Bug 1848532 - Update aa-stroke to fix butt caps. r=gfx-reviewers,lsalzman

Differential Revision: https://phabricator.services.mozilla.com/D186085

.cargo/config.in

@@ -5,9 +5,9 @@
 [source.crates-io]
 replace-with = "vendored-sources"
 
-[source."git+https://github.com/FirefoxGraphics/aa-stroke?rev=cfe9ee39f5af56ae26004835d90c4bb2973ce519"]
+[source."git+https://github.com/FirefoxGraphics/aa-stroke?rev=c1916bc1b5336438207881a362fc3dd921d915e4"]
 git = "https://github.com/FirefoxGraphics/aa-stroke"
-rev = "cfe9ee39f5af56ae26004835d90c4bb2973ce519"
+rev = "c1916bc1b5336438207881a362fc3dd921d915e4"
 replace-with = "vendored-sources"
 
 [source."git+https://github.com/FirefoxGraphics/wpf-gpu-raster?rev=5ab6fe33d00021325ee920b3c10526dc8301cf46"]

Cargo.lock

@@ -5,7 +5,7 @@ version = 3
 [[package]]
 name = "aa-stroke"
 version = "0.1.0"
-source = "git+https://github.com/FirefoxGraphics/aa-stroke?rev=cfe9ee39f5af56ae26004835d90c4bb2973ce519#cfe9ee39f5af56ae26004835d90c4bb2973ce519"
+source = "git+https://github.com/FirefoxGraphics/aa-stroke?rev=c1916bc1b5336438207881a362fc3dd921d915e4#c1916bc1b5336438207881a362fc3dd921d915e4"
 dependencies = [
  "euclid",
 ]

third_party/rust/aa-stroke/.cargo-checksum.json

@@ -1 +1 @@
-{"files":{".github/workflows/rust.yml":"e859b12cfed145b66e4fbf1571dde15880359717ca5b0a9720341229183f2c6f","Cargo.toml":"f507cac11c3c26af28420d68ec3748a5453322d51ef1379a340fdd3b1c9b187a","README.md":"60b34cfa653114d5054009696df2ed2ea1d4926a6bc312d0cac4b84845c2beff","examples/simple.rs":"c196e79568fe4be31a08374aa451c70c9377db5428aef924a985e069c12ed91e","src/bezierflattener.rs":"61687da22490cb1bd901d0b5eb1de3a98802b46c03719ded4163c7a4997f0ad9","src/c_bindings.rs":"23890f7bb5d40d87d72b28842821ada7b2e1509a3b37c9af8ed0055036ceadcc","src/lib.rs":"21d02fdcc8491a03b19ec90dfeae05fb569f73500cf1bb89ba71d6e838dc0b0d","src/tri_rasterize.rs":"fb6f595ab9340d8ea6429b41638c378bbd772c8e4d8f7793e225624c12cd3a21"},"package":null}
+{"files":{".github/workflows/rust.yml":"e859b12cfed145b66e4fbf1571dde15880359717ca5b0a9720341229183f2c6f","Cargo.toml":"f507cac11c3c26af28420d68ec3748a5453322d51ef1379a340fdd3b1c9b187a","README.md":"60b34cfa653114d5054009696df2ed2ea1d4926a6bc312d0cac4b84845c2beff","examples/simple.rs":"c196e79568fe4be31a08374aa451c70c9377db5428aef924a985e069c12ed91e","src/bezierflattener.rs":"61687da22490cb1bd901d0b5eb1de3a98802b46c03719ded4163c7a4997f0ad9","src/c_bindings.rs":"23890f7bb5d40d87d72b28842821ada7b2e1509a3b37c9af8ed0055036ceadcc","src/lib.rs":"022bf8fd13d9f097b5d905d01d3632258b41697c9b07c3674444bc4fa3e9e800","src/tri_rasterize.rs":"fb6f595ab9340d8ea6429b41638c378bbd772c8e4d8f7793e225624c12cd3a21"},"package":null}

third_party/rust/aa-stroke/src/lib.rs

@@ -540,7 +540,7 @@ fn line_intersection(a: Point, a_perp: Vector, b: Point, b_perp: Vector) -> Opti
 
 fn is_interior_angle(a: Vector, b: Vector) -> bool {
     /* angles of 180 and 0 degress will evaluate to 0, however
-     * we to treat 180 as an interior angle and 180 as an exterior angle */
+     * we to treat 0 as an interior angle and 180 as an exterior angle */
     dot(perp(a), b) > 0. || a == b /* 0 degrees is interior */
 }
 
@@ -659,7 +659,9 @@ impl<'z> Stroker<'z> {
     pub fn line_to_capped(&mut self, pt: Point) {
         if let Some(cur_pt) = self.cur_pt {
             let normal = compute_normal(cur_pt, pt).unwrap_or(self.last_normal);
-            self.line_to(if self.stroked_path.aa && self.style.cap == LineCap::Butt { pt - flip(normal) * 0.5} else { pt });
+            // if we have a butt cap end the line half a pixel early so we have room to put the cap.
+            // XXX: this will probably mess things up if the line is shorter than 1/2 pixel long
+            self.line_to(if self.stroked_path.aa && self.style.cap == LineCap::Butt { pt + perp(normal) * 0.5} else { pt });
             if let (Some(cur_pt), Some((_point, _normal))) = (self.cur_pt, self.start_point) {
                 // cap end
                 cap_line(&mut self.stroked_path, &self.style, cur_pt, self.last_normal);
@@ -686,10 +688,13 @@ impl<'z> Stroker<'z> {
                 if self.start_point.is_none() {
                     if !self.closed_subpath {
                         // cap beginning
-                        cap_line(stroked_path, &self.style, cur_pt, flip(normal));
+                        let mut cur_pt = cur_pt;
                         if stroked_path.aa && self.style.cap == LineCap::Butt {
-                            
+                            // adjust the starting point to make room for the cap
+                            // XXX: this will probably mess things up if the line is shorter than 1/2 pixel long
+                            cur_pt += perp(flip(normal)) * 0.5;
                         }
+                        cap_line(stroked_path, &self.style, cur_pt, flip(normal));
                     }
                     self.start_point = Some((cur_pt, normal));
                 } else {
@@ -888,6 +893,21 @@ fn curve() {
     assert_eq!(stroked.len(), 1089);
 }
 
+#[test]
+fn butt_cap() {
+    let mut stroker = Stroker::new(&StrokeStyle{
+        cap: LineCap::Butt,
+        join: LineJoin::Bevel,
+        width: 1.,
+        ..Default::default()});
+    stroker.move_to(Point::new(20., 20.5), false);
+    stroker.line_to_capped(Point::new(40., 20.5));
+    let result = stroker.finish();
+    for v in result {
+        assert!(v.y == 20.5 || v.y == 19.5 || v.y == 21.5);
+    }
+}
+
 #[test]
 fn width_one_radius_arc() {
     // previously this caused us to try to flatten an arc with radius 0

toolkit/library/rust/shared/Cargo.toml

@@ -95,7 +95,7 @@ processtools = { path = "../../../components/processtools" }
 qcms = { path = "../../../../gfx/qcms", features = ["c_bindings", "neon"], default-features = false }
 
 wpf-gpu-raster = { git = "https://github.com/FirefoxGraphics/wpf-gpu-raster", rev = "5ab6fe33d00021325ee920b3c10526dc8301cf46" }
-aa-stroke = { git = "https://github.com/FirefoxGraphics/aa-stroke", rev = "cfe9ee39f5af56ae26004835d90c4bb2973ce519" }
+aa-stroke = { git = "https://github.com/FirefoxGraphics/aa-stroke", rev = "c1916bc1b5336438207881a362fc3dd921d915e4" }
 
 # Force url to stay at 2.1.0. See bug 1734538.
 url = "=2.1.0"