Changeset 225554 in webkit

Timestamp:

Dec 5, 2017 3:30:48 PM (6 years ago)

Author:

Simon Fraser

Message:

Composited frames incorrectly get requestAnimationFrame throttled
​https://bugs.webkit.org/show_bug.cgi?id=178396

Reviewed by Zalan Bujtas.

Source/WebCore:

If a composited iframe was inside overflow:scroll, and the overflow was scrolled to the left
further than the window width, then RenderLayer::childrenClipRect() would return an empty rectangle
and we'd incorrectly consider the iframe out of view, and thus throttle its requestAnimationFrame.

childrenClipRect() was taking unscaledDocumentRect(), applying the clip, and then mapping the result
from local to absolute coordinates (which mapped it through the overflow scroll offset). This is incorrect
because it considers the unscaledDocumentRect() to be in local coordinates, which it is not.

Instead, start with the infinite rect, which essentially tells us if we have any clipping, and then
intersect that with the document rect at the end. Something similar is done in other places that call.
calculateRects().

Test: fast/animation/request-animation-frame-throttle-inside-overflow-scroll.html

• rendering/RenderLayer.cpp:

(WebCore::RenderLayer::calculateClipRects const):

LayoutTests:

• fast/animation/request-animation-frame-throttle-inside-overflow-scroll-expected.txt: Added.
• fast/animation/request-animation-frame-throttle-inside-overflow-scroll.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/fast/animation/request-animation-frame-throttle-inside-overflow-scroll-expected.txt (added)
• LayoutTests/fast/animation/request-animation-frame-throttle-inside-overflow-scroll.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/RenderLayer.cpp (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2017-12-05  Simon Fraser  <simon.fraser@apple.com>
+
+        Composited frames incorrectly get requestAnimationFrame throttled
+        https://bugs.webkit.org/show_bug.cgi?id=178396
+
+        Reviewed by Zalan Bujtas.
+
+        * fast/animation/request-animation-frame-throttle-inside-overflow-scroll-expected.txt: Added.
+        * fast/animation/request-animation-frame-throttle-inside-overflow-scroll.html: Added.
+
 2017-12-05  Joseph Pecoraro  <pecoraro@apple.com>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2017-12-05  Simon Fraser  <simon.fraser@apple.com>
+
+        Composited frames incorrectly get requestAnimationFrame throttled
+        https://bugs.webkit.org/show_bug.cgi?id=178396
+
+        Reviewed by Zalan Bujtas.
+
+        If a composited iframe was inside overflow:scroll, and the overflow was scrolled to the left
+        further than the window width, then RenderLayer::childrenClipRect() would return an empty rectangle
+        and we'd incorrectly consider the iframe out of view, and thus throttle its requestAnimationFrame.
+
+        childrenClipRect() was taking unscaledDocumentRect(), applying the clip, and then mapping the result
+        from local to absolute coordinates (which mapped it through the overflow scroll offset). This is incorrect
+        because it considers the unscaledDocumentRect() to be in local coordinates, which it is not.
+
+        Instead, start with the infinite rect, which essentially tells us if we have any clipping, and then
+        intersect that with the document rect at the end. Something similar is done in other places that call.
+        calculateRects().
+
+        Test: fast/animation/request-animation-frame-throttle-inside-overflow-scroll.html
+
+        * rendering/RenderLayer.cpp:
+        (WebCore::RenderLayer::calculateClipRects const):
+
 2017-12-05  Michael Saboff  <msaboff@apple.com>
 

trunk/Source/WebCore/rendering/RenderLayer.cpp

@@ -5634 +5634 @@
     ClipRectsContext clipRectsContext(clippingRootLayer, TemporaryClipRects);
     // Need to use temporary clip rects, because the value of 'dontClipToOverflow' may be different from the painting path (<rdar://problem/11844909>).
-    calculateRects(clipRectsContext, renderer().view().unscaledDocumentRect(), layerBounds, backgroundRect, foregroundRect, offsetFromAncestor(clipRectsContext.rootLayer));
-    return clippingRootLayer->renderer().localToAbsoluteQuad(FloatQuad(foregroundRect.rect())).enclosingBoundingBox();
+    calculateRects(clipRectsContext, LayoutRect::infiniteRect(), layerBounds, backgroundRect, foregroundRect, offsetFromAncestor(clipRectsContext.rootLayer));
+    if (foregroundRect.rect().isInfinite())
+        return renderer().view().unscaledDocumentRect();
+
+    auto absoluteClippingRect = clippingRootLayer->renderer().localToAbsoluteQuad(FloatQuad(foregroundRect.rect())).enclosingBoundingBox();
+    return intersection(absoluteClippingRect, renderer().view().unscaledDocumentRect());
 }