Modified: trunk/Source/WebCore/page/scrolling/ScrollSnapOffsetsInfo.cpp (279713 => 279714)
--- trunk/Source/WebCore/page/scrolling/ScrollSnapOffsetsInfo.cpp 2021-07-08 07:23:20 UTC (rev 279713)
+++ trunk/Source/WebCore/page/scrolling/ScrollSnapOffsetsInfo.cpp 2021-07-08 07:23:32 UTC (rev 279714)
@@ -199,6 +199,16 @@
}
}
+static std::pair<bool, bool> axesFlippedForWritingModeAndDirection(WritingMode writingMode, TextDirection textDirection)
+{
+ // text-direction flips the inline axis and writing-mode can flip the block axis. Whether or
+ // not the writing-mode is vertical determines the physical orientation of the block and inline axes.
+ bool hasVerticalWritingMode = isVerticalWritingMode(writingMode);
+ bool blockAxisFlipped = isFlippedWritingMode(writingMode);
+ bool inlineAxisFlipped = textDirection == TextDirection::RTL;
+ return std::make_pair(hasVerticalWritingMode ? blockAxisFlipped : inlineAxisFlipped, hasVerticalWritingMode ? inlineAxisFlipped : blockAxisFlipped);
+}
+
void updateSnapOffsetsForScrollableArea(ScrollableArea& scrollableArea, const RenderBox& scrollingElementBox, const RenderStyle& scrollingElementStyle, LayoutRect viewportRectInBorderBoxCoordinates, WritingMode writingMode, TextDirection textDirection)
{
auto scrollSnapType = scrollingElementStyle.scrollSnapType();
@@ -223,14 +233,8 @@
auto maxScrollOffset = scrollableArea.maximumScrollOffset();
auto scrollPosition = LayoutPoint { scrollableArea.scrollPosition() };
- // text-direction flips the inline axis and writing-mode can flip the block axis. Whether or
- // not the writing-mode is vertical determines the physical orientation of the block and inline axes.
+ auto [scrollerXAxisFlipped, scrollerYAxisFlipped] = axesFlippedForWritingModeAndDirection(writingMode, textDirection);
bool scrollerHasVerticalWritingMode = isVerticalWritingMode(writingMode);
- bool blockAxisFlipped = isFlippedWritingMode(writingMode);
- bool inlineAxisFlipped = textDirection == TextDirection::RTL;
- bool xAxisFlipped = scrollerHasVerticalWritingMode ? blockAxisFlipped : inlineAxisFlipped;
- bool yAxisFlipped = scrollerHasVerticalWritingMode ? inlineAxisFlipped : blockAxisFlipped;
-
bool hasHorizontalSnapOffsets = scrollSnapType.axis == ScrollSnapAxis::Both || scrollSnapType.axis == ScrollSnapAxis::XAxis;
bool hasVerticalSnapOffsets = scrollSnapType.axis == ScrollSnapAxis::Both || scrollSnapType.axis == ScrollSnapAxis::YAxis;
if (scrollSnapType.axis == ScrollSnapAxis::Block) {
@@ -263,6 +267,16 @@
auto alignment = child->style().scrollSnapAlign();
auto stop = child->style().scrollSnapStop();
+ // From https://drafts.csswg.org/css-scroll-snap-1/#scroll-snap-align:
+ // "Start and end alignments are resolved with respect to the writing mode of the snap container unless the
+ // scroll snap area is larger than the snapport, in which case they are resolved with respect to the writing
+ // mode of the box itself."
+ bool areaXAxisFlipped = scrollerXAxisFlipped;
+ bool areaYAxisFlipped = scrollerYAxisFlipped;
+ bool areaHasVerticalWritingMode = isVerticalWritingMode(child->style().writingMode());
+ if ((areaHasVerticalWritingMode && scrollSnapArea.height() > scrollSnapPort.height()) || (!areaHasVerticalWritingMode && scrollSnapArea.width() > scrollSnapPort.width()))
+ std::tie(areaXAxisFlipped, areaYAxisFlipped) = axesFlippedForWritingModeAndDirection(child->style().writingMode(), child->style().direction());
+
ScrollSnapAxisAlignType xAlign = scrollerHasVerticalWritingMode ? alignment.blockAlign : alignment.inlineAlign;
ScrollSnapAxisAlignType yAlign = scrollerHasVerticalWritingMode ? alignment.inlineAlign : alignment.blockAlign;
bool snapsHorizontally = hasHorizontalSnapOffsets && xAlign != ScrollSnapAxisAlignType::None;
@@ -270,7 +284,6 @@
if (!snapsHorizontally && !snapsVertically)
continue;
-
// The scroll snap area is defined via its scroll position, so convert the snap area rectangle to be relative to scroll offsets.
auto snapAreaOriginRelativeToBorderEdge = scrollSnapArea.location() - scrollSnapPort.location();
LayoutRect scrollSnapAreaAsOffsets(scrollableArea.scrollOffsetFromPosition(roundedIntPoint(snapAreaOriginRelativeToBorderEdge)), scrollSnapArea.size());
@@ -277,12 +290,12 @@
snapAreas.append(scrollSnapAreaAsOffsets);
if (snapsHorizontally) {
- auto absoluteScrollXPosition = computeScrollSnapAlignOffset(scrollSnapArea.x(), scrollSnapArea.maxX(), xAlign, xAxisFlipped) - computeScrollSnapAlignOffset(scrollSnapPort.x(), scrollSnapPort.maxX(), xAlign, xAxisFlipped);
+ auto absoluteScrollXPosition = computeScrollSnapAlignOffset(scrollSnapArea.x(), scrollSnapArea.maxX(), xAlign, areaXAxisFlipped) - computeScrollSnapAlignOffset(scrollSnapPort.x(), scrollSnapPort.maxX(), xAlign, areaXAxisFlipped);
auto absoluteScrollOffset = clampTo<int>(scrollableArea.scrollOffsetFromPosition({ roundToInt(absoluteScrollXPosition), 0 }).x(), 0, maxScrollOffset.x());
addOrUpdateStopForSnapOffset(horizontalSnapOffsetsMap, { absoluteScrollOffset, stop, snapAreas.size() - 1 });
}
if (snapsVertically) {
- auto absoluteScrollYPosition = computeScrollSnapAlignOffset(scrollSnapArea.y(), scrollSnapArea.maxY(), yAlign, yAxisFlipped) - computeScrollSnapAlignOffset(scrollSnapPort.y(), scrollSnapPort.maxY(), yAlign, yAxisFlipped);
+ auto absoluteScrollYPosition = computeScrollSnapAlignOffset(scrollSnapArea.y(), scrollSnapArea.maxY(), yAlign, areaYAxisFlipped) - computeScrollSnapAlignOffset(scrollSnapPort.y(), scrollSnapPort.maxY(), yAlign, areaYAxisFlipped);
auto absoluteScrollOffset = clampTo<int>(scrollableArea.scrollOffsetFromPosition({ 0, roundToInt(absoluteScrollYPosition) }).y(), 0, maxScrollOffset.y());
addOrUpdateStopForSnapOffset(verticalSnapOffsetsMap, { absoluteScrollOffset, stop, snapAreas.size() - 1 });
}
