Changeset 245742 in webkit

Timestamp:

May 23, 2019, 8:25:27 PM (7 years ago)

Author:

Simon Fraser

Message:

With async overflow scrolling, programmatic scroll to a negative offset fails to clamp the scroll offset
​https://bugs.webkit.org/show_bug.cgi?id=198208
<rdar://problem/49720087>

Reviewed by Zalan Bujtas.

Source/WebCore:

RenderLayer::scrollToOffset() needs to pass the clamped offset to scrollingCoordinator->requestScrollPositionUpdate(),
otherwise the scrolling tree will round-trip a negative value and scrollLeft will end up negative.

Test: fast/scrolling/programmatic-scroll-to-negative-offset.html

• rendering/RenderLayer.cpp:

(WebCore::RenderLayer::scrollToOffset):

LayoutTests:

• fast/scrolling/programmatic-scroll-to-negative-offset-expected.txt: Added.
• fast/scrolling/programmatic-scroll-to-negative-offset.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/fast/scrolling/programmatic-scroll-to-negative-offset-expected.txt (added)
• LayoutTests/fast/scrolling/programmatic-scroll-to-negative-offset.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/RenderLayer.cpp (modified) (2 diffs)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2019-05-23  Simon Fraser  <simon.fraser@apple.com>
+
+        With async overflow scrolling, programmatic scroll to a negative offset fails to clamp the scroll offset
+        https://bugs.webkit.org/show_bug.cgi?id=198208
+        <rdar://problem/49720087>
+
+        Reviewed by Zalan Bujtas.
+
+        * fast/scrolling/programmatic-scroll-to-negative-offset-expected.txt: Added.
+        * fast/scrolling/programmatic-scroll-to-negative-offset.html: Added.
+
 2019-05-23  Fujii Hironori  <Hironori.Fujii@sony.com>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2019-05-23  Simon Fraser  <simon.fraser@apple.com>
+
+        With async overflow scrolling, programmatic scroll to a negative offset fails to clamp the scroll offset
+        https://bugs.webkit.org/show_bug.cgi?id=198208
+        <rdar://problem/49720087>
+
+        Reviewed by Zalan Bujtas.
+
+        RenderLayer::scrollToOffset() needs to pass the clamped offset to scrollingCoordinator->requestScrollPositionUpdate(),
+        otherwise the scrolling tree will round-trip a negative value and scrollLeft will end up negative.
+
+        Test: fast/scrolling/programmatic-scroll-to-negative-offset.html
+
+        * rendering/RenderLayer.cpp:
+        (WebCore::RenderLayer::scrollToOffset):
+
 2019-05-23  Devin Rousso  <drousso@apple.com>
 

trunk/Source/WebCore/rendering/RenderLayer.cpp

@@ -2436 +2436 @@
 void RenderLayer::scrollToOffset(const ScrollOffset& scrollOffset, ScrollType scrollType, ScrollClamping clamping)
 {
-    ScrollOffset newScrollOffset = clamping == ScrollClamping::Clamped ? clampScrollOffset(scrollOffset) : scrollOffset;
-    if (newScrollOffset == this->scrollOffset())
+    ScrollOffset clampedScrollOffset = clamping == ScrollClamping::Clamped ? clampScrollOffset(scrollOffset) : scrollOffset;
+    if (clampedScrollOffset == this->scrollOffset())
         return;
 
@@ -2446 +2446 @@
 #if ENABLE(ASYNC_SCROLLING)
     if (ScrollingCoordinator* scrollingCoordinator = page().scrollingCoordinator())
-        handled = scrollingCoordinator->requestScrollPositionUpdate(*this, scrollPositionFromOffset(scrollOffset));
+        handled = scrollingCoordinator->requestScrollPositionUpdate(*this, scrollPositionFromOffset(clampedScrollOffset));
 #endif
 
     if (!handled)
-        scrollToOffsetWithoutAnimation(newScrollOffset, clamping);
+        scrollToOffsetWithoutAnimation(clampedScrollOffset, clamping);
 
     setCurrentScrollType(previousScrollType);