Changeset 224241 in webkit

Timestamp:

Oct 31, 2017 1:27:18 PM (6 years ago)

Author:

commit-queue@webkit.org

Message:

Layout viewport rect is too wide after window resize
​https://bugs.webkit.org/show_bug.cgi?id=175235

Patch by Ali Juma <​ajuma@chromium.org> on 2017-10-31
Reviewed by Dave Hyatt.

Source/WebCore:

After a window resize, ScrollView::updateScrollbars adds/removes scrollbars and triggers
layout. Each addition or removal triggers another pass, but at most 2 additional passes
are allowed. If a scrollbar is added or removed in the final allowed pass, layout is
left in an inconsistent state wrt the presence of scrollbars.

To avoid unnecessary passes, don't remove both scrollbars when only one needs to be
removed. This saves the extra pass needed to add the scrollbar back.

Test: fast/dom/Window/window-resize-update-scrollbars.html

• platform/ScrollView.cpp:

(WebCore::ScrollView::updateScrollbars):

LayoutTests:

• fast/dom/Window/window-resize-update-scrollbars-expected.txt: Added.
• fast/dom/Window/window-resize-update-scrollbars.html: Added.
• platform/ios/TestExpectations:

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/fast/dom/Window/window-resize-update-scrollbars-expected.txt (added)
• LayoutTests/fast/dom/Window/window-resize-update-scrollbars.html (added)
• LayoutTests/platform/ios/TestExpectations (modified) (1 diff)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/platform/ScrollView.cpp (modified) (2 diffs)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2017-10-31  Ali Juma  <ajuma@chromium.org>
+
+        Layout viewport rect is too wide after window resize
+        https://bugs.webkit.org/show_bug.cgi?id=175235
+
+        Reviewed by Dave Hyatt.
+
+        * fast/dom/Window/window-resize-update-scrollbars-expected.txt: Added.
+        * fast/dom/Window/window-resize-update-scrollbars.html: Added.
+        * platform/ios/TestExpectations:
+
 2017-10-31  Youenn Fablet  <youenn@apple.com>
 

trunk/LayoutTests/platform/ios/TestExpectations

@@ -1659 +1659 @@
 # iOS does not support window resizing or window.resizeTo().
 fast/css-grid-layout/flex-content-sized-columns-resize.html [ Skip ]
+fast/dom/Window/window-resize-update-scrollbars.html [ Skip ]
 fast/dynamic/window-resize-scrollbars-test.html [ Skip ]
 fast/images/animated-gif-window-resizing.html [ Skip ]

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2017-10-31  Ali Juma  <ajuma@chromium.org>
+
+        Layout viewport rect is too wide after window resize
+        https://bugs.webkit.org/show_bug.cgi?id=175235
+
+        Reviewed by Dave Hyatt.
+
+        After a window resize, ScrollView::updateScrollbars adds/removes scrollbars and triggers
+        layout. Each addition or removal triggers another pass, but at most 2 additional passes
+        are allowed. If a scrollbar is added or removed in the final allowed pass, layout is
+        left in an inconsistent state wrt the presence of scrollbars.
+
+        To avoid unnecessary passes, don't remove both scrollbars when only one needs to be
+        removed. This saves the extra pass needed to add the scrollbar back.
+
+        Test: fast/dom/Window/window-resize-update-scrollbars.html
+
+        * platform/ScrollView.cpp:
+        (WebCore::ScrollView::updateScrollbars):
+
 2017-10-31  Wenson Hsieh  <wenson_hsieh@apple.com>
 

trunk/Source/WebCore/platform/ScrollView.cpp

@@ -608 +608 @@
         bool needAnotherPass = false;
         if (!hasOverlayScrollbars) {
-            // If we ever turn one scrollbar off, always turn the other one off too.  Never ever
+            // If we ever turn one scrollbar off, do not turn the other one on. Never ever
             // try to both gain/lose a scrollbar in the same pass.
             if (!m_updateScrollbarsPass && docSize.width() <= fullVisibleSize.width() && docSize.height() <= fullVisibleSize.height()) {
@@ -616 +616 @@
                     newHasVerticalScrollbar = false;
             }
-            if (!newHasHorizontalScrollbar && hasHorizontalScrollbar && vScroll != ScrollbarAlwaysOn) {
+            if (!newHasHorizontalScrollbar && hasHorizontalScrollbar && vScroll != ScrollbarAlwaysOn &&!hasVerticalScrollbar) {
                 newHasVerticalScrollbar = false;
                 needAnotherPass = true;
             }
-            if (!newHasVerticalScrollbar && hasVerticalScrollbar && hScroll != ScrollbarAlwaysOn) {
+            if (!newHasVerticalScrollbar && hasVerticalScrollbar && hScroll != ScrollbarAlwaysOn && !hasHorizontalScrollbar) {
                 newHasHorizontalScrollbar = false;
                 needAnotherPass = true;