Re: scrolling jerky

On Fri, 27 Apr 2012 08:23:18 +0100, Roger Darlington wrote:

> On 25 Apr 2012, Michael Drake wrote:
> > In article <be1b188652.rogerarm@rogerarm.freeuk.com>,
> > Roger Darlington <rogerarm@freeuk.com> wrote:
>
> >> Scrolling very jerky on the vertical slider
>
> > Please see my response to your previous scrolling thread:
>
> > http://www.mail-archive.com/netsurf-users@netsurf-browser.org/msg03976.html
>
> > Your google URL is the scrolling frames issue.
>
> Thanks for that Michael. I have increased the Cache from 20MB to 90MB,
> but there is still a very noticeable difference between scrolling the
> two versions of the very same page (neither of which get anywhere near
> 90MB it must be said...)

Cache won't help, the issue is that "core" scrolls aren't optimised,
so if you scroll a frame the entire contents of that frame will be
redrawn - even if it is only scrolled a pixel. Conversely, if you
scroll using the window scrollbar, the platform code handles the
scroll. Usually the platform code is optimised, and will "shift" the
area and just redraw the newly-exposed bit.

Clearly NetSurf would benefit from some scrolling optimisation in the
core, but I'm not sure if it is as easy as telling the frontend code
to move a particular area and then redraw the newly exposed area.
(not least because frontends don't currently have any concept of "move
a particular area")

Regards
Chris