropBox [20 30 220 230] /Annots [4 0 R 5 0 R] /Resources << >> >>',
+    b'<< /Type /Annot /Subtype /Text /Rect [100 100 120 120] /Contents (<b>Literal comment</b>) /F 4 >>',
+    b'<< /Type /Annot /Subtype /Text /Rect [1000 1000 1020 1020] /Contents (Outside CropBox comment) /F 4 >>',
+]
+data = bytearray(b'%PDF-1.7\n%\xe2\xe3\xcf\xd3\n')
+offsets = [0]
+for index, obj in enumerate(objects, 1):
+    offsets.append(len(data))
+    data += f'{index} 0 obj\n'.encode() + obj + b'\nendobj\n'
+xref = len(data)
+data += f'xref\n0 {len(offsets)}\n0000000000 65535 f \n'.encode()
+for offset in offsets[1:]:
+    data += f'{offset:010d} 00000 n \n'.encode()
+data += f'trailer\n<< /Size {len(offsets)} /Root 1 0 R >>\nstartxref\n{xref}\n%%EOF\n'.encode()
+Path(__file__).with_name('comments.pdf').write_bytes(data)
+
+# Sub-pixel page at 25% zoom: keyboard focus must not invert scroll bounds.
+tiny = bytes(data)
+for original, replacement in [(b'[0 0 240 260]', b'[0 0 1 1]'),
+                              (b'[20 30 220 230]', b'[0 0 1 1]'),
+                              (b'[100 100 120 120]', b'[0 0 0.5 0.5]'),
+                              (b'[1000 1000 1020 1020]', b'[0 0 0.5 0.5]')]:
+    tiny = tiny.replace(original, replacement.ljust(len(original), b' '))
+# Preserve fixed byte widths so the original xref remains exact.
+assert len(tiny) == len(data)
+Path(__file__).with_name('tiny-comments.pdf').write_bytes(tiny)