Merge pull request endoli#31 from tomcur/reading-order-epsilon

focus: make reading order `y` check use relative epsilon

Author: tomcur

docs/issue_focus_direction_and_reading_order.md

@@ -31,7 +31,7 @@ In `DefaultPolicy`:
   1. If both entries have `order: Some(i32)`, compare by `order` (lower first).
   2. Otherwise fall back to **reading order** defined as:
      - Compare by `rect.y0` (ascending).
-     - If `y0` is within a small epsilon, compare by `rect.x0` (ascending).
+     - If `y0` is within a small relative epsilon, compare by `rect.x0` (ascending).
 - Traversal:
   - `Next`: move forward in this sorted list.
   - `Prev`: move backward in this sorted list.

understory_focus/src/lib.rs

@@ -383,10 +383,10 @@ fn compare_linear<K>(a: &FocusEntry<K>, b: &FocusEntry<K>) -> Ordering {
 }
 
 fn compare_rect_reading(a: &Rect, b: &Rect) -> Ordering {
-    const EPS: f64 = 1e-6;
+    const RELATIVE_EPS: f64 = 1e-6;
     let ay = a.y0;
     let by = b.y0;
-    if (ay - by).abs() > EPS {
+    if (ay - by).abs() > f64::max(ay.abs(), by.abs()) * RELATIVE_EPS {
         return ay.partial_cmp(&by).unwrap_or(Ordering::Equal);
     }
     let ax = a.x0;