Bug 36978 – Very bad scrolling-performance with the Trackpad at http://www.apple.com/ipad/app-store/

• Component: New Bugs
• Status: RESOLVED FIXED

[Mehmet]

Hello Webkit-Team,

the two-finger-scrolling-performance is very bad and jerky at following site: http://www.apple.com/ipad/app-store/

Hardware: MacBook 3,1
OS: 10.6.3
Tested with: Safari 4.0.5 and Nightly Build r56912

Thanks in advance.

Mehmet

[Sam Weinig]

<rdar://problem/7820819>

[Simon Fraser (smfr)]

Created attachment 52466 [details]
Patch

[Darin Adler]

Comment on attachment 52466 [details]
Patch

> +        // Check to see if the image changed; we have to do this because the call to
> +        // CGImageCreateCopyWithColorSpace() below can create a new image every time.
> +        if (m_uncorrectedContentsImage && CFEqual(m_uncorrectedContentsImage.get(), newImage))
> +            return;

Wow, does CFEqual actually work on CGImages!? And it compares every bit?

> +        m_uncorrectedContentsImage = m_pendingContentsImage = newImage;

Could you do these on separate lines? It's too easy to overlook the second assignment when it's all on one line.

r=me assuming you tested

[Simon Fraser (smfr)]

(In reply to comment #3)
> (From update of attachment 52466 [details])
> > +        // Check to see if the image changed; we have to do this because the call to
> > +        // CGImageCreateCopyWithColorSpace() below can create a new image every time.
> > +        if (m_uncorrectedContentsImage && CFEqual(m_uncorrectedContentsImage.get(), newImage))
> > +            return;
> 
> Wow, does CFEqual actually work on CGImages!? And it compares every bit?

I don't care about bit-for-bit comparisons; this just checks to see if this image is the same as the last one we set. I guess I could test for pointer equality?

> > +        m_uncorrectedContentsImage = m_pendingContentsImage = newImage;
> 
> Could you do these on separate lines? It's too easy to overlook the second
> assignment when it's all on one line.

Will do.

[Simon Fraser (smfr)]

http://trac.webkit.org/changeset/57039