Don't calculate intersectRatio again. (#5965)

ampproject · Nov 2, 2016 · 72923f1 · 72923f1
1 parent b9fd302
commit 72923f1
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Showing 2 changed files with 7 additions and 3 deletions.
diff --git a/extensions/amp-analytics/0.1/test/test-visibility-impl.js b/extensions/amp-analytics/0.1/test/test-visibility-impl.js
@@ -86,10 +86,14 @@ describe('amp-analytics.visibility', () => {
   function makeIntersectionEntry(boundingClientRect, rootBounds) {
     boundingClientRect = layoutRectLtwh.apply(null, boundingClientRect);
     rootBounds = layoutRectLtwh.apply(null, rootBounds);
+    const intersect = rectIntersection(boundingClientRect, rootBounds);
+    const ratio = (intersect.width * intersect.height)
+        / (boundingClientRect.width * boundingClientRect.height);
     return {
-      intersectionRect: rectIntersection(boundingClientRect, rootBounds),
+      intersectionRect: intersect,
       boundingClientRect,
       rootBounds,
+      intersectionRatio: ratio,
     };
   }
 

diff --git a/extensions/amp-analytics/0.1/visibility-impl.js b/extensions/amp-analytics/0.1/visibility-impl.js
@@ -331,8 +331,8 @@ export class Visibility {
       const change = res.element.getIntersectionChangeEntry();
       const ir = change.intersectionRect;
       const br = change.boundingClientRect;
-      const visible = br.height * br.width == 0 ? 0 :
-          ir.width * ir.height * 100 / (br.height * br.width);
+      const visible =
+          isNaN(change.intersectionRatio) ? 0 : change.intersectionRatio * 100;
 
       const listeners = this.listeners_[res.getId()];
       for (let c = listeners.length - 1; c >= 0; c--) {