Bug 133436 – Don't scroll to non-integral scroll offsets

• Component: New Bugs
• Status: RESOLVED FIXED

[Simon Fraser (smfr)]

Don't scroll to non-integral scroll offsets

[Simon Fraser (smfr)]

Created attachment 232351 [details]
Patch

[Simon Fraser (smfr)]

<rdar://problem/17088336>

[zalan]

Comment on attachment 232351 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=232351&action=review

> Source/WebCore/page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm:324
> +    // FIXME: when we support half-pixel scroll positions on Retina displays, this will need to round to half pixels.

half-pixel -> device pixel

> Source/WebCore/page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm:325
> +    FloatPoint roundedPosition(roundf(scrollPosition.x()), roundf(scrollPosition.y()));

I am wondering whether the input devices that send integral values do integer truncation or rounding. (and whether we should mimic that behavior)

[Darin Adler]

Comment on attachment 232351 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=232351&action=review

>> Source/WebCore/page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm:325
>> +    FloatPoint roundedPosition(roundf(scrollPosition.x()), roundf(scrollPosition.y()));
> 
> I am wondering whether the input devices that send integral values do integer truncation or rounding. (and whether we should mimic that behavior)

Is this the single correct bottleneck for the rounding? What about the setScrollPositionWithoutContentEdgeConstraints and setScrollLayerPosition functions?

[Simon Fraser (smfr)]

(In reply to comment #4)
> (From update of attachment 232351 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=232351&action=review
> 
> >> Source/WebCore/page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm:325
> >> +    FloatPoint roundedPosition(roundf(scrollPosition.x()), roundf(scrollPosition.y()));
> > 
> > I am wondering whether the input devices that send integral values do integer truncation or rounding. (and whether we should mimic that behavior)
> 
> Is this the single correct bottleneck for the rounding? What about the setScrollPositionWithoutContentEdgeConstraints and setScrollLayerPosition functions?

This is the bottleneck, yes.

[WebKit Commit Bot]

Comment on attachment 232351 [details]
Patch

Clearing flags on attachment: 232351

Committed r169519: <http://trac.webkit.org/changeset/169519>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.