Implement gradient borders

niri-visual-tests/src/cases/layout.rs

@@ -51,6 +51,8 @@ impl Layout {
                 width: 4,
                 active_color: Color::new(255, 163, 72, 255),
                 inactive_color: Color::new(50, 50, 50, 255),
+                active_gradient: None,
+                inactive_gradient: None,
             },
             ..Default::default()
         };

niri-visual-tests/src/cases/tile.rs

@@ -104,7 +104,13 @@ impl TestCase for Tile {
         let location = Point::from(((size.w - tile_size.w) / 2, (size.h - tile_size.h) / 2));
 
         self.tile
-            .render(renderer, location, Scale::from(1.), true)
+            .render(
+                renderer,
+                location,
+                Scale::from(1.),
+                size.to_logical(1),
+                true,
+            )
             .map(|elem| Box::new(elem) as _)
             .collect()
     }