69169 - Performance with fixed background images

Status: RESOLVED DUPLICATE of bug 90198

(Core :: Web Painting, defect)

Description

[Pierre Saslawsky]

This bug is extracted from bug 68821.

Scrolling is very slow when there is a fixed background image.  As I wrote in bug 
68821 [2001-02-15 04:15], the problem is that a fixed background causes the frame 
to set the NS_VIEW_PUBLIC_FLAG_DONT_BITBLT on the view, which means that the view 
is entirely redrawn everytime we scroll.  We should instead redraw only the 
portion of the page that contains the image.

See the testcase I attached to the other bug:
http://bugzilla.mozilla.org/showattachment.cgi?attach_id=25333

For the bug to be obvious, the page should not be too small.

Comment 1

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Currently, the view manager isn't told which part of the view is non-blittable.

To track that, we would need an extra rectangle field in each view (or maybe 
just a pointer since we won't need it often), and we'd have to change the view 
manager interface so that layout tells us the non-blittable rectangle. This 
information would have to be updated as the image loads and its size 
information becomes available.

In other words, this would be a real pain.

Comment 2

[Kevin McCluskey (gone)]

Setting target milestone to 1.0.1

Comment 3

[Kevin McCluskey (gone)]

Clearing milestone.

Comment 4

[Kevin McCluskey (gone)]

Set milestone to future

Comment 5

[selmer (gone)]

Does the performance drop off dramatically with CPU speed?  On 500 Mhz there is
no perceptible slowdown on the referenced page.

Comment 6

[Jarto Tarpio]

Can't reproduce this with Mozilla/5.0 (Windows; U; WinNT4.0; en-US; 0.8.1)
Gecko/20010412

Scrolling of the attachment mentioned is really fast thanks to the new imglib.

Comment 7

[Jesse Ruderman]

Additional test pages:
http://www.physics.hmc.edu/courses/p028/
http://www.w3.org/TR/html401/

The physics lab page scrolls slowly for me on Win98 using Mozilla 2001 042908.

Comment 8

[Jan Varga [:janv]]

I see visible slowdown on Linux, K6-2 350

Comment 9

[Jan Varga [:janv]]

less but still visible slowdown on NT4, Celeron 450

Comment 10

[Jan Varga [:janv]]

bigger slowdown on linux was actually caused by bigger screen resolution

Comment 11

[poelzi]

see this on linux,too
sould be platform all -> all

Comment 12

[Xan Lopez]

I think this is a bad dupe of 90198 (Bugzilla Bug 90198 scrolling very slow
(fixed background)), but that bug is assigned to Kevin too! (although I suspect
he doesn't know that). And btw like people say above, this is an ALL/ALL bug,
really.

Comment 13

[Koike Kazuhiko]

Marking dup per xan's comment.

*** This bug has been marked as a duplicate of 90198 ***