Re[3]: [Gnash-dev] Re: gotoAndPlay bug in Gnash

[Eric Hughes]

Sorry about that incomplete last posting--mailer defect.  Here's the 
complete one.

Wednesday, May 9, 2007, 7:05:22 PM, Eric wrote:
EH> Rewinding to a previous execution state and going to a particular point of
EH> execution are distinct and very different operations.  gotoAndPlay is of
EH> the latter type.  It is not rewinding to some previous state, merely moving
EH> a current execution point.

At 11:54 AM 5/9/2007, Udo Giacomozzi wrote:
> Your concept is not exactly clear to me, however we need to jump to a
> previous point in the time line.

I don't know your mind, but I should point out that you may be betraying a 
fundamental conceptual problem.  GOTO can go both forward and backward in 
time.  This may lead to defects, if assumptions are made in the code that 
something has already happened that's not required to have happened.

From http://www.senocular.com/flash/tutorials/depths/?page=2:
> An example of this kind of refreshing is caused by using gotoAndPlay to go 
> to a frame which has already passed; going to frame 5 from frame 10 for 
> example. When this happens, Flash does this refresh allowing it to 
> correctly display the screen at this new frame as the progression of the 
> timeline has diverted from normal playback and therefore must be 
> completely re-conceived by Flash.

The key is that last phrase "completely re-conceived"

Contrast this to what is says on the wiki page about the timeline:
1. A "gotoAndPlay(_currentframe - X)" in a simple movie without any other 
ActionScript code simply restores the exact DisplayList that was active in 
that frame, including matrix and color transforms.

Now these two behaviors are just not the same.  "Restoring a display list" 
and "re-conceiving a frame" are different operations.

It seems like the implementation specification as _de facto_ exists in 
Gnash is wrong.  Well, not wrong in any absolute sense, but wrong in the 
sense that "it doesn't match Adobe Flash".  This point precedes any 
question about code quality issues.

Eric