946317 - hwaccel canvas overdraws shadows on windows when outside clip

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Kevin McCarthy]

Attachment: ffbug.html

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36

Steps to reproduce:

If you use drawImage to draw the contents of 1 canvas to another, the shadow on the source canvas can be drawn repeatedly to the destination if the destination is redrawn with a clip region that excludes the region where the source was placed. This bug only happens w/ acceleration is turned on.


Actual results:

Presumably the source canvas is serialized to a displaylist that is being replayed when the destination is redraw. The clip region is preserving the previous buffer, but not excluding the display list from being re-evaluated, and therefore the shadows compound to eventually produce a solid black color.


Expected results:

The display list should be excluded since it is outside the clip region, and the shadow should not accumulate.

Comment 1

[Kevin McCarthy]

Attachment: Screenshot showing shadow overdraw

Shows bug

Comment 2

[Alice0775 White]

Attachment: adding moz prefix to test for Firefox22 and earlier

Regression window(m-c)
Good:
http://hg.mozilla.org/mozilla-central/rev/450e4d9ea2d5
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0a1) Gecko/20110624 Firefox/7.0a1 ID:20110625025936
Bad:
http://hg.mozilla.org/mozilla-central/rev/48ad4ffc4230
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0a1) Gecko/20110625 Firefox/7.0a1 ID:20110625030821
Pushlog:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=450e4d9ea2d5&tochange=48ad4ffc4230

Regression window(m-i)
Good:
http://hg.mozilla.org/integration/mozilla-inbound/rev/c65f1fb0449d
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0a1) Gecko/20110624 Firefox/7.0a1 ID:20110624094307
Bad:
http://hg.mozilla.org/integration/mozilla-inbound/rev/46c3d095bc75
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0a1) Gecko/20110624 Firefox/7.0a1 ID:20110624104626
Pushlog:
http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=c65f1fb0449d&tochange=46c3d095bc75

Regressed by: Bug 651858

Comment 3

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

Looks like Moz2D/D2D bug

Comment 4

[Bas Schouten (:bas.schouten)]

Highly likely, yes. I already have some suspicion as to the cause.

Comment 5

[Bas Schouten (:bas.schouten)]

This bug is closely related to bug 946475 and will be solved by the patches there. However in addition to this there's an additional issue that this shows that will not be fixed there, but that should be much more rare.

Comment 6

[(mostly gone) XtC4UaLL [:xtc4uall]]

This is WFM as per Bug 946475's checkin.

(In reply to Bas Schouten (:bas.schouten) from comment #5)

> However in addition to this there's an additional issue that this
> shows that will not be fixed there, but that should be much more rare.

Can this get resolved nevertheless? New bug for the other issue?