address review: skip shape gradient fill when the outline is over the point limit

crates/pptx/src/custgeom.rs

@@ -15,10 +15,6 @@ use crate::xml::{A, El, W};
 
 const DEG: f64 = 60_000.0;
 
-/// Distinct path coordinate spaces whose guides are evaluated for one custom geometry; paths in
-/// further spaces are left out.
-const MAX_SPACES: usize = 16;
-
 /// Guide variables for one shape.
 pub struct Guides {
     vars: HashMap<String, f64>,
@@ -155,26 +151,14 @@ fn pt(g: &Guides, e: &El) -> (f64, f64) {
 pub fn read_cust_geom(cg: &El, w_emu: f64, h_emu: f64) -> Vec<CustomPath> {
     let mut out = vec![];
     let Some(pl) = cg.child("pathLst") else { return out };
-    let mut spaces: HashMap<(u64, u64), Guides> = HashMap::new();
-    // The cap on cached spaces saves guide evaluation: a geometry without guides has none to save.
-    let guided = ["avLst", "gdLst"].iter().any(|n| cg.child(n).is_some_and(|l| l.elements().next().is_some()));
     for p in pl.children_named("path").take(1000) {
         let pw = p.f64("w").unwrap_or(0.0);
         let ph = p.f64("h").unwrap_or(0.0);
         // Guides are evaluated in the path's own space when it has one.
         let (gw, gh) = if pw > 0.0 || ph > 0.0 { (pw, ph) } else { (w_emu, h_emu) };
-        // The guide lists are evaluated once per coordinate space, not once per path.
-        let key = (gw.to_bits(), gh.to_bits());
-        if !spaces.contains_key(&key) {
-            if guided && spaces.len() >= MAX_SPACES {
-                continue;
-            }
-            let mut g = Guides::new(gw, gh);
-            g.eval_list(cg.child("avLst"));
-            g.eval_list(cg.child("gdLst"));
-            spaces.insert(key, g);
-        }
-        let Some(g) = spaces.get(&key) else { continue };
+        let mut g = Guides::new(gw, gh);
+        g.eval_list(cg.child("avLst"));
+        g.eval_list(cg.child("gdLst"));
         let mut d = String::new();
         let mut cur = (0.0, 0.0);
         let mut start = (0.0, 0.0);
@@ -182,7 +166,7 @@ pub fn read_cust_geom(cg: &El, w_emu: f64, h_emu: f64) -> Vec<CustomPath> {
             match c.local() {
                 "moveTo" => {
                     if let Some(q) = c.child("pt") {
-                        cur = pt(g, q);
+                        cur = pt(&g, q);
                         start = cur;
                         d.push_str("M ");
                         num(&mut d, cur.0);
@@ -193,7 +177,7 @@ pub fn read_cust_geom(cg: &El, w_emu: f64, h_emu: f64) -> Vec<CustomPath> {
                 }
                 "lnTo" => {
                     if let Some(q) = c.child("pt") {
-                        cur = pt(g, q);
+                        cur = pt(&g, q);
                         d.push_str("L ");
                         num(&mut d, cur.0);
                         d.push(' ');
@@ -202,7 +186,7 @@ pub fn read_cust_geom(cg: &El, w_emu: f64, h_emu: f64) -> Vec<CustomPath> {
                     }
                 }
                 "cubicBezTo" => {
-                    let pts: Vec<(f64, f64)> = c.children_named("pt").map(|q| pt(g, q)).collect();
+                    let pts: Vec<(f64, f64)> = c.children_named("pt").map(|q| pt(&g, q)).collect();
                     if let [a, b, e] = pts.as_slice() {
                         d.push_str("C ");
                         for (x, y) in [a, b, e] {
@@ -215,7 +199,7 @@ pub fn read_cust_geom(cg: &El, w_emu: f64, h_emu: f64) -> Vec<CustomPath> {
                     }
                 }
                 "quadBezTo" => {
-                    let pts: Vec<(f64, f64)> = c.children_named("pt").map(|q| pt(g, q)).collect();
+                    let pts: Vec<(f64, f64)> = c.children_named("pt").map(|q| pt(&g, q)).collect();
                     if let [a, e] = pts.as_slice() {
                         d.push_str("Q ");
                         for (x, y) in [a, e] {
@@ -486,29 +470,6 @@ mod tests {
         assert_eq!(paths[1].d, "M 1 1 Q 2 2 3 1");
     }
 
-    #[test]
-    fn paths_share_guides_and_distinct_spaces_are_capped() {
-        let path = |w: usize| format!(r#"<a:path w="{w}" h="10"><a:moveTo><a:pt x="mid" y="1"/></a:moveTo></a:path>"#);
-        let paths: String = (1..=40).map(|i| path(10 * i)).collect();
-        let x = format!(
-            r#"<a:custGeom xmlns:a="x"><a:gdLst><a:gd name="mid" fmla="*/ w 1 2"/></a:gdLst><a:pathLst>{paths}{}</a:pathLst></a:custGeom>"#,
-            path(10)
-        );
-        let d = parse(x.as_bytes()).unwrap();
-        let out = read_cust_geom(&d.root, 1.0, 1.0);
-        assert_eq!(out.len(), MAX_SPACES + 1, "16 spaces plus the repeat of the first");
-        assert!(out[0].d.starts_with("M 5 1"), "{}", out[0].d);
-        assert!(out[MAX_SPACES].d.starts_with("M 5 1"), "{}", out[MAX_SPACES].d);
-    }
-
-    #[test]
-    fn guide_free_geometries_are_not_capped_by_space() {
-        let paths: String = (1..=40).map(|i| format!(r#"<a:path w="{}" h="10"><a:moveTo><a:pt x="1" y="1"/></a:moveTo></a:path>"#, 10 * i)).collect();
-        let x = format!(r#"<a:custGeom xmlns:a="x"><a:avLst/><a:gdLst/><a:pathLst>{paths}</a:pathLst></a:custGeom>"#);
-        let d = parse(x.as_bytes()).unwrap();
-        assert_eq!(read_cust_geom(&d.root, 1.0, 1.0).len(), 40);
-    }
-
     #[test]
     fn write_then_read_path() {
         let p = CustomPath { w: 100.0, h: 50.0, d: "M 0 0 L 100 0 C 100 10 90 50 50 50 Q 0 50 0 0 Z".into(), fill: FillMode::Norm, stroke: true };

crates/render/src/bevel.rs

@@ -125,7 +125,9 @@ pub fn draw(ctx: &mut RenderContext, bevel: &Bevel, fill: Option<Rgba>, path: &B
     let longest = bounds.width().max(bounds.height()) * k;
     let s = (MAX_SIDE / longest).min(1.0) * k;
     let (pw, ph) = (((bounds.width() * s).ceil() as u32).clamp(1, 2048), ((bounds.height() * s).ceil() as u32).clamp(1, 2048));
-    let polys = crate::pathgrad::polygons(path);
+    // Each pixel tests every edge, so a dense outline is simplified to the raster's edge budget.
+    let pixel = (bounds.width() / f64::from(pw)).min(bounds.height() / f64::from(ph));
+    let polys = crate::pathgrad::simplify(crate::pathgrad::polygons(path), pixel, crate::pathgrad::edge_budget(pw, ph));
     if polys.is_empty() {
         return;
     }

crates/render/src/colr.rs

@@ -11,6 +11,8 @@ use vello_cpu::{RenderContext, peniko};
 
 /// Nesting depth of clips and layers past which a glyph opens no more (hostile fonts).
 const MAX_DEPTH: usize = 64;
+/// Fills and gradient stops one colour glyph may paint; the rest of a hostile glyph is skipped.
+const MAX_WORK: usize = 100_000;
 
 /// Paint `gid` of `face` as a colour glyph, its origin mapped by `at` (y down, points) at `scale`
 /// points per font unit. `fg` is the text colour (palette index 0xFFFF) and `alpha` fades it all.
@@ -26,7 +28,7 @@ pub fn paint(ctx: &mut RenderContext, face: &FontFace, gid: u32, at: Affine, sca
         .unwrap_or_default();
     // Font units are y up; the slide is y down.
     let base = at * Affine::scale(scale) * Affine::scale_non_uniform(1.0, -1.0);
-    let mut p = Painter { ctx, face, base, stack: vec![Affine::IDENTITY], palette, fg, opened: Vec::new() };
+    let mut p = Painter { ctx, face, base, stack: vec![Affine::IDENTITY], palette, fg, opened: Vec::new(), work: 0 };
     p.ctx.push_layer(None, None, Some(alpha.clamp(0.0, 1.0) as f32), None, None);
     let ok = glyph.paint(face.location(), &mut p).is_ok();
     // A malformed glyph may leave layers open: close them all.
@@ -50,6 +52,8 @@ struct Painter<'a> {
     /// Clips and composite groups pushed by the glyph, innermost last: true when a layer was
     /// opened on the context for it (false past `MAX_DEPTH`, so its pop is skipped too).
     opened: Vec<bool>,
+    /// Fills plus gradient stops painted so far, against [`MAX_WORK`].
+    work: usize,
 }
 
 fn affine(t: &Transform) -> Affine {
@@ -174,6 +178,16 @@ impl ColorPainter for Painter<'_> {
     }
 
     fn fill(&mut self, brush: Brush<'_>) {
+        let stops = match &brush {
+            Brush::Solid { .. } => 0,
+            Brush::LinearGradient { color_stops, .. } | Brush::RadialGradient { color_stops, .. } | Brush::SweepGradient { color_stops, .. } => {
+                color_stops.len()
+            }
+        };
+        self.work = self.work.saturating_add(1 + stops);
+        if self.work > MAX_WORK {
+            return;
+        }
         match brush {
             Brush::Solid { palette_index, alpha } => {
                 let c = self.color(palette_index, alpha);

crates/render/src/pathgrad.rs

@@ -25,6 +25,16 @@ const MAX_EDGE_WORK: u64 = 64_000_000;
 /// Fewest edges a simplified polygon keeps, so a coarse outline still has a shape.
 const MIN_POLY_EDGES: usize = 8;
 
+/// Most points `polygons` keeps from one path; a path flattening past this (a huge finite curve) is
+/// not drawn rather than held in memory first.
+const MAX_POINTS: usize = 2_000_000;
+
+/// The edge budget for a `pw` x `ph` raster where each pixel tests every edge.
+pub(crate) fn edge_budget(pw: u32, ph: u32) -> usize {
+    let pixels = u64::from(pw).saturating_mul(u64::from(ph)).max(1);
+    usize::try_from(MAX_EDGE_WORK / pixels).unwrap_or(usize::MAX).max(MIN_POLY_EDGES)
+}
+
 /// Colour position (0 at the focus, 1 at the edge) of `p` for path `kind` in `bounds` with the
 /// focus rect `focus` (fractions inset from left, top, right, bottom), `outline` being the
 /// shape's flattened polygon(s) for `shape`.
@@ -114,21 +124,31 @@ fn shape_position(outline: &[Vec<Point>], c: Point, p: Point) -> f64 {
 pub fn polygons(path: &BezPath) -> Vec<Vec<Point>> {
     let mut out: Vec<Vec<Point>> = Vec::new();
     let mut cur: Vec<Point> = Vec::new();
-    kurbo::flatten(path.iter(), 0.25, |el| match el {
-        PathEl::MoveTo(p) => {
-            if cur.len() > 1 {
-                out.push(std::mem::take(&mut cur));
-            }
-            cur = vec![p];
+    let mut total = 0usize;
+    kurbo::flatten(path.iter(), 0.25, |el| {
+        total += 1;
+        if total > MAX_POINTS {
+            return;
         }
-        PathEl::LineTo(p) => cur.push(p),
-        PathEl::ClosePath => {
-            if let Some(f) = cur.first().copied() {
-                cur.push(f);
+        match el {
+            PathEl::MoveTo(p) => {
+                if cur.len() > 1 {
+                    out.push(std::mem::take(&mut cur));
+                }
+                cur = vec![p];
             }
+            PathEl::LineTo(p) => cur.push(p),
+            PathEl::ClosePath => {
+                if let Some(f) = cur.first().copied() {
+                    cur.push(f);
+                }
+            }
+            _ => {}
         }
-        _ => {}
     });
+    if total > MAX_POINTS {
+        return Vec::new();
+    }
     if cur.len() > 1 {
         out.push(cur);
     }
@@ -146,7 +166,7 @@ pub fn polygons(path: &BezPath) -> Vec<Vec<Point>> {
 /// `outline` cut down to at most about `max_edges` edges in total: first by dropping points
 /// closer than `tol` to the last kept one (detail finer than a raster pixel), then, if still too
 /// many, by keeping every k-th point. Each polygon stays closed. Returns it unchanged when it fits.
-fn simplify(outline: Vec<Vec<Point>>, tol: f64, max_edges: usize) -> Vec<Vec<Point>> {
+pub(crate) fn simplify(outline: Vec<Vec<Point>>, tol: f64, max_edges: usize) -> Vec<Vec<Point>> {
     let edges = |o: &[Vec<Point>]| o.iter().map(|p| p.len().saturating_sub(1)).sum::<usize>();
     if edges(&outline) <= max_edges {
         return outline;
@@ -233,13 +253,17 @@ pub fn fill(ctx: &mut RenderContext, kind: &str, focus: [f64; 4], stops: &[(f64,
     let s = (MAX_SIDE / longest).min(1.0) * k;
     let (pw, ph) = (((bounds.width() * s).ceil() as u32).clamp(1, 4096), ((bounds.height() * s).ceil() as u32).clamp(1, 4096));
     let outline = if kind == "shape" {
-        let pixels = u64::from(pw).saturating_mul(u64::from(ph)).max(1);
-        let max_edges = usize::try_from(MAX_EDGE_WORK / pixels).unwrap_or(usize::MAX).max(MIN_POLY_EDGES);
+        let max_edges = edge_budget(pw, ph);
         let pixel = (bounds.width() / f64::from(pw)).min(bounds.height() / f64::from(ph));
         simplify(polygons(path), pixel, max_edges)
     } else {
         Vec::new()
     };
+    // An outline `polygons` refused (too many points) has no contours: skip the shape rather than
+    // paint it with the rectangle fallback's different gradient.
+    if kind == "shape" && outline.is_empty() {
+        return;
+    }
     let lut = ramp(stops);
     let a = alpha.clamp(0.0, 1.0);
     let mut data = Vec::with_capacity((pw * ph) as usize);
@@ -372,6 +396,20 @@ mod tests {
         assert!(t.elapsed() < std::time::Duration::from_secs(20), "{:?}", t.elapsed());
     }
 
+    #[test]
+    fn a_shape_gradient_with_no_usable_outline_paints_nothing() {
+        // One polygon over the per-polygon cap is dropped by `polygons`.
+        let path = many_segment_square(26_000);
+        assert!(polygons(&path).is_empty());
+        let mut ctx = RenderContext::new(64, 64);
+        let stops = [(0.0, Rgba::rgb(0, 0, 0)), (1.0, Rgba::rgb(255, 255, 255))];
+        fill(&mut ctx, "shape", CENTRE, &stops, Rect::new(0.0, 0.0, 64.0, 64.0), &path, Affine::IDENTITY, 1.0);
+        ctx.flush();
+        let mut px = vec![0u8; 64 * 64 * 4];
+        ctx.render(vello_cpu::PixmapMut::new(64, 64, &mut px).unwrap(), &mut vello_cpu::Resources::new());
+        assert!(px.chunks(4).all(|p| p[3] == 0), "nothing was painted");
+    }
+
     #[test]
     fn the_ramp_runs_through_the_stops() {
         let stops = [(0.0, Rgba::rgb(0, 0, 0)), (0.5, Rgba::rgb(128, 128, 128)), (1.0, Rgba::rgb(255, 255, 255))];