Differences between legacy rendering and direct rendering?

[daver1234]

Hello

I'm having some performance difficulties with a dynamic form (created in livecycle 8.2).  The issue is apparent when forcing the legacy render mode using:

<?originalXFAVersion http://www.xfa.org/schema/xfa-template/2.8/ LegacyRendering:1?>

(Note that the XFA version doesn't appear to make a difference.)

The length of time required for form interactions grows as the user works through the form and memory usage increases.  The memory usage appears to be far more stable when using direct rendering.  In my benchmark test, when using direct rendering, the memory usage rose by 5mb whereas in legacy rendering mode, memory usage crept by 95mb.

Any documentation on the differences between legacy rendering and direct rendering would be extremely useful.  Our target audience is only able to use adobe reader 7 and as such only has legacy rendering mode.

Thank you

Dave

[Former Community Member]

Direct Rendering was added in version 7.5 I think to solve the issues that you are referring to. Previous to that there is no option you had to render the old way (that is what the legacy Rendering does ...turns off direct rendering). I am not sure what document you are looking for to help you with this as there is not much you will be able to do.

Paul

[daver1234]

Paul - thanks for your reply.

The user can not upgrade to 7.5, they are currently on 7.08 so they do not have direct rendering.  Do you know what causes the memory increase?  Is there a way we can clear the memory?  I've tried xfa remerge() and relayout() but both increase memory usage.

Also, a lot of the memory usage seems to come from changing visibility/presence of objects.  This is fundamental to our form structure.  Is there another way of 'hiding' subforms without incurring the memory usage issue in 7.08?

Thanks

David

[Former Community Member]

Unfortunately no ...that is why direct render was adopted......if I remember right there was a time when direct rendering was controlled by a registry entry

(before it was officially supported). I do not remember which versions it was in but woudl having the users adjust a reg setting so that direct rendering was used ...would that be acceptable? If so I can try and find that setting.

Paul

[daver1234]

We can't do a registry key change no.  We don't have any control over the end-user's setup.  But perhaps there is a line we can add to the XML source to do it on a per form basis?  In the same way I forced legacy rendering using

<?originalXFAVersion http://www.xfa.org/schema/xfa-template/2.4/ LegacyRendering:1?>

Failing that, are you aware of any methods that can be used to clear out some of the memory used by the form?  We're also exploring other methods for 'hiding' subforms, we're currently investigating dynamically moving objects in the hierachy at runtime so we can shift the nested subforms off screen temporarily. 

Thanks for your thoughts on this Paul.

David

[Former Community Member]

No the memory cannot be freed until the form is closed. You will not be able to affect the registry from inside of a form this is against the security model.

Sorry but I do not have any other siggestions.

paul