What causes "Failed to draw ellipse" in GraphiteEditor/Graphite?

Clamp and validate radii before the call: early-return unless radius_x/radius_y are finite and >= 0.

Failed to draw ellipse

Error message

Failed to draw ellipse

What it means

Calls ellipse_with_anticlockwise, which maps to JS CanvasRenderingContext2D.ellipse(). The browser throws IndexSizeError when radius_x or radius_y is negative, and errors can also occur with non-finite arguments; wasm-bindgen surfaces any JS throw as Err(JsValue), which this .expect escalates into a Rust panic that aborts the overlay render pass.

Source

Thrown at editor/src/messages/portfolio/document/overlays/utility_types_web.rs:368

			self.render_context
				.set_line_dash(&JsValue::from(array))
				.map_err(|error| log::warn!("Error drawing dashed line: {:?}", error))
				.ok();
		}

		self.render_context.begin_path();
		self.render_context
			.ellipse_with_anticlockwise(
				center.x,
				center.y,
				radius_x,
				radius_y,
				rotation.unwrap_or_default(),
				start_angle.unwrap_or_default(),
				end_angle.unwrap_or(TAU),
				counterclockwise.unwrap_or_default(),
			)
			.expect("Failed to draw ellipse");
		self.render_context.set_stroke_style_str(color_stroke);

		if let Some(fill_color) = color_fill {
			self.render_context.set_fill_style_str(fill_color);
			self.render_context.fill();
		}
		self.render_context.stroke();

		// Reset the dash pattern back to solid
		if dash_width.is_some() {
			self.render_context
				.set_line_dash(&JsValue::from(js_sys::Array::new()))
				.map_err(|error| log::warn!("Error drawing dashed line: {:?}", error))
				.ok();
		}
		if dash_offset.is_some() && dash_offset != Some(0.) {
			self.render_context.set_line_dash_offset(0.);
		}

View on GitHub (pinned to c507b35645)

Solutions

Clamp and validate radii before the call: early-return unless radius_x/radius_y are finite and >= 0.
Trace NaN to its source — add is_finite debug assertions on viewport/document transforms when they are computed, not when they are drawn.
Replace .expect with a logged .ok()/if-let so one bad ellipse cannot kill the whole overlay frame.
Log the ellipse arguments when the call fails so the offending geometry is identifiable in reports.

Example fix

// before
self.render_context
	.ellipse_with_anticlockwise(center.x, center.y, radius_x, radius_y, rotation, start_angle, end_angle, ccw)
	.expect("Failed to draw ellipse");

// after
if radius_x.is_finite() && radius_y.is_finite() && radius_x >= 0. && radius_y >= 0. {
	if let Err(err) = self.render_context.ellipse_with_anticlockwise(center.x, center.y, radius_x, radius_y, rotation, start_angle, end_angle, ccw) {
		log::warn!("Failed to draw ellipse: {:?}", err);
	}
}

Defensive patterns

Strategy: validation

Validate before calling

fn ellipse_args_safe(center: DVec2, radius_x: f64, radius_y: f64) -> bool {
	center.x.is_finite()
		&& center.y.is_finite()
		&& radius_x.is_finite()
		&& radius_y.is_finite()
		&& radius_x >= 0.
		&& radius_y >= 0.
}

Type guard

fn is_drawable_radius(radius: f64) -> bool {
	radius.is_finite() && radius >= 0.
}

Try / catch

if let Err(err) = self
	.render_context
	.ellipse_with_anticlockwise(center.x, center.y, radius_x, radius_y, rot, start, end, ccw)
{
	log::warn!("overlay ellipse failed: {:?}", err);
}

Prevention

Clamp radii with .max(0.) wherever they are derived from bounds or zoom
Assert transforms and bounds are finite when computed, not when drawn
Log geometry values on draw failure so the NaN or negative source is identifiable

When it happens

Trigger: Drawing an ellipse overlay whose radii were computed from degenerate geometry — mirrored or inverted bounds where the width/height difference goes negative, or NaN leaking from a corrupted document/viewport transform — so radius_x/radius_y arrive negative or non-finite.

Common situations: Flipped/mirrored layers producing negative values in bounding-box math; division by zero zoom yielding NaN upstream; fuzzed or malformed documents feeding non-finite geometry into overlay drawing.

Related errors

AI-assisted analysis of GraphiteEditor/Graphite@c507b35645 (2026-08-16). Data as JSON: /api/errors/bea77a217980df88. Report an issue: GitHub.