diff --git a/crates/render/src/text.rs b/crates/render/src/text.rs index 856b2f57..f74cf7c8 100644 --- a/crates/render/src/text.rs +++ b/crates/render/src/text.rs @@ -505,6 +505,19 @@ impl PlacedGlyph { fn bold_in_layer(&self) -> f64 { self.bold * self.m2().mean_scale() } + /// Whether [`Self::bold`] grows the outline as evenly in layer space as in character space: + /// no bold, or a matrix that only rotates and scales uniformly. + fn bold_is_even(&self) -> bool { + let [[a, b, _], [c, d, _], _] = self.m2().0; + let n = a * a + b * b + c * c + d * d; + self.bold == 0.0 || ((a * a + c * c - b * b - d * d).abs() <= 1e-9 * n && (a * b + c * d).abs() <= 1e-9 * n) + } +} + +/// How far a circle of radius `r` reaches along x and along y once mapped by `m`. +fn axis_reach(m: &Mat3, r: f64) -> [f64; 2] { + let [[a, b, _], [c, d, _], _] = m.0; + [r * a.hypot(b), r * c.hypot(d)] } /// How far Faux Bold grows a glyph's outline on every side, as a fraction of its size: Inter @@ -929,12 +942,15 @@ fn runs(geom: &TextGeom) -> Vec<(Vec, bool)> { if g.xf.opacity <= 0.0 { continue; } + // A run grows its outline in layer space by one radius, which matches each glyph grown in + // its own space only when the bold stays round there. if geom.blend == BlendMode::Normal && solid_fill(g, stroke) + && g.bold_is_even() && let Some((run, false)) = out.last_mut() && run.last().is_some_and(|&p| { let q = &geom.glyphs[p]; - solid_fill(q, false) && q.fill == g.fill && (q.bold_in_layer() - g.bold_in_layer()).abs() < 1e-6 + solid_fill(q, false) && q.fill == g.fill && q.bold_is_even() && (q.bold_in_layer() - g.bold_in_layer()).abs() < 1e-6 }) { run.push(gi); @@ -967,13 +983,16 @@ fn draw_glyphs(geom: &TextGeom, img: &mut Image, to_px: &Mat3, s: f64, only: Opt }; let Some(b) = effectcraft_path::bounds(&paths) else { continue }; let blur = [g.xf.blur[0] * s, g.xf.blur[1] * s]; - let pad = (g.stroke_width + 2.0 * bold) * m.mean_scale() + 2.0 + blur[0].max(blur[1]) * 1.5; + // Stroke and bold grow the outline in the paths' space: under a non-uniform `m` they reach + // further along one axis than the other. + let [px, py] = axis_reach(&m, g.stroke_width + 2.0 * bold); + let pad = 2.0 + blur[0].max(blur[1]) * 1.5; let r = m.map_rect(&effectcraft_geom::Rect::new(b.x0, b.y0, b.x1, b.y1)); let rect = [ - ((r.x0 - pad).floor() as i64).max(0), - ((r.y0 - pad).floor() as i64).max(0), - ((r.x1 + pad).ceil() as i64).min(w), - ((r.y1 + pad).ceil() as i64).min(h), + ((r.x0 - px - pad).floor() as i64).max(0), + ((r.y0 - py - pad).floor() as i64).max(0), + ((r.x1 + px + pad).ceil() as i64).min(w), + ((r.y1 + py + pad).ceil() as i64).min(h), ]; if rect[2] <= rect[0] || rect[3] <= rect[1] { continue; @@ -990,8 +1009,9 @@ pub fn render(ctx: &EvalCtx, layer: &Layer, s: f64) -> Buf { let mut bounds: Option = None; for g in &geom.glyphs { if let Some(b) = effectcraft_path::bounds(&[g.path()]) { - let pad = g.stroke_width + 2.0 * g.bold_in_layer() + 2.0 + g.xf.blur[0].max(g.xf.blur[1]) * 1.5; - let b = b.inflate(pad, pad); + let [bx, by] = axis_reach(&g.m2(), 2.0 * g.bold); + let pad = g.stroke_width + 2.0 + g.xf.blur[0].max(g.xf.blur[1]) * 1.5; + let b = b.inflate(pad + bx, pad + by); bounds = Some(bounds.map_or(b, |a| a.union(b))); } } diff --git a/crates/render/src/text/tests.rs b/crates/render/src/text/tests.rs index 3e6800ab..4b1b6680 100644 --- a/crates/render/src/text/tests.rs +++ b/crates/render/src/text/tests.rs @@ -582,6 +582,34 @@ fn faux_bold_and_synthetic_bold_thicken_the_glyphs() { assert!(brb[0] < rb[0] && brb[2] > rb[2], "{rb:?} → {brb:?}"); } +/// #1676: under a non-uniform character Scale the bold is grown in the character's space, so it +/// reaches further along the stretched axis; it is neither clipped nor grown evenly in a run. +#[test] +fn faux_bold_under_a_non_uniform_scale() { + use kurbo::Shape; + let glyph = |x0: f64| PlacedGlyph { + local: kurbo::Rect::new(x0, 4.0, x0 + 4.0, 16.0).to_path(0.1), + m: Mat4::scale(vec3(9.0, 1.0, 1.0)), + xf: CharXf::default(), + fill: [1.0; 4], + stroke: [0.0; 4], + stroke_width: 0.0, + bold: 2.0, + apply_fill: true, + char_index: 0, + rest: [0.0; 2], + }; + let geom = |glyphs| TextGeom { doc: TextDoc::default(), glyphs, fill_stroke: 0, blend: BlendMode::Normal }; + assert_eq!(runs(&geom(vec![glyph(2.0), glyph(6.0)])).len(), 2, "bold glyphs stretched unevenly are drawn one by one"); + // x 6..10 → 54..90, grown by 2 × 9 = 18 → 36..108; y 4..16 grown by 2 → 2..18. + let mut img = crate::Image::new(120, 24); + draw_glyphs(&geom(vec![glyph(6.0)]), &mut img, &Mat3::IDENTITY, 1.0, None); + for (x, y) in [(37, 10), (106, 10), (70, 3)] { + assert!(img.get(x, y)[3] > 0.99, "bold ink at ({x}, {y}): {:?}", img.get(x, y)); + } + assert!(img.get(34, 10)[3] < 0.01 && img.get(110, 10)[3] < 0.01 && img.get(70, 0)[3] < 0.01); +} + /// #1011: what dragging a Range Selector bar to fraction `f` of the text writes. #[test] fn range_bar_drag_values() {