Null Exception During updateContainer()

Richard, Great to hear about the releaseLines() fix! BTW, I don't know if anyone has looked at findFirstAndLastVisibleLine() in ContainerControllerBase, but I think there's a very similar case in that method to the null exception issue in releaseLines(). Something related to getTextLine() on TextFlowLine returning null.

Brian, I'm just using random lorem ipsum strings generated from http://lipsum.com/. After I posted about that, I started having trouble reproducing the issue with the exact same code as I had previously. I keep coming back to thinking that it has something to do with when flushPendingOperations() gets called during the enterFrameHandler() in the edit manager. Seems like sometimes the text flow may happen to be in some in-between state which prevents certain operations from executing successfully. Will try to narrow down some more to provide some better instructions for consistent reproduction.

I can't say for sure that the errors I'm seeing are the same as those reported in the Jira issue you mentioned. Seems like they could at least be related. Now that I look at it again, it looks like the Jira issue is related to the null TextLine issue similar to the releaseLines() thing that Richard mentioned a fix for. I'm not using linked containers in my case, but I am working with longer text flows with content height larger than compose height. I do seem to get errors thrown more often as the flow grows in size. Am still trying to pinpoint the exact scenarios that cause errors.

Thanks,
Brent

Yes, no source. At this point the closest thing you'll get to accurate documentation is in the Gumbo LiveDocs located at http://livedocs.adobe.com/flex/gumbo/langref/. And actually, it looks like they've updated the docs, so they should be fairly accurate as of today. Once you spend some time studying the documentation and experimenting with TLF, it becomes easier to understand how to work with the classes.

I think I've narrowed this down a little more. It seems that sometimes a condition can occur in which the TextFlowLine's textLineExists property will return true and/or isDamaged() will return false, yet the getTextLine() method will return null immediately afterwards. I think that although the stack traces above are different, they're still connected. I'm not positive about this, but I think it's getting closer to the source of the issues. It seems like this situation tends to occur more at times when the text flow is at an in-between state. I still can't provide steps that will reproduce this issue 100% of the time.

As far as a workaround, you'll have to override a method upstream from the TLF methods that are causing issues. In my case, I'm already using custom composer, container controller, and edit manager classes. For your error happening in findFirstAndLastVisibleLine method of ContainerControllerBase (assuming that you're using DisplayObjectContainerController), you'll probably want to extend DisplayObjectContainerController and create a custom container controller class to use for your project that will allow you to override faulting behavior. I think that the container controllers are some of the easiest parts of TLF to extend.

In your case the closest method that you can override is scrollToPosition(activePosition:int, anchorPosition:int):void. The outdated documentation states that scrollToPosition() scrolls so that the text position is visible in the container. So, the first thing I would try is just to wrap the super.scrollToPosition call with a try/catch. I'm guessing that scrollToPosition() is not really a critical method call, if it fails now and then you can probably just ignore it. The other alternative is to try to figure out what the method is supposed to do and rewrite the complete logic for the method. This can take a lot of work, especially without adequate documentation for the classes you're overriding. Also, keep in mind that doing something like this is a WORKAROUND and NOT A SOLUTION. Although overriding and catching the error could get you by for now, hopefully eventually the TLF team will be able to track down the actual problem and then we can remove these overrides. The other pitfall of doing stuff like this with TLF right now is that TLF is still changing every day, and when you update to new builds it's likely that stuff will break on occasion and require a little patching.

Here's what you might try for the scrollToPosition method in your extended container controller:
override public function scrollToPosition(activePosition:int, anchorPosition:int):void
{
try
{
super.scrollToPosition(activePosition, anchorPosition);
}
catch (e:*)
{
trace("Caught error in scrollToPosition");
}
}

Sorry I don't have a better or *real* solution right now, but I hope this helps you to continue working until further progress is made on this issue.

-Brent

Thank you marquinho.a for providing the steps, although from looking at the stack traces I think that you are each seeing different problems.

I am trying to build simple examples that will reproduce each of these. Any code samples you have would be very helpful as I try to get the bugs figured out! Thank you!

I was seeing this immediately after Build 370. Probably somewhere between 370-373. Using SWC's from Gumbo SDK Repo. I was already using an extended version of EditManager and was able to work around the issue with a try/catch somewhere in there. I will pull that out and update to latest SWC's from Gumbo SDK to make sure I can still reproduce and try to provide more specific instructions to do so if I'm still seeing the issue.

Thanks for looking into it.