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KenM76andClaude Opus 5.5
a7b07bfc56
kurbo 0.13.1's stroker can give a cubic that is nearly a line (all control points within a rounding error of its chord) a NaN join, and vello_common's `flatten::fill` drops any path containing NaN, so the whole outline vanished. An Illustrator outline ending in `73.763 -0.536 l 73.764 -0.536 73.764 -0.536 73.764 -0.536 c` did (#4907). kurbo tracks the bug class in linebender/kurbo#617 and #519; #610 is unreleased. Vendored vello_common patch (2): when the expanded stroke is not finite, `flatten::stroke` strokes the path again with every quadratic or cubic whose control points lie within the tolerance of its chord replaced by a line, one element out per element in. A finite outline is unchanged, and a path with non-finite input is still dropped. `stroke` and `StripGenerator::generate_stroked_path` take a `Clone` path; vello_cpu's callers pass `&BezPath` and a copied slice iterator. Tests: `flatten::tests::a_tiny_degenerate_cubic_does_not_drop_the_stroke` and the render crate's `stroke_degenerate_cubic` pixel test fail with the fallback disabled; `a_finite_outline_is_stroked_as_before` and `a_path_with_nan_is_still_dropped` are guards. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01SqmHYx8FiWM5PcsoiErgp9
52 lines
2.6 KiB
Rust
52 lines
2.6 KiB
Rust
//! A contributor-original synthetic page reproducing #4907: an outline that ends in a cubic whose
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//! control points all sit 0.001 pt from its start was not drawn at all, because the stroker put
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//! NaN into its outline and the rasterizer dropped the whole path.
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use pdfcraft_render::{PageRenderer, RenderConfig, RenderRequest};
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use std::sync::Arc;
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/// A one-page 100 × 20 pt PDF drawing `content`, with a cross-reference table.
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fn pdf(content: &str) -> Vec<u8> {
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let objects = [
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"<< /Type /Catalog /Pages 2 0 R >>".to_string(),
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"<< /Type /Pages /Kids [3 0 R] /Count 1 >>".to_string(),
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"<< /Type /Page /Parent 2 0 R /MediaBox [0 0 100 20] /Contents 4 0 R >>".to_string(),
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format!("<< /Length {} >>\nstream\n{content}\nendstream", content.len()),
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];
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let mut bytes = b"%PDF-1.7\n".to_vec();
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let mut offsets = Vec::new();
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for (i, object) in objects.iter().enumerate() {
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offsets.push(bytes.len());
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bytes.extend_from_slice(format!("{} 0 obj\n{object}\nendobj\n", i + 1).as_bytes());
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}
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let xref = bytes.len();
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bytes.extend_from_slice(format!("xref\n0 {}\n0000000000 65535 f \n", objects.len() + 1).as_bytes());
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for offset in offsets {
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bytes.extend_from_slice(format!("{offset:010} 00000 n \n").as_bytes());
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}
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bytes.extend_from_slice(format!("trailer << /Size {} /Root 1 0 R >>\nstartxref\n{xref}\n%%EOF\n", objects.len() + 1).as_bytes());
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bytes
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}
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/// The red channel of the pixel at (`x`, `y`) pt from the top left of `content` rendered at 1×.
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fn red_at(content: &str, x: usize, y: usize) -> u8 {
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let mut renderer = PageRenderer::new(Arc::new(pdf(content)), RenderConfig::default());
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let out = renderer.render(RenderRequest { page: 0, scale: 1.0, ..Default::default() });
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assert!(out.error.is_none(), "{:?}", out.error);
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let at = (y * out.width as usize + x) * 4;
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*out.rgba.get(at).expect("the pixel lies on the page")
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}
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#[test]
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fn a_stroke_ending_in_a_tiny_degenerate_cubic_is_drawn() {
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// The line runs from (10, 10) to about (84, 9.5) in page space; (50, 10) from the top left is
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// inside its 2 pt width. The cubic's exact coordinates are what trigger the NaN. The control,
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// without the cubic, is the baseline: it draws with or without the fix.
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let path = "0 0 m 73.763 -0.536 l 73.764 -0.536 73.764 -0.536 73.764 -0.536 c S";
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let control = "0 0 m 73.763 -0.536 l S";
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for content in [control, path] {
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let content = format!("0 G 2 w 1 0 0 1 10 10 cm {content}");
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let red = red_at(&content, 50, 10);
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assert!(red < 64, "`{content}` left the line's pixel at red {red}, want black");
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}
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}
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