Changes between Version 3 and Version 4 of Scrolling


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Timestamp:
Feb 17, 2019, 4:32:58 PM (6 years ago)
Author:
Simon Fraser
Comment:

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  • Scrolling

    v3 v4  
    1111== Scrolling features
    1212
    13 == Scrolling and RTL
     13=== Momentum
     14
     15After a swipe on the trackpad or iOS screen, the content continues to scroll for a while before decelerating to a stop. This is implemented outside of WebKit, by synthetic mouse wheel events on macOS, and by UIScrollView on iOS.
    1416
    1517=== Rubber-banding ("bouncing")
    1618
     19Rubber-banding is what happens when you reach the extent of a scrollable area. On macOS and iOS, you get a bouncing effect. This is implemented by ScrollController on macOS, and by native UIScrollViews on iOS. Note that while pulling down, the scroll position becomes negative. We expose these negative values to web content, and pages sometimes get confused by them.
     20
    1721=== Latching
     22
     23Latching describes the fact that during a single scroll interaction, only one scrollable area moves. If, in one gesture, you hit the scrollable extent, we don't start scrolling the containing scroller in that gesture. Instead, we'll rubber-band, and the user has to start a new gesture to get the enclosing scroller to scroll.
    1824
    1925=== Scroll snapping
    2026
     27Scroll-snapping is a [CSS feature https://www.w3.org/TR/css-scroll-snap-1/] that allows authors to make a scroller have paging behavior, or anchoring to specific elements. It applies to both page and overflow scrolling.
     28
    2129=== Touch-action
    2230
     31The [touch-action https://w3c.github.io/pointerevents/#the-touch-action-css-property] CSS property determines whether touch input MAY trigger default behavior supplied by user agent. It's impact on scrolling is that it may cause scrolling to lock to an axis.
     32
     33== Scrolling and RTL
     34
     35In RTL documents, scroll position is not a simple positive value. Documents have a scroll origin that is at the top left of the initial containing block, and the scroll position describes the offset of that point from the top left of the viewport (this is a simplification
    2336
    2437
    25 == Coordinated scrolling
     38== Coordinated ("async") scrolling
    2639
    2740
    … …  
    3851Node unparenting and reparenting
    3952
    40 ==== ScrollingTree
     53=== ScrollingTree