x4 zoom in/out slower

[Xhris]

This is the same answer I gave elsewhere. It's a result of caching groups that was added in 3.2, which makes first time redraw slower under some circumstances, but speeds up a lot of other rendering operations.

Options -> Tune Ups. Turn off caching.

I'm not convinced this is right actually Charles; caching does not significantly slow down rendering performance and needs defending. When I turn caching off in Xara 4, it is comparably fast to render the document at different zooms compared to the first render in which caching is also done. I thought the cache throttle ensured this was the case--limiting 5% of redraw time to caching. In other words, I don't see why caching makes it slower by more than 5% at max. (which usually equates to a small amount of time). (Even disabling cache throttling, thereby removing the 5% limit, negligibly impacts redraw times.) And once cached, it is much faster to zoom. Xara 2.0 shows identical findings. Xara 1--which didn't have any caching--performs similarly to the later versions with caching turned off.

In summary, I can't see the original problem here. However, the size of zoom step has also decreased for smoother zooming since 3.2, and again in 4, which may be being mistaken as the issue here.

EDIT: I understand the original description now. It was claimed that when zooming, before a new zoom level is drawn, the entire current view must be completely drawn, and that the older versions of Xara didn't require a full redraw before moving to the next zoom when scroll-wheeling. This is not true, and in all versions of Xara, the entire screen is required to be redrawn before the next zoom operation begins. I think the increased number of zoom steps has given the illusion that it is somehow 'not skipping' zoom steps. There isn't really a bug here, and essentially an effective call for larger zoom steps when wheel-zooming is being made I suspect.

[handrawn]

essentially an effective call for larger zoom steps when wheel-zooming is being made I suspect.

user definable would be nice

[FLySOLO]

if you wheel in and out fast in 3.02 you just get white screen flickering if the zoomed scene is too complex.

in x4 it redraws every zoom stage even if it takes some time.

result:

in 3.02 you can navigate very fast because you know where you're zooming to and your brain doesn't need every inbetween step rendered fully.

in x4 zoooming feels laggy and slow if the scene is a bit more complex (line attributes seem to be especially demanding).

i just attached another test file with a line drawing

x3 - zooms ok

x4 - really has some calculation to do and feels like described above.


bb,

FLy

[PhilM]

Technical info:

Xtreme always uses "background rendering" (unless you've configured it to be turned off.)

Background rendering renders the document for a 10th of a second when there's nothing else going on (e.g. no mouse wheel events coming in) then looks up to see whether anything has changed, and if not renders for another 10th, etc., etc...

However, there's a granularity issue: when a single object takes more than a 10th of a second to render, the background rendering system doesn't get the chance to "look up" until that object has finished.

Earlier versions used to rely only on background rendering and so if you zoomed in several stages, the wheel zoom would be handled in priority to background rendering.

In 4.0, to make wheel zooming more interactive, the wheel zoom event handler does a rendering timeslice directly (a 10th of a second) to ensure that something is rendered immediately. That works fine for most cases but when a single object takes longer than a 10th of a second timeslice to render it will delay the handling of the next mouse wheel event.

Phil

[FLySOLO]

hi phil,

thx for your explanation but if i directly compare the handling and performance of x3.02 and x4 i sadly have to say that i cannot move to x4 as i didn't move to x3.2.

i'm thinking of making a video out of it as it is quite a dramatic difference.

maybe take a look at this too:

http://www.talkgraphics.com/showpost...7&postcount=18

it's the same dramatic speed issue if you compare the apps behaviour with the same file.

bb,

FLy

[PhilM]

Hi Fly,

I was just explaining why it's happening for the record and to remove all the guessing about caching and wotnot.

We will try to fix it but it might be difficult to do so while still retaining the advantages of the new code.

Phil

[FLySOLO]

good to hear - thx for the info.

good luck for the fixing

FLy

[David O'Neil]

...In 4.0, to make wheel zooming more interactive, the wheel zoom event handler does a rendering timeslice directly (a 10th of a second) to ensure that something is rendered immediately. That works fine for most cases but when a single object takes longer than a 10th of a second timeslice to render it will delay the handling of the next mouse wheel event.

So that indicates that all that is needed is to look up every 1/10th of a second, and if there is a mouse wheel notice in the que, discard the rendering of the current zoom frame and start on the next zoom render? Just thinking out loud here--I'm not meaning to imply that it isn't a difficult to implement. I happen to agree with FLy, though--the current implementation is more awkward for high density drawings than the old one was. But I also agree that for non-complex drawings, the new method is *far* better.

[Xhris]

The second file posted shows the problem really well actually. It's true that in pre Xara 4, the wheel zoom was faster and the screen didn't appear to fully redraw before moving on; I was wrong before. Even with smaller zoom steps you can still imagine that kind of speed in pre 4 versions. It never really clicked even though I noticed it was slower to zoom in at times like this. I just put it down to increased number of zoom steps, when really two changes had been made together; the bad effects of one being hidden by the good effects of the other. I suppose thinking back I immediately noticed this when zooming in and out of the famous scope clipart to see how multi-core rendering performance had improved speed, but I just didn't click in my head (not the mouse). The zoom 'flickering' of pre 4 versions seems obvious now.

[FLySOLO]

sorry to be annoying but today's version is still slow.

version april 2nd

bb,

FLy