Fix Vello renderer cropping wide miter joins and square caps (#4108)

* Fix renderer compositing layers cropping wide miter joins and square caps

* Fix double-scaled inflation on the Vello blend layer's clip rect

node-graph/libraries/rendering/src/renderer.rs

@@ -1025,8 +1025,8 @@ impl Render for Table<Vector> {
 					let mut svg = SvgRender::new();
 					vector_item.render_svg(&mut svg, &render_params.for_alignment(applied_stroke_transform));
 					let stroke = vector.style.stroke().unwrap();
-					let weight = stroke.effective_width() * max_scale(applied_stroke_transform);
-					let quad = Quad::from_box(transformed_bounds).inflate(weight);
+					let inflation = stroke.max_aabb_inflation() * max_scale(applied_stroke_transform);
+					let quad = Quad::from_box(transformed_bounds).inflate(inflation);
 					let (x, y) = quad.top_left().into();
 					let (width, height) = (quad.bottom_right() - quad.top_left()).into();
 
@@ -1147,8 +1147,14 @@ impl Render for Table<Vector> {
 			let opacity = (opacity_attr * if render_params.for_mask { 1. } else { opacity_fill_attr }) as f32;
 			if opacity < 1. || blend_mode_attr != BlendMode::default() {
 				layer = true;
-				let weight = element.style.stroke().as_ref().map_or(0., Stroke::effective_width);
-				let quad = Quad::from_box(layer_bounds).inflate(weight * max_scale(applied_stroke_transform));
+				// `max_aabb_inflation` is in `applied_stroke_transform`-space (where the stroke is drawn).
+				// `layer_bounds` is in path-local coords and `push_layer` re-applies `multiplied_transform`.
+				// Divide by `max_scale(applied_stroke_transform)` so the rect, after Vello's transform, ends at the right scene extent.
+				// Skip on a degenerate transform since nothing renders in that case.
+				let scale = max_scale(applied_stroke_transform);
+				let stroke_inflation = element.style.stroke().as_ref().map_or(0., Stroke::max_aabb_inflation);
+				let inflate_amount = if scale > 0. { stroke_inflation / scale } else { 0. };
+				let quad = Quad::from_box(layer_bounds).inflate(inflate_amount);
 				let layer_bounds = quad.bounding_box();
 				scene.push_layer(
 					peniko::Fill::NonZero,
@@ -1306,8 +1312,8 @@ impl Render for Table<Vector> {
 						);
 
 						let bounds = element.bounding_box_with_transform(multiplied_transform).unwrap_or(layer_bounds);
-						let weight = element.style.stroke().as_ref().map_or(0., Stroke::effective_width);
-						let quad = Quad::from_box(bounds).inflate(weight * max_scale(applied_stroke_transform));
+						let inflation = element.style.stroke().as_ref().map_or(0., Stroke::max_aabb_inflation);
+						let quad = Quad::from_box(bounds).inflate(inflation * max_scale(applied_stroke_transform));
 						let bounds = quad.bounding_box();
 						let rect = kurbo::Rect::new(bounds[0].x, bounds[0].y, bounds[1].x, bounds[1].y);
 

node-graph/libraries/vector-types/src/vector/style.rs

@@ -417,6 +417,21 @@ impl Stroke {
 			}
 	}
 
+	/// Worst-case upper bound on the perpendicular extent (per side) of the visible stroke from the path
+	/// centerline, accounting for stroke alignment, miter join overshoot, and square cap diagonal extent.
+	/// Used as a cheap, safe inflation amount for renderer clip rects so alignment compositing layers
+	/// don't crop the actual stroke geometry. Constant-time — no path traversal.
+	///
+	/// Tight for round/bevel joins with butt/round caps. Otherwise overestimates: miter joins are assumed
+	/// to reach the miter limit at every join (most don't), and square caps are assumed to sit at 45° to
+	/// the axes (rarely the case). For an exact bound, use `Vector::stroke_inclusive_bounding_box_with_transform`
+	/// at the cost of running kurbo to compute the stroke's outline path.
+	pub fn max_aabb_inflation(&self) -> f64 {
+		let join_factor = if self.join == StrokeJoin::Miter { self.join_miter_limit.max(1.) } else { 1. };
+		let cap_factor = if self.cap == StrokeCap::Square { core::f64::consts::SQRT_2 } else { 1. };
+		self.effective_width() * 0.5 * join_factor.max(cap_factor)
+	}
+
 	pub fn dash_lengths(&self) -> String {
 		if self.dash_lengths.is_empty() {
 			"none".to_string()