Merge d036e02bb007a6aeaff1beb12451d954a17d9b44 into 9b09146a6b5e936966ed7ee73bce9dd2df3810ae

crates/typst-library/src/visualize/gradient.rs

@@ -1290,9 +1290,21 @@ fn sample_stops(stops: &[(Color, Ratio)], mixing_space: ColorSpace, t: f64) -> C
     if low == 0 {
         low = 1;
     }
+    if t == 1.0 {
+        while stops[low - 1].1 >= stops[low].1 {
+            low -= 1;
+        }
+    } else {
+        while stops[low - 1].1 >= stops[low].1 {
+            low += 1;
+        }
+    }
 
     let (col_0, pos_0) = stops[low - 1];
     let (col_1, pos_1) = stops[low];
+    debug_assert!(pos_0 < pos_1);
+    debug_assert!(pos_0.get() <= t);
+    debug_assert!(t <= pos_1.get());
     let t = (t - pos_0.get()) / (pos_1.get() - pos_0.get());
 
     Color::mix_iter(

tests/suite/visualize/gradient.typ

@@ -666,3 +666,29 @@ $ A = mat(
 #let _ = gradient.linear(..my-gradient.stops())
 #let my-gradient2 = gradient.linear(red, blue).repeat(5, mirror: true)
 #let _ = gradient.linear(..my-gradient2.stops())
+
+--- issue-6162-coincident-gradient-stops-export-png ---
+// Ensure that multiple gradient stops with the same position
+// don't cause a panic.
+#rect(
+  fill: gradient.linear(
+    (red, 0%),
+    (green, 0%),
+    (blue, 100%),
+  )
+)
+#rect(
+  fill: gradient.linear(
+    (red, 0%),
+    (green, 100%),
+    (blue, 100%),
+  )
+)
+#rect(
+  fill: gradient.linear(
+    (white, 0%),
+    (red, 50%),
+    (green, 50%),
+    (blue, 100%),
+  )
+)