M2.6: W/W* clip after whichever path-painting operator ends the path (#362)

ISO 32000-2 §8.5.4: W and W* mark the current path to become the clip
once the path-painting operator that ends it has painted it with the old
clip, and n is only one such operator. The vendored interpreter applied
the clip in n alone. After S, s, f, F, f*, B, B*, b or b* it was never
applied, so everything painted afterwards ignored it, and it stayed
pending until some later, unrelated n (even after Q) clipped content
that should show. Issue #260's test file uses `W* S` on pages 3, 5 and
9: a shading meant for a circle flooded page 3, an image meant for a
rounded rectangle and nested clips on 5 and 9 spilled out.

Every painting operator now applies a pending clip after painting and
clears it (apply_pending_clip, shared with n). The now unused
Context::clip getter is removed.

Test: raster::tests::clipping_path_applies_after_any_painting_operator.
W and W* with each of n, S, s, f, F, f*, B, B*, b, b*: the later red fill
stays inside the square, and a stroking operator's outer half still
shows outside it (painted under the old clip). A clip used by S doesn't
linger for a later n, inside or after q/Q. On main it fails at `W S`.
MuPDF, Poppler and PDFium agree on every case. Page 3 of #260's file now
differs from PDFium by 0.84/255 on average (was 164). Vendored patch
(16).

Co-authored-by: Claude Opus 5.5 <[email protected]>
Co-authored-by: Brandon Thomas <[email protected]>

crates/render/src/raster.rs

@@ -1482,4 +1482,55 @@ trailer << /Root 1 0 R >>
         assert_eq!(px(25, 50), vec![255, 0, 0, 255], "inside the mask");
         assert_eq!(px(75, 50), vec![255, 255, 255, 255], "outside the mask");
     }
+
+    /// ISO 32000-2 §8.5.4: `W` / `W*` clip with the current path once whichever path-painting
+    /// operator ends it has painted it, `S`, `f` or `B` as much as `n`. The vendored interpreter
+    /// applied the clip only on `n`: after `re W* S` everything later painted outside the clip,
+    /// and the forgotten clip stayed pending, so a later `re n` (even after `Q`) clipped
+    /// content that should show. MuPDF, Poppler and PDFium clip in every case below.
+    #[test]
+    fn clipping_path_applies_after_any_painting_operator() {
+        let render = |content: &str| {
+            let pdf = format!(
+                "%PDF-1.7
+1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj
+2 0 obj << /Type /Pages /Kids [3 0 R] /Count 1 >> endobj
+3 0 obj << /Type /Page /Parent 2 0 R /MediaBox [0 0 100 100] /Contents 4 0 R >> endobj
+4 0 obj << /Length {} >> stream
+{content}
+endstream endobj
+trailer << /Root 1 0 R >>
+%%EOF",
+                content.len()
+            );
+            let mut r = PageRenderer::new(Arc::new(pdf.into_bytes()), RenderConfig::default());
+            let p = r.render(RenderRequest { page: 0, kind: RequestKind::Pixels, tile: None, scale: 1.0, tag: 0 });
+            assert!(p.error.is_none(), "{content}: {:?}", p.error);
+            p
+        };
+        let px = |p: &RenderedPage, x: u32, y: u32| p.rgba[((y * p.width + x) * 4) as usize..][..4].to_vec();
+        let red = vec![255, 0, 0, 255];
+        // The clip is the square x 20..60, y 20..60 (device rows 40..80); then the page is filled red.
+        for op in ["n", "S", "s", "f", "F", "f*", "B", "B*", "b", "b*"] {
+            for clip in ["W", "W*"] {
+                let p = render(&format!("q 0 0 1 RG 4 w 0.8 g 20 20 40 40 re {clip} {op} 1 0 0 rg 0 0 100 100 re f Q"));
+                assert_eq!(px(&p, 40, 60), red, "{clip} {op}: inside the clip");
+                assert_ne!(px(&p, 5, 5), red, "{clip} {op}: outside the clip");
+                assert_ne!(px(&p, 95, 95), red, "{clip} {op}: outside the clip");
+                // The operator that ends the path paints under the old clip: the outer half of
+                // the 4 pt stroke (x 18..20) shows outside the new one.
+                let stroked = !["n", "f", "F", "f*"].contains(&op);
+                let edge = if stroked { vec![0, 0, 255, 255] } else { vec![255, 255, 255, 255] };
+                assert_eq!(px(&p, 18, 60), edge, "{clip} {op}: just outside the clip");
+            }
+        }
+        // A clip is used once: it doesn't linger for a later `n`, inside or outside `q`/`Q`.
+        for content in [
+            "q 0 0 1 RG 70 70 10 10 re W S Q q 10 10 20 20 re n 1 0 0 rg 0 0 100 100 re f Q",
+            "q 0 0 1 RG 0 0 100 100 re W S 10 10 20 20 re n 1 0 0 rg 0 0 100 100 re f Q",
+        ] {
+            let p = render(content);
+            assert!([(5, 5), (50, 50), (95, 95)].iter().all(|(x, y)| px(&p, *x, *y) == red), "{content}: no stray clip");
+        }
+    }
 }

vendor/README.md

@@ -7,7 +7,7 @@ the fix. Vendoring copyleft code is never allowed (plan/adr/0001).
 
 | Crate | Version | Licence | Patches | Test |
 |---|---|---|---|---|
-| hayro-interpret | 0.7.0 | Apache-2.0 OR MIT | (1) select `/AP /N` appearance states via `/AS` (checkboxes, radios, stateful icons) and honour the NoView flag; (2) Type3 Unicode fallback to `/Encoding` glyph names, then printable ASCII; (3) `Type3Glyph::advance_width`; (4) `InterpreterSettings::ocg_overrides` for viewer layer toggles; (5) soft masks whose group lacks `/CS` were dropped (Chrome gradient text); (6) paint nesting cap `MAX_PAINT_NESTING` for tiling patterns and Type 3 glyphs (self-referencing content overflowed the stack); (7) CID width ranges in `/W` and `/W2` clamped to `MAX_CID` (a `0 4294967295 w` range hung); (8) `InterpreterSettings::hide_comments` skips markup annotations but keeps widgets and links (View ▸ Hide all comments); (9) `image_size_ok`: images and masks over 2^28 pixels are not decoded (a fuzzed `/W 4294967295` stencil mask allocated 4 GiB); (10) `MAX_NESTED_PAINTS`: nested paints (forms, Type 3 glyphs and tiling patterns inside one another) share a per-page budget of 50,000 (a glyph showing eight glyphs of its own font, sixteen deep, hung); (11) depends on skrifa 0.47 instead of 0.42 (upstream read-fonts fixed a Type 1 tokenizer that recursed through runs of numbers: a fuzzed font hung or overflowed the stack), with the one API change (`Charset::glyph_id` returns `Option`); (12) annotation appearances whose `/BBox` or `/Matrix` collapses to a line or a point are skipped (mapping them onto `/Rect` divided by zero and handed the device infinite or NaN matrices); (13) a Highlight annotation without a usable normal appearance is drawn from its `/QuadPoints`, `/C` and `/CA` with Multiply blending, as pdfcraft-annot draws highlights (it was not drawn at all); (14) simple-font `/Widths` (`read_widths`): entries only for codes 0–255 (one entry per code below `/FirstChar` was allocated: `4294967295` asked for 34 GB), an entry that isn't a number leaves its code missing instead of ending the array, and a `/LastChar` below `/FirstChar` gives no widths instead of discarding the font for a standard one; (15) the appearance box is mapped onto `/Rect` corner to corner: the translation now accounts for the scale (an appearance whose box didn't start at the origin and differed in size from `/Rect` was drawn shifted) | (1) `raster::tests::widget_appearance_states`; (2, 3) `xtask text-oracle` on corpus/pdfjs issue918; (4) `raster::tests::layer_override_hides_content`; (5) `raster::tests::soft_mask_without_group_colour_space_is_applied`; (6) `raster::tests::self_referencing_tiling_pattern_terminates`, `raster::tests::self_referencing_type3_glyph_terminates`; (7) `raster::tests::huge_cid_width_ranges_terminate`; (8) `raster::tests::hiding_comments_keeps_fields`; (9) `raster::tests::absurd_mask_and_fax_sizes_are_refused_before_decoding`; (10) `raster::tests::type3_glyphs_that_fan_out_into_themselves_finish`; (11) `raster::tests::type1_font_programs_with_long_runs_of_numbers_load_quickly`; (12) `raster::tests::degenerate_annotation_appearances_are_skipped`; (13) `raster::tests::highlights_without_an_appearance_are_drawn`; (14) `raster::tests::malformed_simple_font_widths_keep_later_widths_and_the_font`, `raster::tests::huge_simple_font_first_char_terminates`; (15) `raster::tests::annotation_appearance_box_maps_onto_rect` |
+| hayro-interpret | 0.7.0 | Apache-2.0 OR MIT | (1) select `/AP /N` appearance states via `/AS` (checkboxes, radios, stateful icons) and honour the NoView flag; (2) Type3 Unicode fallback to `/Encoding` glyph names, then printable ASCII; (3) `Type3Glyph::advance_width`; (4) `InterpreterSettings::ocg_overrides` for viewer layer toggles; (5) soft masks whose group lacks `/CS` were dropped (Chrome gradient text); (6) paint nesting cap `MAX_PAINT_NESTING` for tiling patterns and Type 3 glyphs (self-referencing content overflowed the stack); (7) CID width ranges in `/W` and `/W2` clamped to `MAX_CID` (a `0 4294967295 w` range hung); (8) `InterpreterSettings::hide_comments` skips markup annotations but keeps widgets and links (View ▸ Hide all comments); (9) `image_size_ok`: images and masks over 2^28 pixels are not decoded (a fuzzed `/W 4294967295` stencil mask allocated 4 GiB); (10) `MAX_NESTED_PAINTS`: nested paints (forms, Type 3 glyphs and tiling patterns inside one another) share a per-page budget of 50,000 (a glyph showing eight glyphs of its own font, sixteen deep, hung); (11) depends on skrifa 0.47 instead of 0.42 (upstream read-fonts fixed a Type 1 tokenizer that recursed through runs of numbers: a fuzzed font hung or overflowed the stack), with the one API change (`Charset::glyph_id` returns `Option`); (12) annotation appearances whose `/BBox` or `/Matrix` collapses to a line or a point are skipped (mapping them onto `/Rect` divided by zero and handed the device infinite or NaN matrices); (13) a Highlight annotation without a usable normal appearance is drawn from its `/QuadPoints`, `/C` and `/CA` with Multiply blending, as pdfcraft-annot draws highlights (it was not drawn at all); (14) simple-font `/Widths` (`read_widths`): entries only for codes 0–255 (one entry per code below `/FirstChar` was allocated: `4294967295` asked for 34 GB), an entry that isn't a number leaves its code missing instead of ending the array, and a `/LastChar` below `/FirstChar` gives no widths instead of discarding the font for a standard one; (15) the appearance box is mapped onto `/Rect` corner to corner: the translation now accounts for the scale (an appearance whose box didn't start at the origin and differed in size from `/Rect` was drawn shifted); (16) a clip set by `W`/`W*` takes effect after whichever path-painting operator ends the path (`S`, `f`, `B`, … as well as `n`; ISO 32000-2 §8.5.4): it was applied only on `n`, so `re W* S` clipped nothing and the clip stayed pending for a later, unrelated `n` | (1) `raster::tests::widget_appearance_states`; (2, 3) `xtask text-oracle` on corpus/pdfjs issue918; (4) `raster::tests::layer_override_hides_content`; (5) `raster::tests::soft_mask_without_group_colour_space_is_applied`; (6) `raster::tests::self_referencing_tiling_pattern_terminates`, `raster::tests::self_referencing_type3_glyph_terminates`; (7) `raster::tests::huge_cid_width_ranges_terminate`; (8) `raster::tests::hiding_comments_keeps_fields`; (9) `raster::tests::absurd_mask_and_fax_sizes_are_refused_before_decoding`; (10) `raster::tests::type3_glyphs_that_fan_out_into_themselves_finish`; (11) `raster::tests::type1_font_programs_with_long_runs_of_numbers_load_quickly`; (12) `raster::tests::degenerate_annotation_appearances_are_skipped`; (13) `raster::tests::highlights_without_an_appearance_are_drawn`; (14) `raster::tests::malformed_simple_font_widths_keep_later_widths_and_the_font`, `raster::tests::huge_simple_font_first_char_terminates`; (15) `raster::tests::annotation_appearance_box_maps_onto_rect`; (16) `raster::tests::clipping_path_applies_after_any_painting_operator` |
 
 | hayro | 0.7.1 | Apache-2.0 OR MIT | (1) `RenderSettings::{x_offset, y_offset}` to render one tile of a large page; (2) images over `MAX_IMAGE_PIXELS` (2^28) are skipped (a fuzzed `/W 4294967295` hung in resampling); (3) `tiling_cell_scale` keeps a tiling pattern's cell pixmap within 3000 px a side whatever its `/XStep`/`/YStep` (a fuzzed step far beyond `/BBox` allocated 2 GB); (4) stroke widths clamped to 4 × (canvas width + height) device pixels (a fuzzed `/LW 9223372036854775807` allocated 10 GB in stroke expansion) | (1) `raster::tests::tiles_match_full_render`; (2) `raster::tests::absurd_image_dimensions_are_skipped`; (3) `raster::tests::tiling_cells_stay_small_whatever_the_step`; (4) `raster::tests::absurd_predictor_columns_and_line_widths_render` |
 | hayro-jbig2 | 0.3.0 | Apache-2.0 OR MIT | (1) at most 2^28 pixels per bitmap, page bitmap, halftone grid and grayscale image (each side could be 65535: 4.3 billion pixels decoded one by one); (2) at most 2^26 symbol pixels per symbol dictionary (a fuzzed dictionary decoded for minutes) | (1) `raster::tests::jbig2_regions_of_billions_of_pixels_are_refused`; (2) the nightly `cargo xtask fuzz` finding, which now finishes in about a second |

vendor/hayro-interpret/src/context.rs

@@ -274,10 +274,6 @@ impl<'a> Context<'a> {
         &mut self.last_point
     }
 
-    pub(crate) fn clip(&self) -> &Option<FillRule> {
-        &self.clip
-    }
-
     pub(crate) fn clip_mut(&mut self) -> &mut Option<FillRule> {
         &mut self.clip
     }

vendor/hayro-interpret/src/interpret/mod.rs

@@ -5,7 +5,7 @@ use crate::convert::{convert_line_cap, convert_line_join};
 use crate::device::Device;
 use crate::font::{Font, FontData, FontQuery, StandardFont};
 use crate::interpret::path::{
-    close_path, fill_path, fill_path_impl, fill_stroke_path, stroke_path,
+    apply_pending_clip, close_path, fill_path, fill_path_impl, fill_stroke_path, stroke_path,
 };
 use crate::interpret::state::{TextStateFont, handle_gs};
 use crate::interpret::text::TextRenderingMode;
@@ -479,15 +479,7 @@ pub fn interpret<'a>(
                 stroke_path(context, device);
             }
             TypedInstruction::EndPath(_) => {
-                if let Some(clip) = *context.clip()
-                    && !context.path().elements().is_empty()
-                {
-                    let clip_path = context.get().ctm * context.path().clone();
-                    context.push_clip_path(clip_path, clip, device);
-
-                    *(context.clip_mut()) = None;
-                }
-
+                apply_pending_clip(context, device);
                 context.path_mut().truncate(0);
             }
             TypedInstruction::NonStrokeColor(c) => {

vendor/hayro-interpret/src/interpret/path.rs

@@ -12,12 +12,14 @@ pub(crate) fn fill_path<'a>(
     fill_rule: FillRule,
 ) {
     fill_path_impl(context, device, fill_rule, None);
+    apply_pending_clip(context, device);
 
     context.path_mut().truncate(0);
 }
 
 pub(crate) fn stroke_path<'a>(context: &mut Context<'a>, device: &mut impl Device<'a>) {
     stroke_path_impl(context, device, None);
+    apply_pending_clip(context, device);
 
     context.path_mut().truncate(0);
 }
@@ -29,10 +31,23 @@ pub(crate) fn fill_stroke_path<'a>(
 ) {
     fill_path_impl(context, device, fill_rule, None);
     stroke_path_impl(context, device, None);
+    apply_pending_clip(context, device);
 
     context.path_mut().truncate(0);
 }
 
+/// PdfCraft patch: a clip set by `W` / `W*` takes effect once the path-painting operator that
+/// ends the path has painted it, whichever operator that is (ISO 32000-2 §8.5.4). Upstream
+/// applied it only on `n`, and otherwise left it pending for some later, unrelated `n`.
+pub(crate) fn apply_pending_clip<'a>(context: &mut Context<'a>, device: &mut impl Device<'a>) {
+    if let Some(rule) = context.clip_mut().take()
+        && !context.path().elements().is_empty()
+    {
+        let clip_path = context.get().ctm * context.path().clone();
+        context.push_clip_path(clip_path, rule, device);
+    }
+}
+
 pub(crate) fn close_path(context: &mut Context<'_>) {
     // This is necessary to prevent artifacts (see for example issue 157),
     // but it does cause some weird lines (maybe conflation artifacts) in