Fix #4937: document artboard fills in exports, print and Export for Screens

docs/file-format-parity.md

@@ -1,6 +1,6 @@
 # File format parity
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-31 · **Change:** minor (PDF import: fonts named with hyphens or with a composite font's CMap find the installed family) · **Target:** Adobe Illustrator 2026 (30.x)
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-11-01 · **Change:** minor (exports draw artboard background colors, #4937) · **Target:** Adobe Illustrator 2026 (30.x)
 
 Every format Illustrator opens, places, saves or exports, against VectorCraft's format table (`FORMATS`,
 `OPEN_EXTS`, `PLACE_EXTS` in `crates/engine/src/cmd/fileio/formats.rs`). Illustrator's list comes from its public
@@ -131,6 +131,7 @@ the app's own editing copy of a file (an EPS after its `%%EOF`, a `.ai`'s `AIPri
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-11-01 | minor | Exports draw each artboard's background color behind its art (#4937): PNG, JPEG, GIF, TIFF, WebP, BMP, Targa and PSD (a layer of its own; on a transparent background too), PDF, SVG and EPS pages, a `.ai` file's PDF pages and PostScript and PDF print; `includeArtboardFill: false` leaves it out. Files with editing data (Preserve Editing, `.ai`, EPS, native) keep it as the artboard's color and reopen without extra art. Not read from the reference app's own `.ai` data, nor written to it. DXF, EMF and WMF leave it out |
 | 2026-10-31 | minor | PDF import finds an installed font whose PDF name holds hyphens (`Noto-Sans-Bold` is Noto Sans, Bold: the longest part before a hyphen that names an installed family) and a composite font by its CIDFont's name rather than its base name, which ends in the CMap's (`Name-Identity-H`, [ISO 32000-1 §9.7.6.1](https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008.pdf)); a missing font is split only before a style part (`Helvetica-BoldOblique`), so it is reported as `MS PGothic`, not `MS`; scores unchanged (estimated) |
 | 2026-10-31 | minor | DXF export (2000–2018): the LAYOUT objects wrote the paper image origin as a point at group codes 148 and 158, but PLOTSETTINGS defines 148 and 149 and no 158, so strict readers could reject the file (Autodesk Fusion reported "DXF File failed to insert", #3085). They now write 148/149, the shade plot mode, resolution and DPI (76–78, 2004 and later) and flag 1024 on the Model layout; the plot style ACDBPLACEHOLDER no longer carries a subclass marker. Test `r2000_and_later_files_have_the_structure_cad_apps_require` (required sections and table entries, handles and references, LAYOUT group codes); exports pass ezdxf's recover and audit; not tested in Fusion itself; scores unchanged |
 | 2026-10-31 | minor | `.ai`/EPS editing data: an envelope whose contents are being edited is written the other way round from one that isn't: its contents, a group on `%_` lines, then its dictionary, which holds the mesh that shapes them. Those contents were read as art, so the undistorted art drew over the distorted art the page draws. The group on `%_` lines before an envelope's dictionary is now left out whatever it holds (text in it stays as hidden text, as the dictionary's own does), as the envelope's mesh already was (#2405). Test `import::ai::tests::an_envelope_s_contents_being_edited_are_not_read_as_art`; checked locally against a user's file: it opens from its layers, 0.0% from its page (it was 9.7%, over the 5% limit); scores unchanged |