Re: Scrolling NSScrollView by fractional amounts - why would values get rounded?
Re: Scrolling NSScrollView by fractional amounts - why would values get rounded?
- Subject: Re: Scrolling NSScrollView by fractional amounts - why would values get rounded?
- From: Martin Redington <email@hidden>
- Date: Fri, 11 Sep 2009 09:29:24 +0100
Hi Jens,
I'm not totally sure that I want to allow scrolling by fractional
amounts - I've definitely seen some smearing, with "copy on scroll"
set, but without that everything (in the textview) seems to render ok,
and the speed is acceptable for now, so I'd at least like the option.
It seems pretty bizarre to me that in one window this works ok, and in
the other I'm getting rounding, despite no apparent differences -
presumably *something* must be different, but I can't work out what
:-(
cheers,
m.
On Thu, Sep 10, 2009 at 7:41 PM, Jens Alfke <email@hidden> wrote:
>
> On Sep 10, 2009, at 7:01 AM, Martin Redington wrote:
>
> This works fine when the new y value is a whole integer, but I'm
> seeing some strange behaviour when trying to scroll by fractional
> amount (e.g. .25 or .5 of a pixel).
>
> Are you sure you want to scroll by fractional pixels? It will be slower,
> because the view has to re-render from scratch, instead of letting the video
> card scroll the pixels. And a lot of things don't render very well at
> non-integer coordinates unless they've been tuned to do so (the most common
> problems are that lines that are supposed to be one pixel wide get smeared
> across two pixels, and images get blurred because every image pixel gets
> interpolated between four screen pixels.)
> —Jens
--
http://www.mildmanneredindustries.com/
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