112861 - several toolkit events created during window creation are unnecessary

Status: RESOLVED FIXED

(Core Graveyard :: GFX, defect)

Description

[Kevin McCluskey (gone)]

When a window is created the following NS_EVENTS are created:

NS_CREATE
NS_SETZLEVEL
NS_MOVE

Each of these events are dispatched to the view system. On pages with large
numbers of views this causes a page load performance hit and most of these
events seem to be unnecessary.  lxr indicates that only NS_MOVE is being used.
It is used in the webshell to record the position of the top-level window. We
should generate a NS_MOVE only for top-level windows, not child windows. The
NS_CREATE and NS_SETZLEVEL do not seem to be used at all and should be suppressed.

In addition, some other events for child windows may not be necessary. We should
investigate:

NS_GOTFOCUS
NS_LOSTFOCUS
NS_ACTIVATE
NS_DEACTIVATE

There are also NS_MOUSE_MOVE events generated every time a child window is
created. We may want to suppress mouse moves events that are generated as the
result of a window create.

As a test, I put a hack into nsViewManager to ignored all of the
NS_CREATE,NS_SETZLEVEL, NS_MOVE events. Loading the 300 combobox testcase
resulted in substantial improvement in load time:


With unnecessary events
-----------------------
12.26
11.696
11.987

With events removed
-------------------
8.7 sec
8.823


Note: this test was done after I had already put in the patch for bug 112525
which removed the O(n^2) traversal of the view's when processing events.

Comment 1

[Kevin McCluskey (gone)]

Attachment: test case with 300 comboboxes taken from bug 39544

Comment 2

[Kevin McCluskey (gone)]

It looks like it is safe for the ViewManager to suppress the NS_MOVE, NS_CREATE
and NS_SETZLEVEL events. nsWebShellWindow uses NS_MOVE and NS_CREATE but handles
it by directly registering an event callback with it's window rather than going
through the viewmanager. 

The other events: NS_GOTFOCUS, NS_LOSTFOCUS, NS_ACTIVATE, NS_DEACTIVATE are used
in the event state manager and the plugin viewer, so they appear to be needed.

Comment 3

[Kevin McCluskey (gone)]

Attachment: Patch to suppress NS_MOVE, NS_CREATE, NS_SETZLEVEL events

Comment 4

[Kevin McCluskey (gone)]

I split off the NS_MOUSE_MOVE issue on WIN32 into bug 113627

Comment 5

[Marc Attinasi]

Comment on attachment 60331 [details] [diff] [review]
Patch to suppress NS_MOVE, NS_CREATE, NS_SETZLEVEL events 

looks good, but do we want to document this for clients of the ViweManager, so
they know NOT to expect these events (and presumably register for them
eventually). sr=attinasi

Comment 6

[rods (gone)]

r=rods

Comment 7

[Kevin McCluskey (gone)]

I don't think clients of the viewmanager expected to receive these events in the
first place. They really only make sense to capture when your managing a
top-level window.

Fix checked in.