Excessive messages for detached event listeners

[GoogleCodeExporter]

What steps will reproduce the problem?
Create a large SVG image with lots of nodes and add a lot of event listeners to 
it and then add the whole tree to the svg document. 

What is the expected output? What do you see instead?
Ideally, this should be one message to flash. Instead, there is one message for 
the xml, and one message for each event listener that was added into that tree. 

If the child is a document fragment, there is one message to suspend redraw, 
another message for the xml, and a final message that unsuspends and adds all 
the event listeners.

The one-message ideal solution is difficult to implement because the 
addEventListener code is in a routine which is decoupled from the code that 
sends the xml to flash and so it is not clear how we can bring those messages 
together. Perhaps suspending at a higher level might do it.

The next best solution is to use the suspend and unsuspend technique for more 
than just document fragments in order to consolidate the addEventListener 
messages whenever nodes are added. Consider that it is more likely that a 
script author will be building a large detached <g> or <svg> element and add 
that to the svg document rather than using a document fragment, so the 
optimization coded for document fragments should apply in this case as well.

By delaying the addition of elements to the live document until the very end, 
heavy svg scripting currently produces messages in the O(n) level: a minimum of 
1+n*p, where n is the number of nodes and p is the average number of event 
listeners per node. But after applying the change above, the minimum number of 
messages drops to 2 for a tree of nodes with event listeners. This is not the 
panacea for performance, but every bit helps and heavy SVG Web scripters should 
take note to build up their SVG elements as a large tree before adding to the 
live SVG document if they want this performance benefit. And use a document 
fragment if you have a forest instead of a tree.

Note that the figures above include another optimization. The current 
implementation of processAppendedChildred sends a message to flash to suspend 
redraw. This is not meant to save rendering time, but merely as a way to 
trigger the message queuing code for the list of event listeners. Ironically, 
the code is sending a message in order to save messages. But that does not 
always work ;)  The proposed solution is to also eliminate this extra message 
by adding a flag to the JavaScript side of suspendRedraw and unsuspendRedraw in 
order to tell them not to send the suspend message to flash and instead to just 
start queuing or dequeuing messages.

Original issue reported on code.google.com by grick23@gmail.com on 30 Jun 2010 at 2:47

[GoogleCodeExporter]

Good find.

Original comment by bradneub...@gmail.com on 2 Jul 2010 at 1:14

[GoogleCodeExporter]

Fixed in r1202.

Original comment by grick23@gmail.com on 2 Jul 2010 at 3:29

• Changed state: Fixed