Hi,
In a few situation we have indeed a few rules that match ".stylename
TD" I'll see if I can get rid of them.
Thanks,
David
On Aug 19, 4:11 pm, Jaime Yap <jaime...@google.com> wrote:
> Setting the styles directly will still run layout. But It will not run style
> matching. This might give you a bit of speed up, but I think you should take
> a second look at the way you are styling your application.
>
> The assumption that CssResource won't help might be a little off. Setting
> the style name might be getting very expensive for you because your CSS
> might be triggering some pathological performance problems. Things to look
> out for:
>
> 1. Are you using a lot of descendant selectors?
> 2. For your descendant selectors, if is important to keep the right most
> component of the selector as specific as possible. Styles are matches right
> to left and not top down as intuition would suggest. If you have .foo div {}
> as a selector, if will first check ALL divs in your page and then walk up to
> find an ancestor .foo!
> 3. Do you have any ie-CSS expressions? These make doing layout a lot slower.
>
> If you used CssResource, Style matching should be very very quick because
> there will generally be no (or very few) descendant selectors. I would do an
> experiment to see if this buys you anything.
>
> -Jaime
>
>
>
> On Thu, Aug 19, 2010 at 9:51 AM, Joel Webber <j...@google.com> wrote:
> > [+some people who have looked at this problem in the past]
>
> > Le 19 août 2010 09:36, stuckagain <david.no...@gmail.com> a écrit :
>
> > Hi,
>
> >> I found out that using something like addStylename() in an onmouseover
> >> can have really catastrophic effects on performance in IE (6/7 and 8).
> >> In fact IE8 seems to be worse than the older versions. In my
> >> applications the browser locks up for many seconds even minutes
> >> running at 100% CPU. DynaTrace reveals that the browser is busy doing
> >> layout calculations.
>
> >> For example we were doing a style change when moving the mouse over a
> >> big table. In some situations this would block the browser for many
> >> seconds (sometimes minutes, depending on the complexity of the UI).
>
> >> If I just directly set the style attribute changes directly in the
> >> code it takes almost no CPU with the same complex UI. The problem here
> >> is that I loose a lot of flexibility in my UI to use CSS to do the
> >> styling (what if I want to change more than just the color for
> >> example).
>
> >> I know there is something like CssResource, but as I understand it, it
> >> will not solve the issue in this case since I still need to use an
> >> addStyleName.
>
> >> Would there be a way, or wouldn't it be an great Idea, that GWT would
> >> have support in CssResource to copy style attributes from the
> >> CssResouce directly in the styles of the element that I am
> >> targetting ? That way I would not need a addStylename/addClassname but
> >> I still have the flexibility to write down these changes in a CSS
> >> file.
>
> >> Or did I overlook such a feature ?
>
> >> As I understood, the declarative UI mechanism in GWT is doing such
> >> things, but in our apps we can not use this.
>
> > We haven't built anything like this, but we've definitely seen this problem
> > before. It doesn't seem unreasonable to be able to extract the text of a
> > CSSResource rule's properties (a bit unfortunate, since it only affects IE
> > and would be slower everywhere else -- maybe it would be better to provide a
> > more abstract mechanism that could "do the right thing" everywhere). There
> > is also some complexity added by the fact that the fastest way to apply such
> > a style would be "Element.style = '{css string}'". But the only efficient
> > way to do this would be to set the whole thing at once (meaning you couldn't
> > easily mix them).
>
> > If I recall correctly (Kelly, Jaime, & John please check me on this), the
> > speed problems on this case in IE tended to be a combination of layout and
> > style matching. Layout can be mitigated a bit if you "separate" the table
> > from the rest of the page by putting it in a position:absolute container
> > (putting it in a layout panel does this), but that may not help enough
> > and/or fit your design.- Hide quoted text -
>
> - Show quoted text -
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